[AArch64] Tweak fixed-length loop.dependence.mask costs#175538
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[AArch64] Tweak fixed-length loop.dependence.mask costs#175538
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@llvm/pr-subscribers-backend-aarch64 Author: Benjamin Maxwell (MacDue) ChangesIt's not free (MOV + XTN) to convert from the predicate result of whilewr/rw to a fixed-length mask, so the cost should be slightly higher. Full diff: https://github.com/llvm/llvm-project/pull/175538.diff 2 Files Affected:
diff --git a/llvm/lib/Target/AArch64/AArch64TargetTransformInfo.cpp b/llvm/lib/Target/AArch64/AArch64TargetTransformInfo.cpp
index 85be8db9d3ae2..59f782b986a4f 100644
--- a/llvm/lib/Target/AArch64/AArch64TargetTransformInfo.cpp
+++ b/llvm/lib/Target/AArch64/AArch64TargetTransformInfo.cpp
@@ -1071,9 +1071,15 @@ AArch64TTIImpl::getIntrinsicInstrCost(const IntrinsicCostAttributes &ICA,
EVT VecVT = getTLI()->getValueType(DL, RetTy);
unsigned EltSizeInBytes =
cast<ConstantInt>(ICA.getArgs()[2])->getZExtValue();
- if (is_contained({1u, 2u, 4u, 8u}, EltSizeInBytes) &&
- VecVT.getVectorMinNumElements() == (16 / EltSizeInBytes))
- return 1;
+ if (!is_contained({1u, 2u, 4u, 8u}, EltSizeInBytes) ||
+ VecVT.getVectorMinNumElements() != (16 / EltSizeInBytes))
+ break;
+ InstructionCost Cost = 1;
+ // For fixed-vector types at least a MOV and XTN are needed to convert
+ // from the predicate to a fixed-length mask.
+ if (isa<FixedVectorType>(RetTy))
+ Cost += 2;
+ return Cost;
}
break;
}
diff --git a/llvm/test/Analysis/CostModel/AArch64/loop_dependence_mask.ll b/llvm/test/Analysis/CostModel/AArch64/loop_dependence_mask.ll
index 5b3070fcf347e..7acd776a91b3c 100644
--- a/llvm/test/Analysis/CostModel/AArch64/loop_dependence_mask.ll
+++ b/llvm/test/Analysis/CostModel/AArch64/loop_dependence_mask.ll
@@ -17,10 +17,10 @@ define void @loop_dependence_war_mask(ptr %a, ptr %b) {
; CHECK-EXPANDED-NEXT: Cost Model: Found an estimated cost of 0 for instruction: ret void
;
; CHECK-LABEL: 'loop_dependence_war_mask'
-; CHECK-NEXT: Cost Model: Found an estimated cost of 1 for instruction: %res1 = call <16 x i1> @llvm.loop.dependence.war.mask.v16i1(ptr %a, ptr %b, i64 1)
-; CHECK-NEXT: Cost Model: Found an estimated cost of 1 for instruction: %res2 = call <8 x i1> @llvm.loop.dependence.war.mask.v8i1(ptr %a, ptr %b, i64 2)
-; CHECK-NEXT: Cost Model: Found an estimated cost of 1 for instruction: %res3 = call <4 x i1> @llvm.loop.dependence.war.mask.v4i1(ptr %a, ptr %b, i64 4)
-; CHECK-NEXT: Cost Model: Found an estimated cost of 1 for instruction: %res4 = call <2 x i1> @llvm.loop.dependence.war.mask.v2i1(ptr %a, ptr %b, i64 8)
+; CHECK-NEXT: Cost Model: Found an estimated cost of 3 for instruction: %res1 = call <16 x i1> @llvm.loop.dependence.war.mask.v16i1(ptr %a, ptr %b, i64 1)
+; CHECK-NEXT: Cost Model: Found an estimated cost of 3 for instruction: %res2 = call <8 x i1> @llvm.loop.dependence.war.mask.v8i1(ptr %a, ptr %b, i64 2)
