Allocate stack storage for .block_descriptor and captured self at -O0.

This way the register allocator will not optimize away the debug info
for captured variables.

Fixes rdar://problem/12767564

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@177086 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 13 insertions, 3 deletions

diff --git a/lib/CodeGen/CGDecl.cpp b/lib/CodeGen/CGDecl.cpp
index f9f48ae9ca..3b33c11b04 100644
--- a/lib/CodeGen/CGDecl.cpp
+++ b/lib/CodeGen/CGDecl.cpp
@@ -1513,17 +1513,29 @@ void CodeGenFunction::EmitParmDecl(const VarDecl &D, llvm::Value *Arg,
 
   Arg->setName(D.getName());
 
+  QualType Ty = D.getType();
+
   // Use better IR generation for certain implicit parameters.
   if (isa<ImplicitParamDecl>(D)) {
     // The only implicit argument a block has is its literal.
     if (BlockInfo) {
       LocalDeclMap[&D] = Arg;
+      llvm::Value *LocalAddr = 0;
+      if (CGM.getCodeGenOpts().OptimizationLevel == 0) {
+        // Allocate a stack slot to let debug info survive the RA.
+        llvm::AllocaInst *Alloc = CreateTempAlloca(ConvertTypeForMem(Ty),
+                                                   D.getName() + ".addr");
+        Alloc->setAlignment(getContext().getDeclAlign(&D).getQuantity());
+        LValue lv = MakeAddrLValue(Alloc, Ty, getContext().getDeclAlign(&D));
+        EmitStoreOfScalar(Arg, lv, /* isInitialization */ true);
+        LocalAddr = Builder.CreateLoad(Alloc);
+      }
 
       if (CGDebugInfo *DI = getDebugInfo()) {
         if (CGM.getCodeGenOpts().getDebugInfo()
               >= CodeGenOptions::LimitedDebugInfo) {
           DI->setLocation(D.getLocation());
-          DI->EmitDeclareOfBlockLiteralArgVariable(*BlockInfo, Arg, Builder);
+          DI->EmitDeclareOfBlockLiteralArgVariable(*BlockInfo, Arg, LocalAddr, Builder);
         }
       }
 
@@ -1531,8 +1543,6 @@ void CodeGenFunction::EmitParmDecl(const VarDecl &D, llvm::Value *Arg,
     }
   }
 
-  QualType Ty = D.getType();
-
   llvm::Value *DeclPtr;
   // If this is an aggregate or variable sized value, reuse the input pointer.
   if (!Ty->isConstantSizeType() ||