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-rw-r--r--llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp20
-rw-r--r--llvm/test/CodeGen/SystemZ/dag-combine-01.ll97
2 files changed, 104 insertions, 13 deletions
diff --git a/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp b/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
index af73b62546e..1cf5c4c913c 100644
--- a/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
+++ b/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
@@ -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.
diff --git a/llvm/test/CodeGen/SystemZ/dag-combine-01.ll b/llvm/test/CodeGen/SystemZ/dag-combine-01.ll
new file mode 100644
index 00000000000..a56a118dada
--- /dev/null
+++ b/llvm/test/CodeGen/SystemZ/dag-combine-01.ll
@@ -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
+}
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