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Jun 28, 2025
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[SimplifyCFG] Use indexType from data layout in switch to table conversion #146207

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23 changes: 10 additions & 13 deletions llvm/lib/Transforms/Utils/SimplifyCFG.cpp
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Expand Up @@ -6347,7 +6347,7 @@ class SwitchLookupTable {

/// Build instructions with Builder to retrieve the value at
/// the position given by Index in the lookup table.
Value *buildLookup(Value *Index, IRBuilder<> &Builder);
Value *buildLookup(Value *Index, IRBuilder<> &Builder, const DataLayout &DL);

/// Return true if a table with TableSize elements of
/// type ElementType would fit in a target-legal register.
Expand Down Expand Up @@ -6533,7 +6533,8 @@ SwitchLookupTable::SwitchLookupTable(
Kind = ArrayKind;
}

Value *SwitchLookupTable::buildLookup(Value *Index, IRBuilder<> &Builder) {
Value *SwitchLookupTable::buildLookup(Value *Index, IRBuilder<> &Builder,
const DataLayout &DL) {
switch (Kind) {
case SingleValueKind:
return SingleValue;
Expand Down Expand Up @@ -6575,16 +6576,12 @@ Value *SwitchLookupTable::buildLookup(Value *Index, IRBuilder<> &Builder) {
return Builder.CreateTrunc(DownShifted, BitMapElementTy, "switch.masked");
}
case ArrayKind: {
// Make sure the table index will not overflow when treated as signed.
IntegerType *IT = cast<IntegerType>(Index->getType());
uint64_t TableSize =
Array->getInitializer()->getType()->getArrayNumElements();
if (TableSize > (1ULL << std::min(IT->getBitWidth() - 1, 63u)))
Index = Builder.CreateZExt(
Index, IntegerType::get(IT->getContext(), IT->getBitWidth() + 1),
"switch.tableidx.zext");

Value *GEPIndices[] = {Builder.getInt32(0), Index};
Type *IndexTy = DL.getIndexType(Array->getType());

if (Index->getType() != IndexTy)
Index = Builder.CreateZExtOrTrunc(Index, IndexTy);

Value *GEPIndices[] = {ConstantInt::get(IndexTy, 0), Index};
Value *GEP = Builder.CreateInBoundsGEP(Array->getValueType(), Array,
GEPIndices, "switch.gep");
return Builder.CreateLoad(
Expand Down Expand Up @@ -7064,7 +7061,7 @@ static bool switchToLookupTable(SwitchInst *SI, IRBuilder<> &Builder,
SwitchLookupTable Table(Mod, TableSize, TableIndexOffset, ResultList, DV,
DL, FuncName);

Value *Result = Table.buildLookup(TableIndex, Builder);
Value *Result = Table.buildLookup(TableIndex, Builder, DL);

