[llvm] a37dfbb - [RISCV] Fallback to scalable lowering costs for fixed length vectors
Philip Reames via llvm-commits
llvm-commits at lists.llvm.org
Mon Mar 13 10:08:08 PDT 2023
Author: Philip Reames
Date: 2023-03-13T10:07:57-07:00
New Revision: a37dfbb79cbfcb619a46df68683c6e6b3848e5ce
URL: https://github.com/llvm/llvm-project/commit/a37dfbb79cbfcb619a46df68683c6e6b3848e5ce
DIFF: https://github.com/llvm/llvm-project/commit/a37dfbb79cbfcb619a46df68683c6e6b3848e5ce.diff
LOG: [RISCV] Fallback to scalable lowering costs for fixed length vectors
Fixed vector costs may be more precise, but the actual lowering will use scalable vectors if nothing better is available. During review, we noticed a case where fixed vector reverse can be improved cost model wise, that will follow seperately.
Differential Revision: https://reviews.llvm.org/D145953
Added:
Modified:
llvm/lib/Target/RISCV/RISCVTargetTransformInfo.cpp
llvm/test/Analysis/CostModel/RISCV/shuffle-reverse.ll
Removed:
################################################################################
diff --git a/llvm/lib/Target/RISCV/RISCVTargetTransformInfo.cpp b/llvm/lib/Target/RISCV/RISCVTargetTransformInfo.cpp
index ae044711624ed..610c62464e189 100644
--- a/llvm/lib/Target/RISCV/RISCVTargetTransformInfo.cpp
+++ b/llvm/lib/Target/RISCV/RISCVTargetTransformInfo.cpp
@@ -250,38 +250,9 @@ InstructionCost RISCVTTIImpl::getShuffleCost(TTI::ShuffleKind Kind,
ArrayRef<const Value *> Args) {
std::pair<InstructionCost, MVT> LT = getTypeLegalizationCost(Tp);
- if (isa<ScalableVectorType>(Tp)) {
- switch (Kind) {
- default:
- // Fallthrough to generic handling.
- // TODO: Most of these cases will return getInvalid in generic code, and
- // must be implemented here.
- break;
- case TTI::SK_Broadcast: {
- return LT.first * 1;
- }
- case TTI::SK_Splice:
- // vslidedown+vslideup.
- // TODO: Multiplying by LT.first implies this legalizes into multiple copies
- // of similar code, but I think we expand through memory.
- return 2 * LT.first * getLMULCost(LT.second);
- case TTI::SK_Reverse:
- // Most of the cost here is producing the vrgather index register
- // Example sequence:
- // csrr a0, vlenb
- // srli a0, a0, 3
- // addi a0, a0, -1
- // vsetvli a1, zero, e8, mf8, ta, mu (ignored)
- // vid.v v9
- // vrsub.vx v10, v9, a0
- // vrgather.vv v9, v8, v10
- if (Tp->getElementType()->isIntegerTy(1))
- // Mask operation additionally required extend and truncate
- return LT.first * 9;
- return LT.first * 6;
- }
- }
-
+ // First, handle cases where having a fixed length vector enables us to
+ // give a more accurate cost than falling back to generic scalable codegen.
+ // TODO: Each of these cases hints at a modeling gap around scalable vectors.
if (isa<FixedVectorType>(Tp)) {
switch (Kind) {
default:
@@ -350,6 +321,36 @@ InstructionCost RISCVTTIImpl::getShuffleCost(TTI::ShuffleKind Kind,
}
};
+ // Handle scalable vectors (and fixed vectors legalized to scalable vectors).
+ switch (Kind) {
+ default:
+ // Fallthrough to generic handling.
+ // TODO: Most of these cases will return getInvalid in generic code, and
+ // must be implemented here.
+ break;
+ case TTI::SK_Broadcast: {
+ return LT.first * 1;
+ }
+ case TTI::SK_Splice:
+ // vslidedown+vslideup.
