From: Anders Carlsson <andersca@mac.com>
Date: Fri, 12 Dec 2008 05:52:00 +0000 (+0000)
Subject: Work in preparation for VLAs. Make sure to restore the stack if necessary (Saving... 
X-Git-Url: https://granicus.if.org/sourcecode?a=commitdiff_plain;h=17d28a3e0b0efaba14534d0e6d6a307283d96b9f;p=clang

Work in preparation for VLAs. Make sure to restore the stack if necessary (Saving the stack isn't implemented right now :)

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@60925 91177308-0d34-0410-b5e6-96231b3b80d8
---

diff --git a/lib/CodeGen/CGStmt.cpp b/lib/CodeGen/CGStmt.cpp
index 0a67e57e34..1c5cb90cbe 100644
--- a/lib/CodeGen/CGStmt.cpp
+++ b/lib/CodeGen/CGStmt.cpp
@@ -16,8 +16,9 @@
 #include "CodeGenFunction.h"
 #include "clang/AST/StmtVisitor.h"
 #include "clang/Basic/TargetInfo.h"
-#include "llvm/InlineAsm.h"
 #include "llvm/ADT/StringExtras.h"
+#include "llvm/InlineAsm.h"
+#include "llvm/Intrinsics.h"
 using namespace clang;
 using namespace CodeGen;
 
@@ -129,6 +130,9 @@ RValue CodeGenFunction::EmitCompoundStmt(const CompoundStmt &S, bool GetLast,
     DI->EmitRegionStart(CurFn, Builder);
   }
 
+  // Push a null stack save value.
+  StackSaveValues.push_back(0);
+  
   for (CompoundStmt::const_body_iterator I = S.body_begin(),
        E = S.body_end()-GetLast; I != E; ++I)
     EmitStmt(*I);
@@ -139,22 +143,33 @@ RValue CodeGenFunction::EmitCompoundStmt(const CompoundStmt &S, bool GetLast,
     DI->EmitRegionEnd(CurFn, Builder);
   }
 
-  if (!GetLast)
-    return RValue::get(0);
+  RValue RV;
+  if (!GetLast) 
+    RV = RValue::get(0);
+  else {
+    // We have to special case labels here.  They are statements, but when put 
+    // at the end of a statement expression, they yield the value of their
+    // subexpression.  Handle this by walking through all labels we encounter,
+    // emitting them before we evaluate the subexpr.
+    const Stmt *LastStmt = S.body_back();
+    while (const LabelStmt *LS = dyn_cast<LabelStmt>(LastStmt)) {
+      EmitLabel(*LS);
+      LastStmt = LS->getSubStmt();
+    }
   
-  // We have to special case labels here.  They are statements, but when put at
-  // the end of a statement expression, they yield the value of their
-  // subexpression.  Handle this by walking through all labels we encounter,
-  // emitting them before we evaluate the subexpr.
-  const Stmt *LastStmt = S.body_back();
-  while (const LabelStmt *LS = dyn_cast<LabelStmt>(LastStmt)) {
-    EmitLabel(*LS);
-    LastStmt = LS->getSubStmt();
+    EnsureInsertPoint();
+    
+    RV = EmitAnyExpr(cast<Expr>(LastStmt), AggLoc);
   }
-  
-  EnsureInsertPoint();
 
-  return EmitAnyExpr(cast<Expr>(LastStmt), AggLoc);
+  if (llvm::Value *V = StackSaveValues.pop_back_val()) {
+    V = Builder.CreateLoad(V, "tmp");
+    
+    llvm::Value *F = CGM.getIntrinsic(llvm::Intrinsic::stackrestore);
+    Builder.CreateCall(F, V);
+  }
+  
+  return RV;
 }
 
 void CodeGenFunction::EmitBlock(llvm::BasicBlock *BB, bool IsFinished) {
diff --git a/lib/CodeGen/CodeGenFunction.h b/lib/CodeGen/CodeGenFunction.h
index 600582c96e..952c3b3c1c 100644
--- a/lib/CodeGen/CodeGenFunction.h
+++ b/lib/CodeGen/CodeGenFunction.h
@@ -166,6 +166,11 @@ private:
   /// statement range in current switch instruction.
   llvm::BasicBlock *CaseRangeBlock;
 
+  /// StackSaveValues - A stack(!) of stack save values. When a new scope is
+  /// entered, a null is pushed on this stack. If a VLA is emitted, then 
+  /// the return value of llvm.stacksave() is stored at the top of this stack.
+  llvm::SmallVector<llvm::Value*, 8> StackSaveValues;
+  
 public:
   CodeGenFunction(CodeGenModule &cgm);