Revert "[x86] combineMul - use computeKnownBits directly to find MUL_IMM constant splat."

zmodem · zmodem · commit 74a98fdbc443 · 2024-10-07T11:48:24.000+02:00
> As we're after a constant splat value we can avoid all the complexities of trying to recreate the correct constant via getTargetConstantFromNode. This caused builds to fail with an assertion: X86ISelLowering.cpp:48569 Assertion `C.getZExtValue() != 0 && C.getZExtValue() != maxUIntN(VT.getScalarSizeInBits()) && "Both cases that could cause potential overflows should have " "already been handled." See llvm#111325 This reverts commit 1bc87c9.
diff --git a/llvm/lib/Target/X86/X86ISelLowering.cpp b/llvm/lib/Target/X86/X86ISelLowering.cpp
@@ -48492,15 +48492,26 @@ static SDValue combineMul(SDNode *N, SelectionDAG &DAG,
       (!VT.isVector() || !VT.isSimple() || !VT.isInteger()))
     return SDValue();
 
-  KnownBits Known1 = DAG.computeKnownBits(N->getOperand(1));
-  if (!Known1.isConstant())
-    return SDValue();
+  ConstantSDNode *CNode = isConstOrConstSplat(
+      N->getOperand(1), /*AllowUndefs*/ true, /*AllowTrunc*/ false);
+  const APInt *C = nullptr;
+  if (!CNode) {
+    if (VT.isVector())
+      if (auto *RawC = getTargetConstantFromNode(N->getOperand(1)))
+        if (auto *SplatC = RawC->getSplatValue())
+          if (auto *SplatCI = dyn_cast<ConstantInt>(SplatC))
+            C = &(SplatCI->getValue());
+
+    if (!C || C->getBitWidth() != VT.getScalarSizeInBits())
+      return SDValue();
+  } else {
+    C = &(CNode->getAPIntValue());
+  }
 
-  const APInt &C = Known1.getConstant();
-  if (isPowerOf2_64(C.getZExtValue()))
+  if (isPowerOf2_64(C->getZExtValue()))
     return SDValue();
 
-  int64_t SignMulAmt = C.getSExtValue();
+  int64_t SignMulAmt = C->getSExtValue();
   assert(SignMulAmt != INT64_MIN && "Int min should have been handled!");
   uint64_t AbsMulAmt = SignMulAmt < 0 ? -SignMulAmt : SignMulAmt;
 
@@ -48559,12 +48570,12 @@ static SDValue combineMul(SDNode *N, SelectionDAG &DAG,
       if (SignMulAmt < 0)
         NewMul = DAG.getNegative(NewMul, DL, VT);
     } else if (!Subtarget.slowLEA())
-      NewMul = combineMulSpecial(C.getZExtValue(), N, DAG, VT, DL);
+      NewMul = combineMulSpecial(C->getZExtValue(), N, DAG, VT, DL);
   }
   if (!NewMul) {
     EVT ShiftVT = VT.isVector() ? VT : MVT::i8;
-    assert(C.getZExtValue() != 0 &&
