[llvm] r365660 - [CodeExtractor] Fix sinking of allocas with multiple bitcast uses (PR42451)
Vedant Kumar via llvm-commits
llvm-commits at lists.llvm.org
Wed Jul 10 09:32:22 PDT 2019
Author: vedantk
Date: Wed Jul 10 09:32:20 2019
New Revision: 365660
URL: http://llvm.org/viewvc/llvm-project?rev=365660&view=rev
Log:
[CodeExtractor] Fix sinking of allocas with multiple bitcast uses (PR42451)
An alloca which can be sunk into the extraction region may have more
than one bitcast use. Move these uses along with the alloca to prevent
use-before-def.
Testing: check-llvm, stage2 build of clang
Fixes llvm.org/PR42451.
Differential Revision: https://reviews.llvm.org/D64463
Added:
llvm/trunk/test/Transforms/HotColdSplit/sink-multiple-bitcasts-of-allocas-pr42451.ll
Modified:
llvm/trunk/lib/Transforms/Utils/CodeExtractor.cpp
llvm/trunk/test/Transforms/CodeExtractor/live_shrink_multiple.ll
Modified: llvm/trunk/lib/Transforms/Utils/CodeExtractor.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/Utils/CodeExtractor.cpp?rev=365660&r1=365659&r2=365660&view=diff
==============================================================================
--- llvm/trunk/lib/Transforms/Utils/CodeExtractor.cpp (original)
+++ llvm/trunk/lib/Transforms/Utils/CodeExtractor.cpp Wed Jul 10 09:32:20 2019
@@ -519,18 +519,20 @@ void CodeExtractor::findAllocas(ValueSet
if (Bitcasts.empty())
continue;
- Instruction *BitcastAddr = Bitcasts.back();
- const LifetimeMarkerInfo &LMI = BitcastLifetimeInfo.back();
- assert(LMI.LifeStart &&
- "Unsafe to sink bitcast without lifetime markers");
- moveOrIgnoreLifetimeMarkers(LMI);
- if (!definedInRegion(Blocks, BitcastAddr)) {
- LLVM_DEBUG(dbgs() << "Sinking bitcast-of-alloca: " << *BitcastAddr
- << "\n");
- SinkCands.insert(BitcastAddr);
- }
LLVM_DEBUG(dbgs() << "Sinking alloca (via bitcast): " << *AI << "\n");
SinkCands.insert(AI);
+ for (unsigned I = 0, E = Bitcasts.size(); I != E; ++I) {
+ Instruction *BitcastAddr = Bitcasts[I];
+ const LifetimeMarkerInfo &LMI = BitcastLifetimeInfo[I];
+ assert(LMI.LifeStart &&
+ "Unsafe to sink bitcast without lifetime markers");
+ moveOrIgnoreLifetimeMarkers(LMI);
+ if (!definedInRegion(Blocks, BitcastAddr)) {
+ LLVM_DEBUG(dbgs() << "Sinking bitcast-of-alloca: " << *BitcastAddr
+ << "\n");
+ SinkCands.insert(BitcastAddr);
+ }
+ }
}
}
}
@@ -1431,9 +1433,23 @@ Function *CodeExtractor::extractCodeRegi
findInputsOutputs(inputs, outputs, SinkingCands);
// Now sink all instructions which only have non-phi uses inside the region.
- for (auto *II : SinkingCands)
- cast<Instruction>(II)->moveBefore(*newFuncRoot,
- newFuncRoot->getFirstInsertionPt());
+ // Group the allocas at the start of the block, so that any bitcast uses of
+ // the allocas are well-defined.
+ AllocaInst *FirstSunkAlloca = nullptr;
+ for (auto *II : SinkingCands) {
+ if (auto *AI = dyn_cast<AllocaInst>(II)) {
+ AI->moveBefore(*newFuncRoot, newFuncRoot->getFirstInsertionPt());
+ if (!FirstSunkAlloca)
+ FirstSunkAlloca = AI;
+ }
+ }
+ assert((SinkingCands.empty() || FirstSunkAlloca) &&
+ "Did not expect a sink candidate without any allocas");
+ for (auto *II : SinkingCands) {
+ if (!isa<AllocaInst>(II)) {
+ cast<Instruction>(II)->moveAfter(FirstSunkAlloca);
+ }
+ }
if (!HoistingCands.empty()) {
auto *HoistToBlock = findOrCreateBlockForHoisting(CommonExit);
Modified: llvm/trunk/test/Transforms/CodeExtractor/live_shrink_multiple.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transforms/CodeExtractor/live_shrink_multiple.ll?rev=365660&r1=365659&r2=365660&view=diff
==============================================================================
--- llvm/trunk/test/Transforms/CodeExtractor/live_shrink_multiple.ll (original)
+++ llvm/trunk/test/Transforms/CodeExtractor/live_shrink_multiple.ll Wed Jul 10 09:32:20 2019
@@ -45,9 +45,9 @@ bb:
; CHECK-LABEL: define internal void @_Z3foov.1.
