[llvm] [SimplifyCFG] Don't use a mask for lookup tables generated from switches with an unreachable default case (PR #94468)
via llvm-commits
llvm-commits at lists.llvm.org
Wed Jun 5 06:37:35 PDT 2024
llvmbot wrote:
<!--LLVM PR SUMMARY COMMENT-->
@llvm/pr-subscribers-llvm-transforms
Author: DaPorkchop_ (DaMatrix)
<details>
<summary>Changes</summary>
When transforming a switch with holes into a lookup table, we currently use a mask to check if the current index is handled by the switch or if it is a hole. If it is a hole, we skip loading from the lookup table. Normally, if the switch's default case is unreachable this has no impact, as the mask test gets optimized away by subsequent passes. However, if the switch is large enough that the number of lookup table entries exceeds the target's register width, we won't be able to fit all the cases into a mask and the switch won't get transformed into a lookup table. If we know that the switch's default case is unreachable, we know that the mask is unnecessary and can skip constructing it entirely, which allows us to transform the switch into a lookup table.
[Example](https://godbolt.org/z/7x7qfx8M1)
In the future, it might be interesting to consider allowing lookup table masks to be more than one register large (e.g. using a constant array of bit flags, similar to `std::bitset`).
---
Patch is 62.80 KiB, truncated to 20.00 KiB below, full version: https://github.com/llvm/llvm-project/pull/94468.diff
4 Files Affected:
- (modified) llvm/lib/Transforms/Utils/SimplifyCFG.cpp (+11-9)
- (modified) llvm/test/Transforms/SimplifyCFG/RISCV/switch-of-powers-of-two.ll (+31-35)
- (modified) llvm/test/Transforms/SimplifyCFG/X86/switch_to_lookup_table.ll (+73-31)
- (added) llvm/test/Transforms/SimplifyCFG/X86/switch_to_lookup_table_big.ll (+1506)
``````````diff
diff --git a/llvm/lib/Transforms/Utils/SimplifyCFG.cpp b/llvm/lib/Transforms/Utils/SimplifyCFG.cpp
index fe6ec8819ff99..1ad71b9a8838d 100644
--- a/llvm/lib/Transforms/Utils/SimplifyCFG.cpp
+++ b/llvm/lib/Transforms/Utils/SimplifyCFG.cpp
@@ -6743,8 +6743,15 @@ static bool SwitchToLookupTable(SwitchInst *SI, IRBuilder<> &Builder,
TableSize =
(MaxCaseVal->getValue() - MinCaseVal->getValue()).getLimitedValue() + 1;
+ // If the default destination is unreachable, or if the lookup table covers
+ // all values of the conditional variable, branch directly to the lookup table
+ // BB. Otherwise, check that the condition is within the case range.
+ bool DefaultIsReachable =
+ !isa<UnreachableInst>(SI->getDefaultDest()->getFirstNonPHIOrDbg());
+
bool TableHasHoles = (NumResults < TableSize);
- bool NeedMask = (TableHasHoles && !HasDefaultResults);
+ bool HolesHaveUndefinedResults = (TableHasHoles && !HasDefaultResults);
+ bool NeedMask = (HolesHaveUndefinedResults && DefaultIsReachable);
if (NeedMask) {
// As an extra penalty for the validity test we require more cases.
if (SI->getNumCases() < 4) // FIXME: Find best threshold value (benchmark).
@@ -6766,12 +6773,6 @@ static bool SwitchToLookupTable(SwitchInst *SI, IRBuilder<> &Builder,
"It is impossible for a switch to have more entries than the max "
"representable value of its input integer type's size.");
- // If the default destination is unreachable, or if the lookup table covers
- // all values of the conditional variable, branch directly to the lookup table
- // BB. Otherwise, check that the condition is within the case range.
- bool DefaultIsReachable =
- !isa<UnreachableInst>(SI->getDefaultDest()->getFirstNonPHIOrDbg());
-
// Create the BB that does the lookups.