-           C.getZExtValue() != maxUIntN(VT.getScalarSizeInBits()) &&
+    assert(C->getZExtValue() != 0 &&
+           C->getZExtValue() != maxUIntN(VT.getScalarSizeInBits()) &&
            "Both cases that could cause potential overflows should have "
            "already been handled.");
     if (isPowerOf2_64(AbsMulAmt - 1)) {
diff --git a/llvm/test/CodeGen/X86/combine-add.ll b/llvm/test/CodeGen/X86/combine-add.ll
@@ -265,8 +265,8 @@ define void @PR52039(ptr %pa, ptr %pb) {
 ; AVX2:       # %bb.0:
 ; AVX2-NEXT:    vpbroadcastd {{.*#+}} ymm0 = [10,10,10,10,10,10,10,10]
 ; AVX2-NEXT:    vpsubd (%rdi), %ymm0, %ymm0
-; AVX2-NEXT:    vpaddd %ymm0, %ymm0, %ymm1
-; AVX2-NEXT:    vpaddd %ymm1, %ymm0, %ymm1
+; AVX2-NEXT:    vpbroadcastd {{.*#+}} ymm1 = [3,3,3,3,3,3,3,3]
+; AVX2-NEXT:    vpmulld %ymm1, %ymm0, %ymm1
 ; AVX2-NEXT:    vmovdqu %ymm0, (%rsi)
 ; AVX2-NEXT:    vmovdqu %ymm1, (%rdi)
 ; AVX2-NEXT:    vzeroupper
diff --git a/llvm/test/CodeGen/X86/vector-mul.ll b/llvm/test/CodeGen/X86/vector-mul.ll
@@ -335,11 +335,22 @@ define <4 x i32> @mul_v4i32_17(<4 x i32> %a0) nounwind {
 ; SSE-NEXT:    paddd %xmm1, %xmm0
 ; SSE-NEXT:    ret{{[l|q]}}
 ;
-; X64-AVX-LABEL: mul_v4i32_17:
-; X64-AVX:       # %bb.0:
-; X64-AVX-NEXT:    vpslld $4, %xmm0, %xmm1
-; X64-AVX-NEXT:    vpaddd %xmm1, %xmm0, %xmm0
-; X64-AVX-NEXT:    retq
+; X64-XOP-LABEL: mul_v4i32_17:
+; X64-XOP:       # %bb.0:
+; X64-XOP-NEXT:    vpslld $4, %xmm0, %xmm1
+; X64-XOP-NEXT:    vpaddd %xmm1, %xmm0, %xmm0
+; X64-XOP-NEXT:    retq
+;
+; X64-AVX2-LABEL: mul_v4i32_17:
+; X64-AVX2:       # %bb.0:
+; X64-AVX2-NEXT:    vpbroadcastd {{.*#+}} xmm1 = [17,17,17,17]
+; X64-AVX2-NEXT:    vpmulld %xmm1, %xmm0, %xmm0
+; X64-AVX2-NEXT:    retq
+;
+; X64-AVX512DQ-LABEL: mul_v4i32_17:
+; X64-AVX512DQ:       # %bb.0:
+; X64-AVX512DQ-NEXT:    vpmulld {{\.?LCPI[0-9]+_[0-9]+}}(%rip){1to4}, %xmm0, %xmm0
+; X64-AVX512DQ-NEXT:    retq
   %1 = mul <4 x i32> %a0, <i32 17, i32 17, i32 17, i32 17>
   ret <4 x i32> %1
 }
@@ -460,14 +471,13 @@ define <8 x i32> @mul_v8i32_17(<8 x i32> %a0) nounwind {
 ;
 ; X64-AVX2-LABEL: mul_v8i32_17:
 ; X64-AVX2:       # %bb.0:
-; X64-AVX2-NEXT:    vpslld $4, %ymm0, %ymm1
-; X64-AVX2-NEXT:    vpaddd %ymm1, %ymm0, %ymm0
+; X64-AVX2-NEXT:    vpbroadcastd {{.*#+}} ymm1 = [17,17,17,17,17,17,17,17]
+; X64-AVX2-NEXT:    vpmulld %ymm1, %ymm0, %ymm0
