diff --git a/CMakeLists.txt b/CMakeLists.txt
index b01b90fc5489..ca1b5f0a7349 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -812,6 +812,8 @@ endif()
 
 include_directories(Externals/picojson)
 
+add_subdirectory(Externals/expr)
+
 add_subdirectory(Externals/rangeset)
 
 ########################################
diff --git a/Externals/expr/CMakeLists.txt b/Externals/expr/CMakeLists.txt
new file mode 100644
index 000000000000..4eb00fa0e954
--- /dev/null
+++ b/Externals/expr/CMakeLists.txt
@@ -0,0 +1,2 @@
+add_library(expr INTERFACE)
+target_include_directories(expr INTERFACE include/)
diff --git a/Externals/expr/LICENSE b/Externals/expr/LICENSE
new file mode 100644
index 000000000000..44113db6d82a
--- /dev/null
+++ b/Externals/expr/LICENSE
@@ -0,0 +1,21 @@
+The MIT License (MIT)
+
+Copyright (c) 2016 Serge Zaitsev
+
+Permission is hereby granted, free of charge, to any person obtaining a copy
+of this software and associated documentation files (the "Software"), to deal
+in the Software without restriction, including without limitation the rights
+to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+copies of the Software, and to permit persons to whom the Software is
+furnished to do so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in all
+copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+SOFTWARE.
diff --git a/Externals/expr/include/expr.h b/Externals/expr/include/expr.h
new file mode 100644
index 000000000000..f531f378dd98
--- /dev/null
+++ b/Externals/expr/include/expr.h
@@ -0,0 +1,930 @@
+#ifndef EXPR_H
+#define EXPR_H
+
+#ifdef _MSC_VER
+#pragma warning(push)
+// Disable warning for zero-sized array:
+#pragma warning(disable : 4200)
+#endif
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+#include <ctype.h> /* for isspace */
+#include <limits.h>
+#include <math.h> /* for pow */
+#include <stdint.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+/*
+ * Simple expandable vector implementation
+ */
+static int vec_expand(char **buf, int *length, int *cap, int memsz) {
+  if (*length + 1 > *cap) {
+    void *ptr;
+    int n = (*cap == 0) ? 1 : *cap << 1;
+    ptr = realloc(*buf, n * memsz);
+    if (ptr == NULL) {
+      return -1; /* allocation failed */
+    }
+    *buf = (char *)ptr;
+    *cap = n;
+  }
+  return 0;
+}
+#define vec(T)                                                                 \
+  struct {                                                                     \
+    T *buf;                                                                    \
+    int len;                                                                   \
+    int cap;                                                                   \
+  }
+#define vec_init()                                                             \
+  { NULL, 0, 0 }
+#define vec_len(v) ((v)->len)
+#define vec_unpack(v)                                                          \
+  (char **)&(v)->buf, &(v)->len, &(v)->cap, sizeof(*(v)->buf)
+#define vec_push(v, val)                                                       \
+  vec_expand(vec_unpack(v)) ? -1 : ((v)->buf[(v)->len++] = (val), 0)
+#define vec_nth(v, i) (v)->buf[i]
+#define vec_peek(v) (v)->buf[(v)->len - 1]
+#define vec_pop(v) (v)->buf[--(v)->len]
+#define vec_free(v) (free((v)->buf), (v)->buf = NULL, (v)->len = (v)->cap = 0)
+#define vec_foreach(v, var, iter)                                              \
+  if ((v)->len > 0)                                                            \
+    for ((iter) = 0; (iter) < (v)->len && (((var) = (v)->buf[(iter)]), 1);     \
+         ++(iter))
+
+/*
+ * Expression data types
+ */
+struct expr;
+struct expr_func;
+
+enum expr_type {
+  OP_UNKNOWN,
+  OP_UNARY_MINUS,
+  OP_UNARY_LOGICAL_NOT,
+  OP_UNARY_BITWISE_NOT,
+
+  OP_POWER,
+  OP_DIVIDE,
+  OP_MULTIPLY,
+  OP_REMAINDER,
+
+  OP_PLUS,
+  OP_MINUS,
+
+  OP_SHL,
+  OP_SHR,
+
+  OP_LT,
+  OP_LE,
+  OP_GT,
+  OP_GE,
+  OP_EQ,
+  OP_NE,
+
+  OP_BITWISE_AND,
+  OP_BITWISE_OR,
+  OP_BITWISE_XOR,
+
+  OP_LOGICAL_AND,
+  OP_LOGICAL_OR,
+
+  OP_ASSIGN,
+  OP_COMMA,
+
+  OP_CONST,
+  OP_VAR,
+  OP_FUNC,
+};
+
+static int prec[] = {0, 1, 1, 1, 2, 2, 2, 2, 3,  3,  4,  4, 5, 5,
+                     5, 5, 5, 5, 6, 7, 8, 9, 10, 11, 12, 0, 0, 0};
+
+typedef vec(struct expr) vec_expr_t;
+typedef void (*exprfn_cleanup_t)(struct expr_func *f, void *context);
+typedef double (*exprfn_t)(struct expr_func *f, vec_expr_t *args, void *context);
+
+struct expr {
+  enum expr_type type;
+  union {
+    struct {
+      double value;
+    } num;
+    struct {
+      double *value;
+    } var;
+    struct {
+      vec_expr_t args;
+    } op;
+    struct {
+      struct expr_func *f;
+      vec_expr_t args;
+      void *context;
+    } func;
+  } param;
+};
+
+#define expr_init()                                                            \
+  { (enum expr_type)0 }
+
+struct expr_string {
+  const char *s;
+  int n;
+};
+struct expr_arg {
+  int oslen;
+  int eslen;
+  vec_expr_t args;
+};
+
+typedef vec(struct expr_string) vec_str_t;
+typedef vec(struct expr_arg) vec_arg_t;
+
+static int expr_is_unary(enum expr_type op) {
+  return op == OP_UNARY_MINUS || op == OP_UNARY_LOGICAL_NOT ||
+         op == OP_UNARY_BITWISE_NOT;
+}
+
+static int expr_is_binary(enum expr_type op) {
+  return !expr_is_unary(op) && op != OP_CONST && op != OP_VAR &&
+         op != OP_FUNC && op != OP_UNKNOWN;
+}
+
+static int expr_prec(enum expr_type a, enum expr_type b) {
+  int left =
+      expr_is_binary(a) && a != OP_ASSIGN && a != OP_POWER && a != OP_COMMA;
+  return (left && prec[a] >= prec[b]) || (prec[a] > prec[b]);
+}
+
+#define isfirstvarchr(c)                                                        \
+  (((unsigned char)c >= '@' && c != '^' && c != '|' && c != '~') || c == '$')
+#define isvarchr(c)                                                             \
+  (((unsigned char)c >= '@' && c != '^' && c != '|' && c != '~') || c == '$' || \
+   c == '#' || (c >= '0' && c <= '9'))
+
+static struct {
+  const char *s;
+  const enum expr_type op;
+} OPS[] = {
+    {"-u", OP_UNARY_MINUS},
+    {"!u", OP_UNARY_LOGICAL_NOT},
+    {"~u", OP_UNARY_BITWISE_NOT},
+    {"**", OP_POWER},
+    {"*", OP_MULTIPLY},
+    {"/", OP_DIVIDE},
+    {"%", OP_REMAINDER},
+    {"+", OP_PLUS},
+    {"-", OP_MINUS},
+    {"<<", OP_SHL},
+    {">>", OP_SHR},
+    {"<", OP_LT},
+    {"<=", OP_LE},
+    {">", OP_GT},
+    {">=", OP_GE},
+    {"==", OP_EQ},
+    {"!=", OP_NE},
+    {"&", OP_BITWISE_AND},
+    {"|", OP_BITWISE_OR},
+    {"^", OP_BITWISE_XOR},
+    {"&&", OP_LOGICAL_AND},
+    {"||", OP_LOGICAL_OR},
+    {"=", OP_ASSIGN},
+    {",", OP_COMMA},
+
+    /* These are used by lexer and must be ignored by parser, so we put
+       them at the end */
+    {"-", OP_UNARY_MINUS},
+    {"!", OP_UNARY_LOGICAL_NOT},
+    {"~", OP_UNARY_BITWISE_NOT},
+};
+
+static enum expr_type expr_op(const char *s, size_t len, int unary) {
+  for (unsigned int i = 0; i < sizeof(OPS) / sizeof(OPS[0]); i++) {
+    if (strlen(OPS[i].s) == len && strncmp(OPS[i].s, s, len) == 0 &&
+        (unary == -1 || expr_is_unary(OPS[i].op) == unary)) {
+      return OPS[i].op;
+    }
+  }
+  return OP_UNKNOWN;
+}
+
+static double expr_parse_number(const char* s, size_t len) {
+  double num = 0;
+  char buf[32];
+  char* sz = buf;
+  char* end = NULL;
+  if (len >= sizeof(buf)) {
+    sz = (char*)calloc(1, len + 1);
+    if (sz == NULL) {
+      return NAN;
+    }
+  }
+  strncpy(sz, s, len);
+  sz[len] = '\0';
+  num = strtod(sz, &end);
+  if (sz != buf) {
+    free(sz);
+  }
+  return (end == sz + len ? num : NAN);
+}
+
+/*
+ * Functions
+ */
+struct expr_func {
+  const char *name;
+  exprfn_t f;
+  exprfn_cleanup_t cleanup;
+  size_t ctxsz;
+};
+
+static struct expr_func *expr_get_func(struct expr_func *funcs, const char *s,