Module &Mod = *CommonDest->getParent()->getParent();
BasicBlock *LookupBB = BasicBlock::Create(
@@ -6895,8 +6896,9 @@ static bool SwitchToLookupTable(SwitchInst *SI, IRBuilder<> &Builder,
for (PHINode *PHI : PHIs) {
const ResultListTy &ResultList = ResultLists[PHI];
- // If using a bitmask, use any value to fill the lookup table holes.
- Constant *DV = NeedMask ? ResultLists[PHI][0].second : DefaultResults[PHI];
+ // Use any value to fill the lookup table holes.
+ Constant *DV = HolesHaveUndefinedResults ? ResultLists[PHI][0].second
+ : DefaultResults[PHI];
StringRef FuncName = Fn->getName();
SwitchLookupTable Table(Mod, TableSize, TableIndexOffset, ResultList, DV,
DL, FuncName);
diff --git a/llvm/test/Transforms/SimplifyCFG/RISCV/switch-of-powers-of-two.ll b/llvm/test/Transforms/SimplifyCFG/RISCV/switch-of-powers-of-two.ll
index 893d1e0ff60b5..2ac94afd95910 100644
--- a/llvm/test/Transforms/SimplifyCFG/RISCV/switch-of-powers-of-two.ll
+++ b/llvm/test/Transforms/SimplifyCFG/RISCV/switch-of-powers-of-two.ll
@@ -11,11 +11,11 @@ define i32 @switch_of_powers(i32 %x) {
; RV64I-LABEL: @switch_of_powers(
; RV64I-NEXT: entry:
; RV64I-NEXT: switch i32 [[X:%.*]], label [[DEFAULT_CASE:%.*]] [
-; RV64I-NEXT: i32 1, label [[RETURN:%.*]]
-; RV64I-NEXT: i32 8, label [[BB2:%.*]]
-; RV64I-NEXT: i32 16, label [[BB3:%.*]]
-; RV64I-NEXT: i32 32, label [[BB4:%.*]]
-; RV64I-NEXT: i32 64, label [[BB5:%.*]]
+; RV64I-NEXT: i32 1, label [[RETURN:%.*]]
+; RV64I-NEXT: i32 8, label [[BB2:%.*]]
+; RV64I-NEXT: i32 16, label [[BB3:%.*]]
+; RV64I-NEXT: i32 32, label [[BB4:%.*]]
+; RV64I-NEXT: i32 64, label [[BB5:%.*]]
; RV64I-NEXT: ]
; RV64I: default_case:
; RV64I-NEXT: unreachable
@@ -34,10 +34,6 @@ 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_MASKINDEX:%.*]] = trunc i32 [[TMP0]] to i8
-; RV64ZBB-NEXT: [[SWITCH_SHIFTED:%.*]] = lshr i8 121, [[SWITCH_MASKINDEX]]
-; RV64ZBB-NEXT: [[SWITCH_LOBIT:%.*]] = trunc i8 [[SWITCH_SHIFTED]] to i1
-; RV64ZBB-NEXT: call void @llvm.assume(i1 [[SWITCH_LOBIT]])
; RV64ZBB-NEXT: [[SWITCH_GEP:%.*]] = getelementptr inbounds [7 x i32], ptr @switch.table.switch_of_powers, i32 0, i32 [[TMP0]]
; RV64ZBB-NEXT: [[SWITCH_LOAD:%.*]] = load i32, ptr [[SWITCH_GEP]], align 4
; RV64ZBB-NEXT: ret i32 [[SWITCH_LOAD]]
@@ -69,11 +65,11 @@ define i32 @switch_of_powers_reachable_default(i32 %x) {
; CHECK-LABEL: @switch_of_powers_reachable_default(
; CHECK-NEXT: entry:
; CHECK-NEXT: switch i32 [[X:%.*]], label [[RETURN:%.*]] [
