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Fixed an infinite loop in the block escape in analysis in ObjCARC caused by 2x blocks each assigned a value via a phi-node causing each to depend on the other.

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A test case is provided as well.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@172368 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Michael Gottesman 2013-01-13 22:12:06 +00:00
parent 50c023d496
commit 6056b85bb5
2 changed files with 100 additions and 3 deletions
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17
lib/Transforms/Scalar/ObjCARC.cpp
View File

@ -30,6 +30,7 @@
#define DEBUG_TYPE "objc-arc"
#include "llvm/ADT/DenseMap.h"
#include "llvm/ADT/SmallPtrSet.h"
#include "llvm/Support/CommandLine.h"
#include "llvm/Support/Debug.h"
#include "llvm/Support/raw_ostream.h"
@ -625,6 +626,10 @@ static bool DoesObjCBlockEscape(const Value *BlockPtr) {
// Walk the def-use chains.
SmallVector<const Value *, 4> Worklist;
Worklist.push_back(BlockPtr);
// Ensure we do not visit any value twice.
SmallPtrSet<const Value *, 4> VisitedSet;
do {
const Value *V = Worklist.pop_back_val();
@ -655,9 +660,15 @@ static bool DoesObjCBlockEscape(const Value *BlockPtr) {
// result is an escape.
if (isa<BitCastInst>(UUser) || isa<GetElementPtrInst>(UUser) ||
isa<PHINode>(UUser) || isa<SelectInst>(UUser)) {
DEBUG(dbgs() << "DoesObjCBlockEscape: User copies value. Escapes if "
"result escapes. Adding to list.\n");
Worklist.push_back(UUser);
if (!VisitedSet.count(UUser)) {
DEBUG(dbgs() << "DoesObjCBlockEscape: User copies value. Escapes if "
"result escapes. Adding to list.\n");
VisitedSet.insert(V);
Worklist.push_back(UUser);
} else {
DEBUG(dbgs() << "DoesObjCBlockEscape: Already visited node.\n");
}
continue;
}
// Use by a load is not an escape.

86
test/Transforms/ObjCARC/dont-infinite-loop-during-block-escape-analysis.ll Normal file
View File

@ -0,0 +1,86 @@
; RUN: opt -S -objc-arc < %s
; rdar://12851911
; Make sure that we do not hang clang during escape analysis.
target datalayout = "e-p:64:64:64-i1:8:8-i8:8:8-i16:16:16-i32:32:32-i64:64:64-f32:32:32-f64:64:64-v64:64:64-v128:128:128-a0:0:64-s0:64:64-f80:128:128-n8:16:32:64-S128"
target triple = "x86_64-darwin"
%struct.__block_descriptor = type { i64, i64 }
%struct.__block_byref_foo = type { i8*, %struct.__block_byref_foo*, i32, i32, i32 }
@_NSConcreteGlobalBlock = external global i8*
@.str = private unnamed_addr constant [6 x i8] c"v8@?0\00", align 1
@__block_descriptor_tmp = internal constant { i64, i64, i8*, i8* } { i64 0, i64 32, i8* getelementptr inbounds ([6 x i8]* @.str, i32 0, i32 0), i8* null }
@__block_literal_global = internal constant { i8**, i32, i32, i8*, %struct.__block_descriptor* } { i8** @_NSConcreteGlobalBlock, i32 1342177280, i32 0, i8* bitcast (void (i8*)* @__hang_clang_block_invoke to i8*), %struct.__block_descriptor* bitcast ({ i64, i64, i8*, i8* }* @__block_descriptor_tmp to %struct.__block_descriptor*) }, align 8
define void @hang_clang() uwtable optsize ssp {
entry:
%foo = alloca %struct.__block_byref_foo, align 8
%byref.isa = getelementptr inbounds %struct.__block_byref_foo* %foo, i64 0, i32 0
store i8* null, i8** %byref.isa, align 8
%byref.forwarding = getelementptr inbounds %struct.__block_byref_foo* %foo, i64 0, i32 1
store %struct.__block_byref_foo* %foo, %struct.__block_byref_foo** %byref.forwarding, align 8
%byref.flags = getelementptr inbounds %struct.__block_byref_foo* %foo, i64 0, i32 2
store i32 536870912, i32* %byref.flags, align 8
%byref.size = getelementptr inbounds %struct.__block_byref_foo* %foo, i64 0, i32 3
store i32 32, i32* %byref.size, align 4
%foo1 = getelementptr inbounds %struct.__block_byref_foo* %foo, i64 0, i32 4
store i32 0, i32* %foo1, align 8, !tbaa !4
br label %for.body
for.body: ; preds = %for.inc.for.body_crit_edge, %entry
%0 = phi i1 [ true, %entry ], [ %phitmp, %for.inc.for.body_crit_edge ]
%i.06 = phi i32 [ 1, %entry ], [ %phitmp8, %for.inc.for.body_crit_edge ]
%block.05 = phi void (...)* [ null, %entry ], [ %block.1, %for.inc.for.body_crit_edge ]
br i1 %0, label %for.inc, label %if.then
if.then: ; preds = %for.body
%1 = call i8* @objc_retainBlock(i8* bitcast ({ i8**, i32, i32, i8*, %struct.__block_descriptor* }* @__block_literal_global to i8*)) nounwind, !clang.arc.copy_on_escape !7
%2 = bitcast i8* %1 to void (...)*
%3 = bitcast void (...)* %block.05 to i8*
call void @objc_release(i8* %3) nounwind, !clang.imprecise_release !7
br label %for.inc
for.inc: ; preds = %for.body, %if.then
%block.1 = phi void (...)* [ %2, %if.then ], [ %block.05, %for.body ]
%exitcond = icmp eq i32 %i.06, 10
br i1 %exitcond, label %for.end, label %for.inc.for.body_crit_edge
for.inc.for.body_crit_edge: ; preds = %for.inc
%.pre = load %struct.__block_byref_foo** %byref.forwarding, align 8
%foo2.phi.trans.insert = getelementptr inbounds %struct.__block_byref_foo* %.pre, i64 0, i32 4
%.pre7 = load i32* %foo2.phi.trans.insert, align 4, !tbaa !4
%phitmp = icmp eq i32 %.pre7, 0
%phitmp8 = add i32 %i.06, 1
br label %for.body
for.end: ; preds = %for.inc
%4 = bitcast %struct.__block_byref_foo* %foo to i8*
call void @_Block_object_dispose(i8* %4, i32 8)
%5 = bitcast void (...)* %block.1 to i8*
call void @objc_release(i8* %5) nounwind, !clang.imprecise_release !7
ret void
}
define internal void @__hang_clang_block_invoke(i8* nocapture %.block_descriptor) nounwind uwtable readnone optsize ssp {
entry:
ret void
}
declare i8* @objc_retainBlock(i8*)
declare void @objc_release(i8*) nonlazybind
declare void @_Block_object_dispose(i8*, i32)
!llvm.module.flags = !{!0, !1, !2, !3}
!0 = metadata !{i32 1, metadata !"Objective-C Version", i32 2}
!1 = metadata !{i32 1, metadata !"Objective-C Image Info Version", i32 0}
!2 = metadata !{i32 1, metadata !"Objective-C Image Info Section", metadata !"__DATA, __objc_imageinfo, regular, no_dead_strip"}
!3 = metadata !{i32 4, metadata !"Objective-C Garbage Collection", i32 0}
!4 = metadata !{metadata !"int", metadata !5}
!5 = metadata !{metadata !"omnipotent char", metadata !6}
!6 = metadata !{metadata !"Simple C/C++ TBAA"}
!7 = metadata !{}