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It turns out that clang does use pointer-to-function types to

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point to ARC-managed pointers sometimes. This fixes rdar://10551239.

llvm-svn: 146577
This commit is contained in:
Dan Gohman 2011-12-14 19:10:53 +00:00
parent bc1bb8d763
commit e9572aa680
3 changed files with 40 additions and 3 deletions
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8
lib/Transforms/Scalar/ObjCARC.cpp
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@ -179,9 +179,13 @@ static bool IsPotentialUse(const Value *Op) {
Arg->hasNestAttr() ||
Arg->hasStructRetAttr())
return false;
// Only consider values with pointer types, and not function pointers.
// Only consider values with pointer types.
// It seemes intuitive to exclude function pointer types as well, since
// functions are never reference-counted, however clang occasionally
// bitcasts reference-counted pointers to function-pointer type
// temporarily.
PointerType *Ty = dyn_cast<PointerType>(Op->getType());
if (!Ty || isa<FunctionType>(Ty->getElementType()))
if (!Ty)
return false;
// Conservatively assume anything else is a potential use.
return true;

4
test/Transforms/ObjCARC/basic.ll
View File

@ -1528,9 +1528,11 @@ define void @test52(i8** %zz, i8** %pp) {
; Like test52, but the pointer has function type, so it's assumed to
; be not reference counted.
; Oops. That's wrong. Clang sometimes uses function types gratuitously.
; See rdar://10551239.
; CHECK: define void @test53(
; CHECK-NOT: @objc_
; CHECK: @objc_
; CHECK: }
define void @test53(void ()** %zz, i8** %pp) {
%p = load i8** %pp

31
test/Transforms/ObjCARC/pointer-types.ll Normal file
View File

@ -0,0 +1,31 @@
; RUN: opt -objc-arc -S < %s | FileCheck %s
; Don't hoist @objc_release past a use of its pointer, even
; if the use has function type, because clang uses function types
; in dubious ways.
; rdar://10551239
; CHECK: define void @test0(
; CHECK: %otherBlock = phi void ()* [ %b1, %if.then ], [ null, %entry ]
; CHECK-NEXT: call void @use_fptr(void ()* %otherBlock)
; CHECK-NEXT: %tmp11 = bitcast void ()* %otherBlock to i8*
; CHECK-NEXT: call void @objc_release(i8* %tmp11)
define void @test0(i1 %tobool, void ()* %b1) {
entry:
br i1 %tobool, label %if.end, label %if.then
if.then: ; preds = %entry
br label %if.end
if.end: ; preds = %if.then, %entry
%otherBlock = phi void ()* [ %b1, %if.then ], [ null, %entry ]
call void @use_fptr(void ()* %otherBlock)
%tmp11 = bitcast void ()* %otherBlock to i8*
call void @objc_release(i8* %tmp11) nounwind
ret void
}
declare void @use_fptr(void ()*)
declare void @objc_release(i8*)