-; CHECK-NEXT: i32 1, label [[BB1:%.*]]
-; CHECK-NEXT: i32 8, label [[BB2:%.*]]
-; CHECK-NEXT: i32 16, label [[BB3:%.*]]
-; CHECK-NEXT: i32 32, label [[BB4:%.*]]
-; CHECK-NEXT: i32 64, label [[BB5:%.*]]
+; CHECK-NEXT: i32 1, label [[BB1:%.*]]
+; CHECK-NEXT: i32 8, label [[BB2:%.*]]
+; CHECK-NEXT: i32 16, label [[BB3:%.*]]
+; CHECK-NEXT: i32 32, label [[BB4:%.*]]
+; CHECK-NEXT: i32 64, label [[BB5:%.*]]
; CHECK-NEXT: ]
; CHECK: bb1:
; CHECK-NEXT: br label [[RETURN]]
@@ -116,11 +112,11 @@ define i32 @switch_of_non_powers(i32 %x) {
; CHECK-LABEL: @switch_of_non_powers(
; CHECK-NEXT: entry:
; CHECK-NEXT: switch i32 [[X:%.*]], label [[DEFAULT_CASE:%.*]] [
-; CHECK-NEXT: i32 0, label [[RETURN:%.*]]
-; CHECK-NEXT: i32 1, label [[BB2:%.*]]
-; CHECK-NEXT: i32 16, label [[BB3:%.*]]
-; CHECK-NEXT: i32 32, label [[BB4:%.*]]
-; CHECK-NEXT: i32 64, label [[BB5:%.*]]
+; CHECK-NEXT: i32 0, label [[RETURN:%.*]]
+; CHECK-NEXT: i32 1, label [[BB2:%.*]]
+; CHECK-NEXT: i32 16, label [[BB3:%.*]]
+; CHECK-NEXT: i32 32, label [[BB4:%.*]]
+; CHECK-NEXT: i32 64, label [[BB5:%.*]]
; CHECK-NEXT: ]
; CHECK: default_case:
; CHECK-NEXT: unreachable
@@ -162,10 +158,10 @@ define i32 @unable_to_create_dense_switch(i32 %x) {
; CHECK-LABEL: @unable_to_create_dense_switch(
; CHECK-NEXT: entry:
; CHECK-NEXT: switch i32 [[X:%.*]], label [[DEFAULT_CASE:%.*]] [
-; CHECK-NEXT: i32 1, label [[RETURN:%.*]]
-; CHECK-NEXT: i32 2, label [[BB3:%.*]]
-; CHECK-NEXT: i32 4, label [[BB4:%.*]]
-; CHECK-NEXT: i32 4096, label [[BB5:%.*]]
+; CHECK-NEXT: i32 1, label [[RETURN:%.*]]
+; CHECK-NEXT: i32 2, label [[BB3:%.*]]
+; CHECK-NEXT: i32 4, label [[BB4:%.*]]
+; CHECK-NEXT: i32 4096, label [[BB5:%.*]]
; CHECK-NEXT: ]
; CHECK: default_case:
; CHECK-NEXT: unreachable
@@ -205,10 +201,10 @@ define i32 @unable_to_generate_lookup_table(i32 %x, i32 %y) {
; RV64I-LABEL: @unable_to_generate_lookup_table(
; RV64I-NEXT: entry:
; RV64I-NEXT: switch i32 [[Y:%.*]], label [[DEFAULT_CASE:%.*]] [
-; RV64I-NEXT: i32 1, label [[BB2:%.*]]
-; RV64I-NEXT: i32 2, label [[BB3:%.*]]
-; RV64I-NEXT: i32 8, label [[BB4:%.*]]
-; RV64I-NEXT: i32 64, label [[BB5:%.*]]
+; RV64I-NEXT: i32 1, label [[BB2:%.*]]
+; RV64I-NEXT: i32 2, label [[BB3:%.*]]
+; RV64I-NEXT: i32 8, label [[BB4:%.*]]
+; RV64I-NEXT: i32 64, label [[BB5:%.*]]
; RV64I-NEXT: ]
; RV64I: default_case:
; RV64I-NEXT: unreachable
@@ -239,10 +235,10 @@ define i32 @unable_to_generate_lookup_table(i32 %x, i32 %y) {
; RV64ZBB-NEXT: entry:
