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[CodeGen] Fix the computation of the alignment of split stores. 

Summary:
Right now the alignment of the lower half of a store is computed as
align/2, which fails for unaligned stores (align = 1), and is overly
pessimitic for, e.g. a 8 byte store aligned to 4 bytes.
Fixes PR44851
Fixes PR44877

Reviewers: gchatelet, spatel, lebedev.ri

Subscribers: hiraditya, llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D74311
This commit is contained in:
Clement Courbet 2020-02-10 11:27:53 +01:00
parent 3bd33ccfdf
commit 15488ff24b
3 changed files with 74 additions and 8 deletions
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13
llvm/lib/CodeGen/CodeGenPrepare.cpp
View File

@ -6864,12 +6864,19 @@ static bool splitMergedValStore(StoreInst &SI, const DataLayout &DL,
Value *Addr = Builder.CreateBitCast(
SI.getOperand(1),
SplitStoreType->getPointerTo(SI.getPointerAddressSpace()));
if ((IsLE && Upper) || (!IsLE && !Upper))
const bool IsOffsetStore = (IsLE && Upper) || (!IsLE && !Upper);
if (IsOffsetStore)
Addr = Builder.CreateGEP(
SplitStoreType, Addr,
ConstantInt::get(Type::getInt32Ty(SI.getContext()), 1));
Builder.CreateAlignedStore(V, Addr,
Upper ? SI.getAlign() / 2 : SI.getAlign());
MaybeAlign Alignment = SI.getAlign();
if (IsOffsetStore && Alignment) {
// When splitting the store in half, naturally one half will retain the
// alignment of the original wider store, regardless of whether it was
// over-aligned or not, while the other will require adjustment.
Alignment = commonAlignment(Alignment, HalfValBitSize / 8);
}
Builder.CreateAlignedStore(V, Addr, Alignment);
};
CreateSplitStore(LValue, false);

44
llvm/test/Transforms/CodeGenPrepare/PowerPC/split-store-alignment.ll
View File

@ -2,6 +2,42 @@
; RUN: opt -S -codegenprepare -mtriple=powerpc64-unknown-linux-gnu -data-layout="E-m:e-i64:64-n32:64" -force-split-store < %s | FileCheck --check-prefixes=ALL,BE %s
; RUN: opt -S -codegenprepare -mtriple=powerpc64le-unknown-linux-gnu -data-layout="e-m:e-i64:64-n32:64" -force-split-store < %s | FileCheck --check-prefixes=ALL,LE %s
define void @split_store_align1(float %x, i64* %p) {
; BE-LABEL: @split_store_align1(
; BE-NEXT: [[B:%.*]] = bitcast float [[X:%.*]] to i32
; BE-NEXT: [[Z:%.*]] = zext i32 0 to i64
; BE-NEXT: [[S:%.*]] = shl nuw nsw i64 [[Z]], 32
; BE-NEXT: [[Z2:%.*]] = zext i32 [[B]] to i64
; BE-NEXT: [[O:%.*]] = or i64 [[S]], [[Z2]]
; BE-NEXT: [[TMP1:%.*]] = bitcast i64* [[P:%.*]] to i32*
; BE-NEXT: [[TMP2:%.*]] = getelementptr i32, i32* [[TMP1]], i32 1
; BE-NEXT: store i32 [[B]], i32* [[TMP2]], align 1
; BE-NEXT: [[TMP3:%.*]] = bitcast i64* [[P]] to i32*
; BE-NEXT: store i32 0, i32* [[TMP3]], align 1
; BE-NEXT: ret void
;
; LE-LABEL: @split_store_align1(
; LE-NEXT: [[B:%.*]] = bitcast float [[X:%.*]] to i32
; LE-NEXT: [[Z:%.*]] = zext i32 0 to i64
; LE-NEXT: [[S:%.*]] = shl nuw nsw i64 [[Z]], 32
; LE-NEXT: [[Z2:%.*]] = zext i32 [[B]] to i64
; LE-NEXT: [[O:%.*]] = or i64 [[S]], [[Z2]]
; LE-NEXT: [[TMP1:%.*]] = bitcast i64* [[P:%.*]] to i32*
; LE-NEXT: store i32 [[B]], i32* [[TMP1]], align 1
; LE-NEXT: [[TMP2:%.*]] = bitcast i64* [[P]] to i32*
; LE-NEXT: [[TMP3:%.*]] = getelementptr i32, i32* [[TMP2]], i32 1
; LE-NEXT: store i32 0, i32* [[TMP3]], align 1
; LE-NEXT: ret void
;
%b = bitcast float %x to i32
%z = zext i32 0 to i64
%s = shl nuw nsw i64 %z, 32
%z2 = zext i32 %b to i64
%o = or i64 %s, %z2
store i64 %o, i64* %p, align 1
ret void
}
define void @split_store_align2(float %x, i64* %p) {
; BE-LABEL: @split_store_align2(
; BE-NEXT: [[B:%.*]] = bitcast float [[X:%.*]] to i32
@ -13,7 +49,7 @@ define void @split_store_align2(float %x, i64* %p) {
; BE-NEXT: [[TMP2:%.*]] = getelementptr i32, i32* [[TMP1]], i32 1
; BE-NEXT: store i32 [[B]], i32* [[TMP2]], align 2
; BE-NEXT: [[TMP3:%.*]] = bitcast i64* [[P]] to i32*
; BE-NEXT: store i32 0, i32* [[TMP3]], align 1
; BE-NEXT: store i32 0, i32* [[TMP3]], align 2
; BE-NEXT: ret void
;
; LE-LABEL: @split_store_align2(
@ -26,7 +62,7 @@ define void @split_store_align2(float %x, i64* %p) {
; LE-NEXT: store i32 [[B]], i32* [[TMP1]], align 2
; LE-NEXT: [[TMP2:%.*]] = bitcast i64* [[P]] to i32*
; LE-NEXT: [[TMP3:%.*]] = getelementptr i32, i32* [[TMP2]], i32 1
; LE-NEXT: store i32 0, i32* [[TMP3]], align 1
; LE-NEXT: store i32 0, i32* [[TMP3]], align 2
; LE-NEXT: ret void
;
%b = bitcast float %x to i32
@ -47,9 +83,9 @@ define void @split_store_align8(float %x, i64* %p) {
; BE-NEXT: [[O:%.*]] = or i64 [[S]], [[Z2]]
; BE-NEXT: [[TMP1:%.*]] = bitcast i64* [[P:%.*]] to i32*
; BE-NEXT: [[TMP2:%.*]] = getelementptr i32, i32* [[TMP1]], i32 1
; BE-NEXT: store i32 [[B]], i32* [[TMP2]], align 8
; BE-NEXT: store i32 [[B]], i32* [[TMP2]], align 4
; BE-NEXT: [[TMP3:%.*]] = bitcast i64* [[P]] to i32*
; BE-NEXT: store i32 0, i32* [[TMP3]], align 4
; BE-NEXT: store i32 0, i32* [[TMP3]], align 8
; BE-NEXT: ret void
;
; LE-LABEL: @split_store_align8(

