Only account for debuginfo if the user requests it.

Author: cjgillot

compiler/rustc_mir_transform/src/dead_store_elimination.rs

@@ -12,6 +12,7 @@
 //!     will still not cause any further changes.
 //!
 
+use crate::simplify::preserve_debug_even_if_never_generated;
 use crate::util::is_within_packed;
 use rustc_middle::bug;
 use rustc_middle::mir::visit::Visitor;
@@ -32,10 +33,16 @@ pub fn eliminate<'tcx>(tcx: TyCtxt<'tcx>, body: &mut Body<'tcx>) {
 
     // If the user requests complete debuginfo, mark the locals that appear in it as live, so
     // we don't remove assignements to them.
-    let mut always_live = debuginfo_locals(body);
-    always_live.union(&borrowed_locals);
-
-    let mut live = MaybeTransitiveLiveLocals::new(&always_live)
+    let mut always_live;
+    let always_live = if preserve_debug_even_if_never_generated(tcx) {
+        always_live = debuginfo_locals(body);
+        always_live.union(&borrowed_locals);
+        &always_live
+    } else {
+        &borrowed_locals
+    };
+
+    let mut live = MaybeTransitiveLiveLocals::new(always_live)
         .into_engine(tcx, body)
         .iterate_to_fixpoint()
         .into_results_cursor(body);

compiler/rustc_mir_transform/src/inline.rs

@@ -12,14 +12,14 @@ use rustc_middle::mir::visit::*;
 use rustc_middle::mir::*;
 use rustc_middle::ty::TypeVisitableExt;
 use rustc_middle::ty::{self, Instance, InstanceKind, ParamEnv, Ty, TyCtxt, TypeFlags};
-use rustc_session::config::{DebugInfo, OptLevel};
+use rustc_session::config::OptLevel;
 use rustc_span::source_map::Spanned;
 use rustc_span::sym;
 use rustc_target::abi::FieldIdx;
 use rustc_target::spec::abi::Abi;
 
 use crate::cost_checker::CostChecker;
-use crate::simplify::simplify_cfg;
+use crate::simplify::{preserve_debug_even_if_never_generated, simplify_cfg};
 use crate::util;
 use crate::validate::validate_types;
 use std::iter;
@@ -696,14 +696,7 @@ impl<'tcx> Inliner<'tcx> {
         // Insert all of the (mapped) parts of the callee body into the caller.
         caller_body.local_decls.extend(callee_body.drain_vars_and_temps());
         caller_body.source_scopes.extend(&mut callee_body.source_scopes.drain(..));
-        if self
-            .tcx
-            .sess
-            .opts
-            .unstable_opts
-            .inline_mir_preserve_debug
-            .unwrap_or(self.tcx.sess.opts.debuginfo != DebugInfo::None)
-        {
+        if preserve_debug_even_if_never_generated(self.tcx) {
             // Note that we need to preserve these in the standard library so that
             // people working on rust can build with or without debuginfo while
             // still getting consistent results from the mir-opt tests.

compiler/rustc_mir_transform/src/simplify.rs

@@ -31,6 +31,7 @@ use rustc_index::{Idx, IndexSlice, IndexVec};
 use rustc_middle::mir::visit::{MutVisitor, MutatingUseContext, PlaceContext, Visitor};
 use rustc_middle::mir::*;
 use rustc_middle::ty::TyCtxt;
+use rustc_session::config::DebugInfo;
 use smallvec::SmallVec;
 
 pub enum SimplifyCfg {
@@ -581,3 +582,12 @@ impl<'tcx> MutVisitor<'tcx> for LocalUpdater<'tcx> {
         *l = self.map[*l].unwrap();
     }
 }
+
+pub(crate) fn preserve_debug_even_if_never_generated(tcx: TyCtxt<'_>) -> bool {
+    tcx.sess.opts.unstable_opts.inline_mir_preserve_debug.unwrap_or_else(|| {
+        match tcx.sess.opts.debuginfo {
+            DebugInfo::None | DebugInfo::LineDirectivesOnly | DebugInfo::LineTablesOnly => false,
+            DebugInfo::Limited | DebugInfo::Full => true,
+        }
+    })
+}

tests/codegen/slice-ref-equality.rs

@@ -1,4 +1,4 @@
-//@ compile-flags: -O -Zmerge-functions=disabled
+//@ compile-flags: -O -Zmerge-functions=disabled -Cdebuginfo=0
 #![crate_type = "lib"]
 
 use std::num::NonZero;

tests/crashes/101962.rs

@@ -1,4 +1,5 @@
 //@ known-bug: #101962
+//@ compile-flags: -Cdebuginfo=2
 
 #![feature(core_intrinsics)]
 

tests/crashes/79409.rs

@@ -1,4 +1,5 @@
 //@ known-bug: #79409
+//@ compile-flags: -Cdebuginfo=2
 
 #![feature(extern_types)]
 #![feature(unsized_locals)]

