[PATCH] D148123: [AArch64][CostModel] Make sext/zext free if folded into a masked load

[David Sherwood via Phabricator via llvm-commits]

david-arm updated this revision to Diff 512847.
david-arm added a comment.

- Address review comments


CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D148123/new/

https://reviews.llvm.org/D148123

Files:
  llvm/lib/Target/AArch64/AArch64TargetTransformInfo.cpp
  llvm/test/Analysis/CostModel/AArch64/masked_ldst.ll


Index: llvm/test/Analysis/CostModel/AArch64/masked_ldst.ll
===================================================================
--- llvm/test/Analysis/CostModel/AArch64/masked_ldst.ll
+++ llvm/test/Analysis/CostModel/AArch64/masked_ldst.ll
@@ -110,29 +110,30 @@
 define void @scalable_ext_loads() {
 ; CHECK-LABEL: 'scalable_ext_loads'
 ; CHECK-NEXT: Cost Model: Found an estimated cost of 1 for instruction:   %load.nxv8i8 = call <vscale x 8 x i8> @llvm.masked.load.nxv8i8.p0(ptr undef, i32 8, <vscale x 8 x i1> undef, <vscale x 8 x i8> undef)
-; CHECK-NEXT: Cost Model: Found an estimated cost of 1 for instruction:   %zext.nxv8i8to16 = zext <vscale x 8 x i8> %load.nxv8i8 to <vscale x 8 x i16>
+; CHECK-NEXT: Cost Model: Found an estimated cost of 0 for instruction:   %zext.nxv8i8to16 = zext <vscale x 8 x i8> %load.nxv8i8 to <vscale x 8 x i16>
 ; CHECK-NEXT: Cost Model: Found an estimated cost of 1 for instruction:   %load.nxv4i8 = call <vscale x 4 x i8> @llvm.masked.load.nxv4i8.p0(ptr undef, i32 8, <vscale x 4 x i1> undef, <vscale x 4 x i8> undef)
-; CHECK-NEXT: Cost Model: Found an estimated cost of 1 for instruction:   %zext.nxv4i8to32 = zext <vscale x 4 x i8> %load.nxv4i8 to <vscale x 4 x i32>
+; CHECK-NEXT: Cost Model: Found an estimated cost of 0 for instruction:   %zext.nxv4i8to32 = zext <vscale x 4 x i8> %load.nxv4i8 to <vscale x 4 x i32>
 ; CHECK-NEXT: Cost Model: Found an estimated cost of 1 for instruction:   %load.nxv2i8 = call <vscale x 2 x i8> @llvm.masked.load.nxv2i8.p0(ptr undef, i32 8, <vscale x 2 x i1> undef, <vscale x 2 x i8> undef)
-; CHECK-NEXT: Cost Model: Found an estimated cost of 1 for instruction:   %zext.nxv2i8to64 = zext <vscale x 2 x i8> %load.nxv2i8 to <vscale x 2 x i64>
+; CHECK-NEXT: Cost Model: Found an estimated cost of 0 for instruction:   %zext.nxv2i8to64 = zext <vscale x 2 x i8> %load.nxv2i8 to <vscale x 2 x i64>
 ; CHECK-NEXT: Cost Model: Found an estimated cost of 1 for instruction:   %load.nxv4i16 = call <vscale x 4 x i16> @llvm.masked.load.nxv4i16.p0(ptr undef, i32 8, <vscale x 4 x i1> undef, <vscale x 4 x i16> undef)
-; CHECK-NEXT: Cost Model: Found an estimated cost of 1 for instruction:   %zext.nxv4i16to32 = zext <vscale x 4 x i16> %load.nxv4i16 to <vscale x 4 x i32>
+; CHECK-NEXT: Cost Model: Found an estimated cost of 0 for instruction:   %zext.nxv4i16to32 = zext <vscale x 4 x i16> %load.nxv4i16 to <vscale x 4 x i32>
 ; CHECK-NEXT: Cost Model: Found an estimated cost of 1 for instruction:   %load.nxv2i16 = call <vscale x 2 x i16> @llvm.masked.load.nxv2i16.p0(ptr undef, i32 8, <vscale x 2 x i1> undef, <vscale x 2 x i16> undef)
-; CHECK-NEXT: Cost Model: Found an estimated cost of 1 for instruction:   %zext.nxv2i16to64 = zext <vscale x 2 x i16> %load.nxv2i16 to <vscale x 2 x i64>
+; CHECK-NEXT: Cost Model: Found an estimated cost of 0 for instruction:   %zext.nxv2i16to64 = zext <vscale x 2 x i16> %load.nxv2i16 to <vscale x 2 x i64>
 ; CHECK-NEXT: Cost Model: Found an estimated cost of 1 for instruction:   %load.nxv2i32 = call <vscale x 2 x i32> @llvm.masked.load.nxv2i32.p0(ptr undef, i32 8, <vscale x 2 x i1> undef, <vscale x 2 x i32> undef)
-; CHECK-NEXT: Cost Model: Found an estimated cost of 1 for instruction:   %zext.nxv2i32to64 = zext <vscale x 2 x i32> %load.nxv2i32 to <vscale x 2 x i64>
+; CHECK-NEXT: Cost Model: Found an estimated cost of 0 for instruction:   %zext.nxv2i32to64 = zext <vscale x 2 x i32> %load.nxv2i32 to <vscale x 2 x i64>
+
 ; CHECK-NEXT: Cost Model: Found an estimated cost of 1 for instruction:   %load2.nxv8i8 = call <vscale x 8 x i8> @llvm.masked.load.nxv8i8.p0(ptr undef, i32 8, <vscale x 8 x i1> undef, <vscale x 8 x i8> undef)
-; CHECK-NEXT: Cost Model: Found an estimated cost of 1 for instruction:   %sext.nxv8i8to16 = sext <vscale x 8 x i8> %load2.nxv8i8 to <vscale x 8 x i16>
+; CHECK-NEXT: Cost Model: Found an estimated cost of 0 for instruction:   %sext.nxv8i8to16 = sext <vscale x 8 x i8> %load2.nxv8i8 to <vscale x 8 x i16>
 ; CHECK-NEXT: Cost Model: Found an estimated cost of 1 for instruction:   %load2.nxv4i8 = call <vscale x 4 x i8> @llvm.masked.load.nxv4i8.p0(ptr undef, i32 8, <vscale x 4 x i1> undef, <vscale x 4 x i8> undef)
-; CHECK-NEXT: Cost Model: Found an estimated cost of 1 for instruction:   %sext.nxv4i8to32 = sext <vscale x 4 x i8> %load2.nxv4i8 to <vscale x 4 x i32>
+; CHECK-NEXT: Cost Model: Found an estimated cost of 0 for instruction:   %sext.nxv4i8to32 = sext <vscale x 4 x i8> %load2.nxv4i8 to <vscale x 4 x i32>
 ; CHECK-NEXT: Cost Model: Found an estimated cost of 1 for instruction:   %load2.nxv2i8 = call <vscale x 2 x i8> @llvm.masked.load.nxv2i8.p0(ptr undef, i32 8, <vscale x 2 x i1> undef, <vscale x 2 x i8> undef)
-; CHECK-NEXT: Cost Model: Found an estimated cost of 1 for instruction:   %sext.nxv2i8to64 = sext <vscale x 2 x i8> %load2.nxv2i8 to <vscale x 2 x i64>
+; CHECK-NEXT: Cost Model: Found an estimated cost of 0 for instruction:   %sext.nxv2i8to64 = sext <vscale x 2 x i8> %load2.nxv2i8 to <vscale x 2 x i64>
 ; CHECK-NEXT: Cost Model: Found an estimated cost of 1 for instruction:   %load2.nxv4i16 = call <vscale x 4 x i16> @llvm.masked.load.nxv4i16.p0(ptr undef, i32 8, <vscale x 4 x i1> undef, <vscale x 4 x i16> undef)
-; CHECK-NEXT: Cost Model: Found an estimated cost of 1 for instruction:   %sext.nxv4i16to32 = sext <vscale x 4 x i16> %load2.nxv4i16 to <vscale x 4 x i32>
+; CHECK-NEXT: Cost Model: Found an estimated cost of 0 for instruction:   %sext.nxv4i16to32 = sext <vscale x 4 x i16> %load2.nxv4i16 to <vscale x 4 x i32>
 ; CHECK-NEXT: Cost Model: Found an estimated cost of 1 for instruction:   %load2.nxv2i16 = call <vscale x 2 x i16> @llvm.masked.load.nxv2i16.p0(ptr undef, i32 8, <vscale x 2 x i1> undef, <vscale x 2 x i16> undef)
-; CHECK-NEXT: Cost Model: Found an estimated cost of 1 for instruction:   %sext.nxv2i16to64 = sext <vscale x 2 x i16> %load2.nxv2i16 to <vscale x 2 x i64>
+; CHECK-NEXT: Cost Model: Found an estimated cost of 0 for instruction:   %sext.nxv2i16to64 = sext <vscale x 2 x i16> %load2.nxv2i16 to <vscale x 2 x i64>
 ; CHECK-NEXT: Cost Model: Found an estimated cost of 1 for instruction:   %load2.nxv2i32 = call <vscale x 2 x i32> @llvm.masked.load.nxv2i32.p0(ptr undef, i32 8, <vscale x 2 x i1> undef, <vscale x 2 x i32> undef)
-; CHECK-NEXT: Cost Model: Found an estimated cost of 1 for instruction:   %sext.nxv2i32to64 = sext <vscale x 2 x i32> %load2.nxv2i32 to <vscale x 2 x i64>
+; CHECK-NEXT: Cost Model: Found an estimated cost of 0 for instruction:   %sext.nxv2i32to64 = sext <vscale x 2 x i32> %load2.nxv2i32 to <vscale x 2 x i64>
 