; RV64ZBB-NEXT: [[TMP0:%.*]] = call i32 @llvm.cttz.i32(i32 [[Y:%.*]], i1 true)
; RV64ZBB-NEXT: switch i32 [[TMP0]], label [[DEFAULT_CASE:%.*]] [
-; RV64ZBB-NEXT: i32 0, label [[BB2:%.*]]
-; RV64ZBB-NEXT: i32 1, label [[BB3:%.*]]
-; RV64ZBB-NEXT: i32 3, label [[BB4:%.*]]
-; RV64ZBB-NEXT: i32 6, label [[BB5:%.*]]
+; RV64ZBB-NEXT: i32 0, label [[BB2:%.*]]
+; RV64ZBB-NEXT: i32 1, label [[BB3:%.*]]
+; RV64ZBB-NEXT: i32 3, label [[BB4:%.*]]
+; RV64ZBB-NEXT: i32 6, label [[BB5:%.*]]
; RV64ZBB-NEXT: ]
; RV64ZBB: default_case:
; RV64ZBB-NEXT: unreachable
@@ -314,10 +310,10 @@ define i128 @switch_with_long_condition(i128 %x) {
; CHECK-LABEL: @switch_with_long_condition(
; CHECK-NEXT: entry:
; CHECK-NEXT: switch i128 [[X:%.*]], label [[DEFAULT_CASE:%.*]] [
-; CHECK-NEXT: i128 1, label [[RETURN:%.*]]
-; CHECK-NEXT: i128 2, label [[BB3:%.*]]
-; CHECK-NEXT: i128 4, label [[BB4:%.*]]
-; CHECK-NEXT: i128 32, label [[BB5:%.*]]
+; CHECK-NEXT: i128 1, label [[RETURN:%.*]]
+; CHECK-NEXT: i128 2, label [[BB3:%.*]]
+; CHECK-NEXT: i128 4, label [[BB4:%.*]]
+; CHECK-NEXT: i128 32, label [[BB5:%.*]]
; CHECK-NEXT: ]
; CHECK: default_case:
; CHECK-NEXT: unreachable
diff --git a/llvm/test/Transforms/SimplifyCFG/X86/switch_to_lookup_table.ll b/llvm/test/Transforms/SimplifyCFG/X86/switch_to_lookup_table.ll
index 9d6502072c16b..dae797068e409 100644
--- a/llvm/test/Transforms/SimplifyCFG/X86/switch_to_lookup_table.ll
+++ b/llvm/test/Transforms/SimplifyCFG/X86/switch_to_lookup_table.ll
@@ -308,10 +308,10 @@ define i32 @overflow(i32 %type) {
; CHECK-LABEL: @overflow(
; CHECK-NEXT: entry:
; CHECK-NEXT: switch i32 [[TYPE:%.*]], label [[IF_END:%.*]] [
-; CHECK-NEXT: i32 3, label [[SW_BB3:%.*]]
-; CHECK-NEXT: i32 -2147483645, label [[SW_BB3]]
-; CHECK-NEXT: i32 1, label [[SW_BB1:%.*]]
-; CHECK-NEXT: i32 2, label [[SW_BB2:%.*]]
+; CHECK-NEXT: i32 3, label [[SW_BB3:%.*]]
+; CHECK-NEXT: i32 -2147483645, label [[SW_BB3]]
+; CHECK-NEXT: i32 1, label [[SW_BB1:%.*]]
+; CHECK-NEXT: i32 2, label [[SW_BB2:%.*]]
; CHECK-NEXT: ]
; CHECK: sw.bb1:
; CHECK-NEXT: br label [[IF_END]]
@@ -931,11 +931,11 @@ define i96 @illegaltype(i32 %c) {
; CHECK-LABEL: @illegaltype(
; CHECK-NEXT: entry:
; CHECK-NEXT: switch i32 [[C:%.*]], label [[SW_DEFAULT:%.*]] [
-; CHECK-NEXT: i32 42, label [[RETURN:%.*]]
-; CHECK-NEXT: i32 43, label [[SW_BB1:%.*]]
-; CHECK-NEXT: i32 44, label [[SW_BB2:%.*]]
-; CHECK-NEXT: i32 45, label [[SW_BB3:%.*]]
-; CHECK-NEXT: i32 46, label [[SW_BB4:%.*]]
+; CHECK-NEXT: i32 42, label [[RETURN:%.*]]
