[clang] Make __builtin_expf constexpr.

clang/include/clang/Basic/Builtins.td

@@ -161,7 +161,22 @@ def ErfcF128 : Builtin {
   let Prototype = "__float128(__float128)";
 }
 
-def ExpF16F128 : Builtin, F16F128MathTemplate {
+def BIExpF : Builtin {
+  let Spellings = ["__builtin_expf"];
+#ifdef LLVM_INTEGRATE_LIBC
+  let Attributes = [FunctionWithBuiltinPrefix, NoThrow, Const, Constexpr];
+#else
+  let Attributes = [FunctionWithBuiltinPrefix, NoThrow,
+                    ConstIgnoringErrnoAndExceptions];
+#endif // LLVM_INTEGRATE_LIBC
+  let Prototype = "float(float)";
+}
+
+def BIExp
+    : Builtin,
+      Template<["double", "long double", "_Float16", "__float128"], ["", "l",
+                                                                     "f16",
+                                                                     "f128"]> {
   let Spellings = ["__builtin_exp"];
   let Attributes = [FunctionWithBuiltinPrefix, NoThrow, ConstIgnoringErrnoAndExceptions];
   let Prototype = "T(T)";
@@ -3742,7 +3757,6 @@ def Exp : FPMathTemplate, LibBuiltin<"math.h"> {
   let Spellings = ["exp"];
   let Attributes = [NoThrow, ConstIgnoringErrnoAndExceptions];
   let Prototype = "T(T)";
-  let AddBuiltinPrefixedAlias = 1;
 }
 
 def Exp2 : FPMathTemplate, LibBuiltin<"math.h"> {

clang/lib/AST/ByteCode/InterpBuiltin.cpp

@@ -18,6 +18,7 @@
 #include "clang/Basic/TargetBuiltins.h"
 #include "clang/Basic/TargetInfo.h"
 #include "llvm/ADT/StringExtras.h"
+#include "llvm/Config/llvm-config.h"
 #include "llvm/Support/SipHash.h"
 
 namespace clang {
@@ -419,6 +420,13 @@ static bool interp__builtin_copysign(InterpState &S, CodePtr OpPC,
   return true;
 }
 
+static bool interp__builtin_exp(InterpState &S, CodePtr OpPC,
+                                const InterpFrame *Frame) {
+  APFloat Result = exp(S.Stk.peek<Floating>().getAPFloat());
+  S.Stk.push<Floating>(Floating(Result));
+  return true;
+}
+
 static bool interp__builtin_fmin(InterpState &S, CodePtr OpPC,
                                  const InterpFrame *Frame, bool IsNumBuiltin) {
   const Floating &LHS = S.Stk.peek<Floating>(align(primSize(PT_Float)) * 2);
@@ -2315,6 +2323,20 @@ bool InterpretBuiltin(InterpState &S, CodePtr OpPC, const CallExpr *Call,
       return false;
     break;
 
+  case Builtin::BI__builtin_exp:
+  case Builtin::BI__builtin_expl:
+  case Builtin::BI__builtin_expf16:
+  case Builtin::BI__builtin_expf128:
+    return false;
+  case Builtin::BI__builtin_expf:
+#ifdef LLVM_INTEGRATE_LIBC
+    if (!interp__builtin_exp(S, OpPC, Frame))
+      return false;
+    break;
+#else
+    return false;
+#endif // LLVM_INTEGRATE_LIBC
+
   case Builtin::BI__builtin_fmin:
   case Builtin::BI__builtin_fminf:
   case Builtin::BI__builtin_fminl:

clang/lib/AST/ExprConstant.cpp

@@ -57,6 +57,7 @@
 #include "llvm/ADT/Sequence.h"
 #include "llvm/ADT/SmallBitVector.h"
 #include "llvm/ADT/StringExtras.h"
+#include "llvm/Config/llvm-config.h"
 #include "llvm/Support/Casting.h"
 #include "llvm/Support/Debug.h"
 #include "llvm/Support/SaveAndRestore.h"
@@ -15711,6 +15712,24 @@ bool FloatExprEvaluator::VisitCallExpr(const CallExpr *E) {
     return true;
   }
 
