[LoongArch] Fix failure to widen operand for `[X]VMSK{LT,GE,NE}Z` #149442

heiher · 2025-07-18T03:05:49Z

Reported-by: tangyan [email protected]

llvmbot · 2025-07-18T03:06:18Z

@llvm/pr-subscribers-backend-loongarch

Author: hev (heiher)

Changes

Reported-by: tangyan <[email protected]>

Full diff: https://github.com/llvm/llvm-project/pull/149442.diff

2 Files Affected:

(modified) llvm/lib/Target/LoongArch/LoongArchISelLowering.cpp (+120-100)
(modified) llvm/test/CodeGen/LoongArch/lsx/vmskcond.ll (+15)

diff --git a/llvm/lib/Target/LoongArch/LoongArchISelLowering.cpp b/llvm/lib/Target/LoongArch/LoongArchISelLowering.cpp
index 2378664ca8155..c870271213dc6 100644
--- a/llvm/lib/Target/LoongArch/LoongArchISelLowering.cpp
+++ b/llvm/lib/Target/LoongArch/LoongArchISelLowering.cpp
@@ -4560,6 +4560,80 @@ static SDValue signExtendBitcastSrcVector(SelectionDAG &DAG, EVT SExtVT,
   llvm_unreachable("Unexpected node type for vXi1 sign extension");
 }
 
+static SDValue
+performSETCC_BITCASTCombine(SDNode *N, SelectionDAG &DAG,
+                            TargetLowering::DAGCombinerInfo &DCI,
+                            const LoongArchSubtarget &Subtarget) {
+  SDLoc DL(N);
+  EVT VT = N->getValueType(0);
+  SDValue Src = N->getOperand(0);
+  EVT SrcVT = Src.getValueType();
+
+  if (Src.getOpcode() != ISD::SETCC || !Src.hasOneUse())
+    return SDValue();
+
+  bool UseLASX;
+  unsigned Opc = ISD::DELETED_NODE;
+  EVT CmpVT = Src.getOperand(0).getValueType();
+  EVT EltVT = CmpVT.getVectorElementType();
+
+  if (Subtarget.hasExtLSX() && CmpVT.getSizeInBits() == 128)
+    UseLASX = false;
+  else if (Subtarget.has32S() && Subtarget.hasExtLASX() &&
+           CmpVT.getSizeInBits() == 256)
+    UseLASX = true;
+  else
+    return SDValue();
+
+  SDValue SrcN1 = Src.getOperand(1);
+  switch (cast<CondCodeSDNode>(Src.getOperand(2))->get()) {
+  default:
+    break;
+  case ISD::SETEQ:
+    // x == 0 => not (vmsknez.b x)
+    if (ISD::isBuildVectorAllZeros(SrcN1.getNode()) && EltVT == MVT::i8)
+      Opc = UseLASX ? LoongArchISD::XVMSKEQZ : LoongArchISD::VMSKEQZ;
+    break;
+  case ISD::SETGT:
+    // x > -1 => vmskgez.b x
+    if (ISD::isBuildVectorAllOnes(SrcN1.getNode()) && EltVT == MVT::i8)
+      Opc = UseLASX ? LoongArchISD::XVMSKGEZ : LoongArchISD::VMSKGEZ;
+    break;
+  case ISD::SETGE:
+    // x >= 0 => vmskgez.b x
+    if (ISD::isBuildVectorAllZeros(SrcN1.getNode()) && EltVT == MVT::i8)
+      Opc = UseLASX ? LoongArchISD::XVMSKGEZ : LoongArchISD::VMSKGEZ;
+    break;
+  case ISD::SETLT:
+    // x < 0 => vmskltz.{b,h,w,d} x
+    if (ISD::isBuildVectorAllZeros(SrcN1.getNode()) &&
+        (EltVT == MVT::i8 || EltVT == MVT::i16 || EltVT == MVT::i32 ||
+         EltVT == MVT::i64))
+      Opc = UseLASX ? LoongArchISD::XVMSKLTZ : LoongArchISD::VMSKLTZ;
+    break;
+  case ISD::SETLE:
+    // x <= -1 => vmskltz.{b,h,w,d} x
+    if (ISD::isBuildVectorAllOnes(SrcN1.getNode()) &&
+        (EltVT == MVT::i8 || EltVT == MVT::i16 || EltVT == MVT::i32 ||
+         EltVT == MVT::i64))
+      Opc = UseLASX ? LoongArchISD::XVMSKLTZ : LoongArchISD::VMSKLTZ;
+    break;
+  case ISD::SETNE:
+    // x != 0 => vmsknez.b x
+    if (ISD::isBuildVectorAllZeros(SrcN1.getNode()) && EltVT == MVT::i8)
+      Opc = UseLASX ? LoongArchISD::XVMSKNEZ : LoongArchISD::VMSKNEZ;
+    break;
+  }
+
+  if (Opc == ISD::DELETED_NODE)
+    return SDValue();
+
+  SDValue V = DAG.getNode(Opc, DL, MVT::i64, Src.getOperand(0));
+  EVT T = EVT::getIntegerVT(*DAG.getContext(), SrcVT.getVectorNumElements());
+  V = DAG.getZExtOrTrunc(V, DL, T);
+  return DAG.getBitcast(VT, V);
+}
+
 static SDValue performBITCASTCombine(SDNode *N, SelectionDAG &DAG,
                                      TargetLowering::DAGCombinerInfo &DCI,
                                      const LoongArchSubtarget &Subtarget) {
@@ -4574,110 +4648,56 @@ static SDValue performBITCASTCombine(SDNode *N, SelectionDAG &DAG,
   if (!SrcVT.isSimple() || SrcVT.getScalarType() != MVT::i1)
     return SDValue();
 