+ // TODO: Multiplying by LT.first implies this legalizes into multiple copies
+ // of similar code, but I think we expand through memory.
+ return 2 * LT.first * getLMULCost(LT.second);
+ case TTI::SK_Reverse:
+ // Most of the cost here is producing the vrgather index register
+ // Example sequence:
+ // csrr a0, vlenb
+ // srli a0, a0, 3
+ // addi a0, a0, -1
+ // vsetvli a1, zero, e8, mf8, ta, mu (ignored)
+ // vid.v v9
+ // vrsub.vx v10, v9, a0
+ // vrgather.vv v9, v8, v10
+ if (Tp->getElementType()->isIntegerTy(1))
+ // Mask operation additionally required extend and truncate
+ return LT.first * 9;
+ return LT.first * 6;
+ }
return BaseT::getShuffleCost(Kind, Tp, Mask, CostKind, Index, SubTp);
}
diff --git a/llvm/test/Analysis/CostModel/RISCV/shuffle-reverse.ll b/llvm/test/Analysis/CostModel/RISCV/shuffle-reverse.ll
index 7de34781a02b9..18e614cf236e3 100644
--- a/llvm/test/Analysis/CostModel/RISCV/shuffle-reverse.ll
+++ b/llvm/test/Analysis/CostModel/RISCV/shuffle-reverse.ll
@@ -9,27 +9,27 @@ define void @reverse() {
;
; CHECK-LABEL: 'reverse'
; CHECK-NEXT: Cost Model: Found an estimated cost of 6 for instruction: %v2i8 = shufflevector <2 x i8> undef, <2 x i8> undef, <2 x i32> <i32 1, i32 0>
-; CHECK-NEXT: Cost Model: Found an estimated cost of 14 for instruction: %v4i8 = shufflevector <4 x i8> undef, <4 x i8> undef, <4 x i32> <i32 3, i32 2, i32 1, i32 0>
-; CHECK-NEXT: Cost Model: Found an estimated cost of 30 for instruction: %v8i8 = shufflevector <8 x i8> undef, <8 x i8> undef, <8 x i32> <i32 7, i32 6, i32 5, i32 4, i32 3, i32 2, i32 1, i32 0>
-; CHECK-NEXT: Cost Model: Found an estimated cost of 62 for instruction: %v16i8 = shufflevector <16 x i8> undef, <16 x i8> undef, <16 x i32> <i32 15, i32 14, i32 13, i32 12, i32 11, i32 10, i32 9, i32 8, i32 7, i32 6, i32 5, i32 4, i32 3, i32 2, i32 1, i32 0>
+; CHECK-NEXT: Cost Model: Found an estimated cost of 6 for instruction: %v4i8 = shufflevector <4 x i8> undef, <4 x i8> undef, <4 x i32> <i32 3, i32 2, i32 1, i32 0>
+; CHECK-NEXT: Cost Model: Found an estimated cost of 6 for instruction: %v8i8 = shufflevector <8 x i8> undef, <8 x i8> undef, <8 x i32> <i32 7, i32 6, i32 5, i32 4, i32 3, i32 2, i32 1, i32 0>
+; CHECK-NEXT: Cost Model: Found an estimated cost of 6 for instruction: %v16i8 = shufflevector <16 x i8> undef, <16 x i8> undef, <16 x i32> <i32 15, i32 14, i32 13, i32 12, i32 11, i32 10, i32 9, i32 8, i32 7, i32 6, i32 5, i32 4, i32 3, i32 2, i32 1, i32 0>
; CHECK-NEXT: Cost Model: Found an estimated cost of 6 for instruction: %v2i16 = shufflevector <2 x i16> undef, <2 x i16> undef, <2 x i32> <i32 1, i32 0>
-; CHECK-NEXT: Cost Model: Found an estimated cost of 14 for instruction: %v4i16 = shufflevector <4 x i16> undef, <4 x i16> undef, <4 x i32> <i32 3, i32 2, i32 1, i32 0>