+  // FIXME: allow other __builtin_exp* to be constexpr.
+  case Builtin::BI__builtin_exp:
+  case Builtin::BI__builtin_expl:
+  case Builtin::BI__builtin_expf16:
+  case Builtin::BI__builtin_expf128:
+    return false;
+  case Builtin::BI__builtin_expf: {
+#ifdef LLVM_INTEGRATE_LIBC
+    APFloat Input(0.);
+    if (!EvaluateFloat(E->getArg(0), Input, Info))
+      return false;
+    Result = exp(Input);
+    return true;
+#else
+    return false;
+#endif // LLVM_INTEGRATE_LIBC
+  }
+
   case Builtin::BI__builtin_fmax:
   case Builtin::BI__builtin_fmaxf:
   case Builtin::BI__builtin_fmaxl:

clang/test/CMakeLists.txt

@@ -27,6 +27,7 @@ llvm_canonicalize_cmake_booleans(
   LLVM_TOOL_LLVM_DRIVER_BUILD
   LLVM_INCLUDE_SPIRV_TOOLS_TESTS
   LLVM_EXPERIMENTAL_KEY_INSTRUCTIONS
+  LLVM_INTEGRATE_LIBC
   )
 
 configure_lit_site_cfg(

clang/test/Preprocessor/feature_tests.cpp

@@ -64,6 +64,16 @@
 #error Clang should have these constexpr builtins
 #endif
 
+#ifdef LLVM_INTEGRATE_LIBC
+#if !__has_constexpr_builtin(__builtin_expf)
+#error Clang should have these constexpr builtins
+#endif
+#else
+#if __has_constexpr_builtin(__builtin_expf)
+#error This builtin should not be constexpr in Clang
+#endif
+#endif // LLVM_INTEGRATE_LIBC
+
 #if !__has_constexpr_builtin(__builtin_convertvector)
 #error Clang should have these constexpr builtins
 #endif

clang/test/Sema/constant-builtins-exp.cpp

@@ -0,0 +1,12 @@
+// RUN: %clang_cc1 -std=c++17 -fsyntax-only -verify %s
+// RUN: %clang_cc1 -std=c++17 -fsyntax-only -verify -fexperimental-new-constant-interpreter %s
+// REQUIRES: llvm_integrate_libc
+// expected-no-diagnostics
+
+constexpr float Inf = __builtin_inff();
+constexpr float NegInf = -__builtin_inff();
+
+static_assert(Inf == __builtin_expf(Inf));
+static_assert(0.0f == __builtin_expf(NegInf));
+static_assert(1.0f == __builtin_expf(0.0f));
+static_assert(0x1.5bf0a8p1f == __builtin_expf(1.0f));

clang/test/lit.cfg.py

@@ -385,3 +385,6 @@ def calculate_arch_features(arch_string):
 # possibly be present in system and user configuration files, so disable
 # default configs for the test runs.
 config.environment["CLANG_NO_DEFAULT_CONFIG"] = "1"
+
+if config.llvm_integrate_libc:
+    config.available_features.add("llvm_integrate_libc")

clang/test/lit.site.cfg.py.in

@@ -49,6 +49,7 @@ config.have_llvm_driver = @LLVM_TOOL_LLVM_DRIVER_BUILD@
 config.spirv_tools_tests = @LLVM_INCLUDE_SPIRV_TOOLS_TESTS@
 config.substitutions.append(("%llvm-version-major", "@LLVM_VERSION_MAJOR@"))
 config.has_key_instructions = @LLVM_EXPERIMENTAL_KEY_INSTRUCTIONS@
+config.llvm_integrate_libc = @LLVM_INTEGRATE_LIBC@
 
 import lit.llvm
 lit.llvm.initialize(lit_config, config)

libc/cmake/modules/LLVMLibCCompileOptionRules.cmake

@@ -106,6 +106,10 @@ function(_get_compile_options_from_config output_var)
     list(APPEND config_options "-DLIBC_MATH=${LIBC_CONF_MATH_OPTIMIZATIONS}")
   endif()
 
+  if(LIBC_CONF_ERRNO_MODE)
+    set(APPEND config_options "-DLIBC_ERRNO_MODE=${LIBC_CONF_ERRNO_MODE}")
+  endif()
+
   set(${output_var} ${config_options} PARENT_SCOPE)
 endfunction(_get_compile_options_from_config)
 

libc/cmake/modules/LLVMLibCTestRules.cmake

@@ -1,5 +1,6 @@
 function(_get_common_test_compile_options output_var c_test flags)
   _get_compile_options_from_flags(compile_flags ${flags})
+  _get_compile_options_from_config(config_flags)
 
