[llvm] [VectorCombine] Use isSafeToSpeculativelyExecute to guard VP scalarization (PR #69494)

[Luke Lau via llvm-commits]

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@@ -825,23 +825,28 @@ bool VectorCombine::scalarizeVPIntrinsic(Instruction &I) {
   ElementCount EC = cast<VectorType>(Op0->getType())->getElementCount();
   Value *EVL = VPI.getArgOperand(3);
   const DataLayout &DL = VPI.getModule()->getDataLayout();
-  bool MustHaveNonZeroVL =
-      IntrID == Intrinsic::vp_sdiv || IntrID == Intrinsic::vp_udiv ||
-      IntrID == Intrinsic::vp_srem || IntrID == Intrinsic::vp_urem;
-
-  if (!MustHaveNonZeroVL || isKnownNonZero(EVL, DL, 0, &AC, &VPI, &DT)) {
-    Value *ScalarOp0 = getSplatValue(Op0);
-    Value *ScalarOp1 = getSplatValue(Op1);
-    Value *ScalarVal =
-        ScalarIntrID
-            ? Builder.CreateIntrinsic(VecTy->getScalarType(), *ScalarIntrID,
-                                      {ScalarOp0, ScalarOp1})
-            : Builder.CreateBinOp((Instruction::BinaryOps)(*FunctionalOpcode),
-                                  ScalarOp0, ScalarOp1);
-    replaceValue(VPI, *Builder.CreateVectorSplat(EC, ScalarVal));
-    return true;
-  }
-  return false;
+
+  bool SafeToSpeculate;
+  if (ScalarIntrID)
+    SafeToSpeculate = Intrinsic::getAttributes(I.getContext(), *ScalarIntrID)
+                          .hasFnAttr(Attribute::AttrKind::Speculatable);
+  else
+    SafeToSpeculate = isSafeToSpeculativelyExecuteWithOpcode(
+        *FunctionalOpcode, &VPI, nullptr, &AC, &DT);
+  if (!SafeToSpeculate && !isKnownNonZero(EVL, DL, 0, &AC, &VPI, &DT))
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lukel97 wrote:

Unless I'm missing something, this isKnownNonZero check isn't checking the divisor, it's checking the explicit vector length. 

https://github.com/llvm/llvm-project/pull/69494