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authorAnders Carlsson <andersca@mac.com>2011-01-30 20:45:54 +0000
committerAnders Carlsson <andersca@mac.com>2011-01-30 20:45:54 +0000
commita03f3a85cb8d7ed86943c12030088fddc05ba1b3 (patch)
treef05b7b39bc94045d4e2dd8f8ac46b4cc732b7b9c /clang/lib/CodeGen/CodeGenModule.cpp
parent9af7afcb7f834ff7a4b78a284051c53db984007c (diff)
downloadbcm5719-llvm-a03f3a85cb8d7ed86943c12030088fddc05ba1b3.tar.gz
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When building with optimizations, emit vtables where the key is not in the
current translation unit as available_externally. This helps devirtualize the second example in PR3100, comment 18: struct S { S() {}; virtual void xyzzy(); }; inline void foo(S *s) { s->xyzzy(); } void bar() { S s; foo(&s); } This involved four major changes: 1. In DefineUsedVTables, always mark virtual member functions as referenced for non-template classes and class template specializations. 2. In CodeGenVTables::ShouldEmitVTableInThisTU return true if optimizations are enabled, even if the key function is not implemented in this translation unit. We don't ever do this for code compiled with -fapple-kext, because we don't ever want to devirtualize virtual member function calls in that case. 3. Give the correct linkage for vtables where the key function is not defined. 4. Update the linkage for RTTI structures when necessary. llvm-svn: 124565
Diffstat (limited to 'clang/lib/CodeGen/CodeGenModule.cpp')
-rw-r--r--clang/lib/CodeGen/CodeGenModule.cpp6
1 files changed, 6 insertions, 0 deletions
diff --git a/clang/lib/CodeGen/CodeGenModule.cpp b/clang/lib/CodeGen/CodeGenModule.cpp
index acf2592c249..b8f91b464dd 100644
--- a/clang/lib/CodeGen/CodeGenModule.cpp
+++ b/clang/lib/CodeGen/CodeGenModule.cpp
@@ -1082,6 +1082,12 @@ CodeGenModule::getVTableLinkage(const CXXRecordDecl *RD) {
switch (KeyFunction->getTemplateSpecializationKind()) {
case TSK_Undeclared:
case TSK_ExplicitSpecialization:
+ // When compiling with optimizations turned on, we emit all vtables,
+ // even if the key function is not defined in the current translation
+ // unit. If this is the case, use available_externally linkage.
+ if (!Def && CodeGenOpts.OptimizationLevel)
+ return llvm::GlobalVariable::AvailableExternallyLinkage;
+
if (KeyFunction->isInlined())
return llvm::GlobalVariable::LinkOnceODRLinkage;
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