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[DAGCombiner] Bugfix for lost chain depenedency.

When MergeConsecutiveStores() combines two loads and two stores into
wider loads and stores, the chain users of both of the original loads
must be transfered to the new load, because it may be that a chain
user only depends on one of the loads.

New test case: test/CodeGen/SystemZ/dag-combine-01.ll

Reviewed by James Y Knight.

Bugzilla: https://llvm.org/bugs/show_bug.cgi?id=25310#c6
llvm-svn: 253779
This commit is contained in:
Jonas Paulsson 2015-11-21 13:25:07 +00:00
parent 6bc8690714
commit 7f3f06c3b2
2 changed files with 104 additions and 13 deletions

View File

@ -11529,7 +11529,7 @@ bool DAGCombiner::MergeConsecutiveStores(StoreSDNode* St) {
StartAddress = LoadNodes[0].OffsetFromBase;
SDValue FirstChain = FirstLoad->getChain();
for (unsigned i = 1; i < LoadNodes.size(); ++i) {
// All loads much share the same chain.
// All loads must share the same chain.
if (LoadNodes[i].MemNode->getChain() != FirstChain)
break;
@ -11621,8 +11621,8 @@ bool DAGCombiner::MergeConsecutiveStores(StoreSDNode* St) {
SDLoc LoadDL(LoadNodes[0].MemNode);
SDLoc StoreDL(StoreNodes[0].MemNode);
// The merged loads are required to have the same chain, so using the first's
// chain is acceptable.
// The merged loads are required to have the same incoming chain, so
// using the first's chain is acceptable.
SDValue NewLoad = DAG.getLoad(
JointMemOpVT, LoadDL, FirstLoad->getChain(), FirstLoad->getBasePtr(),
FirstLoad->getPointerInfo(), false, false, false, FirstLoadAlign);
@ -11634,17 +11634,11 @@ bool DAGCombiner::MergeConsecutiveStores(StoreSDNode* St) {
NewStoreChain, StoreDL, NewLoad, FirstInChain->getBasePtr(),
FirstInChain->getPointerInfo(), false, false, FirstStoreAlign);
// Replace one of the loads with the new load.
LoadSDNode *Ld = cast<LoadSDNode>(LoadNodes[0].MemNode);
DAG.ReplaceAllUsesOfValueWith(SDValue(Ld, 1),
SDValue(NewLoad.getNode(), 1));
// Remove the rest of the load chains.
for (unsigned i = 1; i < NumElem ; ++i) {
// Replace all chain users of the old load nodes with the chain of the new
// load node.
// Transfer chain users from old loads to the new load.
for (unsigned i = 0; i < NumElem; ++i) {
LoadSDNode *Ld = cast<LoadSDNode>(LoadNodes[i].MemNode);
DAG.ReplaceAllUsesOfValueWith(SDValue(Ld, 1), Ld->getChain());
DAG.ReplaceAllUsesOfValueWith(SDValue(Ld, 1),
SDValue(NewLoad.getNode(), 1));
}
// Replace the last store with the new store.