+; CHECK-NEXT: i32 43, label [[SW_BB1:%.*]]
+; CHECK-NEXT: i32 44, label [[SW_BB2:%.*]]
+; CHECK-NEXT: i32 45, label [[SW_BB3:%.*]]
+; CHECK-NEXT: i32 46, label [[SW_BB4:%.*]]
; CHECK-NEXT: ]
; CHECK: sw.bb1:
; CHECK-NEXT: br label [[RETURN]]
@@ -1050,9 +1050,9 @@ define i32 @threecasesholes(i32 %c) {
; CHECK-LABEL: @threecasesholes(
; CHECK-NEXT: entry:
; CHECK-NEXT: switch i32 [[C:%.*]], label [[SW_DEFAULT:%.*]] [
-; CHECK-NEXT: i32 0, label [[RETURN:%.*]]
-; CHECK-NEXT: i32 1, label [[SW_BB1:%.*]]
-; CHECK-NEXT: i32 3, label [[SW_BB2:%.*]]
+; CHECK-NEXT: i32 0, label [[RETURN:%.*]]
+; CHECK-NEXT: i32 1, label [[SW_BB1:%.*]]
+; CHECK-NEXT: i32 3, label [[SW_BB2:%.*]]
; CHECK-NEXT: ]
; CHECK: sw.bb1:
; CHECK-NEXT: br label [[RETURN]]
@@ -1142,9 +1142,9 @@ define ptr @tls(i32 %x) {
; CHECK-LABEL: @tls(
; CHECK-NEXT: entry:
; CHECK-NEXT: switch i32 [[X:%.*]], label [[SW_DEFAULT:%.*]] [
-; CHECK-NEXT: i32 0, label [[RETURN:%.*]]
-; CHECK-NEXT: i32 1, label [[SW_BB1:%.*]]
-; CHECK-NEXT: i32 2, label [[SW_BB2:%.*]]
+; CHECK-NEXT: i32 0, label [[RETURN:%.*]]
+; CHECK-NEXT: i32 1, label [[SW_BB1:%.*]]
+; CHECK-NEXT: i32 2, label [[SW_BB2:%.*]]
; CHECK-NEXT: ]
; CHECK: sw.bb1:
; CHECK-NEXT: br label [[RETURN]]
@@ -1182,9 +1182,9 @@ define ptr @dllimport(i32 %x) {
; CHECK-LABEL: @dllimport(
; CHECK-NEXT: entry:
; CHECK-NEXT: switch i32 [[X:%.*]], label [[SW_DEFAULT:%.*]] [
-; CHECK-NEXT: i32 0, label [[RETURN:%.*]]
-; CHECK-NEXT: i32 1, label [[SW_BB1:%.*]]
-; CHECK-NEXT: i32 2, label [[SW_BB2:%.*]]
+; CHECK-NEXT: i32 0, label [[RETURN:%.*]]
+; CHECK-NEXT: i32 1, label [[SW_BB1:%.*]]
+; CHECK-NEXT: i32 2, label [[SW_BB2:%.*]]
; CHECK-NEXT: ]
; CHECK: sw.bb1:
; CHECK-NEXT: br label [[RETURN]]
@@ -1476,11 +1476,11 @@ define void @pr20210(i8 %x, i1 %y) {
; CHECK-NEXT: br i1 [[Y:%.*]], label [[SW:%.*]], label [[INTERMEDIATE:%.*]]
; CHECK: sw:
; CHECK-NEXT: switch i8 [[X:%.*]], label [[END:%.*]] [
-; CHECK-NEXT: i8 7, label [[INTERMEDIATE]]
-; CHECK-NEXT: i8 3, label [[INTERMEDIATE]]
-; CHECK-NEXT: i8 2, label [[INTERMEDIATE]]
-; CHECK-NEXT: i8 1, label [[INTERMEDIATE]]
-; CHECK-NEXT: i8 0, label [[INTERMEDIATE]]
+; CHECK-NEXT: i8 7, label [[INTERMEDIATE]]
+; CHECK-NEXT: i8 3, label [[INTERMEDIATE]]
+; CHECK-NEXT: i8 2, label [[INTERMEDIATE]]
+; CHECK-NEXT: i8 1, label [[INTERMEDIATE]]
+; CHECK-NEXT: i8 0, label [[INTERMEDIATE]]
; CHECK-NEXT: ]
; CHECK: intermediate:
; CHECK-NEXT: [[Z:%.*]] = zext i8 [[X]] to i32