+; CHECK-NEXT: Cost Model: Found an estimated cost of 3 for instruction: %res3 = call <4 x i1> @llvm.loop.dependence.war.mask.v4i1(ptr %a, ptr %b, i64 4)
+; CHECK-NEXT: Cost Model: Found an estimated cost of 3 for instruction: %res4 = call <2 x i1> @llvm.loop.dependence.war.mask.v2i1(ptr %a, ptr %b, i64 8)
; CHECK-NEXT: Cost Model: Found an estimated cost of 1 for instruction: %res5 = call <vscale x 16 x i1> @llvm.loop.dependence.war.mask.nxv16i1(ptr %a, ptr %b, i64 1)
; CHECK-NEXT: Cost Model: Found an estimated cost of 1 for instruction: %res6 = call <vscale x 8 x i1> @llvm.loop.dependence.war.mask.nxv8i1(ptr %a, ptr %b, i64 2)
; CHECK-NEXT: Cost Model: Found an estimated cost of 1 for instruction: %res7 = call <vscale x 4 x i1> @llvm.loop.dependence.war.mask.nxv4i1(ptr %a, ptr %b, i64 4)
@@ -54,10 +54,10 @@ define void @loop_dependence_raw_mask(ptr %a, ptr %b) {
; CHECK-EXPANDED-NEXT: Cost Model: Found an estimated cost of 0 for instruction: ret void
;
; CHECK-LABEL: 'loop_dependence_raw_mask'
-; CHECK-NEXT: Cost Model: Found an estimated cost of 1 for instruction: %res1 = call <16 x i1> @llvm.loop.dependence.raw.mask.v16i1(ptr %a, ptr %b, i64 1)
-; CHECK-NEXT: Cost Model: Found an estimated cost of 1 for instruction: %res2 = call <8 x i1> @llvm.loop.dependence.raw.mask.v8i1(ptr %a, ptr %b, i64 2)
-; CHECK-NEXT: Cost Model: Found an estimated cost of 1 for instruction: %res3 = call <4 x i1> @llvm.loop.dependence.raw.mask.v4i1(ptr %a, ptr %b, i64 4)
-; CHECK-NEXT: Cost Model: Found an estimated cost of 1 for instruction: %res4 = call <2 x i1> @llvm.loop.dependence.raw.mask.v2i1(ptr %a, ptr %b, i64 8)
+; CHECK-NEXT: Cost Model: Found an estimated cost of 3 for instruction: %res1 = call <16 x i1> @llvm.loop.dependence.raw.mask.v16i1(ptr %a, ptr %b, i64 1)
+; CHECK-NEXT: Cost Model: Found an estimated cost of 3 for instruction: %res2 = call <8 x i1> @llvm.loop.dependence.raw.mask.v8i1(ptr %a, ptr %b, i64 2)
+; CHECK-NEXT: Cost Model: Found an estimated cost of 3 for instruction: %res3 = call <4 x i1> @llvm.loop.dependence.raw.mask.v4i1(ptr %a, ptr %b, i64 4)
+; CHECK-NEXT: Cost Model: Found an estimated cost of 3 for instruction: %res4 = call <2 x i1> @llvm.loop.dependence.raw.mask.v2i1(ptr %a, ptr %b, i64 8)
; CHECK-NEXT: Cost Model: Found an estimated cost of 1 for instruction: %res5 = call <vscale x 16 x i1> @llvm.loop.dependence.raw.mask.nxv16i1(ptr %a, ptr %b, i64 1)
; CHECK-NEXT: Cost Model: Found an estimated cost of 1 for instruction: %res6 = call <vscale x 8 x i1> @llvm.loop.dependence.raw.mask.nxv8i1(ptr %a, ptr %b, i64 2)
; CHECK-NEXT: Cost Model: Found an estimated cost of 1 for instruction: %res7 = call <vscale x 4 x i1> @llvm.loop.dependence.raw.mask.nxv4i1(ptr %a, ptr %b, i64 4)
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Member
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@llvm/pr-subscribers-llvm-analysis Author: Benjamin Maxwell (MacDue) ChangesIt's not free (MOV + XTN) to convert from the predicate result of whilewr/rw to a fixed-length mask, so the cost should be slightly higher. Full diff: https://github.com/llvm/llvm-project/pull/175538.diff 2 Files Affected:
