r281682 - [CodeGen][ObjC] Block captures should inherit the type of the captured

Akira Hatanaka via cfe-commits cfe-commits at lists.llvm.org
Thu Sep 15 17:02:06 PDT 2016


Author: ahatanak
Date: Thu Sep 15 19:02:06 2016
New Revision: 281682

URL: http://llvm.org/viewvc/llvm-project?rev=281682&view=rev
Log:
[CodeGen][ObjC] Block captures should inherit the type of the captured
field in the enclosing lambda or block.

This patch fixes a bug in code-gen where it uses the type of the
declared variable rather than the type of the capture of the enclosing
lambda or block for the block capture. For example, in the following
function, code-gen currently uses i32* for the block capture "a" because
"a" is passed to foo1 as a reference, but it should use i32 since the
enclosing lambda captures "a" by value.

void foo1(int &a) {
  auto lambda = [a]{
    auto block1 = ^{
      i = a;
    };
    block1();
  };
  lambda();
}

rdar://problem/18586386

Differential Revision: https://reviews.llvm.org/D21104

Modified:
    cfe/trunk/lib/CodeGen/CGBlocks.cpp
    cfe/trunk/lib/CodeGen/CGBlocks.h
    cfe/trunk/test/CodeGenObjCXX/lambda-expressions.mm

Modified: cfe/trunk/lib/CodeGen/CGBlocks.cpp
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/CodeGen/CGBlocks.cpp?rev=281682&r1=281681&r2=281682&view=diff
==============================================================================
--- cfe/trunk/lib/CodeGen/CGBlocks.cpp (original)
+++ cfe/trunk/lib/CodeGen/CGBlocks.cpp Thu Sep 15 19:02:06 2016
@@ -199,13 +199,14 @@ namespace {
     Qualifiers::ObjCLifetime Lifetime;
     const BlockDecl::Capture *Capture; // null for 'this'
     llvm::Type *Type;
+    QualType FieldType;
 
     BlockLayoutChunk(CharUnits align, CharUnits size,
                      Qualifiers::ObjCLifetime lifetime,
                      const BlockDecl::Capture *capture,
-                     llvm::Type *type)
+                     llvm::Type *type, QualType fieldType)
       : Alignment(align), Size(size), Lifetime(lifetime),
-        Capture(capture), Type(type) {}
+        Capture(capture), Type(type), FieldType(fieldType) {}
 
     /// Tell the block info that this chunk has the given field index.
     void setIndex(CGBlockInfo &info, unsigned index, CharUnits offset) {
@@ -213,8 +214,8 @@ namespace {
         info.CXXThisIndex = index;
         info.CXXThisOffset = offset;
       } else {
-        info.Captures.insert({Capture->getVariable(),
-                              CGBlockInfo::Capture::makeIndex(index, offset)});
+        auto C = CGBlockInfo::Capture::makeIndex(index, offset, FieldType);
+        info.Captures.insert({Capture->getVariable(), C});
       }
     }
   };
@@ -363,7 +364,7 @@ static void computeBlockInfo(CodeGenModu
 
     layout.push_back(BlockLayoutChunk(tinfo.second, tinfo.first,
                                       Qualifiers::OCL_None,
-                                      nullptr, llvmType));
+                                      nullptr, llvmType, thisType));
   }
 
   // Next, all the block captures.
@@ -380,7 +381,7 @@ static void computeBlockInfo(CodeGenModu
 
       layout.push_back(BlockLayoutChunk(align, CGM.getPointerSize(),
                                         Qualifiers::OCL_None, &CI,
-                                        CGM.VoidPtrTy));
+                                        CGM.VoidPtrTy, variable->getType()));
       continue;
     }
 
@@ -436,6 +437,14 @@ static void computeBlockInfo(CodeGenModu
     }
 
     QualType VT = variable->getType();
+
+    // If the variable is captured by an enclosing block or lambda expression,
+    // use the type of the capture field.
+    if (CGF->BlockInfo && CI.isNested())
+      VT = CGF->BlockInfo->getCapture(variable).fieldType();
+    else if (auto *FD = CGF->LambdaCaptureFields.lookup(variable))
+      VT = FD->getType();
+
     CharUnits size = C.getTypeSizeInChars(VT);
     CharUnits align = C.getDeclAlign(variable);
     
@@ -444,7 +453,8 @@ static void computeBlockInfo(CodeGenModu
     llvm::Type *llvmType =
       CGM.getTypes().ConvertTypeForMem(VT);
     
-    layout.push_back(BlockLayoutChunk(align, size, lifetime, &CI, llvmType));
+    layout.push_back(
+        BlockLayoutChunk(align, size, lifetime, &CI, llvmType, VT));
   }
 
   // If that was everything, we're done here.
@@ -775,7 +785,7 @@ llvm::Value *CodeGenFunction::EmitBlockL
     // Ignore constant captures.
     if (capture.isConstant()) continue;
 
-    QualType type = variable->getType();
+    QualType type = capture.fieldType();
 
     // This will be a [[type]]*, except that a byref entry will just be
     // an i8**.
@@ -1033,9 +1043,8 @@ Address CodeGenFunction::GetAddrOfBlockD
                                  variable->getName());
   }
 