25
llvm/test/Transforms/CodeGenPrepare/X86/split-store-alignment.ll
View File

@ -4,6 +4,29 @@
target datalayout = "e-m:x-p:32:32-p270:32:32-p271:32:32-p272:64:64-i64:64-f80:32-n8:16:32-a:0:32-S32"
target triple = "i686-w64-windows-gnu"
define void @split_store_align1(float %x, i64* %p) {
; CHECK-LABEL: @split_store_align1(
; CHECK-NEXT: [[B:%.*]] = bitcast float [[X:%.*]] to i32
; CHECK-NEXT: [[Z:%.*]] = zext i32 0 to i64
; CHECK-NEXT: [[S:%.*]] = shl nuw nsw i64 [[Z]], 32
; CHECK-NEXT: [[Z2:%.*]] = zext i32 [[B]] to i64
; CHECK-NEXT: [[O:%.*]] = or i64 [[S]], [[Z2]]
; CHECK-NEXT: [[TMP1:%.*]] = bitcast i64* [[P:%.*]] to i32*
; CHECK-NEXT: store i32 [[B]], i32* [[TMP1]], align 1
; CHECK-NEXT: [[TMP2:%.*]] = bitcast i64* [[P]] to i32*
; CHECK-NEXT: [[TMP3:%.*]] = getelementptr i32, i32* [[TMP2]], i32 1
; CHECK-NEXT: store i32 0, i32* [[TMP3]], align 1
; CHECK-NEXT: ret void
;
%b = bitcast float %x to i32
%z = zext i32 0 to i64
%s = shl nuw nsw i64 %z, 32
%z2 = zext i32 %b to i64
%o = or i64 %s, %z2
store i64 %o, i64* %p, align 1
ret void
}
define void @split_store_align2(float %x, i64* %p) {
; CHECK-LABEL: @split_store_align2(
; CHECK-NEXT: [[B:%.*]] = bitcast float [[X:%.*]] to i32
@ -15,7 +38,7 @@ define void @split_store_align2(float %x, i64* %p) {
; CHECK-NEXT: store i32 [[B]], i32* [[TMP1]], align 2
; CHECK-NEXT: [[TMP2:%.*]] = bitcast i64* [[P]] to i32*
; CHECK-NEXT: [[TMP3:%.*]] = getelementptr i32, i32* [[TMP2]], i32 1
; CHECK-NEXT: store i32 0, i32* [[TMP3]], align 1
; CHECK-NEXT: store i32 0, i32* [[TMP3]], align 2
; CHECK-NEXT: ret void
;
%b = bitcast float %x to i32