[PATCH] D143069: [DAGCombine] Allow DAGCombine to remove dead masked stores

[Dinar Temirbulatov via Phabricator via llvm-commits]

dtemirbulatov created this revision.
dtemirbulatov added reviewers: sdesmalen, david-arm, peterwaller-arm, MattDevereau, RKSimon.
Herald added subscribers: ecnelises, pengfei, hiraditya.
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dtemirbulatov requested review of this revision.
Herald added a project: LLVM.

Remove a dead masked store if another one has the same base pointer and mask.


https://reviews.llvm.org/D143069

Files:
  llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
  llvm/test/CodeGen/AArch64/sve-dead-masked-store.ll
  llvm/test/CodeGen/X86/masked_store.ll


Index: llvm/test/CodeGen/AArch64/sve-dead-masked-store.ll
===================================================================
--- /dev/null
+++ llvm/test/CodeGen/AArch64/sve-dead-masked-store.ll
@@ -0,0 +1,13 @@
+; NOTE: Assertions have been autogenerated by utils/update_llc_test_checks.py
+; RUN: llc -mtriple=aarch64--linux-gnu -mattr=+sve < %s | FileCheck %s
+
+define void @dead_masked_store(<vscale x 4 x i32> %val, ptr %a, <vscale x 4 x i1> %mask) nounwind {
+; CHECK-LABEL: dead_masked_store:
+; CHECK:       // %bb.0:
+; CHECK-NEXT:    st1w { z0.s }, p0, [x0]
+; CHECK-NEXT:    ret
+  call void @llvm.masked.store.nxv4i32(<vscale x 4 x i32> %val, ptr %a, i32 4, <vscale x 4 x i1> %mask)
+  call void @llvm.masked.store.nxv4i32(<vscale x 4 x i32> %val, ptr %a, i32 4, <vscale x 4 x i1> %mask)
+  ret void
+}
+declare void @llvm.masked.store.nxv4i32(<vscale x 4 x i32>, <vscale x 4 x i32>*, i32, <vscale x 4 x i1>)
Index: llvm/test/CodeGen/X86/masked_store.ll
===================================================================
--- llvm/test/CodeGen/X86/masked_store.ll
+++ llvm/test/CodeGen/X86/masked_store.ll
@@ -5564,7 +5564,6 @@
 ;
 ; AVX1OR2-LABEL: PR11210:
 ; AVX1OR2:       ## %bb.0:
-; AVX1OR2-NEXT:    vmaskmovps %xmm0, %xmm2, (%rdi)
 ; AVX1OR2-NEXT:    vmaskmovps %xmm1, %xmm2, (%rdi)
 ; AVX1OR2-NEXT:    retq
 ;
@@ -5572,12 +5571,10 @@
 ; AVX512F:       ## %bb.0:
 ; AVX512F-NEXT:    ## kill: def $xmm2 killed $xmm2 def $zmm2
 ; AVX512F-NEXT:    ## kill: def $xmm1 killed $xmm1 def $zmm1
-; AVX512F-NEXT:    ## kill: def $xmm0 killed $xmm0 def $zmm0
-; AVX512F-NEXT:    vpxor %xmm3, %xmm3, %xmm3
-; AVX512F-NEXT:    vpcmpgtd %zmm2, %zmm3, %k0
+; AVX512F-NEXT:    vpxor %xmm0, %xmm0, %xmm0
+; AVX512F-NEXT:    vpcmpgtd %zmm2, %zmm0, %k0
 ; AVX512F-NEXT:    kshiftlw $12, %k0, %k0
 ; AVX512F-NEXT:    kshiftrw $12, %k0, %k1
-; AVX512F-NEXT:    vmovups %zmm0, (%rdi) {%k1}
 ; AVX512F-NEXT:    vmovups %zmm1, (%rdi) {%k1}
 ; AVX512F-NEXT:    vzeroupper
 ; AVX512F-NEXT:    retq
@@ -5585,15 +5582,13 @@
 ; AVX512VLDQ-LABEL: PR11210:
 ; AVX512VLDQ:       ## %bb.0:
 ; AVX512VLDQ-NEXT:    vpmovd2m %xmm2, %k1
-; AVX512VLDQ-NEXT:    vmovups %xmm0, (%rdi) {%k1}
 ; AVX512VLDQ-NEXT:    vmovups %xmm1, (%rdi) {%k1}
 ; AVX512VLDQ-NEXT:    retq
 ;
 ; AVX512VLBW-LABEL: PR11210:
 ; AVX512VLBW:       ## %bb.0:
-; AVX512VLBW-NEXT:    vpxor %xmm3, %xmm3, %xmm3
-; AVX512VLBW-NEXT:    vpcmpgtd %xmm2, %xmm3, %k1
-; AVX512VLBW-NEXT:    vmovups %xmm0, (%rdi) {%k1}
+; AVX512VLBW-NEXT:    vpxor %xmm0, %xmm0, %xmm0
+; AVX512VLBW-NEXT:    vpcmpgtd %xmm2, %xmm0, %k1
 ; AVX512VLBW-NEXT:    vmovups %xmm1, (%rdi) {%k1}
 ; AVX512VLBW-NEXT:    retq
 ;
@@ -5601,7 +5596,6 @@
 ; X86-AVX512:       ## %bb.0:
 ; X86-AVX512-NEXT:    movl {{[0-9]+}}(%esp), %eax
 ; X86-AVX512-NEXT:    vpmovd2m %xmm2, %k1
-; X86-AVX512-NEXT:    vmovups %xmm0, (%eax) {%k1}
 ; X86-AVX512-NEXT:    vmovups %xmm1, (%eax) {%k1}
 ; X86-AVX512-NEXT:    retl
   %bc = bitcast <2 x i64> %mask to <4 x i32>
Index: llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
===================================================================
--- llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
+++ llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
@@ -11161,6 +11161,23 @@
                               /*IsTruncating=*/true);
   }
 
+  // Remove a masked store if base pointers and masks are equal.
+  if (MaskedStoreSDNode *MST1 = dyn_cast<MaskedStoreSDNode>(Chain)) {
+    if (MST->isUnindexed() && MST->isSimple() && MST1->isUnindexed() &&
+        MST1->isSimple() && OptLevel != CodeGenOpt::None &&
+        MST1->getBasePtr() == Ptr && MST1->hasOneUse() &&
+        !MST1->getBasePtr().isUndef() &&
+        MST->getAddressSpace() == MST1->getAddressSpace() &&
+        Mask == MST1->getMask() &&
+        TypeSize::isKnownLE(MST1->getMemoryVT().getStoreSize(),
+                            MST->getMemoryVT().getStoreSize())) {
+      CombineTo(MST1, MST1->getChain());
+      if (N->getOpcode() != ISD::DELETED_NODE)
+        AddToWorklist(N);
+      return SDValue(N, 0);
+    }
+  }
+
   return SDValue();
 }
 


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