-  if (auto refType = variable->getType()->getAs<ReferenceType>()) {
+  if (auto refType = capture.fieldType()->getAs<ReferenceType>())
     addr = EmitLoadOfReference(addr, refType);
-  }
 
   return addr;
 }

Modified: cfe/trunk/lib/CodeGen/CGBlocks.h
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/CodeGen/CGBlocks.h?rev=281682&r1=281681&r2=281682&view=diff
==============================================================================
--- cfe/trunk/lib/CodeGen/CGBlocks.h (original)
+++ cfe/trunk/lib/CodeGen/CGBlocks.h Thu Sep 15 19:02:06 2016
@@ -159,6 +159,11 @@ public:
     EHScopeStack::stable_iterator Cleanup;
     CharUnits::QuantityType Offset;
 
+    /// Type of the capture field. Normally, this is identical to the type of
+    /// the capture's VarDecl, but can be different if there is an enclosing
+    /// lambda.
+    QualType FieldType;
+
   public:
     bool isIndex() const { return (Data & 1) != 0; }
     bool isConstant() const { return !isIndex(); }
@@ -185,10 +190,16 @@ public:
       return reinterpret_cast<llvm::Value*>(Data);
     }
 
-    static Capture makeIndex(unsigned index, CharUnits offset) {
+    QualType fieldType() const {
+      return FieldType;
+    }
+
+    static Capture makeIndex(unsigned index, CharUnits offset,
+                             QualType FieldType) {
       Capture v;
       v.Data = (index << 1) | 1;
       v.Offset = offset.getQuantity();
+      v.FieldType = FieldType;
       return v;
     }
 

Modified: cfe/trunk/test/CodeGenObjCXX/lambda-expressions.mm
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/test/CodeGenObjCXX/lambda-expressions.mm?rev=281682&r1=281681&r2=281682&view=diff
==============================================================================
--- cfe/trunk/test/CodeGenObjCXX/lambda-expressions.mm (original)
+++ cfe/trunk/test/CodeGenObjCXX/lambda-expressions.mm Thu Sep 15 19:02:06 2016
@@ -4,6 +4,8 @@
 typedef int (^fp)();
 fp f() { auto x = []{ return 3; }; return x; }
 
+// ARC: %[[LAMBDACLASS:.*]] = type { i32 }
+
 // MRC: @OBJC_METH_VAR_NAME{{.*}} = private global [5 x i8] c"copy\00"
 // MRC: @OBJC_METH_VAR_NAME{{.*}} = private global [12 x i8] c"autorelease\00"
 // MRC-LABEL: define i32 ()* @_Z1fv(
@@ -60,6 +62,40 @@ void take_block(void (^block)()) { block
 }
 @end
 
+// ARC: define void @_ZN13LambdaCapture4foo1ERi(i32* dereferenceable(4) %{{.*}})
+// ARC:   %[[CAPTURE0:.*]] = getelementptr inbounds %[[LAMBDACLASS]], %[[LAMBDACLASS]]* %{{.*}}, i32 0, i32 0
+// ARC:   store i32 %{{.*}}, i32* %[[CAPTURE0]]
+
+// ARC: define internal void @"_ZZN13LambdaCapture4foo1ERiENK3$_3clEv"(%[[LAMBDACLASS]]* %{{.*}})
+// ARC:   %[[BLOCK:.*]] = alloca <{ i8*, i32, i32, i8*, %struct.__block_descriptor*, i32 }>
+// ARC:   %[[CAPTURE1:.*]] = getelementptr inbounds <{ i8*, i32, i32, i8*, %struct.__block_descriptor*, i32 }>, <{ i8*, i32, i32, i8*, %struct.__block_descriptor*, i32 }>* %[[BLOCK]], i32 0, i32 5
+// ARC:   store i32 %{{.*}}, i32* %[[CAPTURE1]]
+
+// ARC: define internal void @"___ZZN13LambdaCapture4foo1ERiENK3$_3clEv_block_invoke"
+// ARC:   %[[CAPTURE2:.*]] = getelementptr inbounds <{ i8*, i32, i32, i8*, %struct.__block_descriptor*, i32 }>, <{ i8*, i32, i32, i8*, %struct.__block_descriptor*, i32 }>* %{{.*}}, i32 0, i32 5
+// ARC:   store i32 %{{.*}}, i32* %[[CAPTURE2]]
+
+// ARC: define internal void @"___ZZN13LambdaCapture4foo1ERiENK3$_3clEv_block_invoke_2"(i8* %{{.*}})
+// ARC:   %[[CAPTURE3:.*]] = getelementptr inbounds <{ i8*, i32, i32, i8*, %struct.__block_descriptor*, i32 }>, <{ i8*, i32, i32, i8*, %struct.__block_descriptor*, i32 }>* %{{.*}}, i32 0, i32 5
+// ARC:   %[[V1:.*]] = load i32, i32* %[[CAPTURE3]]
+// ARC:   store i32 %[[V1]], i32* @_ZN13LambdaCapture1iE
+
+namespace LambdaCapture {
+  int i;
+  void foo1(int &a) {
+    auto lambda = [a]{
+      auto block1 = ^{
+        auto block2 = ^{
+          i = a;
+        };
+        block2();
+      };
+      block1();
+    };
+    lambda();
+  }
+}
+
 // ARC-LABEL: define linkonce_odr i32 ()* @_ZZNK13StaticMembersIfE1fMUlvE_clEvENKUlvE_cvU13block_pointerFivEEv
 
 // Check lines for BlockInLambda test below




More information about the cfe-commits mailing list