diff --git a/llvm/lib/Target/AArch64/AArch64TargetTransformInfo.cpp b/llvm/lib/Target/AArch64/AArch64TargetTransformInfo.cpp
index 85be8db9d3ae2..59f782b986a4f 100644
--- a/llvm/lib/Target/AArch64/AArch64TargetTransformInfo.cpp
+++ b/llvm/lib/Target/AArch64/AArch64TargetTransformInfo.cpp
@@ -1071,9 +1071,15 @@ AArch64TTIImpl::getIntrinsicInstrCost(const IntrinsicCostAttributes &ICA,
EVT VecVT = getTLI()->getValueType(DL, RetTy);
unsigned EltSizeInBytes =
cast<ConstantInt>(ICA.getArgs()[2])->getZExtValue();
- if (is_contained({1u, 2u, 4u, 8u}, EltSizeInBytes) &&
- VecVT.getVectorMinNumElements() == (16 / EltSizeInBytes))
- return 1;
+ if (!is_contained({1u, 2u, 4u, 8u}, EltSizeInBytes) ||
+ VecVT.getVectorMinNumElements() != (16 / EltSizeInBytes))
+ break;
+ InstructionCost Cost = 1;
+ // For fixed-vector types at least a MOV and XTN are needed to convert
+ // from the predicate to a fixed-length mask.
+ if (isa<FixedVectorType>(RetTy))
+ Cost += 2;
+ return Cost;
}
break;
}
diff --git a/llvm/test/Analysis/CostModel/AArch64/loop_dependence_mask.ll b/llvm/test/Analysis/CostModel/AArch64/loop_dependence_mask.ll
index 5b3070fcf347e..7acd776a91b3c 100644
--- a/llvm/test/Analysis/CostModel/AArch64/loop_dependence_mask.ll
+++ b/llvm/test/Analysis/CostModel/AArch64/loop_dependence_mask.ll
@@ -17,10 +17,10 @@ define void @loop_dependence_war_mask(ptr %a, ptr %b) {
; CHECK-EXPANDED-NEXT: Cost Model: Found an estimated cost of 0 for instruction: ret void
;
; CHECK-LABEL: 'loop_dependence_war_mask'
-; CHECK-NEXT: Cost Model: Found an estimated cost of 1 for instruction: %res1 = call <16 x i1> @llvm.loop.dependence.war.mask.v16i1(ptr %a, ptr %b, i64 1)
-; CHECK-NEXT: Cost Model: Found an estimated cost of 1 for instruction: %res2 = call <8 x i1> @llvm.loop.dependence.war.mask.v8i1(ptr %a, ptr %b, i64 2)
-; CHECK-NEXT: Cost Model: Found an estimated cost of 1 for instruction: %res3 = call <4 x i1> @llvm.loop.dependence.war.mask.v4i1(ptr %a, ptr %b, i64 4)
-; CHECK-NEXT: Cost Model: Found an estimated cost of 1 for instruction: %res4 = call <2 x i1> @llvm.loop.dependence.war.mask.v2i1(ptr %a, ptr %b, i64 8)
+; CHECK-NEXT: Cost Model: Found an estimated cost of 3 for instruction: %res1 = call <16 x i1> @llvm.loop.dependence.war.mask.v16i1(ptr %a, ptr %b, i64 1)
+; CHECK-NEXT: Cost Model: Found an estimated cost of 3 for instruction: %res2 = call <8 x i1> @llvm.loop.dependence.war.mask.v8i1(ptr %a, ptr %b, i64 2)
+; CHECK-NEXT: Cost Model: Found an estimated cost of 3 for instruction: %res3 = call <4 x i1> @llvm.loop.dependence.war.mask.v4i1(ptr %a, ptr %b, i64 4)
+; CHECK-NEXT: Cost Model: Found an estimated cost of 3 for instruction: %res4 = call <2 x i1> @llvm.loop.dependence.war.mask.v2i1(ptr %a, ptr %b, i64 8)
; CHECK-NEXT: Cost Model: Found an estimated cost of 1 for instruction: %res5 = call <vscale x 16 x i1> @llvm.loop.dependence.war.mask.nxv16i1(ptr %a, ptr %b, i64 1)
; CHECK-NEXT: Cost Model: Found an estimated cost of 1 for instruction: %res6 = call <vscale x 8 x i1> @llvm.loop.dependence.war.mask.nxv8i1(ptr %a, ptr %b, i64 2)