// Do a small peephole optimization: re-use the switch table compare if
// possible.
Expand Down
3 changes: 2 additions & 1 deletion llvm/test/Transforms/SimplifyCFG/RISCV/switch-of-powers-of-two.ll
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Expand Up @@ -34,7 +34,8 @@ define i32 @switch_of_powers(i32 %x) {
; RV64ZBB-LABEL: @switch_of_powers(
; RV64ZBB-NEXT: entry:
; RV64ZBB-NEXT: [[TMP0:%.*]] = call i32 @llvm.cttz.i32(i32 [[X:%.*]], i1 true)
; RV64ZBB-NEXT: [[SWITCH_GEP:%.*]] = getelementptr inbounds [7 x i32], ptr @switch.table.switch_of_powers, i32 0, i32 [[TMP0]]
; RV64ZBB-NEXT: [[TMP1:%.*]] = zext i32 [[TMP0]] to i64
; RV64ZBB-NEXT: [[SWITCH_GEP:%.*]] = getelementptr inbounds [7 x i32], ptr @switch.table.switch_of_powers, i64 0, i64 [[TMP1]]
; RV64ZBB-NEXT: [[SWITCH_LOAD:%.*]] = load i32, ptr [[SWITCH_GEP]], align 4
; RV64ZBB-NEXT: ret i32 [[SWITCH_LOAD]]
;
Expand Down
12 changes: 8 additions & 4 deletions llvm/test/Transforms/SimplifyCFG/RISCV/switch_to_lookup_table-rv64.ll
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Expand Up @@ -27,7 +27,8 @@ define i32 @f(i32 %c) {
; CHECK-NEXT: [[TMP0:%.*]] = icmp ult i32 [[SWITCH_TABLEIDX]], 7
; CHECK-NEXT: br i1 [[TMP0]], label [[SWITCH_LOOKUP:%.*]], label [[RETURN:%.*]]
; CHECK: switch.lookup:
; CHECK-NEXT: [[SWITCH_GEP:%.*]] = getelementptr inbounds [7 x i32], ptr @switch.table.f, i32 0, i32 [[SWITCH_TABLEIDX]]
; CHECK-NEXT: [[TMP1:%.*]] = zext i32 [[SWITCH_TABLEIDX]] to i64
; CHECK-NEXT: [[SWITCH_GEP:%.*]] = getelementptr inbounds [7 x i32], ptr @switch.table.f, i64 0, i64 [[TMP1]]
; CHECK-NEXT: [[SWITCH_LOAD:%.*]] = load i32, ptr [[SWITCH_GEP]], align 4
; CHECK-NEXT: br label [[RETURN]]
; CHECK: return:
Expand Down Expand Up @@ -67,7 +68,8 @@ define i8 @char(i32 %c) {
; CHECK-NEXT: [[TMP0:%.*]] = icmp ult i32 [[SWITCH_TABLEIDX]], 9
; CHECK-NEXT: br i1 [[TMP0]], label [[SWITCH_LOOKUP:%.*]], label [[RETURN:%.*]]
; CHECK: switch.lookup:
; CHECK-NEXT: [[SWITCH_GEP:%.*]] = getelementptr inbounds [9 x i8], ptr @switch.table.char, i32 0, i32 [[SWITCH_TABLEIDX]]
; CHECK-NEXT: [[TMP1:%.*]] = zext i32 [[SWITCH_TABLEIDX]] to i64
; CHECK-NEXT: [[SWITCH_GEP:%.*]] = getelementptr inbounds [9 x i8], ptr @switch.table.char, i64 0, i64 [[TMP1]]
; CHECK-NEXT: [[SWITCH_LOAD:%.*]] = load i8, ptr [[SWITCH_GEP]], align 1
; CHECK-NEXT: br label [[RETURN]]
; CHECK: return:
Expand Down Expand Up @@ -114,7 +116,8 @@ define void @h(i32 %x) {
; CHECK-NEXT: [[SWITCH_SHIFTAMT:%.*]] = mul nuw nsw i32 [[X]], 8
; CHECK-NEXT: [[SWITCH_DOWNSHIFT:%.*]] = lshr i32 89655594, [[SWITCH_SHIFTAMT]]
; CHECK-NEXT: [[SWITCH_MASKED:%.*]] = trunc i32 [[SWITCH_DOWNSHIFT]] to i8
; CHECK-NEXT: [[SWITCH_GEP:%.*]] = getelementptr inbounds [4 x float], ptr @switch.table.h, i32 0, i32 [[X]]