 ; X64-AVX2-NEXT:    retq
 ;
 ; X64-AVX512DQ-LABEL: mul_v8i32_17:
 ; X64-AVX512DQ:       # %bb.0:
-; X64-AVX512DQ-NEXT:    vpslld $4, %ymm0, %ymm1
-; X64-AVX512DQ-NEXT:    vpaddd %ymm1, %ymm0, %ymm0
+; X64-AVX512DQ-NEXT:    vpmulld {{\.?LCPI[0-9]+_[0-9]+}}(%rip){1to8}, %ymm0, %ymm0
 ; X64-AVX512DQ-NEXT:    retq
   %1 = mul <8 x i32> %a0, <i32 17, i32 17, i32 17, i32 17, i32 17, i32 17, i32 17, i32 17>
   ret <8 x i32> %1
@@ -586,13 +596,24 @@ define <4 x i32> @mul_v4i32_neg33(<4 x i32> %a0) nounwind {
 ; SSE-NEXT:    psubd %xmm1, %xmm0
 ; SSE-NEXT:    ret{{[l|q]}}
 ;
-; X64-AVX-LABEL: mul_v4i32_neg33:
-; X64-AVX:       # %bb.0:
-; X64-AVX-NEXT:    vpslld $5, %xmm0, %xmm1
-; X64-AVX-NEXT:    vpaddd %xmm1, %xmm0, %xmm0
-; X64-AVX-NEXT:    vpxor %xmm1, %xmm1, %xmm1
-; X64-AVX-NEXT:    vpsubd %xmm0, %xmm1, %xmm0
-; X64-AVX-NEXT:    retq
+; X64-XOP-LABEL: mul_v4i32_neg33:
+; X64-XOP:       # %bb.0:
+; X64-XOP-NEXT:    vpslld $5, %xmm0, %xmm1
+; X64-XOP-NEXT:    vpaddd %xmm1, %xmm0, %xmm0
+; X64-XOP-NEXT:    vpxor %xmm1, %xmm1, %xmm1
+; X64-XOP-NEXT:    vpsubd %xmm0, %xmm1, %xmm0
+; X64-XOP-NEXT:    retq
+;
+; X64-AVX2-LABEL: mul_v4i32_neg33:
+; X64-AVX2:       # %bb.0:
+; X64-AVX2-NEXT:    vpbroadcastd {{.*#+}} xmm1 = [4294967263,4294967263,4294967263,4294967263]
+; X64-AVX2-NEXT:    vpmulld %xmm1, %xmm0, %xmm0
+; X64-AVX2-NEXT:    retq
+;
+; X64-AVX512DQ-LABEL: mul_v4i32_neg33:
+; X64-AVX512DQ:       # %bb.0:
+; X64-AVX512DQ-NEXT:    vpmulld {{\.?LCPI[0-9]+_[0-9]+}}(%rip){1to4}, %xmm0, %xmm0
+; X64-AVX512DQ-NEXT:    retq
   %1 = mul <4 x i32> %a0, <i32 -33, i32 -33, i32 -33, i32 -33>
   ret <4 x i32> %1
 }
@@ -747,18 +768,13 @@ define <8 x i32> @mul_v8i32_neg33(<8 x i32> %a0) nounwind {
 ;
 ; X64-AVX2-LABEL: mul_v8i32_neg33:
 ; X64-AVX2:       # %bb.0:
-; X64-AVX2-NEXT:    vpslld $5, %ymm0, %ymm1
-; X64-AVX2-NEXT:    vpaddd %ymm1, %ymm0, %ymm0
-; X64-AVX2-NEXT:    vpxor %xmm1, %xmm1, %xmm1
-; X64-AVX2-NEXT:    vpsubd %ymm0, %ymm1, %ymm0
+; X64-AVX2-NEXT:    vpbroadcastd {{.*#+}} ymm1 = [4294967263,4294967263,4294967263,4294967263,4294967263,4294967263,4294967263,4294967263]
+; X64-AVX2-NEXT:    vpmulld %ymm1, %ymm0, %ymm0
 ; X64-AVX2-NEXT:    retq
 ;
 ; X64-AVX512DQ-LABEL: mul_v8i32_neg33:
 ; X64-AVX512DQ:       # %bb.0:
-; X64-AVX512DQ-NEXT:    vpslld $5, %ymm0, %ymm1