+                                       size_t len) {
+  for (struct expr_func *f = funcs; f->name; f++) {
+    if (strlen(f->name) == len && strncmp(f->name, s, len) == 0) {
+      return f;
+    }
+  }
+  return NULL;
+}
+
+/*
+ * Variables
+ */
+struct expr_var {
+  double value;
+  struct expr_var *next;
+  char name[];
+};
+
+struct expr_var_list {
+  struct expr_var *head;
+};
+
+static struct expr_var *expr_get_var(struct expr_var_list *vars, const char *s,
+                                     size_t len) {
+  struct expr_var *v = NULL;
+  if (len == 0 || !isfirstvarchr(*s)) {
+    return NULL;
+  }
+  for (v = vars->head; v; v = v->next) {
+    if (strlen(v->name) == len && strncmp(v->name, s, len) == 0) {
+      return v;
+    }
+  }
+  v = (struct expr_var *)calloc(1, sizeof(struct expr_var) + len + 1);
+  if (v == NULL) {
+    return NULL; /* allocation failed */
+  }
+  v->next = vars->head;
+  v->value = 0;
+  strncpy(v->name, s, len);
+  v->name[len] = '\0';
+  vars->head = v;
+  return v;
+}
+
+static int64_t to_int(double x) {
+  if (isnan(x)) {
+    return 0;
+  } else if (isinf(x) != 0) {
+    return INT64_MAX * isinf(x);
+  } else {
+    return (int64_t)x;
+  }
+}
+
+static double expr_eval(struct expr *e) {
+  double n;
+  switch (e->type) {
+  case OP_UNARY_MINUS:
+    return -(expr_eval(&e->param.op.args.buf[0]));
+  case OP_UNARY_LOGICAL_NOT:
+    return !(expr_eval(&e->param.op.args.buf[0]));
+  case OP_UNARY_BITWISE_NOT:
+    return ~(to_int(expr_eval(&e->param.op.args.buf[0])));
+  case OP_POWER:
+    return pow(expr_eval(&e->param.op.args.buf[0]),
+               expr_eval(&e->param.op.args.buf[1]));
+  case OP_MULTIPLY:
+    return expr_eval(&e->param.op.args.buf[0]) *
+           expr_eval(&e->param.op.args.buf[1]);
+  case OP_DIVIDE:
+    return expr_eval(&e->param.op.args.buf[0]) /
+           expr_eval(&e->param.op.args.buf[1]);
+  case OP_REMAINDER:
+    return fmod(expr_eval(&e->param.op.args.buf[0]),
+                expr_eval(&e->param.op.args.buf[1]));
+  case OP_PLUS:
+    return expr_eval(&e->param.op.args.buf[0]) +
+           expr_eval(&e->param.op.args.buf[1]);
+  case OP_MINUS:
+    return expr_eval(&e->param.op.args.buf[0]) -
+           expr_eval(&e->param.op.args.buf[1]);
+  case OP_SHL:
+    return to_int(expr_eval(&e->param.op.args.buf[0]))
+           << to_int(expr_eval(&e->param.op.args.buf[1]));
+  case OP_SHR:
+    return to_int(expr_eval(&e->param.op.args.buf[0])) >>
+           to_int(expr_eval(&e->param.op.args.buf[1]));
+  case OP_LT:
+    return expr_eval(&e->param.op.args.buf[0]) <
+           expr_eval(&e->param.op.args.buf[1]);
+  case OP_LE:
+    return expr_eval(&e->param.op.args.buf[0]) <=
+           expr_eval(&e->param.op.args.buf[1]);
+  case OP_GT:
+    return expr_eval(&e->param.op.args.buf[0]) >
+           expr_eval(&e->param.op.args.buf[1]);
+  case OP_GE:
+    return expr_eval(&e->param.op.args.buf[0]) >=
+           expr_eval(&e->param.op.args.buf[1]);
+  case OP_EQ:
+    return expr_eval(&e->param.op.args.buf[0]) ==
+           expr_eval(&e->param.op.args.buf[1]);
+  case OP_NE:
+    return expr_eval(&e->param.op.args.buf[0]) !=
+           expr_eval(&e->param.op.args.buf[1]);
+  case OP_BITWISE_AND:
+    return to_int(expr_eval(&e->param.op.args.buf[0])) &
+           to_int(expr_eval(&e->param.op.args.buf[1]));
+  case OP_BITWISE_OR:
+    return to_int(expr_eval(&e->param.op.args.buf[0])) |
+           to_int(expr_eval(&e->param.op.args.buf[1]));
+  case OP_BITWISE_XOR:
+    return to_int(expr_eval(&e->param.op.args.buf[0])) ^
+           to_int(expr_eval(&e->param.op.args.buf[1]));
+  case OP_LOGICAL_AND:
+    n = expr_eval(&e->param.op.args.buf[0]);
+    if (n != 0) {
+      n = expr_eval(&e->param.op.args.buf[1]);
+      if (n != 0) {
+        return n;
+      }
+    }
+    return 0;
+  case OP_LOGICAL_OR:
+    n = expr_eval(&e->param.op.args.buf[0]);
+    if (n != 0 && !isnan(n)) {
+      return n;
+    } else {
+      n = expr_eval(&e->param.op.args.buf[1]);
+      if (n != 0) {
+        return n;
+      }
+    }
+    return 0;
+  case OP_ASSIGN:
+    n = expr_eval(&e->param.op.args.buf[1]);
+    if (vec_nth(&e->param.op.args, 0).type == OP_VAR) {
+      *e->param.op.args.buf[0].param.var.value = n;
+    }
+    return n;
+  case OP_COMMA:
+    expr_eval(&e->param.op.args.buf[0]);
+    return expr_eval(&e->param.op.args.buf[1]);
+  case OP_CONST:
+    return e->param.num.value;
+  case OP_VAR:
+    return *e->param.var.value;
+  case OP_FUNC:
+    return e->param.func.f->f(e->param.func.f, &e->param.func.args,
+                              e->param.func.context);
+  default:
+    return NAN;
+  }
+}
+
+#define EXPR_TOP (1 << 0)
+#define EXPR_TOPEN (1 << 1)
+#define EXPR_TCLOSE (1 << 2)
+#define EXPR_TNUMBER (1 << 3)
+#define EXPR_TWORD (1 << 4)
+#define EXPR_TDEFAULT (EXPR_TOPEN | EXPR_TNUMBER | EXPR_TWORD)
+
+#define EXPR_UNARY (1 << 5)
+#define EXPR_COMMA (1 << 6)
+
+static int expr_next_token(const char *s, size_t len, int *flags) {
+  unsigned int i = 0;
+  if (len == 0) {
+    return 0;
+  }
+  char c = s[0];
+  if (c == '#') {
+    for (; i < len && s[i] != '\n'; i++)
+      ;
+    return i;
+  } else if (c == '\n') {
+    for (; i < len && isspace(s[i]); i++)
+      ;
+    if (*flags & EXPR_TOP) {
+      if (i == len || s[i] == ')') {
+        *flags = *flags & (~EXPR_COMMA);
+      } else {
+        *flags = EXPR_TNUMBER | EXPR_TWORD | EXPR_TOPEN | EXPR_COMMA;
+      }
+    }
+    return i;
+  } else if (isspace(c)) {
+    while (i < len && isspace(s[i]) && s[i] != '\n') {
+      i++;
+    }
+    return i;
+  } else if (isdigit(c)) {
+    if ((*flags & EXPR_TNUMBER) == 0) {
+      return -1; // unexpected number
+    }
+    *flags = EXPR_TOP | EXPR_TCLOSE;
+    if (c == '0') {
+      i++;
+      if (i < len && (s[i] == 'x' || s[i] == 'X')) {
+        i++;
+        for (; i < len && isxdigit(s[i]); i++)
+          ;
+        return i;
+      }
+    }
+    for (; i < len && (s[i] == '.' || isdigit(s[i])); i++)
+      ;
+    if (i < len && (s[i] == 'e' || s[i] == 'E')) {
+      i++;
+      if (i < len && (s[i] == '+' || s[i] == '-'))
+        i++;
+      for (; i < len && isdigit(s[i]); i++)
+        ;
+    }
+    return i;
+  } else if (isfirstvarchr(c)) {
+    if ((*flags & EXPR_TWORD) == 0) {
+      return -2; // unexpected word
+    }
+    *flags = EXPR_TOP | EXPR_TOPEN | EXPR_TCLOSE;
+    while ((isvarchr(c)) && i < len) {
+      i++;
+      c = s[i];
+    }
+    return i;
+  } else if (c == '(' || c == ')') {
+    if (c == '(' && (*flags & EXPR_TOPEN) != 0) {
+      *flags = EXPR_TNUMBER | EXPR_TWORD | EXPR_TOPEN | EXPR_TCLOSE;
+    } else if (c == ')' && (*flags & EXPR_TCLOSE) != 0) {
+      *flags = EXPR_TOP | EXPR_TCLOSE;
+    } else {
+      return -3; // unexpected parenthesis
+    }
+    return 1;
+  } else {
+    if ((*flags & EXPR_TOP) == 0) {
+      if (expr_op(&c, 1, 1) == OP_UNKNOWN) {
+        return -4; // missing expected operand
+      }
+      *flags = EXPR_TNUMBER | EXPR_TWORD | EXPR_TOPEN | EXPR_UNARY;
+      return 1;
+    } else {
+      int found = 0;
+      while (!isvarchr(c) && !isspace(c) && c != '(' && c != ')' && i < len) {
+        if (expr_op(s, i + 1, 0) != OP_UNKNOWN) {
+          found = 1;
+        } else if (found) {
+          break;
+        }
+        i++;
+        c = s[i];
+      }
+      if (!found) {
+        return -5; // unknown operator
+      }
+      *flags = EXPR_TNUMBER | EXPR_TWORD | EXPR_TOPEN;
+      return i;
+    }
+  }
+}
+
+#define EXPR_PAREN_ALLOWED 0
+#define EXPR_PAREN_EXPECTED 1
+#define EXPR_PAREN_FORBIDDEN 2
+
+static int expr_bind(const char *s, size_t len, vec_expr_t *es) {
+  enum expr_type op = expr_op(s, len, -1);
+  if (op == OP_UNKNOWN) {
+    return -1;
+  }
+
+  if (expr_is_unary(op)) {
