[PATCH] D46685: [CodeGen] Disable structor optimizations at -O0

[Pavel Labath via Phabricator via cfe-commits]

This revision was automatically updated to reflect the committed changes.
Closed by commit rC332228: [CodeGen] Disable aggressive structor optimizations at -O0 (authored by labath, committed by ).

Changed prior to commit:
  https://reviews.llvm.org/D46685?vs=146309&id=146578#toc

Repository:
  rC Clang

https://reviews.llvm.org/D46685

Files:
  lib/CodeGen/ItaniumCXXABI.cpp
  test/CodeGenCXX/ctor-dtor-alias.cpp
  test/CodeGenCXX/float16-declarations.cpp


Index: test/CodeGenCXX/float16-declarations.cpp
===================================================================
--- test/CodeGenCXX/float16-declarations.cpp
+++ test/CodeGenCXX/float16-declarations.cpp
@@ -103,7 +103,7 @@
 
   C1 c1(f1l);
 // CHECK-DAG:  [[F1L:%[a-z0-9]+]] = load half, half* %{{.*}}, align 2
-// CHECK-DAG:  call void @_ZN2C1C2EDF16_(%class.C1* %{{.*}}, half %{{.*}})
+// CHECK-DAG:  call void @_ZN2C1C1EDF16_(%class.C1* %{{.*}}, half %{{.*}})
 
   S1<_Float16> s1 = { 132.f16 };
 // CHECK-DAG: @_ZZ4mainE2s1 = private unnamed_addr constant %struct.S1 { half 0xH5820 }, align 2
Index: test/CodeGenCXX/ctor-dtor-alias.cpp
===================================================================
--- test/CodeGenCXX/ctor-dtor-alias.cpp
+++ test/CodeGenCXX/ctor-dtor-alias.cpp
@@ -77,11 +77,12 @@
   // CHECK1: call i32 @__cxa_atexit{{.*}}_ZN5test41AD2Ev
   // CHECK1: define linkonce_odr void @_ZN5test41AD2Ev({{.*}} comdat align
 
-  // test that we don't do this optimization at -O0 so that the debugger can
-  // see both destructors.
+  // test that we don't do this optimization at -O0 and call the complete
+  // destructor for B instead. This enables the debugger to see both
+  // destructors.
+  // NOOPT: @_ZN5test41BD1Ev = linkonce_odr alias void {{.*}} @_ZN5test41BD2Ev
   // NOOPT: define internal void @__cxx_global_var_init.2()
-  // NOOPT: call i32 @__cxa_atexit{{.*}}@_ZN5test41BD2Ev
-  // NOOPT: define linkonce_odr void @_ZN5test41BD2Ev({{.*}} comdat align
+  // NOOPT: call i32 @__cxa_atexit{{.*}}@_ZN5test41BD1Ev
   struct A {
     virtual ~A() {}
   };
Index: lib/CodeGen/ItaniumCXXABI.cpp
===================================================================
--- lib/CodeGen/ItaniumCXXABI.cpp
+++ lib/CodeGen/ItaniumCXXABI.cpp
@@ -3630,12 +3630,16 @@
   }
   llvm::GlobalValue::LinkageTypes Linkage = CGM.getFunctionLinkage(AliasDecl);
 
-  if (llvm::GlobalValue::isDiscardableIfUnused(Linkage))
-    return StructorCodegen::RAUW;
-
-  // FIXME: Should we allow available_externally aliases?
-  if (!llvm::GlobalAlias::isValidLinkage(Linkage))
-    return StructorCodegen::RAUW;
+  // Only use RAUW in optimized code, as it makes the complete structor symbol
+  // disappear completely, which degrades debugging experience.
+  if (CGM.getCodeGenOpts().OptimizationLevel > 0) {
+    if (llvm::GlobalValue::isDiscardableIfUnused(Linkage))
+      return StructorCodegen::RAUW;
+
+    // FIXME: Should we allow available_externally aliases?
+    if (!llvm::GlobalAlias::isValidLinkage(Linkage))
+      return StructorCodegen::RAUW;
+  }
 
   if (llvm::GlobalValue::isWeakForLinker(Linkage)) {
     // Only ELF and wasm support COMDATs with arbitrary names (C5/D5).


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