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[AggressiveInstCombine] Use APInt and avoid truncation when folding l…
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…oads

A miscompilation issue has been addressed with improved handling.

Fixes: llvm#118467.
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@antoniofrighetto
antoniofrighetto committed Dec 4, 2024
1 parent 73731d6 commit f68b0e3
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Showing 3 changed files with 53 additions and 22 deletions.
3 changes: 1 addition & 2 deletions llvm/lib/Transforms/AggressiveInstCombine/AggressiveInstCombine.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -803,8 +803,7 @@ static bool foldConsecutiveLoads(Instruction &I, const DataLayout &DL,
APInt Offset1(DL.getIndexTypeSizeInBits(Load1Ptr->getType()), 0);
Load1Ptr = Load1Ptr->stripAndAccumulateConstantOffsets(
DL, Offset1, /* AllowNonInbounds */ true);
Load1Ptr = Builder.CreatePtrAdd(Load1Ptr,
Builder.getInt32(Offset1.getZExtValue()));
Load1Ptr = Builder.CreatePtrAdd(Load1Ptr, Builder.getInt(Offset1));
}
// Generate wider load.
NewLoad = Builder.CreateAlignedLoad(WiderType, Load1Ptr, LI1->getAlign(),
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20 changes: 10 additions & 10 deletions llvm/test/Transforms/AggressiveInstCombine/AArch64/or-load.ll
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Original file line number Diff line number Diff line change
Expand Up @@ -1121,19 +1121,19 @@ entry:

define i32 @loadCombine_4consecutive_metadata(ptr %p, ptr %pstr) {
; LE-LABEL: @loadCombine_4consecutive_metadata(
; LE-NEXT: [[L1:%.*]] = load i32, ptr [[P:%.*]], align 1, !alias.scope !0
; LE-NEXT: store i32 25, ptr [[PSTR:%.*]], align 4, !noalias !0
; LE-NEXT: [[L1:%.*]] = load i32, ptr [[P:%.*]], align 1, !alias.scope [[META0:![0-9]+]]
; LE-NEXT: store i32 25, ptr [[PSTR:%.*]], align 4, !noalias [[META0]]
; LE-NEXT: ret i32 [[L1]]
;
; BE-LABEL: @loadCombine_4consecutive_metadata(
; BE-NEXT: [[P1:%.*]] = getelementptr i8, ptr [[P:%.*]], i32 1
; BE-NEXT: [[P2:%.*]] = getelementptr i8, ptr [[P]], i32 2
; BE-NEXT: [[P3:%.*]] = getelementptr i8, ptr [[P]], i32 3
; BE-NEXT: [[L1:%.*]] = load i8, ptr [[P]], align 1, !alias.scope !0
; BE-NEXT: [[L2:%.*]] = load i8, ptr [[P1]], align 1, !alias.scope !0
; BE-NEXT: [[L3:%.*]] = load i8, ptr [[P2]], align 1, !alias.scope !0
; BE-NEXT: [[L4:%.*]] = load i8, ptr [[P3]], align 1, !alias.scope !0
; BE-NEXT: store i32 25, ptr [[PSTR:%.*]], align 4, !noalias !0
; BE-NEXT: [[L1:%.*]] = load i8, ptr [[P]], align 1, !alias.scope [[META0:![0-9]+]]
; BE-NEXT: [[L2:%.*]] = load i8, ptr [[P1]], align 1, !alias.scope [[META0]]
; BE-NEXT: [[L3:%.*]] = load i8, ptr [[P2]], align 1, !alias.scope [[META0]]
; BE-NEXT: [[L4:%.*]] = load i8, ptr [[P3]], align 1, !alias.scope [[META0]]
; BE-NEXT: store i32 25, ptr [[PSTR:%.*]], align 4, !noalias [[META0]]
; BE-NEXT: [[E1:%.*]] = zext i8 [[L1]] to i32
; BE-NEXT: [[E2:%.*]] = zext i8 [[L2]] to i32
; BE-NEXT: [[E3:%.*]] = zext i8 [[L3]] to i32
Expand Down Expand Up @@ -1869,7 +1869,7 @@ define i32 @loadCombine_4consecutive_badinsert2(ptr %p) {

define i32 @loadCombine_4consecutive_badinsert3(ptr %p) {
; LE-LABEL: @loadCombine_4consecutive_badinsert3(
; LE-NEXT: [[TMP1:%.*]] = getelementptr i8, ptr [[P:%.*]], i32 1
; LE-NEXT: [[TMP1:%.*]] = getelementptr i8, ptr [[P:%.*]], i64 1
; LE-NEXT: [[L1:%.*]] = load i32, ptr [[TMP1]], align 1
; LE-NEXT: ret i32 [[L1]]
;
Expand Down Expand Up @@ -2088,7 +2088,7 @@ define i32 @loadCombine_4consecutive_badinsert6(ptr %p) {