View File

@ -0,0 +1,97 @@
; Test that MergeConsecutiveStores() does not during DAG combining
; incorrectly drop a chain dependency to a store previously chained to
; one of two combined loads.
;
; RUN: llc < %s -mtriple=s390x-linux-gnu -mcpu=z13 | FileCheck %s
@A = common global [2048 x float] zeroinitializer, align 4
; Function Attrs: nounwind
define signext i32 @main(i32 signext %argc, i8** nocapture readnone %argv) #0 {
entry:
br label %for.body
for.body: ; preds = %for.body, %entry
%indvars.iv24 = phi i64 [ 0, %entry ], [ %indvars.iv.next25, %for.body ]
%sum.018 = phi float [ 0.000000e+00, %entry ], [ %add, %for.body ]
%0 = trunc i64 %indvars.iv24 to i32
%conv = sitofp i32 %0 to float
%arrayidx = getelementptr inbounds [2048 x float], [2048 x float]* @A, i64 0, i64 %indvars.iv24
store float %conv, float* %arrayidx, align 4
%add = fadd float %sum.018, %conv
%indvars.iv.next25 = add nuw nsw i64 %indvars.iv24, 1
%exitcond26 = icmp eq i64 %indvars.iv.next25, 2048
br i1 %exitcond26, label %for.end, label %for.body
for.end: ; preds = %for.body
br label %for.body.3.lr.ph.i.preheader
for.body.3.lr.ph.i.preheader: ; preds = %complex_transpose.exit, %for.end
%i.116 = phi i32 [ 0, %for.end ], [ %inc9, %complex_transpose.exit ]
br label %for.body.3.lr.ph.i
for.body.3.lr.ph.i: ; preds = %for.body.3.lr.ph.i.preheader, %for.inc.40.i
%indvars.iv19 = phi i32 [ 1, %for.body.3.lr.ph.i.preheader ], [ %indvars.iv.next20, %for.inc.40.i ]
%indvars.iv57.i = phi i64 [ 1, %for.body.3.lr.ph.i.preheader ], [ %indvars.iv.next58.i, %for.inc.40.i ]
%1 = shl nsw i64 %indvars.iv57.i, 1
%2 = shl nsw i64 %indvars.iv57.i, 6
br label %for.body.3.i
for.body.3.i: ; preds = %for.body.3.i, %for.body.3.lr.ph.i
; CHECK-LABEL: .LBB0_5:
; CHECK-NOT: stfh %r{{.*}}, 0(%r{{.*}})
; CHECK: lg %r{{.*}}, -4(%r{{.*}})
; Overlapping load should go before the store
%indvars.iv.i = phi i64 [ 0, %for.body.3.lr.ph.i ], [ %indvars.iv.next.i, %for.body.3.i ]
%3 = shl nsw i64 %indvars.iv.i, 6
%4 = add nuw nsw i64 %3, %1
%arrayidx.i = getelementptr inbounds [2048 x float], [2048 x float]* @A, i64 0, i64 %4
%5 = bitcast float* %arrayidx.i to i32*
%6 = load i32, i32* %5, align 4
%arrayidx9.i = getelementptr inbounds float, float* getelementptr inbounds ([2048 x float], [2048 x float]* @A, i64 0, i64 1), i64 %4
%7 = bitcast float* %arrayidx9.i to i32*
%8 = load i32, i32* %7, align 4
%9 = shl nsw i64 %indvars.iv.i, 1
%10 = add nuw nsw i64 %9, %2
%arrayidx14.i = getelementptr inbounds [2048 x float], [2048 x float]* @A, i64 0, i64 %10
%11 = bitcast float* %arrayidx14.i to i32*
%12 = load i32, i32* %11, align 4
%arrayidx19.i = getelementptr inbounds float, float* getelementptr inbounds ([2048 x float], [2048 x float]* @A, i64 0, i64 1), i64 %10
%13 = bitcast float* %arrayidx19.i to i32*
%14 = load i32, i32* %13, align 4
store i32 %6, i32* %11, align 4
store i32 %8, i32* %13, align 4
store i32 %12, i32* %5, align 4
store i32 %14, i32* %7, align 4
%indvars.iv.next.i = add nuw nsw i64 %indvars.iv.i, 1
%lftr.wideiv = trunc i64 %indvars.iv.next.i to i32
%exitcond21 = icmp eq i32 %lftr.wideiv, %indvars.iv19
br i1 %exitcond21, label %for.inc.40.i, label %for.body.3.i
for.inc.40.i: ; preds = %for.body.3.i
%indvars.iv.next58.i = add nuw nsw i64 %indvars.iv57.i, 1
%indvars.iv.next20 = add nuw nsw i32 %indvars.iv19, 1
%exitcond22 = icmp eq i64 %indvars.iv.next58.i, 32
br i1 %exitcond22, label %complex_transpose.exit, label %for.body.3.lr.ph.i
complex_transpose.exit: ; preds = %for.inc.40.i
%inc9 = add nuw nsw i32 %i.116, 1
%exitcond23 = icmp eq i32 %inc9, 10
br i1 %exitcond23, label %for.body.14.preheader, label %for.body.3.lr.ph.i.preheader
for.body.14.preheader: ; preds = %complex_transpose.exit
br label %for.body.14
for.body.14: ; preds = %for.body.14.preheader, %for.body.14
%indvars.iv = phi i64 [ %indvars.iv.next, %for.body.14 ], [ 0, %for.body.14.preheader ]
%sum.115 = phi float [ %add17, %for.body.14 ], [ 0.000000e+00, %for.body.14.preheader ]
%arrayidx16 = getelementptr inbounds [2048 x float], [2048 x float]* @A, i64 0, i64 %indvars.iv
%15 = load float, float* %arrayidx16, align 4
%add17 = fadd float %sum.115, %15
%indvars.iv.next = add nuw nsw i64 %indvars.iv, 1
%exitcond = icmp eq i64 %indvars.iv.next, 2048
br i1 %exitcond, label %for.end.20, label %for.body.14
for.end.20: ; preds = %for.body.14
ret i32 0
}