I see. Perhaps this should be an assert?
> On May 2, 2016, at 3:05 PM, Richard Smith <rich...@metafoo.co.uk> wrote: > > On Mon, May 2, 2016 at 2:52 PM, Akira Hatanaka via cfe-commits > <cfe-commits@lists.llvm.org <mailto:cfe-commits@lists.llvm.org>> wrote: > Author: ahatanak > Date: Mon May 2 16:52:57 2016 > New Revision: 268314 > > URL: http://llvm.org/viewvc/llvm-project?rev=268314&view=rev > <http://llvm.org/viewvc/llvm-project?rev=268314&view=rev> > Log: > [CodeGenObjCXX] Don't rematerialize default arguments of function > parameters in the body of a block. > > This fixes a bug where clang would materialize the default argument > inside the body of a block instead of passing the value via the block > descriptor. > > For example, in the code below, foo1 would always print 42 regardless > of the value of argument "a" passed to foo1. > > void foo1(const int a = 42 ) { > auto block = ^{ > printf("%d\n", a); > }; > block(); > } > > rdar://problem/24449235 > > Added: > cfe/trunk/test/CodeGenObjCXX/block-default-arg.mm > <http://block-default-arg.mm/> > Modified: > cfe/trunk/lib/CodeGen/CGBlocks.cpp > > Modified: cfe/trunk/lib/CodeGen/CGBlocks.cpp > URL: > http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/CodeGen/CGBlocks.cpp?rev=268314&r1=268313&r2=268314&view=diff > > <http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/CodeGen/CGBlocks.cpp?rev=268314&r1=268313&r2=268314&view=diff> > ============================================================================== > --- cfe/trunk/lib/CodeGen/CGBlocks.cpp (original) > +++ cfe/trunk/lib/CodeGen/CGBlocks.cpp Mon May 2 16:52:57 2016 > @@ -262,6 +262,11 @@ static bool isSafeForCXXConstantCapture( > static llvm::Constant *tryCaptureAsConstant(CodeGenModule &CGM, > CodeGenFunction *CGF, > const VarDecl *var) { > + // Don't rematerialize default arguments of function parameters. > + if (auto *PD = dyn_cast<ParmVarDecl>(var)) > + if (PD->hasDefaultArg()) > > I don't think you need this test, and I think it somewhat confuses the intent > here. (A reader would wonder why you want to keep going for ParmVarDecls that > don't have default arguments.) > > + return nullptr; > + > QualType type = var->getType(); > > // We can only do this if the variable is const. > > Added: cfe/trunk/test/CodeGenObjCXX/block-default-arg.mm > <http://block-default-arg.mm/> > URL: > http://llvm.org/viewvc/llvm-project/cfe/trunk/test/CodeGenObjCXX/block-default-arg.mm?rev=268314&view=auto > > <http://llvm.org/viewvc/llvm-project/cfe/trunk/test/CodeGenObjCXX/block-default-arg.mm?rev=268314&view=auto> > ============================================================================== > --- cfe/trunk/test/CodeGenObjCXX/block-default-arg.mm > <http://block-default-arg.mm/> (added) > +++ cfe/trunk/test/CodeGenObjCXX/block-default-arg.mm > <http://block-default-arg.mm/> Mon May 2 16:52:57 2016 > @@ -0,0 +1,16 @@ > +// RUN: %clang_cc1 -triple x86_64-apple-darwin10.0.0 -emit-llvm -o - %s > -std=c++11 -fblocks -fobjc-arc | FileCheck %s > + > +// CHECK: define internal void @___Z16test_default_argi_block_invoke(i8* > %[[BLOCK_DESCRIPTOR:.*]]) > +// CHECK: %[[BLOCK:.*]] = bitcast i8* %[[BLOCK_DESCRIPTOR]] to <{ i8*, i32, > i32, i8*, %struct.__block_descriptor*, i32 }>* > +// CHECK: %[[BLOCK_CAPTURE_ADDR:.*]] = getelementptr inbounds <{ i8*, i32, > i32, i8*, %struct.__block_descriptor*, i32 }>, <{ i8*, i32, i32, i8*, > %struct.__block_descriptor*, i32 }>* %[[BLOCK]], i32 0, i32 5 > +// CHECK: %[[V0:.*]] = load i32, i32* %[[BLOCK_CAPTURE_ADDR]] > +// CHECK: call void @_Z4foo1i(i32 %[[V0]]) > + > +void foo1(int); > + > +void test_default_arg(const int a = 42) { > + auto block = ^{ > + foo1(a); > + }; > + block(); > +} > > > _______________________________________________ > cfe-commits mailing list > cfe-commits@lists.llvm.org <mailto:cfe-commits@lists.llvm.org> > http://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits > <http://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits>
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