; CHECK-NEXT: [[TMP1:%.*]] = zext i32 [[X]] to i64
; CHECK-NEXT: [[SWITCH_GEP:%.*]] = getelementptr inbounds [4 x float], ptr @switch.table.h, i64 0, i64 [[TMP1]]
; CHECK-NEXT: [[SWITCH_LOAD:%.*]] = load float, ptr [[SWITCH_GEP]], align 4
; CHECK-NEXT: br label [[SW_EPILOG]]
; CHECK: sw.epilog:
Expand Down Expand Up @@ -159,7 +162,8 @@ define ptr @foostring(i32 %x) {
; CHECK-NEXT: [[TMP0:%.*]] = icmp ult i32 [[X:%.*]], 4
; CHECK-NEXT: br i1 [[TMP0]], label [[SWITCH_LOOKUP:%.*]], label [[RETURN:%.*]]
; CHECK: switch.lookup:
; CHECK-NEXT: [[SWITCH_GEP:%.*]] = getelementptr inbounds [4 x ptr], ptr @switch.table.foostring, i32 0, i32 [[X]]
; CHECK-NEXT: [[TMP1:%.*]] = zext i32 [[X]] to i64
; CHECK-NEXT: [[SWITCH_GEP:%.*]] = getelementptr inbounds [4 x ptr], ptr @switch.table.foostring, i64 0, i64 [[TMP1]]
; CHECK-NEXT: [[SWITCH_LOAD:%.*]] = load ptr, ptr [[SWITCH_GEP]], align 8
; CHECK-NEXT: br label [[RETURN]]
; CHECK: return:
Expand Down
3 changes: 2 additions & 1 deletion llvm/test/Transforms/SimplifyCFG/X86/disable-lookup-table.ll
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Expand Up @@ -50,7 +50,8 @@ define i32 @bar(i32 %c) {
; CHECK-NEXT: [[TMP0:%.*]] = icmp ult i32 [[SWITCH_TABLEIDX]], 4
; CHECK-NEXT: br i1 [[TMP0]], label [[SWITCH_LOOKUP:%.*]], label [[RETURN:%.*]]
; CHECK: switch.lookup:
; CHECK-NEXT: [[SWITCH_GEP:%.*]] = getelementptr inbounds [4 x i32], ptr @switch.table.bar, i32 0, i32 [[SWITCH_TABLEIDX]]
; CHECK-NEXT: [[TMP1:%.*]] = zext i32 [[SWITCH_TABLEIDX]] to i64
; CHECK-NEXT: [[SWITCH_GEP:%.*]] = getelementptr inbounds [4 x i32], ptr @switch.table.bar, i64 0, i64 [[TMP1]]
; CHECK-NEXT: [[SWITCH_LOAD:%.*]] = load i32, ptr [[SWITCH_GEP]], align 4
; CHECK-NEXT: br label [[RETURN]]
; CHECK: return:
Expand Down
4 changes: 2 additions & 2 deletions llvm/test/Transforms/SimplifyCFG/X86/switch-covered-bug.ll
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Expand Up @@ -10,8 +10,8 @@ define i64 @test(i3 %arg) {
; CHECK-LABEL: @test(
; CHECK-NEXT: entry:
; CHECK-NEXT: [[SWITCH_TABLEIDX:%.*]] = sub i3 [[ARG:%.*]], -4
; CHECK-NEXT: [[SWITCH_TABLEIDX_ZEXT:%.*]] = zext i3 [[SWITCH_TABLEIDX]] to i4
; CHECK-NEXT: [[SWITCH_GEP:%.*]] = getelementptr inbounds [8 x i64], ptr @switch.table.test, i32 0, i4 [[SWITCH_TABLEIDX_ZEXT]]
; CHECK-NEXT: [[TMP0:%.*]] = zext i3 [[SWITCH_TABLEIDX]] to i64
; CHECK-NEXT: [[SWITCH_GEP:%.*]] = getelementptr inbounds [8 x i64], ptr @switch.table.test, i64 0, i64 [[TMP0]]
; CHECK-NEXT: [[SWITCH_LOAD:%.*]] = load i64, ptr [[SWITCH_GEP]], align 8
; CHECK-NEXT: [[V3:%.*]] = add i64 [[SWITCH_LOAD]], 0
; CHECK-NEXT: ret i64 [[V3]]
Expand Down
3 changes: 2 additions & 1 deletion llvm/test/Transforms/SimplifyCFG/X86/switch-of-powers-of-two.ll
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Expand Up @@ -8,7 +8,8 @@ define i32 @switch_of_powers_two(i32 %arg) {
