[llvm] [AArch64][SVE] Use FeatureUseFixedOverScalableIfEqualCost for A320 (PR #152156)
Ties Stuij via llvm-commits
llvm-commits at lists.llvm.org
Wed Aug 6 06:36:08 PDT 2025
https://github.com/stuij updated https://github.com/llvm/llvm-project/pull/152156
>From 6d2e2ca3b60274fc60df698126eee23fa9fc8f1b Mon Sep 17 00:00:00 2001
From: Ties Stuij <ties.stuij at arm.com>
Date: Tue, 5 Aug 2025 11:35:00 +0100
Subject: [PATCH] [AArch64][SVE] Use FeatureUseFixedOverScalableIfEqualCost for
A320
With this new A320 in-order core, we follow adding the
FeatureUseFixedOverScalableIfEqualCost feature to A510 and A520
(#132246), which reaps the same code generation benefits of preferring fixed
over scalable when the cost is equal.
So when we have:
```
void foo(float* a, float* b, float* dst, unsigned n) {
for (unsigned i = 0; i < n; ++i)
dst[i] = a[i] + b[i];
}
```
When compiling without the feature enabled, we get:
```
...
ld1b { z0.b }, p0/z, [x0, x10]
ld1b { z2.b }, p0/z, [x1, x10]
add x12, x0, x10
ldr z1, [x12, #1, mul vl]
add x12, x1, x10
ldr z3, [x12, #1, mul vl]
fadd z0.s, z2.s, z0.s
add x12, x2, x10
fadd z1.s, z3.s, z1.s
dech x11
st1b { z0.b }, p0, [x2, x10]
incb x10, all, mul #2
str z1, [x12, #1, mul vl]
...
```
When compiling with, we get:
```
...
ldp q0, q1, [x12, #-16]
ldp q2, q3, [x11, #-16]
subs x13, x13, #8
fadd v0.4s, v2.4s, v0.4s
fadd v1.4s, v3.4s, v1.4s
add x11, x11, #32
add x12, x12, #32
stp q0, q1, [x10, #-16]
add x10, x10, #32
...
```
This patch also moves FeatureUseFixedOverScalableIfEqualCost for A510 and A520
from the CPU features to the tune features.
---
llvm/lib/Target/AArch64/AArch64Processors.td | 11 +--
.../AArch64/sve-fixed-width-inorder-core.ll | 70 +++++++++++++++++++
2 files changed, 76 insertions(+), 5 deletions(-)
diff --git a/llvm/lib/Target/AArch64/AArch64Processors.td b/llvm/lib/Target/AArch64/AArch64Processors.td
index adc984ad795af..1bc1d98a6f65b 100644
--- a/llvm/lib/Target/AArch64/AArch64Processors.td
+++ b/llvm/lib/Target/AArch64/AArch64Processors.td
@@ -22,7 +22,8 @@ def TuneA320 : SubtargetFeature<"a320", "ARMProcFamily", "CortexA320",
FeatureFuseAES,
FeatureFuseAdrpAdd,
FeaturePostRAScheduler,
- FeatureUseWzrToVecMove]>;
+ FeatureUseWzrToVecMove,
+ FeatureUseFixedOverScalableIfEqualCost]>;
def TuneA53 : SubtargetFeature<"a53", "ARMProcFamily", "CortexA53",
"Cortex-A53 ARM processors", [
@@ -45,7 +46,8 @@ def TuneA510 : SubtargetFeature<"a510", "ARMProcFamily", "CortexA510",
FeatureFuseAES,
FeatureFuseAdrpAdd,
FeaturePostRAScheduler,
- FeatureUseWzrToVecMove
+ FeatureUseWzrToVecMove,
+ FeatureUseFixedOverScalableIfEqualCost