@@ -1612,15 +1612,15 @@ define void @wineh_test(i64 %val) personality ptr @__CxxFrameHandler3 {
; CHECK-LABEL: @wineh_test(
; CHECK-NEXT: entry:
; CHECK-NEXT: invoke void @throw(i1 false)
-; CHECK-NEXT: to label [[UNREACHABLE:%.*]] unwind label [[CLEANUP1:%.*]]
+; CHECK-NEXT: to label [[UNREACHABLE:%.*]] unwind label [[CLEANUP1:%.*]]
; CHECK: unreachable:
; CHECK-NEXT: unreachable
; CHECK: cleanup1:
; CHECK-NEXT: [[CLEANUPPAD1:%.*]] = cleanuppad within none []
; CHECK-NEXT: switch i64 [[VAL:%.*]], label [[CLEANUPDONE2:%.*]] [
-; CHECK-NEXT: i64 0, label [[CLEANUPDONE1:%.*]]
-; CHECK-NEXT: i64 1, label [[CLEANUPDONE1]]
-; CHECK-NEXT: i64 6, label [[CLEANUPDONE1]]
+; CHECK-NEXT: i64 0, label [[CLEANUPDONE1:%.*]]
+; CHECK-NEXT: i64 1, label [[CLEANUPDONE1]]
+; CHECK-NEXT: i64 6, label [[CLEANUPDONE1]]
; CHECK-NEXT: ]
; CHECK: cleanupdone1:
; CHECK-NEXT: cleanupret from [[CLEANUPPAD1]] unwind label [[CLEANUP2:%.*]]
@@ -1732,12 +1732,53 @@ define i32 @signed_overflow2(i8 %n) {
; CHECK-LABEL: @signed_overflow2(
; CHECK-NEXT: start:
; CHECK-NEXT: [[TRUNC:%.*]] = trunc i8 [[N:%.*]] to i2
-; CHECK-NEXT: switch i2 [[TRUNC]], label [[BB1:%.*]] [
-; CHECK-NEXT: i2 1, label [[BB6:%.*]]
-; CHECK-NEXT: i2 -2, label [[BB4:%.*]]
-; CHECK-NEXT: i2 -1, label [[BB5:%.*]]
+; CHECK-NEXT: [[SWITCH_TABLEIDX:%.*]] = sub i2 [[TRUNC]], -2
+; CHECK-NEXT: [[SWITCH_TABLEIDX_ZEXT:%.*]] = zext i2 [[SWITCH_TABLEIDX]] to i3
+; CHECK-NEXT: [[SWITCH_GEP:%.*]] = getelementptr inbounds [4 x i32], ptr @switch.table.signed_overflow2, i32 0, i3 [[SWITCH_TABLEIDX_ZEXT]]
+; CHECK-NEXT: [[SWITCH_LOAD:%.*]] = load i32, ptr [[SWITCH_GEP]], align 4
+; CHECK-NEXT: ret i32 [[SWITCH_LOAD]]
+;
+start:
+ %trunc = trunc i8 %n to i2
+ switch i2 %trunc, label %bb1 [
+ i2 1, label %bb3
+ i2 -2, label %bb4
+ i2 -1, label %bb5
+ ]
+
+bb1: ; preds = %start
+ unreachable
+
+bb3: ; preds = %start
+ br label %bb6
+
+bb4: ; preds = %start
+ br label %bb6
+
+bb5: ; preds = %start
+ br label %bb6
+
+bb6: ; preds = %start, %bb3, %bb4, %bb5
+ %.sroa.0.0 = phi i32 [ 4444, %bb5 ], [ 3333, %bb4 ], [ 2222, %bb3 ]
+ ret i32 %.sroa.0.0
+}
+
+; This is the same as @signed_overflow2 except that the default case calls @exit(), so it
+; isn't treated as unreachable
+define i32 @signed_overflow3(i8 %n) {
+; CHECK-LABEL: @signed_overflow3(
+; CHECK-NEXT: start:
+; CHECK-NEXT: [[TRUNC:%.*]] = trunc i8 [[N:%.*]] to i2
+; CHECK-NEXT: switch i2 [[TRUNC]], label [[START_UNREACHABLEDEFAULT:%.*]] [