; CHECK-SAME: i32 [[ARG:%.*]]) {
; CHECK-NEXT: [[ENTRY:.*:]]
; CHECK-NEXT: [[TMP0:%.*]] = call i32 @llvm.cttz.i32(i32 [[ARG]], i1 true)
; CHECK-NEXT: [[SWITCH_GEP:%.*]] = getelementptr inbounds [7 x i32], ptr @switch.table.switch_of_powers_two, i32 0, i32 [[TMP0]]
; CHECK-NEXT: [[TMP1:%.*]] = zext i32 [[TMP0]] to i64
; CHECK-NEXT: [[SWITCH_GEP:%.*]] = getelementptr inbounds [7 x i32], ptr @switch.table.switch_of_powers_two, i64 0, i64 [[TMP1]]
; CHECK-NEXT: [[SWITCH_LOAD:%.*]] = load i32, ptr [[SWITCH_GEP]], align 4
; CHECK-NEXT: ret i32 [[SWITCH_LOAD]]
;
Expand Down
4 changes: 2 additions & 2 deletions llvm/test/Transforms/SimplifyCFG/X86/switch-table-bug.ll
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Expand Up @@ -10,8 +10,8 @@ define i64 @_TFO6reduce1E5toRawfS0_FT_Si(i2) {
; CHECK-LABEL: @_TFO6reduce1E5toRawfS0_FT_Si(
; CHECK-NEXT: entry:
; CHECK-NEXT: [[SWITCH_TABLEIDX:%.*]] = sub i2 [[TMP0:%.*]], -2
; CHECK-NEXT: [[SWITCH_TABLEIDX_ZEXT:%.*]] = zext i2 [[SWITCH_TABLEIDX]] to i3
; CHECK-NEXT: [[SWITCH_GEP:%.*]] = getelementptr inbounds [4 x i64], ptr @switch.table._TFO6reduce1E5toRawfS0_FT_Si, i32 0, i3 [[SWITCH_TABLEIDX_ZEXT]]
; CHECK-NEXT: [[TMP1:%.*]] = zext i2 [[SWITCH_TABLEIDX]] to i64
; CHECK-NEXT: [[SWITCH_GEP:%.*]] = getelementptr inbounds [4 x i64], ptr @switch.table._TFO6reduce1E5toRawfS0_FT_Si, i64 0, i64 [[TMP1]]
; CHECK-NEXT: [[SWITCH_LOAD:%.*]] = load i64, ptr [[SWITCH_GEP]], align 8
; CHECK-NEXT: ret i64 [[SWITCH_LOAD]]
;
Expand Down
3 changes: 2 additions & 1 deletion llvm/test/Transforms/SimplifyCFG/X86/switch-to-lookup-bitcast.ll
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Expand Up @@ -9,7 +9,8 @@ target triple = "x86_64-unknown-linux-gnu"
define { ptr, i64 } @switch_to_lookup_bitcast(i8 %0) unnamed_addr {
; CHECK-LABEL: @switch_to_lookup_bitcast(
; CHECK-NEXT: start:
; CHECK-NEXT: [[SWITCH_GEP:%.*]] = getelementptr inbounds [3 x ptr], ptr @switch.table.switch_to_lookup_bitcast, i32 0, i8 [[TMP0:%.*]]
; CHECK-NEXT: [[TMP3:%.*]] = zext i8 [[TMP0:%.*]] to i64
; CHECK-NEXT: [[SWITCH_GEP:%.*]] = getelementptr inbounds [3 x ptr], ptr @switch.table.switch_to_lookup_bitcast, i64 0, i64 [[TMP3]]
; CHECK-NEXT: [[SWITCH_LOAD:%.*]] = load ptr, ptr [[SWITCH_GEP]], align 8
; CHECK-NEXT: [[TMP1:%.*]] = insertvalue { ptr, i64 } undef, ptr [[SWITCH_LOAD]], 0
; CHECK-NEXT: [[TMP2:%.*]] = insertvalue { ptr, i64 } [[TMP1]], i64 1, 1
Expand Down
3 changes: 2 additions & 1 deletion llvm/test/Transforms/SimplifyCFG/X86/switch-to-lookup-gep.ll
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Expand Up @@ -9,7 +9,8 @@ target triple = "x86_64-unknown-linux-gnu"
define { ptr, i64 } @switch_to_lookup_gep(i8 %0) unnamed_addr {
; CHECK-LABEL: @switch_to_lookup_gep(