   %load.nxv8i8 = call <vscale x 8 x i8> @llvm.masked.load.nxv8i8.p0(ptr undef, i32 8, <vscale x 8 x i1> undef, <vscale x 8 x i8> undef)
   %zext.nxv8i8to16 = zext <vscale x 8 x i8> %load.nxv8i8 to <vscale x 8 x i16>
Index: llvm/lib/Target/AArch64/AArch64TargetTransformInfo.cpp
===================================================================
--- llvm/lib/Target/AArch64/AArch64TargetTransformInfo.cpp
+++ llvm/lib/Target/AArch64/AArch64TargetTransformInfo.cpp
@@ -2124,6 +2124,12 @@
             FP16Tbl, ISD, DstTy.getSimpleVT(), SrcTy.getSimpleVT()))
       return AdjustCost(Entry->Cost);
 
+  // The BasicTTIImpl version only deals with CCH==TTI::CastContextHint::Normal,
+  // but we also want to include the TTI::CastContextHint::Masked case too.
+  if ((ISD == ISD::ZERO_EXTEND || ISD == ISD::SIGN_EXTEND) &&
+      (CCH == TTI::CastContextHint::Masked) && ST->hasSVEorSME())
+    CCH = TTI::CastContextHint::Normal;
+
   return AdjustCost(
       BaseT::getCastInstrCost(Opcode, Dst, Src, CCH, CostKind, I));
 }


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