   # Remove -fno-math-errno if it was added.
   if(LIBC_ADD_FNO_MATH_ERRNO)
@@ -9,7 +10,8 @@ function(_get_common_test_compile_options output_var c_test flags)
   set(compile_options
       ${LIBC_COMPILE_OPTIONS_DEFAULT}
       ${LIBC_TEST_COMPILE_OPTIONS_DEFAULT}
-      ${compile_flags})
+      ${compile_flags}
+      ${config_flags})
 
   if(LLVM_LIBC_COMPILER_IS_GCC_COMPATIBLE)
     list(APPEND compile_options "-fpie")

libc/docs/configure.rst

@@ -33,7 +33,7 @@ to learn about the defaults for your platform and target.
 * **"general" options**
     - ``LIBC_ADD_NULL_CHECKS``: Add nullptr checks in the library's implementations to some functions for which passing nullptr is undefined behavior.
 * **"math" options**
-    - ``LIBC_CONF_FREXP_INF_NAN_EXPONENT``: The value written back to the second parameter when calling frexp/frexpf/frexpl` with `+/-Inf`/`NaN` is unspecified.  Configure an explicit exp value for Inf/NaN inputs.
+    - ``LIBC_CONF_FREXP_INF_NAN_EXPONENT``: The value written back to the second parameter when calling frexp/frexpf/frexpl` with `+/-Inf`/`NaN` is unspecified.  Configue an explicit exp value for Inf/NaN inputs.
     - ``LIBC_CONF_MATH_OPTIMIZATIONS``: Configures optimizations for math functions. Values accepted are LIBC_MATH_SKIP_ACCURATE_PASS, LIBC_MATH_SMALL_TABLES, LIBC_MATH_NO_ERRNO, LIBC_MATH_NO_EXCEPT, and LIBC_MATH_FAST.
 * **"printf" options**
     - ``LIBC_CONF_PRINTF_DISABLE_FIXED_POINT``: Disable printing fixed point values in printf and friends.

libc/docs/dev/code_style.rst

@@ -101,7 +101,7 @@ test infrastructure itself can be affected. To avoid perturbing the unit test
 infrastructure around the setting of ``errno``, the following rules are to be
 followed:
 
-#. A special macro named ``libc_errno`` defined in ``src/errno/libc_errno.h``
+#. A special macro named ``libc_errno`` defined in ``src/__support/libc_errno.h``
    should be used when setting ``errno`` from libc runtime code. For example,
    code to set ``errno`` to ``EINVAL`` should be:
 
@@ -117,7 +117,7 @@ followed:
    `ErrorOr <https://github.com/llvm/llvm-project/blob/main/libc/src/__support/error_or.h>`_
    to return error values.
 
-#. The header file ``src/errno/libc_errno.h`` is shipped as part of the target
+#. The header file ``src/__support/libc_errno.h`` is shipped as part of the target
    corresponding to the ``errno`` entrypoint ``libc.src.errno.errno``. We do
    not in general allow dependencies between entrypoints. However, the ``errno``
    entrypoint is the only exceptional entrypoint on which other entrypoints

libc/shared/math.h

@@ -0,0 +1,22 @@
+//===-- Floating point math functions ---------------------------*- C++ -*-===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_LIBC_SHARED_MATH_H
+#define LLVM_LIBC_SHARED_MATH_H
+
+#include "src/__support/math/expf.h"
+
+namespace LIBC_NAMESPACE_DECL {
+namespace shared {
+
+using math::expf;
+
+} // namespace shared
+} // namespace LIBC_NAMESPACE_DECL
+
+#endif // LLVM_LIBC_SHARED_FP_BITS_H

libc/src/__support/CMakeLists.txt

@@ -381,3 +381,5 @@ add_subdirectory(HashTable)
 add_subdirectory(fixed_point)
 
 add_subdirectory(time)
+
+add_subdirectory(math)

libc/src/__support/FPUtil/FEnvImpl.h

@@ -12,10 +12,10 @@
 #include "hdr/fenv_macros.h"
 #include "hdr/math_macros.h"
 #include "hdr/types/fenv_t.h"
+#include "src/__support/libc_errno.h"
 #include "src/__support/macros/attributes.h" // LIBC_INLINE
 #include "src/__support/macros/config.h"
 #include "src/__support/macros/properties/architectures.h"
-#include "src/errno/libc_errno.h"
 
