[llvm] [GVN] Handle scalable vectors with the same size in VNCoercion (PR #123984)
David Green via llvm-commits
llvm-commits at lists.llvm.org
Thu Jan 23 09:59:45 PST 2025
https://github.com/davemgreen updated https://github.com/llvm/llvm-project/pull/123984
>From 7171d8500bf8ebd1365cb3d9d3e4769da01fad1f Mon Sep 17 00:00:00 2001
From: David Green <david.green at arm.com>
Date: Thu, 23 Jan 2025 17:58:11 +0000
Subject: [PATCH] [GVN] Handle scalable vectors with the same size in
VNCoercion
This allows us to forward to a load even if the types do not match (nxv4i32 vs
nxv2i64 for example). Scalable types are alloweed in
canCoerceMustAliasedValueToLoad so long as the size (minelts * scalarsize) is
the same, and some follow-on code is adjusted to make sure it handles scalable
sizes correctly. Methods like analyzeLoadFromClobberingWrite and
analyzeLoadFromClobberingStore still do nothing for scalable vectors, as
Offsets and mismatching types are not supported.
---
llvm/lib/Transforms/Utils/VNCoercion.cpp | 30 ++++++++++++++++++------
llvm/test/Transforms/GVN/vscale.ll | 24 +++++++++----------
2 files changed, 35 insertions(+), 19 deletions(-)
diff --git a/llvm/lib/Transforms/Utils/VNCoercion.cpp b/llvm/lib/Transforms/Utils/VNCoercion.cpp
index 1e0ae280516410..7a61ab74166389 100644
--- a/llvm/lib/Transforms/Utils/VNCoercion.cpp
+++ b/llvm/lib/Transforms/Utils/VNCoercion.cpp
@@ -21,6 +21,10 @@ bool canCoerceMustAliasedValueToLoad(Value *StoredVal, Type *LoadTy,
if (StoredTy == LoadTy)
return true;
+ if (isa<ScalableVectorType>(StoredTy) && isa<ScalableVectorType>(LoadTy) &&
+ DL.getTypeSizeInBits(StoredTy) == DL.getTypeSizeInBits(LoadTy))
+ return true;
+
// If the loaded/stored value is a first class array/struct, or scalable type,
// don't try to transform them. We need to be able to bitcast to integer.
if (isFirstClassAggregateOrScalableType(LoadTy) ||
@@ -83,8 +87,8 @@ Value *coerceAvailableValueToLoadType(Value *StoredVal, Type *LoadedTy,
// If this is already the right type, just return it.
Type *StoredValTy = StoredVal->getType();
- uint64_t StoredValSize = DL.getTypeSizeInBits(StoredValTy).getFixedValue();
- uint64_t LoadedValSize = DL.getTypeSizeInBits(LoadedTy).getFixedValue();
+ TypeSize StoredValSize = DL.getTypeSizeInBits(StoredValTy);
+ TypeSize LoadedValSize = DL.getTypeSizeInBits(LoadedTy);
// If the store and reload are the same size, we can always reuse it.
if (StoredValSize == LoadedValSize) {
@@ -118,7 +122,8 @@ Value *coerceAvailableValueToLoadType(Value *StoredVal, Type *LoadedTy,
// If the loaded value is smaller than the available value, then we can
// extract out a piece from it. If the available value is too small, then we
// can't do anything.
- assert(StoredValSize >= LoadedValSize &&
+ assert(!StoredValSize.isScalable() &&
+ TypeSize::isKnownGE(StoredValSize, LoadedValSize) &&
"canCoerceMustAliasedValueToLoad fail");
// Convert source pointers to integers, which can be manipulated.
@@ -303,6 +308,13 @@ static Value *getStoreValueForLoadHelper(Value *SrcVal, unsigned Offset,
return SrcVal;
}
+ // Return scalable values directly to avoid needing to bitcast to integer
+ // types, as we do not support non-zero Offsets.
