[llvm-branch-commits] [SPARC] Promote i32 CTTZ when we have VIS3 (PR #135894)

[Sergei Barannikov via llvm-branch-commits]

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@@ -3599,6 +3615,15 @@ bool SparcTargetLowering::isFPImmLegal(const APFloat &Imm, EVT VT,
 
 bool SparcTargetLowering::isCtlzFast() const { return Subtarget->isVIS3(); }
 
+bool SparcTargetLowering::isCheapToSpeculateCttz(Type *Ty) const {
+  // We lack native cttz, however,
+  // On 64-bit targets it is cheap to implement it in terms of popc.
+  if (Subtarget->is64Bit() && Subtarget->usePopc())
+    return true;
+  // Otherwise, implementing cttz in terms of ctlz is still cheap.
+  return isCheapToSpeculateCtlz(Ty);
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s-barannikov wrote:

Never mind, I saw it in tests :)

https://github.com/llvm/llvm-project/pull/135894