-; CHECK-NEXT: Cost Model: Found an estimated cost of 30 for instruction: %v8i16 = shufflevector <8 x i16> undef, <8 x i16> undef, <8 x i32> <i32 7, i32 6, i32 5, i32 4, i32 3, i32 2, i32 1, i32 0>
-; CHECK-NEXT: Cost Model: Found an estimated cost of 62 for instruction: %v16i16 = shufflevector <16 x i16> undef, <16 x i16> undef, <16 x i32> <i32 15, i32 14, i32 13, i32 12, i32 11, i32 10, i32 9, i32 8, i32 7, i32 6, i32 5, i32 4, i32 3, i32 2, i32 1, i32 0>
+; CHECK-NEXT: Cost Model: Found an estimated cost of 6 for instruction: %v4i16 = shufflevector <4 x i16> undef, <4 x i16> undef, <4 x i32> <i32 3, i32 2, i32 1, i32 0>
+; CHECK-NEXT: Cost Model: Found an estimated cost of 6 for instruction: %v8i16 = shufflevector <8 x i16> undef, <8 x i16> undef, <8 x i32> <i32 7, i32 6, i32 5, i32 4, i32 3, i32 2, i32 1, i32 0>
+; CHECK-NEXT: Cost Model: Found an estimated cost of 6 for instruction: %v16i16 = shufflevector <16 x i16> undef, <16 x i16> undef, <16 x i32> <i32 15, i32 14, i32 13, i32 12, i32 11, i32 10, i32 9, i32 8, i32 7, i32 6, i32 5, i32 4, i32 3, i32 2, i32 1, i32 0>
; CHECK-NEXT: Cost Model: Found an estimated cost of 6 for instruction: %v2i32 = shufflevector <2 x i32> undef, <2 x i32> undef, <2 x i32> <i32 1, i32 0>
-; CHECK-NEXT: Cost Model: Found an estimated cost of 14 for instruction: %v4i32 = shufflevector <4 x i32> undef, <4 x i32> undef, <4 x i32> <i32 3, i32 2, i32 1, i32 0>
-; CHECK-NEXT: Cost Model: Found an estimated cost of 30 for instruction: %v8i32 = shufflevector <8 x i32> undef, <8 x i32> undef, <8 x i32> <i32 7, i32 6, i32 5, i32 4, i32 3, i32 2, i32 1, i32 0>
-; CHECK-NEXT: Cost Model: Found an estimated cost of 16 for instruction: %v2i64 = shufflevector <2 x i64> undef, <2 x i64> undef, <2 x i32> <i32 1, i32 0>
-; CHECK-NEXT: Cost Model: Found an estimated cost of 34 for instruction: %v4i64 = shufflevector <4 x i64> undef, <4 x i64> undef, <4 x i32> <i32 3, i32 2, i32 1, i32 0>
+; CHECK-NEXT: Cost Model: Found an estimated cost of 6 for instruction: %v4i32 = shufflevector <4 x i32> undef, <4 x i32> undef, <4 x i32> <i32 3, i32 2, i32 1, i32 0>
+; CHECK-NEXT: Cost Model: Found an estimated cost of 6 for instruction: %v8i32 = shufflevector <8 x i32> undef, <8 x i32> undef, <8 x i32> <i32 7, i32 6, i32 5, i32 4, i32 3, i32 2, i32 1, i32 0>
+; CHECK-NEXT: Cost Model: Found an estimated cost of 6 for instruction: %v2i64 = shufflevector <2 x i64> undef, <2 x i64> undef, <2 x i32> <i32 1, i32 0>
+; CHECK-NEXT: Cost Model: Found an estimated cost of 6 for instruction: %v4i64 = shufflevector <4 x i64> undef, <4 x i64> undef, <4 x i32> <i32 3, i32 2, i32 1, i32 0>
; CHECK-NEXT: Cost Model: Found an estimated cost of 6 for instruction: %v2f16 = shufflevector <2 x half> undef, <2 x half> undef, <2 x i32> <i32 1, i32 0>