define void @nested_gep(ptr %p, ptr %dest) {
; LE-LABEL: @nested_gep(
; LE-NEXT: [[TMP1:%.*]] = getelementptr i8, ptr [[P:%.*]], i32 68
; LE-NEXT: [[TMP1:%.*]] = getelementptr i8, ptr [[P:%.*]], i64 68
; LE-NEXT: [[LD2:%.*]] = load i64, ptr [[TMP1]], align 4
; LE-NEXT: [[TRUNC:%.*]] = trunc i64 [[LD2]] to i32
; LE-NEXT: store i32 [[TRUNC]], ptr [[DEST:%.*]], align 4
Expand Down Expand Up @@ -2128,7 +2128,7 @@ define void @nested_gep(ptr %p, ptr %dest) {

define void @bitcast_gep(ptr %p, ptr %dest) {
; LE-LABEL: @bitcast_gep(
; LE-NEXT: [[TMP1:%.*]] = getelementptr i8, ptr [[P:%.*]], i32 68
; LE-NEXT: [[TMP1:%.*]] = getelementptr i8, ptr [[P:%.*]], i64 68
; LE-NEXT: [[LD2:%.*]] = load i64, ptr [[TMP1]], align 4
; LE-NEXT: [[TRUNC:%.*]] = trunc i64 [[LD2]] to i32
; LE-NEXT: store i32 [[TRUNC]], ptr [[DEST:%.*]], align 4
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52 changes: 42 additions & 10 deletions llvm/test/Transforms/AggressiveInstCombine/X86/or-load.ll
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Original file line number Diff line number Diff line change
Expand Up @@ -1205,19 +1205,19 @@ entry:

define i32 @loadCombine_4consecutive_metadata(ptr %p, ptr %pstr) {
; LE-LABEL: @loadCombine_4consecutive_metadata(
; LE-NEXT: [[L1:%.*]] = load i32, ptr [[P:%.*]], align 1, !alias.scope !0
; LE-NEXT: store i32 25, ptr [[PSTR:%.*]], align 4, !noalias !0
; LE-NEXT: [[L1:%.*]] = load i32, ptr [[P:%.*]], align 1, !alias.scope [[META0:![0-9]+]]
; LE-NEXT: store i32 25, ptr [[PSTR:%.*]], align 4, !noalias [[META0]]
; LE-NEXT: ret i32 [[L1]]
;
; BE-LABEL: @loadCombine_4consecutive_metadata(
; BE-NEXT: [[P1:%.*]] = getelementptr i8, ptr [[P:%.*]], i32 1
; BE-NEXT: [[P2:%.*]] = getelementptr i8, ptr [[P]], i32 2
; BE-NEXT: [[P3:%.*]] = getelementptr i8, ptr [[P]], i32 3
; BE-NEXT: [[L1:%.*]] = load i8, ptr [[P]], align 1, !alias.scope !0
; BE-NEXT: [[L2:%.*]] = load i8, ptr [[P1]], align 1, !alias.scope !0
; BE-NEXT: [[L3:%.*]] = load i8, ptr [[P2]], align 1, !alias.scope !0
; BE-NEXT: [[L4:%.*]] = load i8, ptr [[P3]], align 1, !alias.scope !0
; BE-NEXT: store i32 25, ptr [[PSTR:%.*]], align 4, !noalias !0
; BE-NEXT: [[L1:%.*]] = load i8, ptr [[P]], align 1, !alias.scope [[META0:![0-9]+]]
; BE-NEXT: [[L2:%.*]] = load i8, ptr [[P1]], align 1, !alias.scope [[META0]]
; BE-NEXT: [[L3:%.*]] = load i8, ptr [[P2]], align 1, !alias.scope [[META0]]
; BE-NEXT: [[L4:%.*]] = load i8, ptr [[P3]], align 1, !alias.scope [[META0]]
; BE-NEXT: store i32 25, ptr [[PSTR:%.*]], align 4, !noalias [[META0]]
; BE-NEXT: [[E1:%.*]] = zext i8 [[L1]] to i32
; BE-NEXT: [[E2:%.*]] = zext i8 [[L2]] to i32
; BE-NEXT: [[E3:%.*]] = zext i8 [[L3]] to i32
Expand Down Expand Up @@ -2005,7 +2005,7 @@ define i32 @loadCombine_4consecutive_badinsert2(ptr %p) {