+    if (vec_len(es) < 1) {
+      return -1;
+    }
+    struct expr arg = vec_pop(es);
+    struct expr unary = expr_init();
+    unary.type = op;
+    vec_push(&unary.param.op.args, arg);
+    vec_push(es, unary);
+  } else {
+    if (vec_len(es) < 2) {
+      return -1;
+    }
+    struct expr b = vec_pop(es);
+    struct expr a = vec_pop(es);
+    struct expr binary = expr_init();
+    binary.type = op;
+    if (op == OP_ASSIGN && a.type != OP_VAR) {
+      return -1; /* Bad assignment */
+    }
+    vec_push(&binary.param.op.args, a);
+    vec_push(&binary.param.op.args, b);
+    vec_push(es, binary);
+  }
+  return 0;
+}
+
+static struct expr expr_const(double value) {
+  struct expr e = expr_init();
+  e.type = OP_CONST;
+  e.param.num.value = value;
+  return e;
+}
+
+static struct expr expr_varref(struct expr_var *v) {
+  struct expr e = expr_init();
+  e.type = OP_VAR;
+  e.param.var.value = &v->value;
+  return e;
+}
+
+static struct expr expr_binary(enum expr_type type, struct expr a,
+                               struct expr b) {
+  struct expr e = expr_init();
+  e.type = type;
+  vec_push(&e.param.op.args, a);
+  vec_push(&e.param.op.args, b);
+  return e;
+}
+
+static inline void expr_copy(struct expr *dst, struct expr *src) {
+  int i;
+  struct expr arg;
+  dst->type = src->type;
+  if (src->type == OP_FUNC) {
+    dst->param.func.f = src->param.func.f;
+    vec_foreach(&src->param.func.args, arg, i) {
+      struct expr tmp = expr_init();
+      expr_copy(&tmp, &arg);
+      vec_push(&dst->param.func.args, tmp);
+    }
+    if (src->param.func.f->ctxsz > 0) {
+      dst->param.func.context = calloc(1, src->param.func.f->ctxsz);
+    }
+  } else if (src->type == OP_CONST) {
+    dst->param.num.value = src->param.num.value;
+  } else if (src->type == OP_VAR) {
+    dst->param.var.value = src->param.var.value;
+  } else {
+    vec_foreach(&src->param.op.args, arg, i) {
+      struct expr tmp = expr_init();
+      expr_copy(&tmp, &arg);
+      vec_push(&dst->param.op.args, tmp);
+    }
+  }
+}
+
+static void expr_destroy_args(struct expr *e);
+
+static struct expr *expr_create(const char *s, size_t len,
+                                struct expr_var_list *vars,
+                                struct expr_func *funcs) {
+  double num;
+  const char *id = NULL;
+  size_t idn = 0;
+
+  struct expr *result = NULL;
+
+  vec_expr_t es = vec_init();
+  vec_str_t os = vec_init();
+  vec_arg_t as = vec_init();
+
+  struct macro {
+    char *name;
+    vec_expr_t body;
+  };
+  vec(struct macro) macros = vec_init();
+
+  int flags = EXPR_TDEFAULT;
+  int paren = EXPR_PAREN_ALLOWED;
+  for (;;) {
+    int n = expr_next_token(s, len, &flags);
+    if (n == 0) {
+      break;
+    } else if (n < 0) {
+      goto cleanup;
+    }
+    const char *tok = s;
+    s = s + n;
+    len = len - n;
+    if (*tok == '#') {
+      continue;
+    }
+    if (flags & EXPR_UNARY) {
+      if (n == 1) {
+        switch (*tok) {
+        case '-':
+          tok = "-u";
+          break;
+        case '~':
+          tok = "~u";
+          break;
+        case '!':
+          tok = "!u";
+          break;
+        default:
+          goto cleanup;
+        }
+        n = 2;
+      }
+    }
+    if (*tok == '\n' && (flags & EXPR_COMMA)) {
+      flags = flags & (~EXPR_COMMA);
+      n = 1;
+      tok = ",";
+    }
+    if (isspace(*tok)) {
+      continue;
+    }
+    int paren_next = EXPR_PAREN_ALLOWED;
+
+    if (idn > 0) {
+      struct expr_var *v;
+      if (n == 1 && *tok == '(') {
+        int i;
+        int has_macro = 0;
+        struct macro m;
+        vec_foreach(&macros, m, i) {
+          if (strlen(m.name) == idn && strncmp(m.name, id, idn) == 0) {
+            has_macro = 1;
+            break;
+          }
+        }
+        if ((idn == 1 && id[0] == '$') || has_macro ||
+            expr_get_func(funcs, id, idn) != NULL) {
+          struct expr_string str = {id, (int)idn};
+          vec_push(&os, str);
+          paren = EXPR_PAREN_EXPECTED;
+        } else {
+          goto cleanup; /* invalid function name */
+        }
+      } else if ((v = expr_get_var(vars, id, idn)) != NULL) {
+        vec_push(&es, expr_varref(v));
+        paren = EXPR_PAREN_FORBIDDEN;
+      }
+      id = NULL;
+      idn = 0;
+    }
+
+    if (n == 1 && *tok == '(') {
+      if (paren == EXPR_PAREN_EXPECTED) {
+        struct expr_string str = {"{", 1};
+        vec_push(&os, str);
+        struct expr_arg arg = {vec_len(&os), vec_len(&es), vec_init()};
+        vec_push(&as, arg);
+      } else if (paren == EXPR_PAREN_ALLOWED) {
+        struct expr_string str = {"(", 1};
+        vec_push(&os, str);
+      } else {
+        goto cleanup; // Bad call
+      }
+    } else if (paren == EXPR_PAREN_EXPECTED) {
+      goto cleanup; // Bad call
+    } else if (n == 1 && *tok == ')') {
+      int minlen = (vec_len(&as) > 0 ? vec_peek(&as).oslen : 0);
+      while (vec_len(&os) > minlen && *vec_peek(&os).s != '(' &&
+             *vec_peek(&os).s != '{') {
+        struct expr_string str = vec_pop(&os);
+        if (expr_bind(str.s, str.n, &es) == -1) {
+          goto cleanup;
+        }
+      }
+      if (vec_len(&os) == 0) {
+        goto cleanup; // Bad parens
+      }
+      struct expr_string str = vec_pop(&os);
+      if (str.n == 1 && *str.s == '{') {
+        str = vec_pop(&os);
+        struct expr_arg arg = vec_pop(&as);
+        if (vec_len(&es) > arg.eslen) {
+          vec_push(&arg.args, vec_pop(&es));
+        }
+        if (str.n == 1 && str.s[0] == '$') {
+          if (vec_len(&arg.args) < 1) {
+            vec_free(&arg.args);
+            goto cleanup; /* too few arguments for $() function */
+          }
+          struct expr *u = &vec_nth(&arg.args, 0);
+          if (u->type != OP_VAR) {
+            vec_free(&arg.args);
+            goto cleanup; /* first argument is not a variable */
+          }
+          for (struct expr_var *v = vars->head; v; v = v->next) {
+            if (&v->value == u->param.var.value) {
+              struct macro m = {v->name, arg.args};
+              vec_push(&macros, m);
+              break;
+            }
+          }
+          vec_push(&es, expr_const(0));
+        } else {
+          int i = 0;
+          int found = -1;
+          struct macro m;
+          vec_foreach(&macros, m, i) {
+            if (strlen(m.name) == (size_t)str.n &&
+                strncmp(m.name, str.s, str.n) == 0) {
+              found = i;
+            }
+          }
+          if (found != -1) {
+            m = vec_nth(&macros, found);
+            struct expr root = expr_const(0);
+            struct expr *p = &root;
+            /* Assign macro parameters */
+            for (int j = 0; j < vec_len(&arg.args); j++) {
+              char varname[12];
+              snprintf(varname, sizeof(varname), "$%d", (j + 1));
+              struct expr_var *v = expr_get_var(vars, varname, strlen(varname));
+              struct expr ev = expr_varref(v);
+              struct expr assign =
+                  expr_binary(OP_ASSIGN, ev, vec_nth(&arg.args, j));
+              *p = expr_binary(OP_COMMA, assign, expr_const(0));
+              p = &vec_nth(&p->param.op.args, 1);
+            }
+            /* Expand macro body */
+            for (int j = 1; j < vec_len(&m.body); j++) {
+              if (j < vec_len(&m.body) - 1) {
+                *p = expr_binary(OP_COMMA, expr_const(0), expr_const(0));
+                expr_copy(&vec_nth(&p->param.op.args, 0), &vec_nth(&m.body, j));
+              } else {
+                expr_copy(p, &vec_nth(&m.body, j));
+              }
+              p = &vec_nth(&p->param.op.args, 1);
+            }
+            vec_push(&es, root);
+            vec_free(&arg.args);
+          } else {