 #if defined(LIBC_TARGET_ARCH_IS_AARCH64) && defined(__ARM_FP)
 #if defined(__APPLE__)

libc/src/__support/File/dir.cpp

@@ -11,8 +11,8 @@
 #include "src/__support/CPP/mutex.h" // lock_guard
 #include "src/__support/CPP/new.h"
 #include "src/__support/error_or.h"
+#include "src/__support/libc_errno.h" // For error macros
 #include "src/__support/macros/config.h"
-#include "src/errno/libc_errno.h" // For error macros
 
 namespace LIBC_NAMESPACE_DECL {
 

libc/src/__support/File/file.cpp

@@ -13,8 +13,8 @@
 #include "hdr/types/off_t.h"
 #include "src/__support/CPP/new.h"
 #include "src/__support/CPP/span.h"
+#include "src/__support/libc_errno.h" // For error macros
 #include "src/__support/macros/config.h"
-#include "src/errno/libc_errno.h" // For error macros
 
 namespace LIBC_NAMESPACE_DECL {
 

libc/src/__support/File/linux/file.cpp

@@ -15,8 +15,8 @@
 #include "src/__support/File/linux/lseekImpl.h"
 #include "src/__support/OSUtil/fcntl.h"
 #include "src/__support/OSUtil/syscall.h" // For internal syscall function.
+#include "src/__support/libc_errno.h"     // For error macros
 #include "src/__support/macros/config.h"
-#include "src/errno/libc_errno.h" // For error macros
 
 #include "hdr/fcntl_macros.h" // For mode_t and other flags to the open syscall
 #include <sys/stat.h>    // For S_IS*, S_IF*, and S_IR* flags.

libc/src/__support/File/linux/lseekImpl.h

@@ -13,8 +13,8 @@
 #include "src/__support/OSUtil/syscall.h" // For internal syscall function.
 #include "src/__support/common.h"
 #include "src/__support/error_or.h"
+#include "src/__support/libc_errno.h"
 #include "src/__support/macros/config.h"
-#include "src/errno/libc_errno.h"
 
 #include <stdint.h>      // For uint64_t.
 #include <sys/syscall.h> // For syscall numbers.

libc/src/__support/HashTable/randomness.h

@@ -14,7 +14,7 @@
 #include "src/__support/macros/attributes.h"
 #include "src/__support/macros/config.h"
 #if defined(LIBC_HASHTABLE_USE_GETRANDOM)
-#include "src/errno/libc_errno.h"
+#include "src/__support/libc_errno.h"
 #include "src/sys/random/getrandom.h"
 #endif
 

libc/src/__support/OSUtil/linux/fcntl.cpp

@@ -15,8 +15,8 @@
 #include "hdr/types/struct_flock64.h"
 #include "src/__support/OSUtil/syscall.h" // For internal syscall function.
 #include "src/__support/common.h"
+#include "src/__support/libc_errno.h"
 #include "src/__support/macros/config.h"
-#include "src/errno/libc_errno.h"
 
 #include <stdarg.h>
 #include <sys/syscall.h> // For syscall numbers.

libc/src/__support/OSUtil/linux/vdso.cpp

@@ -11,9 +11,9 @@
 #include "src/__support/CPP/array.h"
 #include "src/__support/CPP/optional.h"
 #include "src/__support/CPP/string_view.h"
+#include "src/__support/libc_errno.h"
 #include "src/__support/threads/callonce.h"
 #include "src/__support/threads/linux/futex_word.h"
-#include "src/errno/libc_errno.h"
 #include "src/sys/auxv/getauxval.h"
 #include <linux/auxvec.h>
 

libc/src/__support/StringUtil/tables/linux_extension_errors.h

@@ -10,8 +10,8 @@
 #define LLVM_LIBC_SRC___SUPPORT_STRINGUTIL_TABLES_LINUX_EXTENSION_ERRORS_H
 
 #include "src/__support/StringUtil/message_mapper.h"
+#include "src/__support/libc_errno.h"
 #include "src/__support/macros/config.h"
-#include "src/errno/libc_errno.h"
 
 namespace LIBC_NAMESPACE_DECL {