]>;
def TuneA520 : SubtargetFeature<"a520", "ARMProcFamily", "CortexA520",
@@ -53,7 +55,8 @@ def TuneA520 : SubtargetFeature<"a520", "ARMProcFamily", "CortexA520",
FeatureFuseAES,
FeatureFuseAdrpAdd,
FeaturePostRAScheduler,
- FeatureUseWzrToVecMove]>;
+ FeatureUseWzrToVecMove,
+ FeatureUseFixedOverScalableIfEqualCost]>;
def TuneA520AE : SubtargetFeature<"a520ae", "ARMProcFamily", "CortexA520",
"Cortex-A520AE ARM processors", [
@@ -756,7 +759,6 @@ def ProcessorFeatures {
FeatureSB, FeaturePAuth, FeatureSSBS, FeatureSVE, FeatureSVE2,
FeatureComplxNum, FeatureCRC, FeatureDotProd,
FeatureFPARMv8,FeatureFullFP16, FeatureJS, FeatureLSE,
- FeatureUseFixedOverScalableIfEqualCost,
FeatureRAS, FeatureRCPC, FeatureRDM, FeatureFPAC];
list<SubtargetFeature> A520 = [HasV9_2aOps, FeaturePerfMon, FeatureAM,
FeatureMTE, FeatureETE, FeatureSVEBitPerm,
@@ -766,7 +768,6 @@ def ProcessorFeatures {
FeatureSVE, FeatureSVE2, FeatureBF16, FeatureComplxNum, FeatureCRC,
FeatureFPARMv8, FeatureFullFP16, FeatureMatMulInt8, FeatureJS,
FeatureNEON, FeatureLSE, FeatureRAS, FeatureRCPC, FeatureRDM,
- FeatureUseFixedOverScalableIfEqualCost,
FeatureDotProd, FeatureFPAC];
list<SubtargetFeature> A520AE = [HasV9_2aOps, FeaturePerfMon, FeatureAM,
FeatureMTE, FeatureETE, FeatureSVEBitPerm,
diff --git a/llvm/test/Transforms/LoopVectorize/AArch64/sve-fixed-width-inorder-core.ll b/llvm/test/Transforms/LoopVectorize/AArch64/sve-fixed-width-inorder-core.ll
index 20bc0af648458..76a7536501bd6 100644
--- a/llvm/test/Transforms/LoopVectorize/AArch64/sve-fixed-width-inorder-core.ll
+++ b/llvm/test/Transforms/LoopVectorize/AArch64/sve-fixed-width-inorder-core.ll
@@ -1,6 +1,7 @@
; NOTE: Assertions have been autogenerated by utils/update_test_checks.py UTC_ARGS: --version 5
; RUN: opt < %s -mtriple=aarch64-none-elf -mcpu=cortex-a510 -mattr=+sve -passes=loop-vectorize -S | FileCheck %s --check-prefix=CHECK-CA510
; RUN: opt < %s -mtriple=aarch64-none-elf -mcpu=cortex-a520 -mattr=+sve -passes=loop-vectorize -S | FileCheck %s --check-prefix=CHECK-CA520
+; RUN: opt < %s -mtriple=aarch64-none-elf -mcpu=cortex-a320 -mattr=+sve -passes=loop-vectorize -S | FileCheck %s --check-prefix=CHECK-CA320
define void @sve_add(ptr %dst, ptr %a, ptr %b, i64 %n) {
; CHECK-CA510-LABEL: define void @sve_add(
@@ -131,6 +132,70 @@ define void @sve_add(ptr %dst, ptr %a, ptr %b, i64 %n) {
; CHECK-CA520: [[FOR_COND_CLEANUP]]:
; CHECK-CA520-NEXT: ret void
;
+; CHECK-CA320-LABEL: define void @sve_add(
+; CHECK-CA320-SAME: ptr [[DST:%.*]], ptr [[A:%.*]], ptr [[B:%.*]], i64 [[N:%.*]]) #[[ATTR0:[0-9]+]] {