+            struct expr_func *f = expr_get_func(funcs, str.s, str.n);
+            struct expr bound_func = expr_init();
+            bound_func.type = OP_FUNC;
+            bound_func.param.func.f = f;
+            bound_func.param.func.args = arg.args;
+            if (f->ctxsz > 0) {
+              void *p = calloc(1, f->ctxsz);
+              if (p == NULL) {
+                goto cleanup; /* allocation failed */
+              }
+              bound_func.param.func.context = p;
+            }
+            vec_push(&es, bound_func);
+          }
+        }
+      }
+      paren_next = EXPR_PAREN_FORBIDDEN;
+    } else if (!isnan(num = expr_parse_number(tok, n))) {
+      vec_push(&es, expr_const(num));
+      paren_next = EXPR_PAREN_FORBIDDEN;
+    } else if (expr_op(tok, n, -1) != OP_UNKNOWN) {
+      enum expr_type op = expr_op(tok, n, -1);
+      struct expr_string o2 = {NULL, 0};
+      if (vec_len(&os) > 0) {
+        o2 = vec_peek(&os);
+      }
+      for (;;) {
+        if (n == 1 && *tok == ',' && vec_len(&os) > 0) {
+          struct expr_string str = vec_peek(&os);
+          if (str.n == 1 && *str.s == '{') {
+            struct expr e = vec_pop(&es);
+            vec_push(&vec_peek(&as).args, e);
+            break;
+          }
+        }
+        enum expr_type type2 = expr_op(o2.s, o2.n, -1);
+        if (!(type2 != OP_UNKNOWN && expr_prec(op, type2))) {
+          struct expr_string str = {tok, n};
+          vec_push(&os, str);
+          break;
+        }
+
+        if (expr_bind(o2.s, o2.n, &es) == -1) {
+          goto cleanup;
+        }
+        (void)vec_pop(&os);
+        if (vec_len(&os) > 0) {
+          o2 = vec_peek(&os);
+        } else {
+          o2.n = 0;
+        }
+      }
+    } else {
+      if (n > 0 && !isdigit(*tok)) {
+        /* Valid identifier, a variable or a function */
+        id = tok;
+        idn = n;
+      } else {
+        goto cleanup; // Bad variable name, e.g. '2.3.4' or '4ever'
+      }
+    }
+    paren = paren_next;
+  }
+
+  if (idn > 0) {
+    vec_push(&es, expr_varref(expr_get_var(vars, id, idn)));
+  }
+
+  while (vec_len(&os) > 0) {
+    struct expr_string rest = vec_pop(&os);
+    if (rest.n == 1 && (*rest.s == '(' || *rest.s == ')')) {
+      goto cleanup; // Bad paren
+    }
+    if (expr_bind(rest.s, rest.n, &es) == -1) {
+      goto cleanup;
+    }
+  }
+
+  result = (struct expr *)calloc(1, sizeof(struct expr));
+  if (result != NULL) {
+    if (vec_len(&es) == 0) {
+      result->type = OP_CONST;
+    } else {
+      *result = vec_pop(&es);
+    }
+  }
+
+  int i, j;
+  struct macro m;
+  struct expr e;
+  struct expr_arg a;
+cleanup:
+  vec_foreach(&macros, m, i) {
+    struct expr e2;
+    vec_foreach(&m.body, e2, j) { expr_destroy_args(&e2); }
+    vec_free(&m.body);
+  }
+  vec_free(&macros);
+
+  vec_foreach(&es, e, i) { expr_destroy_args(&e); }
+  vec_free(&es);
+
+  vec_foreach(&as, a, i) {
+    vec_foreach(&a.args, e, j) { expr_destroy_args(&e); }
+    vec_free(&a.args);
+  }
+  vec_free(&as);
+
+  /*vec_foreach(&os, o, i) {vec_free(&m.body);}*/
+  vec_free(&os);
+  return result;
+}
+
+static void expr_destroy_args(struct expr *e) {
+  int i;
+  struct expr arg;
+  if (e->type == OP_FUNC) {
+    vec_foreach(&e->param.func.args, arg, i) { expr_destroy_args(&arg); }
+    vec_free(&e->param.func.args);
+    if (e->param.func.context != NULL) {
+      if (e->param.func.f->cleanup != NULL) {
+        e->param.func.f->cleanup(e->param.func.f, e->param.func.context);
+      }
+      free(e->param.func.context);
+    }
+  } else if (e->type != OP_CONST && e->type != OP_VAR) {
+    vec_foreach(&e->param.op.args, arg, i) { expr_destroy_args(&arg); }
+    vec_free(&e->param.op.args);
+  }
+}
+
+static void expr_destroy(struct expr *e, struct expr_var_list *vars) {
+  if (e != NULL) {
+    expr_destroy_args(e);
+    free(e);
+  }
+  if (vars != NULL) {
+    for (struct expr_var *v = vars->head; v;) {
+      struct expr_var *next = v->next;
+      free(v);
+      v = next;
+    }
+  }
+}
+
+#ifdef __cplusplus
+} /* extern "C" */
+#endif
+
+#ifdef _MSC_VER
+#pragma warning(pop)
+#endif
+
+#endif /* EXPR_H */
diff --git a/Externals/licenses.md b/Externals/licenses.md
index f7b20041b9d9..beef359494a2 100644
--- a/Externals/licenses.md
+++ b/Externals/licenses.md
@@ -14,6 +14,8 @@ Dolphin includes or links code of the following third-party software projects:
    [MIT](https://github.com/discordapp/discord-rpc/blob/master/LICENSE)
 - [ENet](http://enet.bespin.org/):
    [MIT](http://enet.bespin.org/License.html)
+- [expr](https://github.com/zserge/expr):
+   [MIT](https://github.com/zserge/expr/blob/master/LICENSE)
 - [GCEmu](http://sourceforge.net/projects/gcemu-project/):
    GPLv2+
 - [gettext](https://www.gnu.org/software/gettext/):
diff --git a/Source/Core/Core/CMakeLists.txt b/Source/Core/Core/CMakeLists.txt
index de8fd8ac93ad..1098add11ee2 100644
--- a/Source/Core/Core/CMakeLists.txt
+++ b/Source/Core/Core/CMakeLists.txt
@@ -424,6 +424,8 @@ add_library(core
   PowerPC/BreakPoints.h
   PowerPC/ConditionRegister.cpp
   PowerPC/ConditionRegister.h
+  PowerPC/Expression.cpp
+  PowerPC/Expression.h
   PowerPC/JitInterface.cpp
   PowerPC/JitInterface.h
   PowerPC/MMU.cpp
@@ -555,6 +557,7 @@ PUBLIC
   cubeb
   discio
   enet
+  expr
   inputcommon
   ${MBEDTLS_LIBRARIES}
   pugixml
diff --git a/Source/Core/Core/Core.vcxproj b/Source/Core/Core/Core.vcxproj
index a7ada5b18ecf..355a8e1eb7d9 100644
--- a/Source/Core/Core/Core.vcxproj
+++ b/Source/Core/Core/Core.vcxproj
@@ -241,6 +241,7 @@
     <ClCompile Include="PowerPC\CachedInterpreter\CachedInterpreter.cpp" />
     <ClCompile Include="PowerPC\CachedInterpreter\InterpreterBlockCache.cpp" />
     <ClCompile Include="PowerPC\ConditionRegister.cpp" />
+    <ClCompile Include="PowerPC\Expression.cpp" />
     <ClCompile Include="PowerPC\Interpreter\Interpreter.cpp" />
     <ClCompile Include="PowerPC\Interpreter\Interpreter_Branch.cpp" />
     <ClCompile Include="PowerPC\Interpreter\Interpreter_FloatingPoint.cpp" />
@@ -596,6 +597,7 @@
     <ClInclude Include="PatchEngine.h" />
     <ClInclude Include="PowerPC\BreakPoints.h" />
     <ClInclude Include="PowerPC\CPUCoreBase.h" />
+    <ClInclude Include="PowerPC\Expression.h" />
     <ClInclude Include="PowerPC\Gekko.h" />
     <ClInclude Include="PowerPC\CachedInterpreter\CachedInterpreter.h" />
     <ClInclude Include="PowerPC\CachedInterpreter\InterpreterBlockCache.h" />
diff --git a/Source/Core/Core/Core.vcxproj.filters b/Source/Core/Core/Core.vcxproj.filters
index 749b81b9c2ca..e7d6d5d3e801 100644
--- a/Source/Core/Core/Core.vcxproj.filters
+++ b/Source/Core/Core/Core.vcxproj.filters
@@ -328,6 +328,9 @@
     <ClCompile Include="PowerPC\BreakPoints.cpp">
       <Filter>PowerPC</Filter>
     </ClCompile>
+    <ClCompile Include="PowerPC\Expression.cpp">
+      <Filter>PowerPC</Filter>
+    </ClCompile>
     <ClCompile Include="PowerPC\CachedInterpreter\CachedInterpreter.cpp">
       <Filter>PowerPC\Cached Interpreter</Filter>
     </ClCompile>
@@ -1410,6 +1413,9 @@
     <ClInclude Include="PowerPC\CPUCoreBase.h">
       <Filter>PowerPC</Filter>
     </ClInclude>
+    <ClInclude Include="PowerPC\Expression.h">
+      <Filter>PowerPC</Filter>
+    </ClInclude>
     <ClInclude Include="PowerPC\Gekko.h">
       <Filter>PowerPC</Filter>
     </ClInclude>
diff --git a/Source/Core/Core/PowerPC/BreakPoints.cpp b/Source/Core/Core/PowerPC/BreakPoints.cpp
index bf1e1643d115..0f5990fdbc0b 100644
--- a/Source/Core/Core/PowerPC/BreakPoints.cpp
+++ b/Source/Core/Core/PowerPC/BreakPoints.cpp
@@ -14,6 +14,7 @@
 #include "Common/DebugInterface.h"
 #include "Common/Logging/Log.h"
 #include "Core/Core.h"
+#include "Core/PowerPC/Expression.h"
 #include "Core/PowerPC/JitInterface.h"
 #include "Core/PowerPC/MMU.h"
 
