[CodeGen][ObjC] Build the global block structure before emitting the

body of global block invoke functions.

This commit fixes an infinite loop in IRGen that occurs when compiling
the following code:

void FUNC2() {
  static void (^const block1)(int) = ^(int a){
    if (a--)
      block1(a);
  };
}

This is how IRGen gets stuck in the infinite loop:

1. GenerateBlockFunction is called to emit the body of "block1".

2. GetAddrOfGlobalBlock is called to get the address of "block1". The
   function calls getAddrOfGlobalBlockIfEmitted to check whether the
   global block has been emitted. If it hasn't been emitted, it then
   tries to emit the body of the block function by calling
   GenerateBlockFunction, which goes back to step 1.

This commit prevents the inifinite loop by building the global block in
GenerateBlockFunction before emitting the body of the block function.

rdar://problem/34541684

Differential Revision: https://reviews.llvm.org/D38118

llvm-svn: 314029

5 files changed, 32 insertions, 17 deletions

diff --git a/clang/lib/CodeGen/CGBlocks.cpp b/clang/lib/CodeGen/CGBlocks.cpp
index 8d82898fda9..6cf7f71ba5f 100644
--- a/clang/lib/CodeGen/CGBlocks.cpp
+++ b/clang/lib/CodeGen/CGBlocks.cpp
@@ -725,12 +725,13 @@ llvm::Value *CodeGenFunction::EmitBlockLiteral(const CGBlockInfo &blockInfo) {
   llvm::Constant *blockFn
     = CodeGenFunction(CGM, true).GenerateBlockFunction(CurGD, blockInfo,
                                                        LocalDeclMap,
-                                                       isLambdaConv);
+                                                       isLambdaConv,
+                                                       blockInfo.CanBeGlobal);
   blockFn = llvm::ConstantExpr::getBitCast(blockFn, VoidPtrTy);
 
   // If there is nothing to capture, we can emit this as a global block.
   if (blockInfo.CanBeGlobal)
-    return buildGlobalBlock(CGM, blockInfo, blockFn);
+    return CGM.getAddrOfGlobalBlockIfEmitted(blockInfo.BlockExpression);
 
   // Otherwise, we have to emit this as a local block.
 
@@ -1114,17 +1115,14 @@ CodeGenModule::GetAddrOfGlobalBlock(const BlockExpr *BE,
   computeBlockInfo(*this, nullptr, blockInfo);
 
   // Using that metadata, generate the actual block function.
-  llvm::Constant *blockFn;
   {
     CodeGenFunction::DeclMapTy LocalDeclMap;
-    blockFn = CodeGenFunction(*this).GenerateBlockFunction(GlobalDecl(),
-                                                           blockInfo,
-                                                           LocalDeclMap,
-                                                           false);
+    CodeGenFunction(*this).GenerateBlockFunction(
+        GlobalDecl(), blockInfo, LocalDeclMap,
+        /*IsLambdaConversionToBlock*/ false, /*BuildGlobalBlock*/ true);
   }
-  blockFn = llvm::ConstantExpr::getBitCast(blockFn, VoidPtrTy);
 
-  return buildGlobalBlock(*this, blockInfo, blockFn);
+  return getAddrOfGlobalBlockIfEmitted(BE);
 }
 
 static llvm::Constant *buildGlobalBlock(CodeGenModule &CGM,
@@ -1226,7 +1224,8 @@ llvm::Function *
 CodeGenFunction::GenerateBlockFunction(GlobalDecl GD,
                                        const CGBlockInfo &blockInfo,
                                        const DeclMapTy &ldm,
-                                       bool IsLambdaConversionToBlock) {
+                                       bool IsLambdaConversionToBlock,
+                                       bool BuildGlobalBlock) {
   const BlockDecl *blockDecl = blockInfo.getBlockDecl();
 
   CurGD = GD;
@@ -1285,6 +1284,10 @@ CodeGenFunction::GenerateBlockFunction(GlobalDecl GD,
       fnLLVMType, llvm::GlobalValue::InternalLinkage, name, &CGM.getModule());
   CGM.SetInternalFunctionAttributes(blockDecl, fn, fnInfo);
 
+  if (BuildGlobalBlock)
+    buildGlobalBlock(CGM, blockInfo,
+                     llvm::ConstantExpr::getBitCast(fn, VoidPtrTy));
+
   // Begin generating the function.
   StartFunction(blockDecl, fnType->getReturnType(), fn, fnInfo, args,
                 blockDecl->getLocation(),
diff --git a/clang/lib/CodeGen/CodeGenFunction.h b/clang/lib/CodeGen/CodeGenFunction.h
index 7dca3805973..d77cea48b02 100644
--- a/clang/lib/CodeGen/CodeGenFunction.h
+++ b/clang/lib/CodeGen/CodeGenFunction.h
@@ -1586,7 +1586,8 @@ public:
   llvm::Function *GenerateBlockFunction(GlobalDecl GD,
                                         const CGBlockInfo &Info,
                                         const DeclMapTy &ldm,
-                                        bool IsLambdaConversionToBlock);
+                                        bool IsLambdaConversionToBlock,
+                                        bool BuildGlobalBlock);
 
   llvm::Constant *GenerateCopyHelperFunction(const CGBlockInfo &blockInfo);
   llvm::Constant *GenerateDestroyHelperFunction(const CGBlockInfo &blockInfo);
diff --git a/clang/test/CodeGen/mangle-blocks.c b/clang/test/CodeGen/mangle-blocks.c
index e8de92d8b40..4ea5a550c8b 100644
--- a/clang/test/CodeGen/mangle-blocks.c
+++ b/clang/test/CodeGen/mangle-blocks.c
@@ -12,12 +12,12 @@ void (^mangle(void))(void) {
 }
 