+; CHECK-NEXT: i2 1, label [[BB6:%.*]]
+; CHECK-NEXT: i2 -2, label [[BB4:%.*]]
+; CHECK-NEXT: i2 -1, label [[BB5:%.*]]
+; CHECK-NEXT: i2 0, label [[BB1:%.*]]
; CHECK-NEXT: ]
+; CHECK: start.unreachabledefault:
+; CHECK-NEXT: unreachable
; CHECK: bb1:
+; CHECK-NEXT: call void @exit(i32 1)
; CHECK-NEXT: unreachable
; CHECK: bb4:
; CHECK-NEXT: br label [[BB6]]
@@ -1756,6 +1797,7 @@ start:
]
bb1: ; preds = %start
+ call void @exit(i32 1)
unreachable
bb3: ; preds = %start
diff --git a/llvm/test/Transforms/SimplifyCFG/X86/switch_to_lookup_table_big.ll b/llvm/test/Transforms/SimplifyCFG/X86/switch_to_lookup_table_big.ll
new file mode 100644
index 0000000000000..349436bc4c1f1
--- /dev/null
+++ b/llvm/test/Transforms/SimplifyCFG/X86/switch_to_lookup_table_big.ll
@@ -0,0 +1,1506 @@
+; NOTE: Assertions have been autogenerated by utils/update_test_checks.py UTC_ARGS: --check-globals
+; RUN: opt < %s -passes=simplifycfg -switch-to-lookup=true -keep-loops=false -S -mtriple=x86_64-unknown-linux-gnu | FileCheck %s
+; RUN: opt < %s -passes='simplifycfg<no-keep-loops;switch-to-lookup>' -S -mtriple=x86_64-unknown-linux-gnu | FileCheck %s
+target datalayout = "e-p:64:64:64-i1:8:8-i32:8:8-i16:16:16-i32:32:32-i32:64:64-f32:32:32-f64:64:64-v64:64:64-v128:128:128-a0:0:64-s0:64:64-f80:128:128-n8:16:32:64-S128"
+target triple = "x86_64-unknown-linux-gnu"
+
+;.
+; CHECK: @switch.table.reachable_default_dense_0to63 = private unnamed_addr constant [64 x i32] [i32 0, i32 7, i32 6, i32 5, i32 4, i32 3, i32 2, i32 1, i32 0, i32 7, i32 6, i32 5, i32 4, i32 3, i32 2, i32 1, i32 0, i32 7, i32 6, i32 5, i32 4, i32 3, i32 2, i32 1, i32 0, i32 7, i32 6, i32 5, i32 4, i32 3, i32 2, i32 1, i32 0, i32 7, i32 6, i32 5, i32 4, i32 3, i32 2, i32 1, i32 0, i32 7, i32 6, i32 5, i32 4, i32 3, i32 2, i32 1, i32 0, i32 7, i32 6, i32 5, i32 4, i32 3, i32 2, i32 1, i32 0, i32 7, i32 6, i32 5, i32 4, i32 3, i32 2, i32 1], align 8
+; CHECK: @switch.table.unreachable_default_dense_0to63 = private unnamed_addr constant [64 x i32] [i32 0, i32 7, i32 6, i32 5, i32 4, i32 3, i32 2, i32 1, i32 0, i32 7, i32 6, i32 5, i32 4, i32 3, i32 2, i32 1, i32 0, i32 7, i32 6, i32 5, i32 4, i32 3, i32 2, i32 1, i32 0, i32 7, i32 6, i32 5, i32 4, i32 3, i32 2, i32 1, i32 0, i32 7, i32 6, i32 5, i32 4, i32 3, i32 2, i32 1, i32 0, i32 7, i32 6, i32 5, i32 4, i32 3, i32 2, i32 1, i32 0, i32 7, i32 6, i32 5, i32 4, i32 3, i32 2, i32 1, i32 0, i32 7, i32 6, i32 5, i32 4, i32 3, i32 2, i32 1], align 8
