r314029 - [CodeGen][ObjC] Build the global block structure before emitting the

Akira Hatanaka via cfe-commits cfe-commits at lists.llvm.org
Fri Sep 22 14:32:06 PDT 2017


Author: ahatanak
Date: Fri Sep 22 14:32:06 2017
New Revision: 314029

URL: http://llvm.org/viewvc/llvm-project?rev=314029&view=rev
Log:
[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

Modified:
    cfe/trunk/lib/CodeGen/CGBlocks.cpp
    cfe/trunk/lib/CodeGen/CodeGenFunction.h
    cfe/trunk/test/CodeGen/mangle-blocks.c
    cfe/trunk/test/CodeGenObjC/local-static-block.m
    cfe/trunk/test/CodeGenObjC/mangle-blocks.m

Modified: cfe/trunk/lib/CodeGen/CGBlocks.cpp
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/CodeGen/CGBlocks.cpp?rev=314029&r1=314028&r2=314029&view=diff
==============================================================================
--- cfe/trunk/lib/CodeGen/CGBlocks.cpp (original)
+++ cfe/trunk/lib/CodeGen/CGBlocks.cpp Fri Sep 22 14:32:06 2017
@@ -725,12 +725,13 @@ llvm::Value *CodeGenFunction::EmitBlockL
   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(cons
   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(G
       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(),

Modified: cfe/trunk/lib/CodeGen/CodeGenFunction.h
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/CodeGen/CodeGenFunction.h?rev=314029&r1=314028&r2=314029&view=diff
==============================================================================
--- cfe/trunk/lib/CodeGen/CodeGenFunction.h (original)
+++ cfe/trunk/lib/CodeGen/CodeGenFunction.h Fri Sep 22 14:32:06 2017
@@ -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);

Modified: cfe/trunk/test/CodeGen/mangle-blocks.c
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/test/CodeGen/mangle-blocks.c?rev=314029&r1=314028&r2=314029&view=diff
==============================================================================
--- cfe/trunk/test/CodeGen/mangle-blocks.c (original)
+++ cfe/trunk/test/CodeGen/mangle-blocks.c Fri Sep 22 14:32:06 2017
@@ -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: }
 

Modified: cfe/trunk/test/CodeGenObjC/local-static-block.m
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/test/CodeGenObjC/local-static-block.m?rev=314029&r1=314028&r2=314029&view=diff
==============================================================================
--- cfe/trunk/test/CodeGenObjC/local-static-block.m (original)
+++ cfe/trunk/test/CodeGenObjC/local-static-block.m Fri Sep 22 14:32:06 2017
@@ -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) {

Modified: cfe/trunk/test/CodeGenObjC/mangle-blocks.m
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/test/CodeGenObjC/mangle-blocks.m?rev=314029&r1=314028&r2=314029&view=diff
==============================================================================
--- cfe/trunk/test/CodeGenObjC/mangle-blocks.m (original)
+++ cfe/trunk/test/CodeGenObjC/mangle-blocks.m Fri Sep 22 14:32:06 2017
@@ -18,11 +18,11 @@ void __assert_rtn(const char *, const ch
 @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: }




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