@@ -33,7 +34,7 @@ bool BreakPoints::IsTempBreakPoint(u32 address) const
 bool BreakPoints::IsBreakPointBreakOnHit(u32 address) const
 {
   return std::any_of(m_breakpoints.begin(), m_breakpoints.end(), [address](const auto& bp) {
-    return bp.address == address && bp.break_on_hit;
+    return bp.address == address && bp.break_on_hit && EvaluateCondition(bp.condition);
   });
 }
 
@@ -51,9 +52,16 @@ BreakPoints::TBreakPointsStr BreakPoints::GetStrings() const
     if (!bp.is_temporary)
     {
       std::ostringstream ss;
-      ss << std::hex << bp.address << " " << (bp.is_enabled ? "n" : "")
-         << (bp.log_on_hit ? "l" : "") << (bp.break_on_hit ? "b" : "");
-      bp_strings.push_back(ss.str());
+      ss << fmt::format("${:08x} ", bp.address);
+      if (bp.is_enabled)
+        ss << "n";
+      if (bp.log_on_hit)
+        ss << "l";
+      if (bp.break_on_hit)
+        ss << "b";
+      if (bp.condition)
+        ss << "c " << bp.condition->GetText();
+      bp_strings.emplace_back(ss.str());
     }
   }
 
@@ -67,31 +75,43 @@ void BreakPoints::AddFromStrings(const TBreakPointsStr& bp_strings)
     TBreakPoint bp;
     std::stringstream ss;
     ss << std::hex << bp_string;
+    if (ss.peek() == '$')
+      ss.ignore();
     ss >> bp.address;
-    bp.is_enabled = bp_string.find('n') != bp_string.npos;
-    bp.log_on_hit = bp_string.find('l') != bp_string.npos;
-    bp.break_on_hit = bp_string.find('b') != bp_string.npos;
+    std::string flags;
+    ss >> flags;
+    bp.is_enabled = flags.find('n') != std::string::npos;
+    bp.log_on_hit = flags.find('l') != std::string::npos;
+    bp.break_on_hit = flags.find('b') != std::string::npos;
+    if (flags.find('c') != std::string::npos)
+    {
+      ss >> std::ws;
+      std::string condition;
+      std::getline(ss, condition);
+      bp.condition = Expression::TryParse(condition);
+    }
     bp.is_temporary = false;
-    Add(bp);
+    Add(std::move(bp));
   }
 }
 
