r219690 - DebugInfo: Don't leak location information from one function into the prologue of the next function.

[David Blaikie]

Author: dblaikie
Date: Tue Oct 14 11:43:46 2014
New Revision: 219690

URL: http://llvm.org/viewvc/llvm-project?rev=219690&view=rev
Log:
DebugInfo: Don't leak location information from one function into the prologue of the next function.

CodeGenFunction objects aren't really designed to be reused for more
than one function, and doing so can leak debug info location information
from one function into the prologue of the next.

Add an assertion in to catch reuses of CodeGenFunction, which
surprisingly only caught the ObjC atomic getter/setter cases. Fix those
and add a test to demonstrate the issue.

The test is a bit slim, because we're just testing for the absence of a
debug location on the prologue instructions, which by itself probably
wouldn't be the end of the world - but the particular debug location
that was ending up there was for the previous function's last
instruction. This produced debug info for another function within this
function, which is something I'm trying to remove all cases of as its a
substantial source of bugs, especially around inlining (see r219215).

Modified:
    cfe/trunk/lib/CodeGen/CGObjC.cpp
    cfe/trunk/lib/CodeGen/CodeGenFunction.cpp
    cfe/trunk/test/CodeGenObjCXX/property-objects.mm

Modified: cfe/trunk/lib/CodeGen/CGObjC.cpp
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/CodeGen/CGObjC.cpp?rev=219690&r1=219689&r2=219690&view=diff
==============================================================================
--- cfe/trunk/lib/CodeGen/CGObjC.cpp (original)
+++ cfe/trunk/lib/CodeGen/CGObjC.cpp Tue Oct 14 11:43:46 2014
@@ -756,8 +756,8 @@ PropertyImplStrategy::PropertyImplStrate
 /// is illegal within a category.
 void CodeGenFunction::GenerateObjCGetter(ObjCImplementationDecl *IMP,
                                          const ObjCPropertyImplDecl *PID) {
-  llvm::Constant *AtomicHelperFn = 
-    GenerateObjCAtomicGetterCopyHelperFunction(PID);
+  llvm::Constant *AtomicHelperFn =
+      CodeGenFunction(CGM).GenerateObjCAtomicGetterCopyHelperFunction(PID);
   const ObjCPropertyDecl *PD = PID->getPropertyDecl();
   ObjCMethodDecl *OMD = PD->getGetterMethodDecl();
   assert(OMD && "Invalid call to generate getter (empty method)");
@@ -1285,8 +1285,8 @@ CodeGenFunction::generateObjCSetterBody(
 /// is illegal within a category.
 void CodeGenFunction::GenerateObjCSetter(ObjCImplementationDecl *IMP,
                                          const ObjCPropertyImplDecl *PID) {
-  llvm::Constant *AtomicHelperFn = 
-    GenerateObjCAtomicSetterCopyHelperFunction(PID);
+  llvm::Constant *AtomicHelperFn =
+      CodeGenFunction(CGM).GenerateObjCAtomicSetterCopyHelperFunction(PID);
   const ObjCPropertyDecl *PD = PID->getPropertyDecl();
   ObjCMethodDecl *OMD = PD->getSetterMethodDecl();
   assert(OMD && "Invalid call to generate setter (empty method)");

Modified: cfe/trunk/lib/CodeGen/CodeGenFunction.cpp
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/CodeGen/CodeGenFunction.cpp?rev=219690&r1=219689&r2=219690&view=diff
==============================================================================
--- cfe/trunk/lib/CodeGen/CodeGenFunction.cpp (original)
+++ cfe/trunk/lib/CodeGen/CodeGenFunction.cpp Tue Oct 14 11:43:46 2014
@@ -36,7 +36,7 @@ using namespace CodeGen;
 CodeGenFunction::CodeGenFunction(CodeGenModule &cgm, bool suppressNewContext)
     : CodeGenTypeCache(cgm), CGM(cgm), Target(cgm.getTarget()),
       Builder(cgm.getModule().getContext(), llvm::ConstantFolder(),
-              CGBuilderInserterTy(this)),
+              CGBuilderInserterTy(this)), CurFn(nullptr),
       CapturedStmtInfo(nullptr), SanOpts(&CGM.getLangOpts().Sanitize),
       IsSanitizerScope(false), CurFuncIsThunk(false), AutoreleaseResult(false),
       SawAsmBlock(false), BlockInfo(nullptr), BlockPointer(nullptr),
@@ -565,6 +565,9 @@ void CodeGenFunction::StartFunction(Glob
                                     const FunctionArgList &Args,
                                     SourceLocation Loc,
                                     SourceLocation StartLoc) {
+  assert(!CurFn &&
+         "Do not use a CodeGenFunction object for more than one function");
+
   const Decl *D = GD.getDecl();
 
   DidCallStackSave = false;

Modified: cfe/trunk/test/CodeGenObjCXX/property-objects.mm
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/test/CodeGenObjCXX/property-objects.mm?rev=219690&r1=219689&r2=219690&view=diff
==============================================================================
--- cfe/trunk/test/CodeGenObjCXX/property-objects.mm (original)
+++ cfe/trunk/test/CodeGenObjCXX/property-objects.mm Tue Oct 14 11:43:46 2014
@@ -1,4 +1,4 @@
-// RUN: %clang_cc1 %s -triple=x86_64-apple-darwin10 -emit-llvm -o - | FileCheck %s
+// RUN: %clang_cc1 %s -triple=x86_64-apple-darwin10 -emit-llvm -g -o - | FileCheck %s
 
 class S {
 public:
@@ -35,6 +35,11 @@ struct CGRect {
 // CHECK: call dereferenceable({{[0-9]+}}) %class.S* @_ZN1SaSERKS_
 // CHECK-NEXT: ret void
 
+// Don't attach debug locations to the prologue instructions. These were
+// leaking over from the previous function emission by accident.
+// CHECK: define internal void @"\01-[I setBounds:]"
+// CHECK-NOT: !dbg
+// CHECK: call void @llvm.dbg.declare
 - (void)setFrame:(CGRect)frameRect {}
 - (CGRect)frame {return bounds;}