+; CHECK-CA320-NEXT: [[ENTRY:.*:]]
+; CHECK-CA320-NEXT: [[B3:%.*]] = ptrtoint ptr [[B]] to i64
+; CHECK-CA320-NEXT: [[A2:%.*]] = ptrtoint ptr [[A]] to i64
+; CHECK-CA320-NEXT: [[DST1:%.*]] = ptrtoint ptr [[DST]] to i64
+; CHECK-CA320-NEXT: [[CMP9_NOT:%.*]] = icmp eq i64 [[N]], 0
+; CHECK-CA320-NEXT: br i1 [[CMP9_NOT]], label %[[FOR_COND_CLEANUP:.*]], label %[[FOR_BODY_PREHEADER:.*]]
+; CHECK-CA320: [[FOR_BODY_PREHEADER]]:
+; CHECK-CA320-NEXT: [[MIN_ITERS_CHECK:%.*]] = icmp ult i64 [[N]], 8
+; CHECK-CA320-NEXT: br i1 [[MIN_ITERS_CHECK]], label %[[SCALAR_PH:.*]], label %[[VECTOR_MEMCHECK:.*]]
+; CHECK-CA320: [[VECTOR_MEMCHECK]]:
+; CHECK-CA320-NEXT: [[TMP0:%.*]] = sub i64 [[DST1]], [[A2]]
+; CHECK-CA320-NEXT: [[DIFF_CHECK:%.*]] = icmp ult i64 [[TMP0]], 32
+; CHECK-CA320-NEXT: [[TMP1:%.*]] = sub i64 [[DST1]], [[B3]]
+; CHECK-CA320-NEXT: [[DIFF_CHECK4:%.*]] = icmp ult i64 [[TMP1]], 32
+; CHECK-CA320-NEXT: [[CONFLICT_RDX:%.*]] = or i1 [[DIFF_CHECK]], [[DIFF_CHECK4]]
+; CHECK-CA320-NEXT: br i1 [[CONFLICT_RDX]], label %[[SCALAR_PH]], label %[[VECTOR_PH:.*]]
+; CHECK-CA320: [[VECTOR_PH]]:
+; CHECK-CA320-NEXT: [[N_MOD_VF:%.*]] = urem i64 [[N]], 8
+; CHECK-CA320-NEXT: [[N_VEC:%.*]] = sub i64 [[N]], [[N_MOD_VF]]
+; CHECK-CA320-NEXT: br label %[[VECTOR_BODY:.*]]
+; CHECK-CA320: [[VECTOR_BODY]]:
+; CHECK-CA320-NEXT: [[INDEX:%.*]] = phi i64 [ 0, %[[VECTOR_PH]] ], [ [[INDEX_NEXT:%.*]], %[[VECTOR_BODY]] ]
+; CHECK-CA320-NEXT: [[TMP2:%.*]] = getelementptr inbounds nuw float, ptr [[A]], i64 [[INDEX]]
+; CHECK-CA320-NEXT: [[TMP3:%.*]] = getelementptr inbounds nuw float, ptr [[TMP2]], i32 4
+; CHECK-CA320-NEXT: [[WIDE_LOAD:%.*]] = load <4 x float>, ptr [[TMP2]], align 4
+; CHECK-CA320-NEXT: [[WIDE_LOAD5:%.*]] = load <4 x float>, ptr [[TMP3]], align 4
+; CHECK-CA320-NEXT: [[TMP4:%.*]] = getelementptr inbounds nuw float, ptr [[B]], i64 [[INDEX]]
+; CHECK-CA320-NEXT: [[TMP5:%.*]] = getelementptr inbounds nuw float, ptr [[TMP4]], i32 4
+; CHECK-CA320-NEXT: [[WIDE_LOAD6:%.*]] = load <4 x float>, ptr [[TMP4]], align 4
+; CHECK-CA320-NEXT: [[WIDE_LOAD7:%.*]] = load <4 x float>, ptr [[TMP5]], align 4
+; CHECK-CA320-NEXT: [[TMP6:%.*]] = fadd fast <4 x float> [[WIDE_LOAD6]], [[WIDE_LOAD]]
+; CHECK-CA320-NEXT: [[TMP7:%.*]] = fadd fast <4 x float> [[WIDE_LOAD7]], [[WIDE_LOAD5]]
+; CHECK-CA320-NEXT: [[TMP8:%.*]] = getelementptr inbounds nuw float, ptr [[DST]], i64 [[INDEX]]
+; CHECK-CA320-NEXT: [[TMP9:%.*]] = getelementptr inbounds nuw float, ptr [[TMP8]], i32 4
+; CHECK-CA320-NEXT: store <4 x float> [[TMP6]], ptr [[TMP8]], align 4