-void BreakPoints::Add(const TBreakPoint& bp)
+void BreakPoints::Add(TBreakPoint bp)
 {
   if (IsAddressBreakPoint(bp.address))
     return;
 
-  m_breakpoints.push_back(bp);
-
   JitInterface::InvalidateICache(bp.address, 4, true);
+
+  m_breakpoints.emplace_back(std::move(bp));
 }
 
 void BreakPoints::Add(u32 address, bool temp)
 {
-  BreakPoints::Add(address, temp, true, false);
+  BreakPoints::Add(address, temp, true, false, {});
 }
 
-void BreakPoints::Add(u32 address, bool temp, bool break_on_hit, bool log_on_hit)
+void BreakPoints::Add(u32 address, bool temp, bool break_on_hit, bool log_on_hit,
+                      std::optional<Expression> condition)
 {
   // Only add new addresses
   if (IsAddressBreakPoint(address))
@@ -103,8 +123,9 @@ void BreakPoints::Add(u32 address, bool temp, bool break_on_hit, bool log_on_hit
   bp.break_on_hit = break_on_hit;
   bp.log_on_hit = log_on_hit;
   bp.address = address;
+  bp.condition = std::move(condition);
 
-  m_breakpoints.push_back(bp);
+  m_breakpoints.emplace_back(std::move(bp));
 
   JitInterface::InvalidateICache(address, 4, true);
 }
diff --git a/Source/Core/Core/PowerPC/BreakPoints.h b/Source/Core/Core/PowerPC/BreakPoints.h
index 571427f47d16..4f58d011f96c 100644
--- a/Source/Core/Core/PowerPC/BreakPoints.h
+++ b/Source/Core/Core/PowerPC/BreakPoints.h
@@ -5,10 +5,12 @@
 #pragma once
 
 #include <cstddef>
+#include <optional>
 #include <string>
 #include <vector>
 
 #include "Common/CommonTypes.h"
+#include "Core/PowerPC/Expression.h"
 
 namespace Common
 {
@@ -22,6 +24,7 @@ struct TBreakPoint
   bool is_temporary = false;
   bool log_on_hit = false;
   bool break_on_hit = false;
+  std::optional<Expression> condition;
 };
 
 struct TMemCheck
@@ -62,9 +65,10 @@ class BreakPoints
   bool IsBreakPointLogOnHit(u32 address) const;
 
   // Add BreakPoint
-  void Add(u32 address, bool temp, bool break_on_hit, bool log_on_hit);
+  void Add(u32 address, bool temp, bool break_on_hit, bool log_on_hit,
+           std::optional<Expression> condition);
   void Add(u32 address, bool temp = false);
-  void Add(const TBreakPoint& bp);
+  void Add(TBreakPoint bp);
 