; CHECK-NEXT: start:
; CHECK-NEXT: [[SWITCH_GEP:%.*]] = getelementptr inbounds [3 x ptr], ptr @switch.table.switch_to_lookup_gep, i32 0, i8 [[TMP0:%.*]]
; CHECK-NEXT: [[TMP3:%.*]] = zext i8 [[TMP0:%.*]] to i64
; CHECK-NEXT: [[SWITCH_GEP:%.*]] = getelementptr inbounds [3 x ptr], ptr @switch.table.switch_to_lookup_gep, i64 0, i64 [[TMP3]]
; CHECK-NEXT: [[SWITCH_LOAD:%.*]] = load ptr, ptr [[SWITCH_GEP]], align 8
; CHECK-NEXT: [[TMP1:%.*]] = insertvalue { ptr, i64 } undef, ptr [[SWITCH_LOAD]], 0
; CHECK-NEXT: [[TMP2:%.*]] = insertvalue { ptr, i64 } [[TMP1]], i64 1, 1
Expand Down
3 changes: 2 additions & 1 deletion llvm/test/Transforms/SimplifyCFG/X86/switch-to-lookup-globals.ll
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Expand Up @@ -13,7 +13,8 @@ define i1 @zot(i32 %arg) {
; CHECK-NEXT: %0 = icmp ult i32 %arg, 3
; CHECK-NEXT: br i1 %0, label %switch.lookup, label %bb6
; CHECK: switch.lookup:
; CHECK-NEXT: %switch.gep = getelementptr inbounds [3 x ptr], ptr @switch.table.zot, i32 0, i32 %arg
; CHECK-NEXT: %1 = zext i32 %arg to i64
; CHECK-NEXT: %switch.gep = getelementptr inbounds [3 x ptr], ptr @switch.table.zot, i64 0, i64 %1
; CHECK-NEXT: %switch.load = load ptr, ptr %switch.gep, align 8
; CHECK-NEXT: br label %bb6
; CHECK: bb6:
Expand Down
5 changes: 3 additions & 2 deletions llvm/test/Transforms/SimplifyCFG/X86/switch-to-lookup-large-types.ll
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Expand Up @@ -17,7 +17,7 @@ define i8 @switch_to_lookup_i64(i64 %x){
; CHECK-NEXT: [[COMMON_RET_OP:%.*]] = phi i8 [ [[SWITCH_LOAD:%.*]], [[SWITCH_LOOKUP]] ], [ 10, [[START:%.*]] ]
; CHECK-NEXT: ret i8 [[COMMON_RET_OP]]
; CHECK: switch.lookup:
; CHECK-NEXT: [[SWITCH_GEP:%.*]] = getelementptr inbounds [3 x i8], ptr @switch.table.switch_to_lookup_i64, i32 0, i64 [[X]]
; CHECK-NEXT: [[SWITCH_GEP:%.*]] = getelementptr inbounds [3 x i8], ptr @switch.table.switch_to_lookup_i64, i64 0, i64 [[X]]
; CHECK-NEXT: [[SWITCH_LOAD]] = load i8, ptr [[SWITCH_GEP]], align 1
; CHECK-NEXT: br label [[COMMON_RET]]
;
Expand Down Expand Up @@ -61,7 +61,8 @@ define i8 @switch_to_lookup_i128(i128 %x){
; CHECK-NEXT: [[COMMON_RET_OP:%.*]] = phi i8 [ [[SWITCH_LOAD:%.*]], [[SWITCH_LOOKUP]] ], [ 10, [[START:%.*]] ]
; CHECK-NEXT: ret i8 [[COMMON_RET_OP]]
; CHECK: switch.lookup:
; CHECK-NEXT: [[SWITCH_GEP:%.*]] = getelementptr inbounds [3 x i8], ptr @switch.table.switch_to_lookup_i128, i32 0, i128 [[X]]
; CHECK-NEXT: [[TMP1:%.*]] = trunc i128 [[X]] to i64
; CHECK-NEXT: [[SWITCH_GEP:%.*]] = getelementptr inbounds [3 x i8], ptr @switch.table.switch_to_lookup_i128, i64 0, i64 [[TMP1]]
; CHECK-NEXT: [[SWITCH_LOAD]] = load i8, ptr [[SWITCH_GEP]], align 1
; CHECK-NEXT: br label [[COMMON_RET]]
;
Expand Down
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