Do not generate LLVM IR for available_externally function bodies at
-O0, since we won't be using the definitions for anything anyway. For
lib/System/Path.o when built in Debug+Asserts mode, this leads to a 4%
improvement in compile time (and suppresses 440 function bodies).
<rdar://problem/7987644>
git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@108156 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/CodeGen/CodeGenModule.cpp b/lib/CodeGen/CodeGenModule.cpp
index cb83ffd..d544d4c 100644
--- a/lib/CodeGen/CodeGenModule.cpp
+++ b/lib/CodeGen/CodeGenModule.cpp
@@ -817,14 +817,22 @@
if (Method->isVirtual())
getVTables().EmitThunks(GD);
- if (const CXXConstructorDecl *CD = dyn_cast<CXXConstructorDecl>(D))
- return EmitCXXConstructor(CD, GD.getCtorType());
+ if (const FunctionDecl *Function = dyn_cast<FunctionDecl>(D)) {
+ // At -O0, don't generate IR for functions with available_externally
+ // linkage.
+ if (CodeGenOpts.OptimizationLevel == 0 &&
+ getFunctionLinkage(Function)
+ == llvm::Function::AvailableExternallyLinkage)
+ return;
+
+ if (const CXXConstructorDecl *CD = dyn_cast<CXXConstructorDecl>(Function))
+ return EmitCXXConstructor(CD, GD.getCtorType());
- if (const CXXDestructorDecl *DD = dyn_cast<CXXDestructorDecl>(D))
- return EmitCXXDestructor(DD, GD.getDtorType());
+ if (const CXXDestructorDecl *DD = dyn_cast<CXXDestructorDecl>(Function))
+ return EmitCXXDestructor(DD, GD.getDtorType());
- if (isa<FunctionDecl>(D))
return EmitGlobalFunctionDefinition(GD);
+ }
if (const VarDecl *VD = dyn_cast<VarDecl>(D))
return EmitGlobalVarDefinition(VD);