+; CHECK-CA320-NEXT: store <4 x float> [[TMP7]], ptr [[TMP9]], align 4
+; CHECK-CA320-NEXT: [[INDEX_NEXT]] = add nuw i64 [[INDEX]], 8
+; CHECK-CA320-NEXT: [[TMP10:%.*]] = icmp eq i64 [[INDEX_NEXT]], [[N_VEC]]
+; CHECK-CA320-NEXT: br i1 [[TMP10]], label %[[MIDDLE_BLOCK:.*]], label %[[VECTOR_BODY]], !llvm.loop [[LOOP0:![0-9]+]]
+; CHECK-CA320: [[MIDDLE_BLOCK]]:
+; CHECK-CA320-NEXT: [[CMP_N:%.*]] = icmp eq i64 [[N]], [[N_VEC]]
+; CHECK-CA320-NEXT: br i1 [[CMP_N]], label %[[FOR_COND_CLEANUP_LOOPEXIT:.*]], label %[[SCALAR_PH]]
+; CHECK-CA320: [[SCALAR_PH]]:
+; CHECK-CA320-NEXT: [[BC_RESUME_VAL:%.*]] = phi i64 [ [[N_VEC]], %[[MIDDLE_BLOCK]] ], [ 0, %[[FOR_BODY_PREHEADER]] ], [ 0, %[[VECTOR_MEMCHECK]] ]
+; CHECK-CA320-NEXT: br label %[[FOR_BODY:.*]]
+; CHECK-CA320: [[FOR_BODY]]:
+; CHECK-CA320-NEXT: [[INDVARS_IV:%.*]] = phi i64 [ [[INDVARS_IV_NEXT:%.*]], %[[FOR_BODY]] ], [ [[BC_RESUME_VAL]], %[[SCALAR_PH]] ]
+; CHECK-CA320-NEXT: [[ARRAYIDX:%.*]] = getelementptr inbounds nuw float, ptr [[A]], i64 [[INDVARS_IV]]
+; CHECK-CA320-NEXT: [[TMP11:%.*]] = load float, ptr [[ARRAYIDX]], align 4
+; CHECK-CA320-NEXT: [[ARRAYIDX2:%.*]] = getelementptr inbounds nuw float, ptr [[B]], i64 [[INDVARS_IV]]
+; CHECK-CA320-NEXT: [[TMP12:%.*]] = load float, ptr [[ARRAYIDX2]], align 4
+; CHECK-CA320-NEXT: [[ADD:%.*]] = fadd fast float [[TMP12]], [[TMP11]]
+; CHECK-CA320-NEXT: [[ARRAYIDX4:%.*]] = getelementptr inbounds nuw float, ptr [[DST]], i64 [[INDVARS_IV]]
+; CHECK-CA320-NEXT: store float [[ADD]], ptr [[ARRAYIDX4]], align 4
+; CHECK-CA320-NEXT: [[INDVARS_IV_NEXT]] = add nuw nsw i64 [[INDVARS_IV]], 1
+; CHECK-CA320-NEXT: [[EXITCOND_NOT:%.*]] = icmp eq i64 [[INDVARS_IV_NEXT]], [[N]]
+; CHECK-CA320-NEXT: br i1 [[EXITCOND_NOT]], label %[[FOR_COND_CLEANUP_LOOPEXIT]], label %[[FOR_BODY]], !llvm.loop [[LOOP3:![0-9]+]]
+; CHECK-CA320: [[FOR_COND_CLEANUP_LOOPEXIT]]:
+; CHECK-CA320-NEXT: br label %[[FOR_COND_CLEANUP]]
+; CHECK-CA320: [[FOR_COND_CLEANUP]]:
+; CHECK-CA320-NEXT: ret void
+;
entry:
%cmp9.not = icmp eq i64 %n, 0
br i1 %cmp9.not, label %for.cond.cleanup, label %for.body
@@ -160,3 +225,8 @@ for.cond.cleanup: ; preds = %for.cond.cleanup.lo
; CHECK-CA520: [[META2]] = !{!"llvm.loop.unroll.runtime.disable"}
; CHECK-CA520: [[LOOP3]] = distinct !{[[LOOP3]], [[META1]]}
;.
+; CHECK-CA320: [[LOOP0]] = distinct !{[[LOOP0]], [[META1:![0-9]+]], [[META2:![0-9]+]]}
+; CHECK-CA320: [[META1]] = !{!"llvm.loop.isvectorized", i32 1}
+; CHECK-CA320: [[META2]] = !{!"llvm.loop.unroll.runtime.disable"}
+; CHECK-CA320: [[LOOP3]] = distinct !{[[LOOP3]], [[META1]]}
+;.
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