-  unsigned Opc = ISD::DELETED_NODE;
   // Combine SETCC and BITCAST into [X]VMSK{LT,GE,NE} when possible
-  if (Src.getOpcode() == ISD::SETCC && Src.hasOneUse()) {
-    bool UseLASX;
-    EVT CmpVT = Src.getOperand(0).getValueType();
-    EVT EltVT = CmpVT.getVectorElementType();
-
-    if (Subtarget.hasExtLSX() && CmpVT.getSizeInBits() <= 128)
-      UseLASX = false;
-    else if (Subtarget.has32S() && Subtarget.hasExtLASX() &&
-             CmpVT.getSizeInBits() <= 256)
-      UseLASX = true;
-    else
-      return SDValue();
-
-    SDValue SrcN1 = Src.getOperand(1);
-    switch (cast<CondCodeSDNode>(Src.getOperand(2))->get()) {
-    default:
-      break;
-    case ISD::SETEQ:
-      // x == 0 => not (vmsknez.b x)
-      if (ISD::isBuildVectorAllZeros(SrcN1.getNode()) && EltVT == MVT::i8)
-        Opc = UseLASX ? LoongArchISD::XVMSKEQZ : LoongArchISD::VMSKEQZ;
-      break;
-    case ISD::SETGT:
-      // x > -1 => vmskgez.b x
-      if (ISD::isBuildVectorAllOnes(SrcN1.getNode()) && EltVT == MVT::i8)
-        Opc = UseLASX ? LoongArchISD::XVMSKGEZ : LoongArchISD::VMSKGEZ;
-      break;
-    case ISD::SETGE:
-      // x >= 0 => vmskgez.b x
-      if (ISD::isBuildVectorAllZeros(SrcN1.getNode()) && EltVT == MVT::i8)
-        Opc = UseLASX ? LoongArchISD::XVMSKGEZ : LoongArchISD::VMSKGEZ;
-      break;
-    case ISD::SETLT:
-      // x < 0 => vmskltz.{b,h,w,d} x
-      if (ISD::isBuildVectorAllZeros(SrcN1.getNode()) &&
-          (EltVT == MVT::i8 || EltVT == MVT::i16 || EltVT == MVT::i32 ||
-           EltVT == MVT::i64))
-        Opc = UseLASX ? LoongArchISD::XVMSKLTZ : LoongArchISD::VMSKLTZ;
-      break;
-    case ISD::SETLE:
-      // x <= -1 => vmskltz.{b,h,w,d} x
-      if (ISD::isBuildVectorAllOnes(SrcN1.getNode()) &&
-          (EltVT == MVT::i8 || EltVT == MVT::i16 || EltVT == MVT::i32 ||
-           EltVT == MVT::i64))
-        Opc = UseLASX ? LoongArchISD::XVMSKLTZ : LoongArchISD::VMSKLTZ;
-      break;
-    case ISD::SETNE:
-      // x != 0 => vmsknez.b x
-      if (ISD::isBuildVectorAllZeros(SrcN1.getNode()) && EltVT == MVT::i8)
-        Opc = UseLASX ? LoongArchISD::XVMSKNEZ : LoongArchISD::VMSKNEZ;
-      break;
-    }
-  }
+  SDValue Res = performSETCC_BITCASTCombine(N, DAG, DCI, Subtarget);
+  if (Res)
+    return Res;
 
