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[SimplifyCFG] Handle trunc condition in foldBranchToCommonDest. #135490

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Merged
merged 1 commit into from
Apr 13, 2025
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[SimplifyCFG] Handle trunc condition in foldBranchToCommonDest. #135490

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4 changes: 1 addition & 3 deletions llvm/lib/Transforms/Utils/SimplifyCFG.cpp
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Expand Up @@ -4087,9 +4087,7 @@ bool llvm::foldBranchToCommonDest(BranchInst *BI, DomTreeUpdater *DTU,

Instruction *Cond = dyn_cast<Instruction>(BI->getCondition());

if (!Cond ||
(!isa<CmpInst>(Cond) && !isa<BinaryOperator>(Cond) &&
!isa<SelectInst>(Cond)) ||
if (!Cond || !isa<CmpInst, BinaryOperator, SelectInst, TruncInst>(Cond) ||
Cond->getParent() != BB || !Cond->hasOneUse())
return false;

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11 changes: 5 additions & 6 deletions llvm/test/Transforms/SimplifyCFG/X86/switch_to_lookup_table.ll
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Expand Up @@ -1028,15 +1028,14 @@ define i32 @nodefaultwithholes(i32 %c) {
; CHECK-LABEL: @nodefaultwithholes(
; CHECK-NEXT: entry:
; CHECK-NEXT: [[TMP0:%.*]] = icmp ult i32 [[C:%.*]], 6
; CHECK-NEXT: br i1 [[TMP0]], label [[SWITCH_HOLE_CHECK:%.*]], label [[SW_DEFAULT:%.*]]
; CHECK: sw.default:
; CHECK-NEXT: call void @exit(i32 1)
; CHECK-NEXT: unreachable
; CHECK: switch.hole_check:
; CHECK-NEXT: [[SWITCH_MASKINDEX:%.*]] = trunc i32 [[C]] to i8
; CHECK-NEXT: [[SWITCH_SHIFTED:%.*]] = lshr i8 47, [[SWITCH_MASKINDEX]]
; CHECK-NEXT: [[SWITCH_LOBIT:%.*]] = trunc i8 [[SWITCH_SHIFTED]] to i1
; CHECK-NEXT: br i1 [[SWITCH_LOBIT]], label [[SWITCH_LOOKUP:%.*]], label [[SW_DEFAULT]]
; CHECK-NEXT: [[OR_COND:%.*]] = select i1 [[TMP0]], i1 [[SWITCH_LOBIT]], i1 false
; CHECK-NEXT: br i1 [[OR_COND]], label [[SWITCH_LOOKUP:%.*]], label [[SW_DEFAULT:%.*]]
; CHECK: sw.default:
; CHECK-NEXT: call void @exit(i32 1)
; CHECK-NEXT: unreachable
; CHECK: switch.lookup:
; CHECK-NEXT: [[SWITCH_GEP:%.*]] = getelementptr inbounds [6 x i32], ptr @switch.table.nodefaultwithholes, i32 0, i32 [[C]]
; CHECK-NEXT: [[SWITCH_LOAD:%.*]] = load i32, ptr [[SWITCH_GEP]], align 4
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7 changes: 3 additions & 4 deletions llvm/test/Transforms/SimplifyCFG/X86/switch_to_lookup_table_big.ll
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Expand Up @@ -143,17 +143,16 @@ define i32 @reachable_default_holes_0to31(i32 %x, i32 %y) {
; CHECK-LABEL: @reachable_default_holes_0to31(
; CHECK-NEXT: entry:
; CHECK-NEXT: [[TMP0:%.*]] = icmp ult i32 [[X:%.*]], 32
; CHECK-NEXT: br i1 [[TMP0]], label [[SWITCH_HOLE_CHECK:%.*]], label [[RETURN:%.*]]
; CHECK: switch.hole_check:
; CHECK-NEXT: [[SWITCH_SHIFTED:%.*]] = lshr i32 -277094665, [[X]]
; CHECK-NEXT: [[SWITCH_LOBIT:%.*]] = trunc i32 [[SWITCH_SHIFTED]] to i1
; CHECK-NEXT: br i1 [[SWITCH_LOBIT]], label [[SWITCH_LOOKUP:%.*]], label [[RETURN]]
; CHECK-NEXT: [[OR_COND:%.*]] = select i1 [[TMP0]], i1 [[SWITCH_LOBIT]], i1 false
; CHECK-NEXT: br i1 [[OR_COND]], label [[SWITCH_LOOKUP:%.*]], label [[RETURN:%.*]]
; CHECK: switch.lookup:
; CHECK-NEXT: [[SWITCH_GEP:%.*]] = getelementptr inbounds [32 x i32], ptr @switch.table.reachable_default_holes_0to31, i32 0, i32 [[X]]
; CHECK-NEXT: [[SWITCH_LOAD:%.*]] = load i32, ptr [[SWITCH_GEP]], align 4
; CHECK-NEXT: br label [[RETURN]]
; CHECK: return:
; CHECK-NEXT: [[RES:%.*]] = phi i32 [ [[SWITCH_LOAD]], [[SWITCH_LOOKUP]] ], [ [[Y:%.*]], [[SWITCH_HOLE_CHECK]] ], [ [[Y]], [[ENTRY:%.*]] ]
; CHECK-NEXT: [[RES:%.*]] = phi i32 [ [[SWITCH_LOAD]], [[SWITCH_LOOKUP]] ], [ [[Y:%.*]], [[ENTRY:%.*]] ]
; CHECK-NEXT: ret i32 [[RES]]
;
entry:
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5 changes: 2 additions & 3 deletions llvm/test/Transforms/SimplifyCFG/fold-branch-to-common-dest.ll
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Expand Up @@ -88,10 +88,9 @@ define void @one_pred_trunc_cond(i8 %v0, i8 %v1) {
; CHECK-LABEL: @one_pred_trunc_cond(
; CHECK-NEXT: pred:
; CHECK-NEXT: [[C0:%.*]] = icmp eq i8 [[V0:%.*]], 0
; CHECK-NEXT: br i1 [[C0]], label [[DISPATCH:%.*]], label [[FINAL_RIGHT:%.*]]
; CHECK: dispatch:
; CHECK-NEXT: [[C1:%.*]] = trunc i8 [[V1:%.*]] to i1
; CHECK-NEXT: br i1 [[C1]], label [[FINAL_LEFT:%.*]], label [[FINAL_RIGHT]]
; CHECK-NEXT: [[OR_COND:%.*]] = select i1 [[C0]], i1 [[C1]], i1 false
; CHECK-NEXT: br i1 [[OR_COND]], label [[FINAL_LEFT:%.*]], label [[FINAL_RIGHT:%.*]]
; CHECK: common.ret:
; CHECK-NEXT: ret void
; CHECK: final_left:
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