From 6056b85bb5e863f3b174ed21bd70e22a03ed61f7 Mon Sep 17 00:00:00 2001 From: Michael Gottesman Date: Sun, 13 Jan 2013 22:12:06 +0000 Subject: [PATCH] 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. A test case is provided as well. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@172368 91177308-0d34-0410-b5e6-96231b3b80d8 --- lib/Transforms/Scalar/ObjCARC.cpp | 17 +++- ...inite-loop-during-block-escape-analysis.ll | 86 +++++++++++++++++++ 2 files changed, 100 insertions(+), 3 deletions(-) create mode 100644 test/Transforms/ObjCARC/dont-infinite-loop-during-block-escape-analysis.ll diff --git a/lib/Transforms/Scalar/ObjCARC.cpp b/lib/Transforms/Scalar/ObjCARC.cpp index 794d354ed6d..2e75bb9391c 100644 --- a/lib/Transforms/Scalar/ObjCARC.cpp +++ b/lib/Transforms/Scalar/ObjCARC.cpp @@ -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 Worklist; Worklist.push_back(BlockPtr); + + // Ensure we do not visit any value twice. + SmallPtrSet 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(UUser) || isa(UUser) || isa(UUser) || isa(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. diff --git a/test/Transforms/ObjCARC/dont-infinite-loop-during-block-escape-analysis.ll b/test/Transforms/ObjCARC/dont-infinite-loop-during-block-escape-analysis.ll new file mode 100644 index 00000000000..185d4fc47ff --- /dev/null +++ b/test/Transforms/ObjCARC/dont-infinite-loop-during-block-escape-analysis.ll @@ -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 !{} -- 2.34.1