   // Generate vXi1 using [X]VMSKLTZ
-  if (Opc == ISD::DELETED_NODE) {
-    MVT SExtVT;
-    bool UseLASX = false;
-    bool PropagateSExt = false;
-    switch (SrcVT.getSimpleVT().SimpleTy) {
-    default:
-      return SDValue();
-    case MVT::v2i1:
-      SExtVT = MVT::v2i64;
-      break;
-    case MVT::v4i1:
-      SExtVT = MVT::v4i32;
-      if (Subtarget.hasExtLASX() && checkBitcastSrcVectorSize(Src, 256, 0)) {
-        SExtVT = MVT::v4i64;
-        UseLASX = true;
-        PropagateSExt = true;
-      }
-      break;
-    case MVT::v8i1:
-      SExtVT = MVT::v8i16;
-      if (Subtarget.hasExtLASX() && checkBitcastSrcVectorSize(Src, 256, 0)) {
-        SExtVT = MVT::v8i32;
-        UseLASX = true;
-        PropagateSExt = true;
-      }
-      break;
-    case MVT::v16i1:
-      SExtVT = MVT::v16i8;
-      if (Subtarget.hasExtLASX() && checkBitcastSrcVectorSize(Src, 256, 0)) {
-        SExtVT = MVT::v16i16;
-        UseLASX = true;
-        PropagateSExt = true;
-      }
-      break;
-    case MVT::v32i1:
-      SExtVT = MVT::v32i8;
+  MVT SExtVT;
+  unsigned Opc;
+  bool UseLASX = false;
+  bool PropagateSExt = false;
+  switch (SrcVT.getSimpleVT().SimpleTy) {
+  default:
+    return SDValue();
+  case MVT::v2i1:
+    SExtVT = MVT::v2i64;
+    break;
+  case MVT::v4i1:
+    SExtVT = MVT::v4i32;
+    if (Subtarget.hasExtLASX() && checkBitcastSrcVectorSize(Src, 256, 0)) {
+      SExtVT = MVT::v4i64;
       UseLASX = true;
-      break;
-    };
-    if (UseLASX && !Subtarget.has32S() && !Subtarget.hasExtLASX())
-      return SDValue();
-    Src = PropagateSExt ? signExtendBitcastSrcVector(DAG, SExtVT, Src, DL)
-                        : DAG.getNode(ISD::SIGN_EXTEND, DL, SExtVT, Src);
-    Opc = UseLASX ? LoongArchISD::XVMSKLTZ : LoongArchISD::VMSKLTZ;
-  } else {
-    Src = Src.getOperand(0);
-  }
+      PropagateSExt = true;
+    }
+    break;
+  case MVT::v8i1:
+    SExtVT = MVT::v8i16;
+    if (Subtarget.hasExtLASX() && checkBitcastSrcVectorSize(Src, 256, 0)) {
+      SExtVT = MVT::v8i32;
+      UseLASX = true;
+      PropagateSExt = true;
+    }
+    break;
+  case MVT::v16i1:
+    SExtVT = MVT::v16i8;
+    if (Subtarget.hasExtLASX() && checkBitcastSrcVectorSize(Src, 256, 0)) {
+      SExtVT = MVT::v16i16;
+      UseLASX = true;
+      PropagateSExt = true;
+    }
+    break;
+  case MVT::v32i1:
+    SExtVT = MVT::v32i8;
+    UseLASX = true;
+    break;
+  };
+  if (UseLASX && !Subtarget.has32S() && !Subtarget.hasExtLASX())
+    return SDValue();
+  Src = PropagateSExt ? signExtendBitcastSrcVector(DAG, SExtVT, Src, DL)
+                      : DAG.getNode(ISD::SIGN_EXTEND, DL, SExtVT, Src);
+  Opc = UseLASX ? LoongArchISD::XVMSKLTZ : LoongArchISD::VMSKLTZ;
 
   SDValue V = DAG.getNode(Opc, DL, MVT::i64, Src);
   EVT T = EVT::getIntegerVT(*DAG.getContext(), SrcVT.getVectorNumElements());
diff --git a/llvm/test/CodeGen/LoongArch/lsx/vmskcond.ll b/llvm/test/CodeGen/LoongArch/lsx/vmskcond.ll
index 0ee30120f77a6..ad57bbf9ee5c0 100644
--- a/llvm/test/CodeGen/LoongArch/lsx/vmskcond.ll
+++ b/llvm/test/CodeGen/LoongArch/lsx/vmskcond.ll
@@ -588,3 +588,18 @@ define i2 @vmsk_trunc_i64(<2 x i64> %a) {
   %res = bitcast <2 x i1> %y to i2
   ret i2 %res
 }
+
+define i4 @vmsk_eq_allzeros_v4i8(<4 x i8> %a) {
+; CHECK-LABEL: vmsk_eq_allzeros_v4i8:
+; CHECK:       # %bb.0:
+; CHECK-NEXT:    vseqi.b $vr0, $vr0, 0
+; CHECK-NEXT:    vilvl.b $vr0, $vr0, $vr0
+; CHECK-NEXT:    vilvl.h $vr0, $vr0, $vr0
+; CHECK-NEXT:    vslli.w $vr0, $vr0, 24
+; CHECK-NEXT:    vmskltz.w $vr0, $vr0
+; CHECK-NEXT:    vpickve2gr.hu $a0, $vr0, 0
+; CHECK-NEXT:    ret
+  %1 = icmp eq <4 x i8> %a, zeroinitializer
+  %2 = bitcast <4 x i1> %1 to i4
+  ret i4 %2
+}