   // Remove Breakpoint
   void Remove(u32 address);
diff --git a/Source/Core/Core/PowerPC/Expression.cpp b/Source/Core/Core/PowerPC/Expression.cpp
new file mode 100644
index 000000000000..472471da765e
--- /dev/null
+++ b/Source/Core/Core/PowerPC/Expression.cpp
@@ -0,0 +1,240 @@
+// Copyright 2020 Dolphin Emulator Project
+// Licensed under GPLv2+
+// Refer to the license.txt file included.
+
+#include "Core/PowerPC/Expression.h"
+
+#include <cstdlib>
+#include <optional>
+#include <string>
+#include <string_view>
+#include <unordered_map>
+#include <utility>
+
+#include <expr.h>
+
+#include "Common/BitUtils.h"
+#include "Common/CommonTypes.h"
+#include "Core/PowerPC/MMU.h"
+#include "Core/PowerPC/PowerPC.h"
+
+template <typename T>
+static T HostRead(u32 address);
+
+template <typename T>
+static void HostWrite(T var, u32 address);
+
+template <>
+u8 HostRead(u32 address)
+{
+  return PowerPC::HostRead_U8(address);
+}
+
+template <>
+u16 HostRead(u32 address)
+{
+  return PowerPC::HostRead_U16(address);
+}
+
+template <>
+u32 HostRead(u32 address)
+{
+  return PowerPC::HostRead_U32(address);
+}
+
+template <>
+u64 HostRead(u32 address)
+{
+  return PowerPC::HostRead_U64(address);
+}
+
+template <>
+void HostWrite(u8 var, u32 address)
+{
+  PowerPC::HostWrite_U8(var, address);
+}
+
+template <>
+void HostWrite(u16 var, u32 address)
+{
+  PowerPC::HostWrite_U16(var, address);
+}
+
+template <>
+void HostWrite(u32 var, u32 address)
+{
+  PowerPC::HostWrite_U32(var, address);
+}
+
+template <>
+void HostWrite(u64 var, u32 address)
+{
+  PowerPC::HostWrite_U64(var, address);
+}
+
+template <typename T, typename U = T>
+static double HostReadFunc(expr_func* f, vec_expr_t* args, void* c)
+{
+  if (vec_len(args) != 1)
+    return 0;
+  u32 address = static_cast<u32>(expr_eval(&vec_nth(args, 0)));
+  return Common::BitCast<T>(HostRead<U>(address));
+}
+
+template <typename T, typename U = T>
+static double HostWriteFunc(expr_func* f, vec_expr_t* args, void* c)
+{
+  if (vec_len(args) != 2)
+    return 0;
+  T var = static_cast<T>(expr_eval(&vec_nth(args, 0)));
+  u32 address = static_cast<u32>(expr_eval(&vec_nth(args, 1)));
+  HostWrite<U>(Common::BitCast<U>(var), address);
+  return var;
+}
+
+template <typename T, typename U = T>
+static double CastFunc(expr_func* f, vec_expr_t* args, void* c)
+{
+  if (vec_len(args) != 1)
+    return 0;
+  return Common::BitCast<T>(static_cast<U>(expr_eval(&vec_nth(args, 0))));
+}
+
+static std::array<expr_func, 21> g_expr_funcs{{
+    {"read_u8", HostReadFunc<u8>},
+    {"read_s8", HostReadFunc<s8, u8>},
+    {"read_u16", HostReadFunc<u16>},
+    {"read_s16", HostReadFunc<s16, u16>},
+    {"read_u32", HostReadFunc<u32>},
+    {"read_s32", HostReadFunc<s32, u32>},
+    {"read_f32", HostReadFunc<float, u32>},
+    {"read_f64", HostReadFunc<double, u64>},
+    {"write_u8", HostWriteFunc<u8>},
+    {"write_u16", HostWriteFunc<u16>},
+    {"write_u32", HostWriteFunc<u32>},
+    {"write_f32", HostWriteFunc<float, u32>},
+    {"write_f64", HostWriteFunc<double, u64>},
+    {"u8", CastFunc<u8>},
+    {"s8", CastFunc<s8, u8>},
+    {"u16", CastFunc<u16>},
+    {"s16", CastFunc<s16, u16>},
+    {"u32", CastFunc<u32>},
+    {"s32", CastFunc<s32, u32>},
+    {},
+}};
+
+void ExprDeleter::operator()(expr* expression) const
+{
+  expr_destroy(expression, nullptr);
+}
+
+void ExprVarListDeleter::operator()(expr_var_list* vars) const
+{
+  // Free list elements
+  expr_destroy(nullptr, vars);
+  // Free list object
+  delete vars;
+}
+
+Expression::Expression(std::string_view text, ExprPointer ex, ExprVarListPointer vars)
+    : m_text(text), m_expr(std::move(ex)), m_vars(std::move(vars))
+{
+  for (auto* v = m_vars->head; v != nullptr; v = v->next)
+  {
+    const std::string_view name = v->name;
+    VarBinding bind;
+
+    if (name.length() >= 2 && name.length() <= 3)
+    {
+      if (name[0] == 'r' || name[0] == 'f')
+      {
+        char* end = nullptr;
+        int index = std::strtol(name.data() + 1, &end, 10);
+        if (index >= 0 && index <= 31 && end == name.data() + name.length())
+        {
+          bind.type = name[0] == 'r' ? VarBindingType::GPR : VarBindingType::FPR;
+          bind.index = index;
+        }
+      }
+      else if (name == "lr")
+      {
+        bind.type = VarBindingType::SPR;
+        bind.index = SPR_LR;
+      }
+      else if (name == "ctr")
+      {
+        bind.type = VarBindingType::SPR;
+        bind.index = SPR_CTR;
+      }
+      else if (name == "pc")
+      {
+        bind.type = VarBindingType::PCtr;
+      }
+    }
+
+    m_binds.emplace_back(bind);
+  }
+}
+
+std::optional<Expression> Expression::TryParse(std::string_view text)
+{
+  ExprVarListPointer vars{new expr_var_list{}};
+  ExprPointer ex{expr_create(text.data(), text.length(), vars.get(), g_expr_funcs.data())};
+  if (!ex)
+    return {};
+
+  return Expression{text, std::move(ex), std::move(vars)};
+}
+
+double Expression::Evaluate() const
+{
+  SynchronizeBindings(SynchronizeDirection::From);
+
+  double result = expr_eval(m_expr.get());
+
+  SynchronizeBindings(SynchronizeDirection::To);
+
+  return result;
+}
+
+void Expression::SynchronizeBindings(SynchronizeDirection dir) const
+{
+  auto bind = m_binds.begin();
+  for (auto* v = m_vars->head; v != nullptr; v = v->next, ++bind)
+  {
+    switch (bind->type)
+    {
+    case VarBindingType::Zero:
+      if (dir == SynchronizeDirection::From)
+        v->value = 0;
+      break;
+    case VarBindingType::GPR:
+      if (dir == SynchronizeDirection::From)
+        v->value = static_cast<double>(GPR(bind->index));
+      else
+        GPR(bind->index) = static_cast<u32>(static_cast<s64>(v->value));
+      break;
+    case VarBindingType::FPR:
+      if (dir == SynchronizeDirection::From)
+        v->value = rPS(bind->index).PS0AsDouble();
+      else
+        rPS(bind->index).SetPS0(v->value);
+      break;
+    case VarBindingType::SPR:
+      if (dir == SynchronizeDirection::From)
+        v->value = static_cast<double>(rSPR(bind->index));
+      else
+        rSPR(bind->index) = static_cast<u32>(static_cast<s64>(v->value));
+      break;
+    case VarBindingType::PCtr:
+      if (dir == SynchronizeDirection::From)
+        v->value = static_cast<double>(PC);
+      break;
+    }
+  }
+}
+
+std::string Expression::GetText() const
+{
+  return m_text;
+}
diff --git a/Source/Core/Core/PowerPC/Expression.h b/Source/Core/Core/PowerPC/Expression.h
new file mode 100644
index 000000000000..17679e7f46d4
--- /dev/null
+++ b/Source/Core/Core/PowerPC/Expression.h
@@ -0,0 +1,74 @@
+// Copyright 2020 Dolphin Emulator Project
+// Licensed under GPLv2+
+// Refer to the license.txt file included.
+
+#pragma once
+
+#include <memory>
+#include <optional>
+#include <string>
+#include <string_view>
+#include <vector>
+
+struct expr;
+struct expr_var_list;
+
+struct ExprDeleter
+{
+  void operator()(expr* expression) const;
+};
+
+using ExprPointer = std::unique_ptr<expr, ExprDeleter>;
+
+struct ExprVarListDeleter
+{
+  void operator()(expr_var_list* vars) const;
+};
+
+using ExprVarListPointer = std::unique_ptr<expr_var_list, ExprVarListDeleter>;
+
+class Expression
+{
+public:
+  static std::optional<Expression> TryParse(std::string_view text);
+
+  double Evaluate() const;
+
+  std::string GetText() const;
+
+private:
+  enum class SynchronizeDirection
+  {
+    From,
+    To,
+  };
+
+  enum class VarBindingType
+  {
+    Zero,
+    GPR,
+    FPR,
+    SPR,
+    PCtr,
+  };
+
+  struct VarBinding
+  {
+    VarBindingType type = VarBindingType::Zero;
+    int index = -1;
+  };
+
+  Expression(std::string_view text, ExprPointer ex, ExprVarListPointer vars);
+
+  void SynchronizeBindings(SynchronizeDirection dir) const;
+
+  std::string m_text;
+  ExprPointer m_expr;
+  ExprVarListPointer m_vars;
+  std::vector<VarBinding> m_binds;
+};
+
+inline bool EvaluateCondition(const std::optional<Expression>& condition)
+{
+  return !condition || condition->Evaluate() != 0;
+}
diff --git a/Source/Core/DolphinQt/Debugger/BreakpointWidget.cpp b/Source/Core/DolphinQt/Debugger/BreakpointWidget.cpp
index 8ba4f6144298..fc8ac79774e5 100644
--- a/Source/Core/DolphinQt/Debugger/BreakpointWidget.cpp
+++ b/Source/Core/DolphinQt/Debugger/BreakpointWidget.cpp
@@ -14,6 +14,7 @@
 #include "Core/ConfigManager.h"
 #include "Core/Core.h"
 #include "Core/PowerPC/BreakPoints.h"
+#include "Core/PowerPC/Expression.h"
 #include "Core/PowerPC/PPCSymbolDB.h"
 #include "Core/PowerPC/PowerPC.h"
 
