Fixed an infinite loop in the block escape in analysis in ObjCARC caused by 2x blocks...

A test case is provided as well.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@172368 91177308-0d34-0410-b5e6-96231b3b80d8

diff --git a/lib/Transforms/Scalar/ObjCARC.cpp b/lib/Transforms/Scalar/ObjCARC.cpp
index 794d354ed6d255434aee37ef4ede7f9fde795cdf..2e75bb9391cda9b02d22a0740bed66d9dce14a52 100644 (file)
--- 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<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.

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 (file)
index 0000000..185d4fc
--- /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 !{}