heiher · 2025-07-18T03:10:30Z

llvm/lib/Target/LoongArch/LoongArchISelLowering.cpp

NOTE: performSETCC_BITCASTCombine was split out from performBITCASTCombine. Additionally, the condition was changed from CmpVT.getSizeInBits() <= 128 to CmpVT.getSizeInBits() == 128. The same applies to the 256-bit case.

Reported-by: tangyan <[email protected]>

tangaac

LGTM

heiher · 2025-07-21T08:37:48Z

/cherry-pick 8a307ae

llvmbot · 2025-07-21T08:43:43Z

/pull-request #149778

…vm#149442) Reported-by: tangyan <[email protected]> (cherry picked from commit 8a307ae)

…vm#149442) Reported-by: tangyan <[email protected]>

llvmbot added the backend:loongarch label Jul 18, 2025

heiher commented Jul 18, 2025

View reviewed changes

heiher requested review from SixWeining, tangaac and wangleiat July 18, 2025 03:30

heiher marked this pull request as draft July 18, 2025 06:59

heiher force-pushed the fix-vmsk branch from 664fd6e to e13360f Compare July 18, 2025 08:20

heiher marked this pull request as ready for review July 18, 2025 11:17

heiher force-pushed the fix-vmsk branch from e13360f to 4f8bb3e Compare July 18, 2025 11:36

[LoongArch] Fix failure to widen operand for [X]VMSK{LT,GE,NE}Z

4f8bb3e

Reported-by: tangyan <[email protected]>

tangaac approved these changes Jul 21, 2025

View reviewed changes

heiher merged commit 8a307ae into llvm:main Jul 21, 2025
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heiher deleted the fix-vmsk branch July 21, 2025 08:36

heiher added this to the LLVM 21.x Release milestone Jul 21, 2025

github-project-automation bot added this to LLVM Release Status Jul 21, 2025

github-project-automation bot moved this to Needs Triage in LLVM Release Status Jul 21, 2025

llvmbot moved this from Needs Triage to Done in LLVM Release Status Jul 21, 2025

heiher mentioned this pull request Jul 22, 2025

[LoongArch] Canadian build failed for loongarch64-linux-* : LLVM ERROR: Do not know how to widen this operator's operand! #149636

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tru pushed a commit to llvmbot/llvm-project that referenced this pull request Jul 22, 2025

[LoongArch] Fix failure to widen operand for [X]VMSK{LT,GE,NE}Z (ll…

7fd16ee

…vm#149442) Reported-by: tangyan <[email protected]> (cherry picked from commit 8a307ae)

This was referenced Jul 23, 2025

test abhinavgaba/llvm-project#2

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Add dataFence plugin interface abhinavgaba/llvm-project#3

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mahesh-attarde pushed a commit to mahesh-attarde/llvm-project that referenced this pull request Jul 28, 2025

[LoongArch] Fix failure to widen operand for [X]VMSK{LT,GE,NE}Z (ll…

e11bc93

…vm#149442) Reported-by: tangyan <[email protected]>

dwblaikie mentioned this pull request Sep 16, 2025

port 5b4819e to release #159209

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[LLVM] Update CUDA ELF flags for their new ABI #159451

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[LoongArch] Fix failure to widen operand for `[X]VMSK{LT,GE,NE}Z` #149442

[LoongArch] Fix failure to widen operand for `[X]VMSK{LT,GE,NE}Z` #149442

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[LoongArch] Fix failure to widen operand for [X]VMSK{LT,GE,NE}Z #149442

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[LoongArch] Fix failure to widen operand for `[X]VMSK{LT,GE,NE}Z` #149442

[LoongArch] Fix failure to widen operand for `[X]VMSK{LT,GE,NE}Z` #149442

heiher commented Jul 18, 2025 •

edited by tangaac

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