 // CHECK: @__func__.__mangle_block_invoke_2 = private unnamed_addr constant [22 x i8] c"mangle_block_invoke_2\00", align 1
-// CHECK: @.str = private unnamed_addr constant {{.*}}, align 1
-// CHECK: @.str.1 = private unnamed_addr constant [7 x i8] c"mangle\00", align 1
+// CHECK: @.str{{.*}} = private unnamed_addr constant {{.*}}, align 1
+// CHECK: @.str[[STR1:.*]] = private unnamed_addr constant [7 x i8] c"mangle\00", align 1
 
 // CHECK: define internal void @__mangle_block_invoke(i8* %.block_descriptor)
 
 // CHECK: define internal void @__mangle_block_invoke_2(i8* %.block_descriptor){{.*}}{
-// CHECK:   call void @__assert_rtn(i8* getelementptr inbounds ([22 x i8], [22 x i8]* @__func__.__mangle_block_invoke_2, i32 0, i32 0), i8* getelementptr inbounds {{.*}}, i32 9, i8* getelementptr inbounds ([7 x i8], [7 x i8]* @.str.1, i32 0, i32 0))
+// CHECK:   call void @__assert_rtn(i8* getelementptr inbounds ([22 x i8], [22 x i8]* @__func__.__mangle_block_invoke_2, i32 0, i32 0), i8* getelementptr inbounds {{.*}}, i32 9, i8* getelementptr inbounds ([7 x i8], [7 x i8]* @.str[[STR1]], i32 0, i32 0))
 // CHECK: }
 
diff --git a/clang/test/CodeGenObjC/local-static-block.m b/clang/test/CodeGenObjC/local-static-block.m
index 73c670f5c92..67ede63fc0a 100644
--- a/clang/test/CodeGenObjC/local-static-block.m
+++ b/clang/test/CodeGenObjC/local-static-block.m
@@ -46,6 +46,17 @@ void FUNC()
  }
 }
 
+void FUNC2() {
+  static void (^const block1)(int) = ^(int a){
+    if (a--)
+      block1(a);
+  };
+}
+
+// CHECK-LABEL-LP64: define void @FUNC2(
+// CHECK: define internal void @_block_invoke{{.*}}(
+// CHECK: call void %{{.*}}(i8* bitcast ({ i8**, i32, i32, i8*, %struct.__block_descriptor* }* @__block_literal_global{{.*}} to i8*), i32 %{{.*}})
+
 void FUNC1()
 {
  static  NSArray *(^ArrayRecurs)(NSArray *addresses, unsigned long level) = ^(NSArray *addresses, unsigned long level) {
diff --git a/clang/test/CodeGenObjC/mangle-blocks.m b/clang/test/CodeGenObjC/mangle-blocks.m
index 4cc32040332..73522cd41c6 100644
--- a/clang/test/CodeGenObjC/mangle-blocks.m
+++ b/clang/test/CodeGenObjC/mangle-blocks.m
@@ -18,11 +18,11 @@ void __assert_rtn(const char *, const char *, int, const char *);
 @end
 
 // CHECK: @"__func__.__14-[Test mangle]_block_invoke_2" = private unnamed_addr constant [30 x i8] c"-[Test mangle]_block_invoke_2\00", align 1
-// CHECK: @.str = private unnamed_addr constant {{.*}}, align 1
-// CHECK: @.str.1 = private unnamed_addr constant [7 x i8] c"mangle\00", align 1
+// CHECK: @.str{{.*}} = private unnamed_addr constant {{.*}}, align 1
+// CHECK: @.str[[STR1:.*]] = private unnamed_addr constant [7 x i8] c"mangle\00", align 1
 
 // CHECK: define internal void @"__14-[Test mangle]_block_invoke"(i8* %.block_descriptor)
 
 // CHECK: define internal void @"__14-[Test mangle]_block_invoke_2"(i8* %.block_descriptor){{.*}}{
-// CHECK: call void @__assert_rtn(i8* getelementptr inbounds ([30 x i8], [30 x i8]* @"__func__.__14-[Test mangle]_block_invoke_2", i32 0, i32 0), i8* getelementptr inbounds {{.*}}, i32 14, i8* getelementptr inbounds ([7 x i8], [7 x i8]* @.str.1, i32 0, i32 0))
+// CHECK: call void @__assert_rtn(i8* getelementptr inbounds ([30 x i8], [30 x i8]* @"__func__.__14-[Test mangle]_block_invoke_2", i32 0, i32 0), i8* getelementptr inbounds {{.*}}, i32 14, i8* getelementptr inbounds ([7 x i8], [7 x i8]* @.str[[STR1]], i32 0, i32 0))
 // CHECK: }