+; CHECK: @switch.table.reachable_default_holes_0to63 = private unnamed_addr constant [64 x i32] [i32 0, i32 7, i32 6, i32 0, i32 4, i32 3, i32 2, i32 1, i32 0, i32 7, i32 6, i32 5, i32 4, i32 0, i32 2, i32 1, i32 0, i32 7, i32 0, i32 5, i32 4, i32 3, i32 2, i32 0, i32 0, i32 7, i32 6, i32 5, i32 0, i32 3, i32 2, i32 1, i32 0, i32 0, i32 6, i32 5, i32 4, i32 3, i32 0, i32 1, i32 0, i32 7, i32 6, i32 0, i32 4, i32 3, i32 2, i32 1, i32 0, i32 7, i32 6, i32 5, i32 4, i32 0, i32 2, i32 1, i32 0, i32 7, i32 0, i32 5, i32 4, i32 3, i32 2, i32 1], align 8
+; CHECK: @switch.table.unreachable_default_holes_0to63 = private unnamed_addr constant [64 x i32] [i32 0, i32 7, i32 6, i32 0, i32 4, i32 3, i32 2, i32 1, i32 0, i32 7, i32 6, i32 5, i32 4, i32 0, i32 2, i32 1, i32 0, i32 7, i32 0, i32 5, i32 4, i32 3, i32 2, i32 0, i32 0, i32 7, i32 6, i32 5, i32 0, i32 3, i32 2, i32 1, i32 0, i32 0, i32 6, i32 5, i32 4, i32 3, i32 0, i32 1, i32 0, i32 7, i32 6, i32 0, i32 4, i32 3, i32 2, i32 1, i32 0, i32 7, i32 6, i32 5, i32 4, i32 0, i32 2, i32 1, i32 0, i32 7, i32 0, i32 5, i32 4, i32 3, i32 2, i32 1], align 8
+; CHECK: @switch.table.reachable_default_dense_0to64 = private unnamed_addr constant [65 x i32] [i32 0, i32 7, i32 6, i32 5, i32 4, i32 3, i32 2, i32 1, i32 0, i32 7, i32 6, i32 5, i32 4, i32 3, i32 2, i32 1, i32 0, i32 7, i32 6, i32 5, i32 4, i32 3, i32 2, i32 1, i32 0, i32 7, i32 6, i32 5, i32 4, i32 3, i32 2, i32 1, i32 0, i32 7, i32 6, i32 5, i32 4, i32 3, i32 2, i32 1, i32 0, i32 7, i32 6, i32 5, i32 4, i32 3, i32 2, i32 1, i32 0, i32 7, i32 6, i32 5, i32 4, i32 3, i32 2, i32 1, i32 0, i32 7, i32 6, i32 5, i32 4, i32 3, i32 2, i32 1, i32 0], align 8
+; CHECK: @switch.table.unreachable_default_dense_0to64 = private unnamed_addr constant [65 x i32] [i32 0, i32 7, i32 6, i32 5, i32 4, i32 3, i32 2, i32 1, i32 0, i32 7, i32 6, i32 5, i32 4, i32 3, i32 2, i32 1, i32 0, i32 7, i32 6, i32 5, i32 4, i32 3, i32 2, i32 1, i32 0, i32 7, i32 6, i32 5, i32 4, i32 3, i32 2, i32 1, i32 0, i32 7, i32 6, i32 5, i32 4, i32 3, i32 2, i32 1, i32 0, i32 7, i32 6, i32 5, i32 4, i32 3, i32 2, i32 1, i32 0, i32 7, i32 6, i32 5, i32 4, i32 3, i32 2, i32 1, i32 0, i32 7, i32 6, i32 5, i32 4, i32 3, i32 2, i32 1, i32 0], align 8
+; CHECK: @switch.table.unreachable_default_holes_0to64 = private unnamed_addr constant [65 x i32] ...
[truncated]
``````````
</details>
https://github.com/llvm/llvm-project/pull/94468
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