-; CHECK-NEXT: Cost Model: Found an estimated cost of 14 for instruction: %v4f16 = shufflevector <4 x half> undef, <4 x half> undef, <4 x i32> <i32 3, i32 2, i32 1, i32 0>
-; CHECK-NEXT: Cost Model: Found an estimated cost of 30 for instruction: %v8f16 = shufflevector <8 x half> undef, <8 x half> undef, <8 x i32> <i32 7, i32 6, i32 5, i32 4, i32 3, i32 2, i32 1, i32 0>
-; CHECK-NEXT: Cost Model: Found an estimated cost of 62 for instruction: %v16f16 = shufflevector <16 x half> undef, <16 x half> undef, <16 x i32> <i32 15, i32 14, i32 13, i32 12, i32 11, i32 10, i32 9, i32 8, i32 7, i32 6, i32 5, i32 4, i32 3, i32 2, i32 1, i32 0>
+; CHECK-NEXT: Cost Model: Found an estimated cost of 6 for instruction: %v4f16 = shufflevector <4 x half> undef, <4 x half> undef, <4 x i32> <i32 3, i32 2, i32 1, i32 0>
+; CHECK-NEXT: Cost Model: Found an estimated cost of 6 for instruction: %v8f16 = shufflevector <8 x half> undef, <8 x half> undef, <8 x i32> <i32 7, i32 6, i32 5, i32 4, i32 3, i32 2, i32 1, i32 0>
+; CHECK-NEXT: Cost Model: Found an estimated cost of 6 for instruction: %v16f16 = shufflevector <16 x half> undef, <16 x half> undef, <16 x i32> <i32 15, i32 14, i32 13, i32 12, i32 11, i32 10, i32 9, i32 8, i32 7, i32 6, i32 5, i32 4, i32 3, i32 2, i32 1, i32 0>
; CHECK-NEXT: Cost Model: Found an estimated cost of 6 for instruction: %v2f32 = shufflevector <2 x float> undef, <2 x float> undef, <2 x i32> <i32 1, i32 0>
-; CHECK-NEXT: Cost Model: Found an estimated cost of 14 for instruction: %v4f32 = shufflevector <4 x float> undef, <4 x float> undef, <4 x i32> <i32 3, i32 2, i32 1, i32 0>
-; CHECK-NEXT: Cost Model: Found an estimated cost of 30 for instruction: %v8f32 = shufflevector <8 x float> undef, <8 x float> undef, <8 x i32> <i32 7, i32 6, i32 5, i32 4, i32 3, i32 2, i32 1, i32 0>
+; CHECK-NEXT: Cost Model: Found an estimated cost of 6 for instruction: %v4f32 = shufflevector <4 x float> undef, <4 x float> undef, <4 x i32> <i32 3, i32 2, i32 1, i32 0>
+; CHECK-NEXT: Cost Model: Found an estimated cost of 6 for instruction: %v8f32 = shufflevector <8 x float> undef, <8 x float> undef, <8 x i32> <i32 7, i32 6, i32 5, i32 4, i32 3, i32 2, i32 1, i32 0>
; CHECK-NEXT: Cost Model: Found an estimated cost of 6 for instruction: %v2f64 = shufflevector <2 x double> undef, <2 x double> undef, <2 x i32> <i32 1, i32 0>
-; CHECK-NEXT: Cost Model: Found an estimated cost of 14 for instruction: %v4f64 = shufflevector <4 x double> undef, <4 x double> undef, <4 x i32> <i32 3, i32 2, i32 1, i32 0>
+; CHECK-NEXT: Cost Model: Found an estimated cost of 6 for instruction: %v4f64 = shufflevector <4 x double> undef, <4 x double> undef, <4 x i32> <i32 3, i32 2, i32 1, i32 0>
; CHECK-NEXT: Cost Model: Found an estimated cost of 1 for instruction: ret void
;
%v2i8 = shufflevector <2 x i8> undef, <2 x i8> undef, <2 x i32> <i32 1, i32 0>
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