[llvm] [RISCV] Sink vp.splat operands of VP intrinsic. (PR #133245)

[Min-Yih Hsu via llvm-commits]

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@@ -2772,6 +2772,40 @@ bool RISCVTTIImpl::canSplatOperand(Instruction *I, int Operand) const {
   }
 }
 
+bool RISCVTTIImpl::tryToSinkVPSplat(VPIntrinsic *VPI,
+                                    SmallVectorImpl<Use *> &Ops) const {
+  Value *EVL = VPI->getVectorLengthParam();
+  if (!EVL)
+    return false;
+
+  for (auto &Op : VPI->operands()) {
+    auto *I = dyn_cast<Instruction>(Op.get());
+    if (!I || I->getParent() == VPI->getParent() ||
+        llvm::is_contained(Ops, &Op))
+      continue;
+
+    // We are looking for a vp.splat that can be sunk.
+    if (!match(I, m_Intrinsic<Intrinsic::experimental_vp_splat>(
+                      m_Value(), m_AllOnes(), m_Specific(EVL))))
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mshockwave wrote:

I understand that vp.splat is most likely to be all ones, I'm just a little concerned (and maybe playing devil's advocate here) that we might miss some optimizations opportunities. But please don't let me block this patch.

https://github.com/llvm/llvm-project/pull/133245