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

4 files changed, 47 insertions, 16 deletions

diff --git a/lib/CodeGen/CGBlocks.cpp b/lib/CodeGen/CGBlocks.cpp
index c521bf9472..77e29bd119 100644
--- a/lib/CodeGen/CGBlocks.cpp
+++ b/lib/CodeGen/CGBlocks.cpp
@@ -1157,10 +1157,24 @@ CodeGenFunction::GenerateBlockFunction(GlobalDecl GD,
     // There might not be a capture for 'self', but if there is...
     if (blockInfo.Captures.count(self)) {
       const CGBlockInfo::Capture &capture = blockInfo.getCapture(self);
+
       llvm::Value *selfAddr = Builder.CreateStructGEP(BlockPointer,
                                                       capture.getIndex(),
                                                       "block.captured-self");
-      LocalDeclMap[self] = selfAddr;
+
+      // At -O0 we generate an explicit alloca for self to facilitate debugging.
+      if (CGM.getCodeGenOpts().OptimizationLevel == 0) {
+	llvm::Value *load = Builder.CreateLoad(selfAddr);
+
+	// Allocate a stack slot for it, so we can generate debug info for it
+	llvm::AllocaInst *alloca = CreateTempAlloca(load->getType(),
+                                                   "block.captured-self.addr");
+        unsigned align = getContext().getDeclAlign(self).getQuantity();
+        alloca->setAlignment(align);
+	Builder.CreateAlignedStore(load, alloca, align);
+        LocalDeclMap[self] = alloca;
+      } else
+        LocalDeclMap[self] = selfAddr;
     }
   }
 
@@ -1177,7 +1191,7 @@ CodeGenFunction::GenerateBlockFunction(GlobalDecl GD,
       CreateMemTemp(variable->getType(), "block.captured-const");
     alloca->setAlignment(align);
 
-    Builder.CreateStore(capture.getConstant(), alloca, align);
+    Builder.CreateAlignedStore(capture.getConstant(), alloca, align);
 
     LocalDeclMap[variable] = alloca;
   }
diff --git a/lib/CodeGen/CGDebugInfo.cpp b/lib/CodeGen/CGDebugInfo.cpp
index 4aed943689..6b0edbcafe 100644
--- a/lib/CodeGen/CGDebugInfo.cpp
+++ b/lib/CodeGen/CGDebugInfo.cpp
@@ -2680,7 +2680,8 @@ namespace {
 }
 
 void CGDebugInfo::EmitDeclareOfBlockLiteralArgVariable(const CGBlockInfo &block,
-                                                       llvm::Value *addr,
+                                                       llvm::Value *Arg,
+                                                       llvm::Value *LocalAddr,
                                                        CGBuilderTy &Builder) {
   assert(CGM.getCodeGenOpts().getDebugInfo() >= CodeGenOptions::LimitedDebugInfo);
   ASTContext &C = CGM.getContext();
@@ -2807,21 +2808,26 @@ void CGDebugInfo::EmitDeclareOfBlockLiteralArgVariable(const CGBlockInfo &block,
   // Get overall information about the block.
   unsigned flags = llvm::DIDescriptor::FlagArtificial;
   llvm::MDNode *scope = LexicalBlockStack.back();
-  StringRef name = ".block_descriptor";
 
   // Create the descriptor for the parameter.
   llvm::DIVariable debugVar =
     DBuilder.createLocalVariable(llvm::dwarf::DW_TAG_arg_variable,
                                  llvm::DIDescriptor(scope), 
-                                 name, tunit, line, type, 
+                                 Arg->getName(), tunit, line, type,
                                  CGM.getLangOpts().Optimize, flags,
-                                 cast<llvm::Argument>(addr)->getArgNo() + 1);
-    
-  // Insert an llvm.dbg.value into the current block.
-  llvm::Instruction *declare =
-    DBuilder.insertDbgValueIntrinsic(addr, 0, debugVar,
-                                     Builder.GetInsertBlock());
-  declare->setDebugLoc(llvm::DebugLoc::get(line, column, scope));
+                                 cast<llvm::Argument>(Arg)->getArgNo() + 1);
+
+  // Matching the code in EmitParmDecl, depending on optimization level.
+  llvm::Instruction *Call;
+  if (LocalAddr)
+    // Insert an llvm.dbg.value into the current block.
+    Call = DBuilder.insertDbgValueIntrinsic(LocalAddr, 0, debugVar,
+                                            Builder.GetInsertBlock());
+  else
+    // Insert an llvm.dbg.declare into the current block.
+    Call = DBuilder.insertDeclare(Arg, debugVar, Builder.GetInsertBlock());
+
+  Call->setDebugLoc(llvm::DebugLoc::get(line, column, scope));
 }
 
 /// getStaticDataMemberDeclaration - If D is an out-of-class definition of
diff --git a/lib/CodeGen/CGDebugInfo.h b/lib/CodeGen/CGDebugInfo.h
index 73dd15317e..0d9c92e24d 100644
--- a/lib/CodeGen/CGDebugInfo.h
+++ b/lib/CodeGen/CGDebugInfo.h
@@ -248,7 +248,8 @@ public:
   /// llvm.dbg.declare for the block-literal argument to a block
   /// invocation function.
   void EmitDeclareOfBlockLiteralArgVariable(const CGBlockInfo &block,
-                                            llvm::Value *addr,
+                                            llvm::Value *Arg,
+                                            llvm::Value *LocalAddr,
                                             CGBuilderTy &Builder);
 
   /// EmitGlobalVariable - Emit information about a global variable.
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() ||