+ if (isa<ScalableVectorType>(LoadTy)) {
+ assert(Offset == 0 && "Expected a zero offset for scalable types");
+ return SrcVal;
+ }
+
uint64_t StoreSize =
(DL.getTypeSizeInBits(SrcVal->getType()).getFixedValue() + 7) / 8;
uint64_t LoadSize = (DL.getTypeSizeInBits(LoadTy).getFixedValue() + 7) / 8;
@@ -333,11 +345,15 @@ static Value *getStoreValueForLoadHelper(Value *SrcVal, unsigned Offset,
Value *getValueForLoad(Value *SrcVal, unsigned Offset, Type *LoadTy,
Instruction *InsertPt, const DataLayout &DL) {
-
#ifndef NDEBUG
- unsigned SrcValSize = DL.getTypeStoreSize(SrcVal->getType()).getFixedValue();
- unsigned LoadSize = DL.getTypeStoreSize(LoadTy).getFixedValue();
- assert(Offset + LoadSize <= SrcValSize);
+ TypeSize SrcValSize = DL.getTypeStoreSize(SrcVal->getType());
+ TypeSize LoadSize = DL.getTypeStoreSize(LoadTy);
+ assert(SrcValSize.isScalable() == LoadSize.isScalable());
+ assert((SrcValSize.isScalable() || Offset + LoadSize <= SrcValSize) &&
+ "Expected Offset + LoadSize <= SrcValSize");
+ assert(
+ (!SrcValSize.isScalable() || (Offset == 0 && LoadSize == SrcValSize)) &&
+ "Expected scalable type sizes to match");
#endif
IRBuilder<> Builder(InsertPt);
SrcVal = getStoreValueForLoadHelper(SrcVal, Offset, LoadTy, Builder, DL);
diff --git a/llvm/test/Transforms/GVN/vscale.ll b/llvm/test/Transforms/GVN/vscale.ll
index f6e0f8c1a64944..67cbfc2f05ef84 100644
--- a/llvm/test/Transforms/GVN/vscale.ll
+++ b/llvm/test/Transforms/GVN/vscale.ll
@@ -393,7 +393,7 @@ if.else:
define <vscale x 16 x i8> @load_v16i8_store_v4i32_forward_load(ptr %p, <vscale x 4 x i32> %x) {
; CHECK-LABEL: @load_v16i8_store_v4i32_forward_load(
; CHECK-NEXT: store <vscale x 4 x i32> [[X:%.*]], ptr [[P:%.*]], align 16
-; CHECK-NEXT: [[LOAD:%.*]] = load <vscale x 16 x i8>, ptr [[P]], align 16
+; CHECK-NEXT: [[LOAD:%.*]] = bitcast <vscale x 4 x i32> [[X]] to <vscale x 16 x i8>
; CHECK-NEXT: ret <vscale x 16 x i8> [[LOAD]]
;
store <vscale x 4 x i32> %x, ptr %p
@@ -404,7 +404,7 @@ define <vscale x 16 x i8> @load_v16i8_store_v4i32_forward_load(ptr %p, <vscale x
define <vscale x 4 x float> @load_v4f32_store_v4i32_forward_load(ptr %p, <vscale x 4 x i32> %x) {
; CHECK-LABEL: @load_v4f32_store_v4i32_forward_load(
; CHECK-NEXT: store <vscale x 4 x i32> [[X:%.*]], ptr [[P:%.*]], align 16
-; CHECK-NEXT: [[LOAD:%.*]] = load <vscale x 4 x float>, ptr [[P]], align 16
+; CHECK-NEXT: [[LOAD:%.*]] = bitcast <vscale x 4 x i32> [[X]] to <vscale x 4 x float>
; CHECK-NEXT: ret <vscale x 4 x float> [[LOAD]]
;
store <vscale x 4 x i32> %x, ptr %p