tests/incremental/hashes/enum_constructors.rs

@@ -318,9 +318,9 @@ pub fn change_constructor_variant_c_like() {
 }
 
 #[cfg(not(any(cfail1,cfail4)))]
-#[rustc_clean(cfg="cfail2", except="opt_hir_owner_nodes,optimized_mir")]
+#[rustc_clean(cfg="cfail2", except="opt_hir_owner_nodes")]
 #[rustc_clean(cfg="cfail3")]
-#[rustc_clean(cfg="cfail5", except="opt_hir_owner_nodes,optimized_mir")]
+#[rustc_clean(cfg="cfail5", except="opt_hir_owner_nodes")]
 #[rustc_clean(cfg="cfail6")]
 pub fn change_constructor_variant_c_like() {
     let _x = Clike::C;

tests/incremental/hashes/for_loops.rs

@@ -28,9 +28,9 @@ pub fn change_loop_body() {
 }
 
 #[cfg(not(any(cfail1,cfail4)))]
-#[rustc_clean(cfg="cfail2", except="opt_hir_owner_nodes, optimized_mir")]
+#[rustc_clean(cfg="cfail2", except="opt_hir_owner_nodes")]
 #[rustc_clean(cfg="cfail3")]
-#[rustc_clean(cfg="cfail5", except="opt_hir_owner_nodes, optimized_mir")]
+#[rustc_clean(cfg="cfail5", except="opt_hir_owner_nodes")]
 #[rustc_clean(cfg="cfail6")]
 pub fn change_loop_body() {
     let mut _x = 0;
@@ -180,7 +180,7 @@ pub fn add_loop_label_to_break() {
 #[cfg(not(any(cfail1,cfail4)))]
 #[rustc_clean(cfg="cfail2", except="opt_hir_owner_nodes")]
 #[rustc_clean(cfg="cfail3")]
-#[rustc_clean(cfg="cfail5", except="opt_hir_owner_nodes, optimized_mir")]
+#[rustc_clean(cfg="cfail5", except="opt_hir_owner_nodes")]
 #[rustc_clean(cfg="cfail6")]
 pub fn add_loop_label_to_break() {
     let mut _x = 0;

tests/incremental/hashes/let_expressions.rs

@@ -91,7 +91,7 @@ pub fn change_mutability_of_slot() {
 }
 
 #[cfg(not(any(cfail1,cfail4)))]
-#[rustc_clean(cfg="cfail2", except="opt_hir_owner_nodes,typeck")]
+#[rustc_clean(cfg="cfail2", except="opt_hir_owner_nodes,typeck,optimized_mir")]
 #[rustc_clean(cfg="cfail3")]
 #[rustc_clean(cfg="cfail5", except="opt_hir_owner_nodes,typeck,optimized_mir")]
 #[rustc_clean(cfg="cfail6")]
@@ -176,7 +176,7 @@ pub fn change_mutability_of_binding_in_pattern() {
 }
 
 #[cfg(not(any(cfail1,cfail4)))]
-#[rustc_clean(cfg="cfail2", except="opt_hir_owner_nodes,typeck")]
+#[rustc_clean(cfg="cfail2", except="opt_hir_owner_nodes,typeck,optimized_mir")]
 #[rustc_clean(cfg="cfail3")]
 #[rustc_clean(cfg="cfail5", except="opt_hir_owner_nodes,typeck,optimized_mir")]
 #[rustc_clean(cfg="cfail6")]
@@ -193,9 +193,9 @@ pub fn add_initializer() {
 }
 
 #[cfg(not(any(cfail1,cfail4)))]
-#[rustc_clean(cfg="cfail2", except="opt_hir_owner_nodes,typeck,optimized_mir")]
+#[rustc_clean(cfg="cfail2", except="opt_hir_owner_nodes,typeck")]
 #[rustc_clean(cfg="cfail3")]
-#[rustc_clean(cfg="cfail5", except="opt_hir_owner_nodes,typeck,optimized_mir")]
+#[rustc_clean(cfg="cfail5", except="opt_hir_owner_nodes,typeck")]
 #[rustc_clean(cfg="cfail6")]
 pub fn add_initializer() {
     let _x: i16 = 3i16;
@@ -210,9 +210,9 @@ pub fn change_initializer() {
 }
 
 #[cfg(not(any(cfail1,cfail4)))]
-#[rustc_clean(cfg="cfail2", except="opt_hir_owner_nodes, optimized_mir")]
+#[rustc_clean(cfg="cfail2", except="opt_hir_owner_nodes")]
 #[rustc_clean(cfg="cfail3")]
-#[rustc_clean(cfg="cfail5", except="opt_hir_owner_nodes, optimized_mir")]
+#[rustc_clean(cfg="cfail5", except="opt_hir_owner_nodes")]
 #[rustc_clean(cfg="cfail6")]
 pub fn change_initializer() {
     let _x = 5u16;

tests/incremental/hashes/loop_expressions.rs

@@ -28,9 +28,9 @@ pub fn change_loop_body() {
 }
 
 #[cfg(not(any(cfail1,cfail4)))]
-#[rustc_clean(cfg="cfail2", except="opt_hir_owner_nodes, optimized_mir")]
+#[rustc_clean(cfg="cfail2", except="opt_hir_owner_nodes")]
 #[rustc_clean(cfg="cfail3")]
-#[rustc_clean(cfg="cfail5", except="opt_hir_owner_nodes, optimized_mir")]
+#[rustc_clean(cfg="cfail5", except="opt_hir_owner_nodes")]
 #[rustc_clean(cfg="cfail6")]
 pub fn change_loop_body() {
     let mut _x = 0;