; CHECK-NEXT: Cost Model: Found an estimated cost of 1 for instruction: %res7 = call <vscale x 4 x i1> @llvm.loop.dependence.war.mask.nxv4i1(ptr %a, ptr %b, i64 4)
@@ -54,10 +54,10 @@ define void @loop_dependence_raw_mask(ptr %a, ptr %b) {
; CHECK-EXPANDED-NEXT: Cost Model: Found an estimated cost of 0 for instruction: ret void
;
; CHECK-LABEL: 'loop_dependence_raw_mask'
-; CHECK-NEXT: Cost Model: Found an estimated cost of 1 for instruction: %res1 = call <16 x i1> @llvm.loop.dependence.raw.mask.v16i1(ptr %a, ptr %b, i64 1)
-; CHECK-NEXT: Cost Model: Found an estimated cost of 1 for instruction: %res2 = call <8 x i1> @llvm.loop.dependence.raw.mask.v8i1(ptr %a, ptr %b, i64 2)
-; CHECK-NEXT: Cost Model: Found an estimated cost of 1 for instruction: %res3 = call <4 x i1> @llvm.loop.dependence.raw.mask.v4i1(ptr %a, ptr %b, i64 4)
-; CHECK-NEXT: Cost Model: Found an estimated cost of 1 for instruction: %res4 = call <2 x i1> @llvm.loop.dependence.raw.mask.v2i1(ptr %a, ptr %b, i64 8)
+; CHECK-NEXT: Cost Model: Found an estimated cost of 3 for instruction: %res1 = call <16 x i1> @llvm.loop.dependence.raw.mask.v16i1(ptr %a, ptr %b, i64 1)
+; CHECK-NEXT: Cost Model: Found an estimated cost of 3 for instruction: %res2 = call <8 x i1> @llvm.loop.dependence.raw.mask.v8i1(ptr %a, ptr %b, i64 2)
+; CHECK-NEXT: Cost Model: Found an estimated cost of 3 for instruction: %res3 = call <4 x i1> @llvm.loop.dependence.raw.mask.v4i1(ptr %a, ptr %b, i64 4)
+; CHECK-NEXT: Cost Model: Found an estimated cost of 3 for instruction: %res4 = call <2 x i1> @llvm.loop.dependence.raw.mask.v2i1(ptr %a, ptr %b, i64 8)
; CHECK-NEXT: Cost Model: Found an estimated cost of 1 for instruction: %res5 = call <vscale x 16 x i1> @llvm.loop.dependence.raw.mask.nxv16i1(ptr %a, ptr %b, i64 1)
; CHECK-NEXT: Cost Model: Found an estimated cost of 1 for instruction: %res6 = call <vscale x 8 x i1> @llvm.loop.dependence.raw.mask.nxv8i1(ptr %a, ptr %b, i64 2)
; CHECK-NEXT: Cost Model: Found an estimated cost of 1 for instruction: %res7 = call <vscale x 4 x i1> @llvm.loop.dependence.raw.mask.nxv4i1(ptr %a, ptr %b, i64 4)
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It's not free (MOV + XTN) to convert from the predicate result of whilewr/rw to a fixed-length mask, so the cost should be slightly higher.
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sdesmalen-arm
approved these changes
Feb 6, 2026
rishabhmadan19
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Feb 9, 2026
For fixed-length masks we need to AND the result of the whilewr/rw with `ptrue vl*` (which is at least one more instruction).
Xinlong-Chen
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Feb 12, 2026
For fixed-length masks we need to AND the result of the whilewr/rw with `ptrue vl*` (which is at least one more instruction).
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For fixed-length masks we need to AND the result of the whilewr/rw with
ptrue vl*(which is at least one more instruction).