[llvm-branch-commits] [llvm] AMDGPU: Report special input intrinsics as free (PR #141948)

[Matt Arsenault via llvm-branch-commits]

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@@ -704,8 +704,29 @@ static bool intrinsicHasPackedVectorBenefit(Intrinsic::ID ID) {
 InstructionCost
 GCNTTIImpl::getIntrinsicInstrCost(const IntrinsicCostAttributes &ICA,
                                   TTI::TargetCostKind CostKind) const {
-  if (ICA.getID() == Intrinsic::fabs)
+  switch (ICA.getID()) {
+  case Intrinsic::fabs:
+    // Free source modifier in the common case.
+    return 0;
+  case Intrinsic::amdgcn_workitem_id_x:
+  case Intrinsic::amdgcn_workitem_id_y:
+  case Intrinsic::amdgcn_workitem_id_z:
+    // TODO: If hasPackedTID, or if the calling context is not an entry point
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arsenm wrote:

For some reason the calling instruction isn't set in the context where this gets called from, so I can't figure out if it's a kernel or not so I left this for later 

https://github.com/llvm/llvm-project/pull/141948