; CHECK: newFuncRoot:
; CHECK-NEXT: alloca
+; CHECK-NEXT: alloca
; CHECK-NEXT: bitcast
; CHECK-NEXT: call void @llvm.lifetime.start.p0i8
-; CHECK-NEXT: alloca
; CHECK-NEXT: bitcast
; CHECK-NEXT: call void @llvm.lifetime.start.p0i8
; CHECK: call void @llvm.lifetime.end.p0i8
Added: llvm/trunk/test/Transforms/HotColdSplit/sink-multiple-bitcasts-of-allocas-pr42451.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transforms/HotColdSplit/sink-multiple-bitcasts-of-allocas-pr42451.ll?rev=365660&view=auto
==============================================================================
--- llvm/trunk/test/Transforms/HotColdSplit/sink-multiple-bitcasts-of-allocas-pr42451.ll (added)
+++ llvm/trunk/test/Transforms/HotColdSplit/sink-multiple-bitcasts-of-allocas-pr42451.ll Wed Jul 10 09:32:20 2019
@@ -0,0 +1,74 @@
+; RUN: opt -hotcoldsplit -hotcoldsplit-threshold=-1 -S < %s | FileCheck %s
+
+target datalayout = "e-m:o-i64:64-f80:128-n8:16:32:64-S128"
+target triple = "x86_64-apple-macosx10.14.0"
+
+ at c = common global i32 0, align 4
+ at h = common global i32 0, align 4
+
+declare void @llvm.lifetime.start.p0i8(i64 immarg, i8* nocapture) #1
+
+declare void @llvm.lifetime.end.p0i8(i64 immarg, i8* nocapture) #1
+
+declare void @llvm.memset.p0i8.i64(i8* nocapture writeonly, i8, i64, i1 immarg) #1
+
+declare i32* @m()
+
+; CHECK-LABEL: define void @main()
+; CHECK-NEXT: %.sroa.4.i = alloca [20 x i8], align 2
+; CHECK-NEXT: %.sroa.5.i = alloca [6 x i8], align 8
+; CHECK-NEXT: %1 = bitcast [6 x i8]* %.sroa.5.i to i8*
+
+define void @main() #0 {
+ %.sroa.4.i = alloca [20 x i8], align 2
+ %.sroa.5.i = alloca [6 x i8], align 8
+ %1 = bitcast [6 x i8]* %.sroa.5.i to i8*
+ %2 = load i32, i32* @h, align 4, !tbaa !4
+ %3 = icmp ne i32 %2, 0
+ br i1 %3, label %12, label %4
+
+4: ; preds = %0
+ %5 = call i32* @m() #3
+ %.sroa.4.0..sroa_idx21.i = getelementptr inbounds [20 x i8], [20 x i8]* %.sroa.4.i, i64 0, i64 0
+ call void @llvm.lifetime.start.p0i8(i64 20, i8* %.sroa.4.0..sroa_idx21.i) #3
+ %.sroa.5.0..sroa_idx16.i = getelementptr inbounds [6 x i8], [6 x i8]* %.sroa.5.i, i64 0, i64 0
+ call void @llvm.lifetime.start.p0i8(i64 6, i8* %.sroa.5.0..sroa_idx16.i) #3
+ call void @llvm.memset.p0i8.i64(i8* align 2 %.sroa.4.0..sroa_idx21.i, i8 0, i64 20, i1 false) #3
+ call void @llvm.memset.p0i8.i64(i8* align 8 %.sroa.5.0..sroa_idx16.i, i8 0, i64 6, i1 false) #3
+ %6 = load i32, i32* @c, align 4, !tbaa !4
+ %7 = trunc i32 %6 to i16
+ call void @llvm.lifetime.end.p0i8(i64 20, i8* %.sroa.4.0..sroa_idx21.i) #3
+ call void @llvm.lifetime.end.p0i8(i64 6, i8* %.sroa.5.0..sroa_idx16.i) #3
+ call void @llvm.lifetime.start.p0i8(i64 6, i8* %1) #3
+ call void @llvm.memset.p0i8.i64(i8* align 1 %1, i8 3, i64 6, i1 false)
+ br label %8
+
+8: ; preds = %8, %4
+ %.0.i = phi i32 [ 0, %4 ], [ %10, %8 ]
+ %9 = sext i32 %.0.i to i64
+ %10 = add nsw i32 %.0.i, 1
+ %11 = icmp slt i32 %10, 6
+ br i1 %11, label %8, label %l.exit
+
+l.exit: ; preds = %8
+ call void @llvm.lifetime.end.p0i8(i64 6, i8* %1) #3
+ br label %12
+
+12: ; preds = %l.exit, %0
+ %13 = phi i1 [ true, %0 ], [ true, %l.exit ]
+ ret void
+}
+
+attributes #0 = { cold }
+
+!llvm.module.flags = !{!0, !1, !2}
+!llvm.ident = !{!3}
+
+!0 = !{i32 2, !"SDK Version", [2 x i32] [i32 10, i32 14]}
+!1 = !{i32 1, !"wchar_size", i32 4}
+!2 = !{i32 7, !"PIC Level", i32 2}
+!3 = !{!"Apple clang version 11.0.0 (clang-1100.0.20.17)"}
+!4 = !{!5, !5, i64 0}
+!5 = !{!"int", !6, i64 0}
+!6 = !{!"omnipotent char", !7, i64 0}
+!7 = !{!"Simple C/C++ TBAA"}
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