[llvm] 08d45e6 - [AArch64][SVEIntrinsicOpts] Fix: predicated SVE mul/fmul are not commutative
Igor Kirillov via llvm-commits
llvm-commits at lists.llvm.org
Fri Nov 26 04:41:38 PST 2021
Author: Igor Kirillov
Date: 2021-11-26T12:41:27Z
New Revision: 08d45e6f4da03836dc2380b7bae650ae80cfae35
URL: https://github.com/llvm/llvm-project/commit/08d45e6f4da03836dc2380b7bae650ae80cfae35
DIFF: https://github.com/llvm/llvm-project/commit/08d45e6f4da03836dc2380b7bae650ae80cfae35.diff
LOG: [AArch64][SVEIntrinsicOpts] Fix: predicated SVE mul/fmul are not commutative
We can not swap multiplicand and multiplier because the sve intrinsics
are predicated. Imagine lanes in vectors having the following values:
pg = 0
multiplicand = 1 (from dup)
multiplier = 2
The resulting value should be 1, but if we swap multiplicand and multiplier it will become 2,
which is incorrect.
Differential Revision: https://reviews.llvm.org/D114577
Added:
Modified:
llvm/lib/Target/AArch64/AArch64TargetTransformInfo.cpp
llvm/test/Transforms/InstCombine/AArch64/sve-intrinsic-fmul-idempotency.ll
llvm/test/Transforms/InstCombine/AArch64/sve-intrinsic-mul-idempotency.ll
Removed:
################################################################################
diff --git a/llvm/lib/Target/AArch64/AArch64TargetTransformInfo.cpp b/llvm/lib/Target/AArch64/AArch64TargetTransformInfo.cpp
index ea21ad1f3cc50..34015d2dbd49a 100644
--- a/llvm/lib/Target/AArch64/AArch64TargetTransformInfo.cpp
+++ b/llvm/lib/Target/AArch64/AArch64TargetTransformInfo.cpp
@@ -833,17 +833,12 @@ static Optional<Instruction *> instCombineSVEVectorMul(InstCombiner &IC,
return match(SplatValue, m_FPOne()) || match(SplatValue, m_One());
};
- // The OpMultiplier variable should always point to the dup (if any), so
- // swap if necessary.
- if (IsUnitDup(OpMultiplicand) || IsUnitSplat(OpMultiplicand))
- std::swap(OpMultiplier, OpMultiplicand);
-
if (IsUnitSplat(OpMultiplier)) {
- // [f]mul pg (dupx 1) %n => %n
+ // [f]mul pg %n, (dupx 1) => %n
OpMultiplicand->takeName(&II);
return IC.replaceInstUsesWith(II, OpMultiplicand);
} else if (IsUnitDup(OpMultiplier)) {
- // [f]mul pg (dup pg 1) %n => %n
+ // [f]mul pg %n, (dup pg 1) => %n
auto *DupInst = cast<IntrinsicInst>(OpMultiplier);
auto *DupPg = DupInst->getOperand(1);
// TODO: this is naive. The optimization is still valid if DupPg
diff --git a/llvm/test/Transforms/InstCombine/AArch64/sve-intrinsic-fmul-idempotency.ll b/llvm/test/Transforms/InstCombine/AArch64/sve-intrinsic-fmul-idempotency.ll
index 9bc48d8777954..77c76ea3671a2 100644
--- a/llvm/test/Transforms/InstCombine/AArch64/sve-intrinsic-fmul-idempotency.ll
+++ b/llvm/test/Transforms/InstCombine/AArch64/sve-intrinsic-fmul-idempotency.ll
@@ -32,7 +32,8 @@ define <vscale x 2 x double> @idempotent_fmul_f64(<vscale x 2 x i1> %pg, <vscale
define <vscale x 2 x double> @idempotent_fmul_
diff erent_argument_order(<vscale x 2 x i1> %pg, <vscale x 2 x double> %a) #0 {
; CHECK-LABEL: @idempotent_fmul_
diff erent_argument_order(
-; CHECK-NEXT: ret <vscale x 2 x double> [[A:%.*]]
+; CHECK-NEXT: [[TMP1:%.*]] = call <vscale x 2 x double> @llvm.aarch64.sve.fmul.nxv2f64(<vscale x 2 x i1> [[PG:%.*]], <vscale x 2 x double> shufflevector (<vscale x 2 x double> insertelement (<vscale x 2 x double> poison, double 1.000000e+00, i32 0), <vscale x 2 x double> poison, <vscale x 2 x i32> zeroinitializer), <vscale x 2 x double> [[A:%.*]])
+; CHECK-NEXT: ret <vscale x 2 x double> [[TMP1]]
;
%1 = call <vscale x 2 x double> @llvm.aarch64.sve.dup.x.nxv2f64(double 1.0)
; Different argument order to the above tests.
diff --git a/llvm/test/Transforms/InstCombine/AArch64/sve-intrinsic-mul-idempotency.ll b/llvm/test/Transforms/InstCombine/AArch64/sve-intrinsic-mul-idempotency.ll
index e07fa9263a355..e6acd3676c168 100644
--- a/llvm/test/Transforms/InstCombine/AArch64/sve-intrinsic-mul-idempotency.ll
+++ b/llvm/test/Transforms/InstCombine/AArch64/sve-intrinsic-mul-idempotency.ll
@@ -32,7 +32,8 @@ define <vscale x 2 x i64> @idempotent_mul_i64(<vscale x 2 x i1> %pg, <vscale x 2
define <vscale x 2 x i64> @idempotent_mul_
diff erent_argument_order(<vscale x 2 x i1> %pg, <vscale x 2 x i64> %a) #0 {
; CHECK-LABEL: @idempotent_mul_
diff erent_argument_order(
-; CHECK-NEXT: ret <vscale x 2 x i64> [[A:%.*]]
+; CHECK-NEXT: [[TMP1:%.*]] = call <vscale x 2 x i64> @llvm.aarch64.sve.mul.nxv2i64(<vscale x 2 x i1> [[PG:%.*]], <vscale x 2 x i64> shufflevector (<vscale x 2 x i64> insertelement (<vscale x 2 x i64> poison, i64 1, i32 0), <vscale x 2 x i64> poison, <vscale x 2 x i32> zeroinitializer), <vscale x 2 x i64> [[A:%.*]])
+; CHECK-NEXT: ret <vscale x 2 x i64> [[TMP1]]
;
%1 = call <vscale x 2 x i64> @llvm.aarch64.sve.dup.x.nxv2i64(i64 1)
; Different argument order to the above tests.
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