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[DFAJumpThreading] Don't insert existing edge to DomTree while unfolding #163296

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merged 2 commits into from
Oct 14, 2025
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[DFAJumpThreading] Don't insert existing edge to DomTree while unfolding #163296

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9d7b3bb
Precommit test
UsmanNadeem Oct 13, 2025
6288b92
[DFAJumpThreading] Dont insert existing edge to DomTree
UsmanNadeem Oct 13, 2025
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3 changes: 1 addition & 2 deletions llvm/lib/Transforms/Scalar/DFAJumpThreading.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -266,8 +266,7 @@ void DFAJumpThreading::unfold(DomTreeUpdater *DTU, LoopInfo *LI,
if (!ProfcheckDisableMetadataFixes)
BI->setMetadata(LLVMContext::MD_prof,
SI->getMetadata(LLVMContext::MD_prof));
DTU->applyUpdates({{DominatorTree::Insert, StartBlock, EndBlock},
{DominatorTree::Insert, StartBlock, NewBlock}});
DTU->applyUpdates({{DominatorTree::Insert, StartBlock, NewBlock}});
} else {
BasicBlock *EndBlock = SIUse->getParent();
BasicBlock *NewBlockT = BasicBlock::Create(
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58 changes: 58 additions & 0 deletions llvm/test/Transforms/DFAJumpThreading/dfa-jump-threading-transform.ll
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Expand Up @@ -445,9 +445,67 @@ bb2: ; preds = %select.unfold
unreachable
}


define i16 @DTU_update_crash() {
; CHECK-LABEL: @DTU_update_crash(
; CHECK-NEXT: entry:
; CHECK-NEXT: br label [[FOR_BODY_SELECTBLOCK:%.*]]
; CHECK: for.body.selectblock:
; CHECK-NEXT: br i1 false, label [[SWITCHBLOCK_JT0:%.*]], label [[SEL_SI_UNFOLD_FALSE_JT0:%.*]]
; CHECK: sel.si.unfold.false:
; CHECK-NEXT: br label [[SWITCHBLOCK:%.*]]
; CHECK: sel.si.unfold.false.jt0:
; CHECK-NEXT: [[DOTSI_UNFOLD_PHI_JT0:%.*]] = phi i32 [ 0, [[FOR_BODY_SELECTBLOCK]] ]
; CHECK-NEXT: br label [[SWITCHBLOCK_JT0]]
; CHECK: switchblock:
; CHECK-NEXT: [[SWITCHBLOCK_PHI:%.*]] = phi i32 [ poison, [[SEL_SI_UNFOLD_FALSE:%.*]] ]
; CHECK-NEXT: [[P_24_ADDR_3:%.*]] = phi i32 [ 0, [[SEL_SI_UNFOLD_FALSE]] ]
; CHECK-NEXT: switch i32 [[SWITCHBLOCK_PHI]], label [[CLEANUP:%.*]] [
; CHECK-NEXT: i32 0, label [[FOR_INC:%.*]]
; CHECK-NEXT: i32 1, label [[CLEANUP]]
; CHECK-NEXT: i32 5, label [[FOR_BODY_SELECTBLOCK]]
; CHECK-NEXT: ]
; CHECK: switchblock.jt0:
; CHECK-NEXT: [[SWITCHBLOCK_PHI_JT0:%.*]] = phi i32 [ 0, [[FOR_BODY_SELECTBLOCK]] ], [ [[DOTSI_UNFOLD_PHI_JT0]], [[SEL_SI_UNFOLD_FALSE_JT0]] ]
; CHECK-NEXT: [[P_24_ADDR_3_JT0:%.*]] = phi i32 [ 0, [[FOR_BODY_SELECTBLOCK]] ], [ 0, [[SEL_SI_UNFOLD_FALSE_JT0]] ]
; CHECK-NEXT: br label [[FOR_INC]]
; CHECK: for.inc:
; CHECK-NEXT: br i1 false, label [[FOR_BODY_SELECTBLOCK]], label [[CLEANUP]]
; CHECK: cleanup:
; CHECK-NEXT: call void (...) @llvm.fake.use(i32 [[P_24_ADDR_3_JT0]])
; CHECK-NEXT: ret i16 0
;
entry:
br label %for.body.selectblock

for.body.selectblock: ; preds = %for.inc, %switchblock, %entry
%sel = select i1 false, i32 0, i32 0
br label %switchblock

switchblock: ; preds = %for.body.selectblock
%switchblock.phi = phi i32 [ %sel, %for.body.selectblock ]
%p_24.addr.3 = phi i32 [ 0, %for.body.selectblock ]
switch i32 %switchblock.phi, label %cleanup [
i32 0, label %for.inc
i32 1, label %cleanup
i32 5, label %for.body.selectblock
]

for.inc: ; preds = %switchblock
br i1 false, label %for.body.selectblock, label %cleanup

cleanup: ; preds = %for.inc, %switchblock, %switchblock
call void (...) @llvm.fake.use(i32 %p_24.addr.3)
ret i16 0
}

declare void @llvm.fake.use(...)

!0 = !{!"function_entry_count", i32 10}
!1 = !{!"branch_weights", i32 3, i32 5}
;.
; CHECK: attributes #[[ATTR0:[0-9]+]] = { nocallback nofree nosync nounwind willreturn memory(inaccessiblemem: readwrite) }
;.
; CHECK: [[META0:![0-9]+]] = !{!"function_entry_count", i32 10}
; CHECK: [[PROF1]] = !{!"branch_weights", i32 3, i32 5}
;.