-; X64-AVX512DQ-NEXT:    vpaddd %ymm1, %ymm0, %ymm0
-; X64-AVX512DQ-NEXT:    vpxor %xmm1, %xmm1, %xmm1
-; X64-AVX512DQ-NEXT:    vpsubd %ymm0, %ymm1, %ymm0
+; X64-AVX512DQ-NEXT:    vpmulld {{\.?LCPI[0-9]+_[0-9]+}}(%rip){1to8}, %ymm0, %ymm0
 ; X64-AVX512DQ-NEXT:    retq
   %1 = mul <8 x i32> %a0, <i32 -33, i32 -33, i32 -33, i32 -33, i32 -33, i32 -33, i32 -33, i32 -33>
   ret <8 x i32> %1
@@ -1097,11 +1113,22 @@ define <4 x i32> @mul_v4i32_7(<4 x i32> %a0) nounwind {
 ; SSE-NEXT:    movdqa %xmm1, %xmm0
 ; SSE-NEXT:    ret{{[l|q]}}
 ;
-; X64-AVX-LABEL: mul_v4i32_7:
-; X64-AVX:       # %bb.0:
-; X64-AVX-NEXT:    vpslld $3, %xmm0, %xmm1
-; X64-AVX-NEXT:    vpsubd %xmm0, %xmm1, %xmm0
-; X64-AVX-NEXT:    retq
+; X64-XOP-LABEL: mul_v4i32_7:
+; X64-XOP:       # %bb.0:
+; X64-XOP-NEXT:    vpslld $3, %xmm0, %xmm1
+; X64-XOP-NEXT:    vpsubd %xmm0, %xmm1, %xmm0
+; X64-XOP-NEXT:    retq
+;
+; X64-AVX2-LABEL: mul_v4i32_7:
+; X64-AVX2:       # %bb.0:
+; X64-AVX2-NEXT:    vpbroadcastd {{.*#+}} xmm1 = [7,7,7,7]
+; X64-AVX2-NEXT:    vpmulld %xmm1, %xmm0, %xmm0
+; X64-AVX2-NEXT:    retq
+;
+; X64-AVX512DQ-LABEL: mul_v4i32_7:
+; X64-AVX512DQ:       # %bb.0:
+; X64-AVX512DQ-NEXT:    vpmulld {{\.?LCPI[0-9]+_[0-9]+}}(%rip){1to4}, %xmm0, %xmm0
+; X64-AVX512DQ-NEXT:    retq
   %1 = mul <4 x i32> %a0, <i32 7, i32 7, i32 7, i32 7>
   ret <4 x i32> %1
 }
@@ -1195,11 +1222,22 @@ define <4 x i32> @mul_v4i32_neg63(<4 x i32> %a0) nounwind {
 ; SSE-NEXT:    psubd %xmm1, %xmm0
 ; SSE-NEXT:    ret{{[l|q]}}
 ;
-; X64-AVX-LABEL: mul_v4i32_neg63:
-; X64-AVX:       # %bb.0:
-; X64-AVX-NEXT:    vpslld $6, %xmm0, %xmm1
-; X64-AVX-NEXT:    vpsubd %xmm1, %xmm0, %xmm0
-; X64-AVX-NEXT:    retq
+; X64-XOP-LABEL: mul_v4i32_neg63:
+; X64-XOP:       # %bb.0:
+; X64-XOP-NEXT:    vpslld $6, %xmm0, %xmm1
+; X64-XOP-NEXT:    vpsubd %xmm1, %xmm0, %xmm0
+; X64-XOP-NEXT:    retq
+;
+; X64-AVX2-LABEL: mul_v4i32_neg63:
+; X64-AVX2:       # %bb.0:
+; X64-AVX2-NEXT:    vpbroadcastd {{.*#+}} xmm1 = [4294967233,4294967233,4294967233,4294967233]
+; X64-AVX2-NEXT:    vpmulld %xmm1, %xmm0, %xmm0
+; X64-AVX2-NEXT:    retq
+;
+; X64-AVX512DQ-LABEL: mul_v4i32_neg63:
+; X64-AVX512DQ:       # %bb.0:
+; X64-AVX512DQ-NEXT:    vpmulld {{\.?LCPI[0-9]+_[0-9]+}}(%rip){1to4}, %xmm0, %xmm0
+; X64-AVX512DQ-NEXT:    retq
   %1 = mul <4 x i32> %a0, <i32 -63, i32 -63, i32 -63, i32 -63>
   ret <4 x i32> %1
 }
