MS ABI: Don't push destructor cleanups for aggregate parameters in thunks

The target method of the thunk will perform the cleanup.  This can't be
tested in 32-bit x86 yet because passing something by value would create
an inalloca, and we refuse to generate broken code for that.

llvm-svn: 213976

4 files changed, 18 insertions, 11 deletions

diff --git a/clang/lib/CodeGen/CGDecl.cpp b/clang/lib/CodeGen/CGDecl.cpp
index 91f80419304..b42a44342c4 100644
--- a/clang/lib/CodeGen/CGDecl.cpp
+++ b/clang/lib/CodeGen/CGDecl.cpp
@@ -1656,7 +1656,9 @@ void CodeGenFunction::EmitParmDecl(const VarDecl &D, llvm::Value *Arg,
     DeclPtr = Arg->getType() == IRTy ? Arg : Builder.CreateBitCast(Arg, IRTy,
                                                                    D.getName());
     // Push a destructor cleanup for this parameter if the ABI requires it.
-    if (!IsScalar &&
+    // Don't push a cleanup in a thunk for a method that will also emit a
+    // cleanup.
+    if (!IsScalar && !CurFuncIsThunk &&
         getTarget().getCXXABI().areArgsDestroyedLeftToRightInCallee()) {
       const CXXRecordDecl *RD = Ty->getAsCXXRecordDecl();
       if (RD && RD->hasNonTrivialDestructor())
diff --git a/clang/lib/CodeGen/CGVTables.cpp b/clang/lib/CodeGen/CGVTables.cpp
index 0df2c43d11b..c53e7ed33d4 100644
--- a/clang/lib/CodeGen/CGVTables.cpp
+++ b/clang/lib/CodeGen/CGVTables.cpp
@@ -194,6 +194,7 @@ void CodeGenFunction::StartThunk(llvm::Function *Fn, GlobalDecl GD,
                                  const CGFunctionInfo &FnInfo) {
   assert(!CurGD.getDecl() && "CurGD was already set!");
   CurGD = GD;
+  CurFuncIsThunk = true;
 
   // Build FunctionArgs.
   const CXXMethodDecl *MD = cast<CXXMethodDecl>(GD.getDecl());
diff --git a/clang/lib/CodeGen/CodeGenFunction.cpp b/clang/lib/CodeGen/CodeGenFunction.cpp
index 5ca3a78bb4f..67eae450e8c 100644
--- a/clang/lib/CodeGen/CodeGenFunction.cpp
+++ b/clang/lib/CodeGen/CodeGenFunction.cpp
@@ -38,16 +38,16 @@ CodeGenFunction::CodeGenFunction(CodeGenModule &cgm, bool suppressNewContext)
       Builder(cgm.getModule().getContext(), llvm::ConstantFolder(),
               CGBuilderInserterTy(this)),
       CapturedStmtInfo(nullptr), SanOpts(&CGM.getLangOpts().Sanitize),
-      IsSanitizerScope(false), AutoreleaseResult(false), BlockInfo(nullptr),
-      BlockPointer(nullptr), LambdaThisCaptureField(nullptr),
-      NormalCleanupDest(nullptr), NextCleanupDestIndex(1),
-      FirstBlockInfo(nullptr), EHResumeBlock(nullptr), ExceptionSlot(nullptr),
-      EHSelectorSlot(nullptr), DebugInfo(CGM.getModuleDebugInfo()),
-      DisableDebugInfo(false), DidCallStackSave(false), IndirectBranch(nullptr),
-      PGO(cgm), SwitchInsn(nullptr), SwitchWeights(nullptr),
-      CaseRangeBlock(nullptr), UnreachableBlock(nullptr), NumReturnExprs(0),
-      NumSimpleReturnExprs(0), CXXABIThisDecl(nullptr),
-      CXXABIThisValue(nullptr), CXXThisValue(nullptr),
+      IsSanitizerScope(false), CurFuncIsThunk(false), AutoreleaseResult(false),
+      BlockInfo(nullptr), BlockPointer(nullptr),
+      LambdaThisCaptureField(nullptr), NormalCleanupDest(nullptr),
+      NextCleanupDestIndex(1), FirstBlockInfo(nullptr), EHResumeBlock(nullptr),
+      ExceptionSlot(nullptr), EHSelectorSlot(nullptr),
+      DebugInfo(CGM.getModuleDebugInfo()), DisableDebugInfo(false),
+      DidCallStackSave(false), IndirectBranch(nullptr), PGO(cgm),
+      SwitchInsn(nullptr), SwitchWeights(nullptr), CaseRangeBlock(nullptr),
+      UnreachableBlock(nullptr), NumReturnExprs(0), NumSimpleReturnExprs(0),
+      CXXABIThisDecl(nullptr), CXXABIThisValue(nullptr), CXXThisValue(nullptr),
       CXXDefaultInitExprThis(nullptr), CXXStructorImplicitParamDecl(nullptr),
       CXXStructorImplicitParamValue(nullptr), OutermostConditional(nullptr),
       CurLexicalScope(nullptr), TerminateLandingPad(nullptr),
diff --git a/clang/lib/CodeGen/CodeGenFunction.h b/clang/lib/CodeGen/CodeGenFunction.h
index 335a8910e82..ccf7651fdcc 100644
--- a/clang/lib/CodeGen/CodeGenFunction.h
+++ b/clang/lib/CodeGen/CodeGenFunction.h
@@ -258,6 +258,10 @@ public:
     ~SanitizerScope();
   };
 
+  /// In C++, whether we are code generating a thunk.  This controls whether we
+  /// should emit cleanups.
+  bool CurFuncIsThunk;
+
   /// In ARC, whether we should autorelease the return value.
   bool AutoreleaseResult;