@@ -78,7 +79,7 @@ void BreakpointWidget::CreateWidgets()
   m_table = new QTableWidget;
   m_table->setTabKeyNavigation(false);
   m_table->setContentsMargins(0, 0, 0, 0);
-  m_table->setColumnCount(5);
+  m_table->setColumnCount(6);
   m_table->setSelectionMode(QAbstractItemView::SingleSelection);
   m_table->setSelectionBehavior(QAbstractItemView::SelectRows);
   m_table->setEditTriggers(QAbstractItemView::NoEditTriggers);
@@ -156,7 +157,7 @@ void BreakpointWidget::Update()
   m_table->clear();
 
   m_table->setHorizontalHeaderLabels(
-      {tr("Active"), tr("Type"), tr("Function"), tr("Address"), tr("Flags")});
+      {tr("Active"), tr("Type"), tr("Function"), tr("Address"), tr("Flags"), tr("Condition")});
 
   int i = 0;
   m_table->setRowCount(i);
@@ -198,6 +199,13 @@ void BreakpointWidget::Update()
 
     m_table->setItem(i, 4, create_item(flags));
 
+    QString condition;
+
+    if (bp.condition)
+      condition = QString::fromStdString(bp.condition->GetText());
+
+    m_table->setItem(i, 5, create_item(condition));
+
     i++;
   }
 
@@ -316,12 +324,15 @@ void BreakpointWidget::OnSave()
 
 void BreakpointWidget::AddBP(u32 addr)
 {
-  AddBP(addr, false, true, true);
+  AddBP(addr, false, true, true, {});
 }
 
-void BreakpointWidget::AddBP(u32 addr, bool temp, bool break_on_hit, bool log_on_hit)
+void BreakpointWidget::AddBP(u32 addr, bool temp, bool break_on_hit, bool log_on_hit,
+                             const QString& condition)
 {
-  PowerPC::breakpoints.Add(addr, temp, break_on_hit, log_on_hit);
+  PowerPC::breakpoints.Add(
+      addr, temp, break_on_hit, log_on_hit,
+      !condition.isEmpty() ? Expression::TryParse(condition.toUtf8().constData()) : std::nullopt);
 
   Update();
 }
diff --git a/Source/Core/DolphinQt/Debugger/BreakpointWidget.h b/Source/Core/DolphinQt/Debugger/BreakpointWidget.h
index 570bb02b515e..b741e4e0c58d 100644
--- a/Source/Core/DolphinQt/Debugger/BreakpointWidget.h
+++ b/Source/Core/DolphinQt/Debugger/BreakpointWidget.h
@@ -22,7 +22,7 @@ class BreakpointWidget : public QDockWidget
   ~BreakpointWidget();
 
   void AddBP(u32 addr);
-  void AddBP(u32 addr, bool temp, bool break_on_hit, bool log_on_hit);
+  void AddBP(u32 addr, bool temp, bool break_on_hit, bool log_on_hit, const QString& condition);
   void AddAddressMBP(u32 addr, bool on_read = true, bool on_write = true, bool do_log = true,
                      bool do_break = true);
   void AddRangedMBP(u32 from, u32 to, bool do_read = true, bool do_write = true, bool do_log = true,
diff --git a/Source/Core/DolphinQt/Debugger/NewBreakpointDialog.cpp b/Source/Core/DolphinQt/Debugger/NewBreakpointDialog.cpp
index 4ad30016cd76..18a5c50e6c8b 100644
--- a/Source/Core/DolphinQt/Debugger/NewBreakpointDialog.cpp
+++ b/Source/Core/DolphinQt/Debugger/NewBreakpointDialog.cpp
@@ -14,6 +14,7 @@
 #include <QRadioButton>
 #include <QVBoxLayout>
 
+#include "Core/PowerPC/Expression.h"
 #include "DolphinQt/Debugger/BreakpointWidget.h"
 #include "DolphinQt/QtUtils/ModalMessageBox.h"
 
@@ -37,11 +38,14 @@ void NewBreakpointDialog::CreateWidgets()
   m_instruction_bp->setChecked(true);
   m_instruction_box = new QGroupBox;
   m_instruction_address = new QLineEdit;
+  m_instruction_condition = new QLineEdit;
 
-  auto* instruction_layout = new QHBoxLayout;
+  auto* instruction_layout = new QGridLayout;
   m_instruction_box->setLayout(instruction_layout);
-  instruction_layout->addWidget(new QLabel(tr("Address:")));
-  instruction_layout->addWidget(m_instruction_address);
+  instruction_layout->addWidget(new QLabel(tr("Address:")), 0, 0);
+  instruction_layout->addWidget(m_instruction_address, 0, 1);
+  instruction_layout->addWidget(new QLabel(tr("Condition:")), 1, 0);
+  instruction_layout->addWidget(m_instruction_condition, 1, 1);
 
   // Memory BP
   m_memory_bp = new QRadioButton(tr("Memory Breakpoint"));
@@ -165,7 +169,15 @@ void NewBreakpointDialog::accept()
       return;
     }
 
-    m_parent->AddBP(address, false, do_break, do_log);
+    const QString condition = m_instruction_condition->text().trimmed();
+
+    if (!condition.isEmpty() && !Expression::TryParse(condition.toUtf8().constData()))
+    {
+      invalid_input(tr("Condition"));
+      return;
+    }
+
+    m_parent->AddBP(address, false, do_break, do_log, condition);
   }
   else
   {
diff --git a/Source/Core/DolphinQt/Debugger/NewBreakpointDialog.h b/Source/Core/DolphinQt/Debugger/NewBreakpointDialog.h
index d9d2958c2bed..646a58c4e810 100644
--- a/Source/Core/DolphinQt/Debugger/NewBreakpointDialog.h
+++ b/Source/Core/DolphinQt/Debugger/NewBreakpointDialog.h
@@ -35,6 +35,7 @@ class NewBreakpointDialog : public QDialog
   QRadioButton* m_instruction_bp;
   QGroupBox* m_instruction_box;
   QLineEdit* m_instruction_address;
+  QLineEdit* m_instruction_condition;
 
   // Memory BPs
   QRadioButton* m_memory_bp;
diff --git a/Source/VSProps/Base.props b/Source/VSProps/Base.props
index 804ed54fcc70..20800f1f4d31 100644
--- a/Source/VSProps/Base.props
+++ b/Source/VSProps/Base.props
@@ -26,6 +26,7 @@
       <AdditionalIncludeDirectories>$(ExternalsDir)discord-rpc\include;%(AdditionalIncludeDirectories)</AdditionalIncludeDirectories>
       <AdditionalIncludeDirectories>$(ExternalsDir)ed25519;%(AdditionalIncludeDirectories)</AdditionalIncludeDirectories>
       <AdditionalIncludeDirectories>$(ExternalsDir)enet\include;%(AdditionalIncludeDirectories)</AdditionalIncludeDirectories>
+      <AdditionalIncludeDirectories>$(ExternalsDir)expr\include;%(AdditionalIncludeDirectories)</AdditionalIncludeDirectories>
       <AdditionalIncludeDirectories>$(ExternalsDir)ffmpeg\include;%(AdditionalIncludeDirectories)</AdditionalIncludeDirectories>
       <AdditionalIncludeDirectories>$(ExternalsDir)fmt\include;%(AdditionalIncludeDirectories)</AdditionalIncludeDirectories>
       <AdditionalIncludeDirectories>$(ExternalsDir)GL;%(AdditionalIncludeDirectories)</AdditionalIncludeDirectories>