@@ -415,7 +415,7 @@ define <vscale x 4 x float> @load_v4f32_store_v4i32_forward_load(ptr %p, <vscale
define <vscale x 4 x float> @load_v4f32_store_v16i8_forward_load(ptr %p, <vscale x 16 x i8> %x) {
; CHECK-LABEL: @load_v4f32_store_v16i8_forward_load(
; CHECK-NEXT: store <vscale x 16 x i8> [[X:%.*]], ptr [[P:%.*]], align 16
-; CHECK-NEXT: [[LOAD:%.*]] = load <vscale x 4 x float>, ptr [[P]], align 16
+; CHECK-NEXT: [[LOAD:%.*]] = bitcast <vscale x 16 x i8> [[X]] to <vscale x 4 x float>
; CHECK-NEXT: ret <vscale x 4 x float> [[LOAD]]
;
store <vscale x 16 x i8> %x, ptr %p
@@ -426,7 +426,7 @@ define <vscale x 4 x float> @load_v4f32_store_v16i8_forward_load(ptr %p, <vscale
define <vscale x 4 x i32> @load_v4i32_store_v4f32_forward_load(ptr %p, <vscale x 4 x float> %x) {
; CHECK-LABEL: @load_v4i32_store_v4f32_forward_load(
; CHECK-NEXT: store <vscale x 4 x float> [[X:%.*]], ptr [[P:%.*]], align 16
-; CHECK-NEXT: [[LOAD:%.*]] = load <vscale x 4 x i32>, ptr [[P]], align 16
+; CHECK-NEXT: [[LOAD:%.*]] = bitcast <vscale x 4 x float> [[X]] to <vscale x 4 x i32>
; CHECK-NEXT: ret <vscale x 4 x i32> [[LOAD]]
;
store <vscale x 4 x float> %x, ptr %p
@@ -496,7 +496,8 @@ define <vscale x 2 x i32> @load_v2i32_store_v4i32_forward_load_offsetc(ptr %p, <
define <vscale x 2 x ptr> @load_v2p0_store_v4i32_forward_load(ptr %p, <vscale x 4 x i32> %x) {
; CHECK-LABEL: @load_v2p0_store_v4i32_forward_load(
; CHECK-NEXT: store <vscale x 4 x i32> [[X:%.*]], ptr [[P:%.*]], align 16
-; CHECK-NEXT: [[LOAD:%.*]] = load <vscale x 2 x ptr>, ptr [[P]], align 16
+; CHECK-NEXT: [[TMP1:%.*]] = bitcast <vscale x 4 x i32> [[X]] to <vscale x 2 x i64>
+; CHECK-NEXT: [[LOAD:%.*]] = inttoptr <vscale x 2 x i64> [[TMP1]] to <vscale x 2 x ptr>
; CHECK-NEXT: ret <vscale x 2 x ptr> [[LOAD]]
;
store <vscale x 4 x i32> %x, ptr %p
@@ -507,7 +508,7 @@ define <vscale x 2 x ptr> @load_v2p0_store_v4i32_forward_load(ptr %p, <vscale x
define <vscale x 2 x i64> @load_v2i64_store_v2p0_forward_load(ptr %p, <vscale x 2 x ptr> %x) {
; CHECK-LABEL: @load_v2i64_store_v2p0_forward_load(
; CHECK-NEXT: store <vscale x 2 x ptr> [[X:%.*]], ptr [[P:%.*]], align 16
-; CHECK-NEXT: [[LOAD:%.*]] = load <vscale x 2 x i64>, ptr [[P]], align 16
+; CHECK-NEXT: [[LOAD:%.*]] = ptrtoint <vscale x 2 x ptr> [[X]] to <vscale x 2 x i64>
; CHECK-NEXT: ret <vscale x 2 x i64> [[LOAD]]
;
store <vscale x 2 x ptr> %x, ptr %p
@@ -540,8 +541,7 @@ define <16 x i8> @load_v16i8_store_nxv4i32_forward_load(ptr %p, <vscale x 4 x i3
define <vscale x 16 x i8> @load_v16i8_store_v4i32_forward_constant(ptr %p) {