define i32 @loadCombine_4consecutive_badinsert3(ptr %p) {
; LE-LABEL: @loadCombine_4consecutive_badinsert3(
; LE-NEXT: [[TMP1:%.*]] = getelementptr i8, ptr [[P:%.*]], i32 1
; LE-NEXT: [[TMP1:%.*]] = getelementptr i8, ptr [[P:%.*]], i64 1
; LE-NEXT: [[L1:%.*]] = load i32, ptr [[TMP1]], align 1
; LE-NEXT: ret i32 [[L1]]
;
Expand Down Expand Up @@ -2306,7 +2306,7 @@ define i64 @loadCombine_nonConstShift2(ptr %arg, i8 %b) {

define void @nested_gep(ptr %p, ptr %dest) {
; LE-LABEL: @nested_gep(
; LE-NEXT: [[TMP1:%.*]] = getelementptr i8, ptr [[P:%.*]], i32 68
; LE-NEXT: [[TMP1:%.*]] = getelementptr i8, ptr [[P:%.*]], i64 68
; LE-NEXT: [[LD2:%.*]] = load i64, ptr [[TMP1]], align 4
; LE-NEXT: [[TRUNC:%.*]] = trunc i64 [[LD2]] to i32
; LE-NEXT: store i32 [[TRUNC]], ptr [[DEST:%.*]], align 4
Expand Down Expand Up @@ -2346,7 +2346,7 @@ define void @nested_gep(ptr %p, ptr %dest) {

define void @bitcast_gep(ptr %p, ptr %dest) {
; LE-LABEL: @bitcast_gep(
; LE-NEXT: [[TMP1:%.*]] = getelementptr i8, ptr [[P:%.*]], i32 68
; LE-NEXT: [[TMP1:%.*]] = getelementptr i8, ptr [[P:%.*]], i64 68
; LE-NEXT: [[LD2:%.*]] = load i64, ptr [[TMP1]], align 4
; LE-NEXT: [[TRUNC:%.*]] = trunc i64 [[LD2]] to i32
; LE-NEXT: store i32 [[TRUNC]], ptr [[DEST:%.*]], align 4
Expand Down Expand Up @@ -2382,3 +2382,35 @@ define void @bitcast_gep(ptr %p, ptr %dest) {
store i32 %trunc, ptr %dest, align 4
ret void
}

define i32 @loadcombine_consecutive_idx_64(ptr %data) {
; LE-LABEL: @loadcombine_consecutive_idx_64(
; LE-NEXT: entry:
; LE-NEXT: [[TMP0:%.*]] = getelementptr i8, ptr [[DATA:%.*]], i64 2149675576
; LE-NEXT: [[VAL_2:%.*]] = load i16, ptr [[TMP0]], align 1
; LE-NEXT: [[TMP1:%.*]] = zext i16 [[VAL_2]] to i32
; LE-NEXT: ret i32 [[TMP1]]
;
; BE-LABEL: @loadcombine_consecutive_idx_64(
; BE-NEXT: entry:
; BE-NEXT: [[ARRAYIDX:%.*]] = getelementptr inbounds nuw i8, ptr [[DATA:%.*]], i64 2149675577
; BE-NEXT: [[VAL:%.*]] = load i8, ptr [[ARRAYIDX]], align 1
; BE-NEXT: [[CONV:%.*]] = zext i8 [[VAL]] to i32
; BE-NEXT: [[ARRAYIDX_2:%.*]] = getelementptr inbounds nuw i8, ptr [[DATA]], i64 2149675576
; BE-NEXT: [[VAL_2:%.*]] = load i8, ptr [[ARRAYIDX_2]], align 1
; BE-NEXT: [[CONV_2:%.*]] = zext i8 [[VAL_2]] to i32
; BE-NEXT: [[SHL:%.*]] = shl nuw nsw i32 [[CONV]], 8
; BE-NEXT: [[OR:%.*]] = or disjoint i32 [[SHL]], [[CONV_2]]
; BE-NEXT: ret i32 [[OR]]
;
entry:
%arrayidx = getelementptr inbounds nuw i8, ptr %data, i64 2149675577
%val = load i8, ptr %arrayidx, align 1
%conv = zext i8 %val to i32
%arrayidx.2 = getelementptr inbounds nuw i8, ptr %data, i64 2149675576
%val.2 = load i8, ptr %arrayidx.2, align 1
%conv.2 = zext i8 %val.2 to i32
%shl = shl nuw nsw i32 %conv, 8
%or = or disjoint i32 %shl, %conv.2
ret i32 %or
}

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