r300287 - [ObjC] Fix lifetime markers of loop variable in EmitObjCForCollectionStmt

[Kuba Mracek via cfe-commits]

Author: kuba.brecka
Date: Thu Apr 13 19:32:43 2017
New Revision: 300287

URL: http://llvm.org/viewvc/llvm-project?rev=300287&view=rev
Log:
[ObjC] Fix lifetime markers of loop variable in EmitObjCForCollectionStmt

CodeGenFunction::EmitObjCForCollectionStmt currently emits lifetime markers for the loop variable in an inconsistent way:  lifetime.start is emitted before the loop is entered, but lifetime.end is emitted inside the loop.  AddressSanitizer uses these markers to track out-of-scope accesses to local variables, and we get false positives in Obj-C foreach loops (in the 2nd iteration of the loop). The markers of the loop variable need to be either both inside the loop (so that we poison and unpoison the variable in each iteration), or both outside. This patch implements the "both inside" approach.

Differential Revision: https://reviews.llvm.org/D32029


Modified:
    cfe/trunk/lib/CodeGen/CGObjC.cpp
    cfe/trunk/test/CodeGenObjC/arc-foreach.m
    cfe/trunk/test/CodeGenObjC/arc-ternary-op.m

Modified: cfe/trunk/lib/CodeGen/CGObjC.cpp
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/CodeGen/CGObjC.cpp?rev=300287&r1=300286&r2=300287&view=diff
==============================================================================
--- cfe/trunk/lib/CodeGen/CGObjC.cpp (original)
+++ cfe/trunk/lib/CodeGen/CGObjC.cpp Thu Apr 13 19:32:43 2017
@@ -1469,11 +1469,6 @@ void CodeGenFunction::EmitObjCForCollect
   if (DI)
     DI->EmitLexicalBlockStart(Builder, S.getSourceRange().getBegin());
 
-  // The local variable comes into scope immediately.
-  AutoVarEmission variable = AutoVarEmission::invalid();
-  if (const DeclStmt *SD = dyn_cast<DeclStmt>(S.getElement()))
-    variable = EmitAutoVarAlloca(*cast<VarDecl>(SD->getSingleDecl()));
-
   JumpDest LoopEnd = getJumpDestInCurrentScope("forcoll.end");
 
   // Fast enumeration state.
@@ -1625,8 +1620,10 @@ void CodeGenFunction::EmitObjCForCollect
   bool elementIsVariable;
   LValue elementLValue;
   QualType elementType;
+  AutoVarEmission variable = AutoVarEmission::invalid();
   if (const DeclStmt *SD = dyn_cast<DeclStmt>(S.getElement())) {
     // Initialize the variable, in case it's a __block variable or something.
+    variable = EmitAutoVarAlloca(*cast<VarDecl>(SD->getSingleDecl()));
     EmitAutoVarInit(variable);
 
     const VarDecl* D = cast<VarDecl>(SD->getSingleDecl());

Modified: cfe/trunk/test/CodeGenObjC/arc-foreach.m
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/test/CodeGenObjC/arc-foreach.m?rev=300287&r1=300286&r2=300287&view=diff
==============================================================================
--- cfe/trunk/test/CodeGenObjC/arc-foreach.m (original)
+++ cfe/trunk/test/CodeGenObjC/arc-foreach.m Thu Apr 13 19:32:43 2017
@@ -24,9 +24,9 @@ void test0(NSArray *array) {
 
 // CHECK-LP64-LABEL:    define void @test0(
 // CHECK-LP64:      [[ARRAY:%.*]] = alloca [[ARRAY_T:%.*]]*,
-// CHECK-LP64-NEXT: [[X:%.*]] = alloca i8*,
 // CHECK-LP64-NEXT: [[STATE:%.*]] = alloca [[STATE_T:%.*]],
 // CHECK-LP64-NEXT: [[BUFFER:%.*]] = alloca [16 x i8*], align 8
+// CHECK-LP64-NEXT: [[X:%.*]] = alloca i8*,
 // CHECK-LP64-NEXT: [[BLOCK:%.*]] = alloca [[BLOCK_T:<{.*}>]],
 
 // Initialize 'array'.
@@ -97,9 +97,9 @@ void test1(NSArray *array) {
 
 // CHECK-LP64-LABEL:    define void @test1(
 // CHECK-LP64:      alloca [[ARRAY_T:%.*]]*,
-// CHECK-LP64-NEXT: [[X:%.*]] = alloca i8*,
 // CHECK-LP64-NEXT: [[STATE:%.*]] = alloca [[STATE_T:%.*]],
 // CHECK-LP64-NEXT: alloca [16 x i8*], align 8
+// CHECK-LP64-NEXT: [[X:%.*]] = alloca i8*,
 // CHECK-LP64-NEXT: [[BLOCK:%.*]] = alloca [[BLOCK_T:<{.*}>]],
 
 // CHECK-LP64:      [[T0:%.*]] = getelementptr inbounds [[STATE_T]], [[STATE_T]]* [[STATE]], i32 0, i32 1
@@ -160,7 +160,7 @@ void test3(NSArray *array) {
 
   // CHECK-LP64-LABEL:    define void @test3(
   // CHECK-LP64:      [[ARRAY:%.*]] = alloca [[ARRAY_T]]*, align 8
-  // CHECK-LP64-NEXT: [[X:%.*]] = alloca i8*, align 8
+  // CHECK-LP64:      [[X:%.*]] = alloca i8*, align 8
   // CHECK-LP64:      [[T0:%.*]] = load i8*, i8** [[X]], align 8
   // CHECK-LP64-NEXT: [[T1:%.*]] = icmp ne i8* [[T0]], null
   // CHECK-LP64-NEXT: br i1 [[T1]],

Modified: cfe/trunk/test/CodeGenObjC/arc-ternary-op.m
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/test/CodeGenObjC/arc-ternary-op.m?rev=300287&r1=300286&r2=300287&view=diff
==============================================================================
--- cfe/trunk/test/CodeGenObjC/arc-ternary-op.m (original)
+++ cfe/trunk/test/CodeGenObjC/arc-ternary-op.m Thu Apr 13 19:32:43 2017
@@ -120,9 +120,9 @@ void test2(int cond) {
 
   // CHECK-LABEL:    define void @test2(
   // CHECK:      [[COND:%.*]] = alloca i32,
-  // CHECK:      alloca i8*
   // CHECK:      [[CLEANUP_SAVE:%.*]] = alloca i8*
   // CHECK:      [[RUN_CLEANUP:%.*]] = alloca i1
+  // CHECK:      alloca i8*
   //   Evaluate condition; cleanup disabled by default.
   // CHECK:      [[T0:%.*]] = load i32, i32* [[COND]],
   // CHECK-NEXT: icmp ne i32 [[T0]], 0