; CHECK-LABEL: @load_v16i8_store_v4i32_forward_constant(
; CHECK-NEXT: store <vscale x 4 x i32> splat (i32 4), ptr [[P:%.*]], align 16
-; CHECK-NEXT: [[LOAD:%.*]] = load <vscale x 16 x i8>, ptr [[P]], align 16
-; CHECK-NEXT: ret <vscale x 16 x i8> [[LOAD]]
+; CHECK-NEXT: ret <vscale x 16 x i8> bitcast (<vscale x 4 x i32> splat (i32 4) to <vscale x 16 x i8>)
;
store <vscale x 4 x i32> splat (i32 4), ptr %p
%load = load <vscale x 16 x i8>, ptr %p
@@ -590,13 +590,13 @@ define { <vscale x 16 x i8>, <vscale x 16 x i8>, <vscale x 16 x i8>, <vscale x 1
; CHECK-NEXT: [[REF_TMP_REPACK5:%.*]] = getelementptr inbounds i8, ptr [[REF_TMP]], i64 [[TMP5]]
; CHECK-NEXT: [[A_ELT6:%.*]] = extractvalue { <vscale x 4 x i32>, <vscale x 4 x i32>, <vscale x 4 x i32>, <vscale x 4 x i32> } [[A]], 3
; CHECK-NEXT: store <vscale x 4 x i32> [[A_ELT6]], ptr [[REF_TMP_REPACK5]], align 16
-; CHECK-NEXT: [[DOTUNPACK:%.*]] = load <vscale x 16 x i8>, ptr [[REF_TMP]], align 16
+; CHECK-NEXT: [[DOTUNPACK:%.*]] = bitcast <vscale x 4 x i32> [[A_ELT]] to <vscale x 16 x i8>
; CHECK-NEXT: [[TMP6:%.*]] = insertvalue { <vscale x 16 x i8>, <vscale x 16 x i8>, <vscale x 16 x i8>, <vscale x 16 x i8> } poison, <vscale x 16 x i8> [[DOTUNPACK]], 0
-; CHECK-NEXT: [[DOTUNPACK8:%.*]] = load <vscale x 16 x i8>, ptr [[REF_TMP_REPACK1]], align 16
+; CHECK-NEXT: [[DOTUNPACK8:%.*]] = bitcast <vscale x 4 x i32> [[A_ELT2]] to <vscale x 16 x i8>
; CHECK-NEXT: [[TMP9:%.*]] = insertvalue { <vscale x 16 x i8>, <vscale x 16 x i8>, <vscale x 16 x i8>, <vscale x 16 x i8> } [[TMP6]], <vscale x 16 x i8> [[DOTUNPACK8]], 1
-; CHECK-NEXT: [[DOTUNPACK10:%.*]] = load <vscale x 16 x i8>, ptr [[REF_TMP_REPACK3]], align 16
+; CHECK-NEXT: [[DOTUNPACK10:%.*]] = bitcast <vscale x 4 x i32> [[A_ELT4]] to <vscale x 16 x i8>
; CHECK-NEXT: [[TMP12:%.*]] = insertvalue { <vscale x 16 x i8>, <vscale x 16 x i8>, <vscale x 16 x i8>, <vscale x 16 x i8> } [[TMP9]], <vscale x 16 x i8> [[DOTUNPACK10]], 2
-; CHECK-NEXT: [[DOTUNPACK12:%.*]] = load <vscale x 16 x i8>, ptr [[REF_TMP_REPACK5]], align 16
+; CHECK-NEXT: [[DOTUNPACK12:%.*]] = bitcast <vscale x 4 x i32> [[A_ELT6]] to <vscale x 16 x i8>
; CHECK-NEXT: [[TMP15:%.*]] = insertvalue { <vscale x 16 x i8>, <vscale x 16 x i8>, <vscale x 16 x i8>, <vscale x 16 x i8> } [[TMP12]], <vscale x 16 x i8> [[DOTUNPACK12]], 3
; CHECK-NEXT: call void @llvm.lifetime.end.p0(i64 -1, ptr nonnull [[REF_TMP]])
; CHECK-NEXT: ret { <vscale x 16 x i8>, <vscale x 16 x i8>, <vscale x 16 x i8>, <vscale x 16 x i8> } [[TMP15]]
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