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release/19.x: [SimpleLoopUnswitch] Fix LCSSA phi node invalidation #118870

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5 changes: 3 additions & 2 deletions llvm/lib/Transforms/Scalar/SimpleLoopUnswitch.cpp
Original file line number Diff line number Diff line change
Expand Up @@ -1249,8 +1249,9 @@ static BasicBlock *buildClonedLoopBlocks(
assert(VMap.lookup(&I) == &ClonedI && "Mismatch in the value map!");

// Forget SCEVs based on exit phis in case SCEV looked through the phi.
if (SE && isa<PHINode>(I))
SE->forgetValue(&I);
if (SE)
if (auto *PN = dyn_cast<PHINode>(&I))
SE->forgetLcssaPhiWithNewPredecessor(&L, PN);

BasicBlock::iterator InsertPt = MergeBB->getFirstInsertionPt();

Expand Down
92 changes: 92 additions & 0 deletions llvm/test/Transforms/SimpleLoopUnswitch/pr117537.ll
Original file line number Diff line number Diff line change
@@ -0,0 +1,92 @@
; NOTE: Assertions have been autogenerated by utils/update_test_checks.py UTC_ARGS: --version 5
; RUN: opt -S -passes='print<scalar-evolution>,simple-loop-unswitch<nontrivial>,print<scalar-evolution>' -verify-scev < %s 2>/dev/null | FileCheck %s

; Make sure we don't assert due to insufficient SCEV invalidation.

define void @test(ptr %p) {
; CHECK-LABEL: define void @test(
; CHECK-SAME: ptr [[P:%.*]]) {
; CHECK-NEXT: [[ENTRY:.*:]]
; CHECK-NEXT: [[CHECK:%.*]] = icmp eq ptr [[P]], null
; CHECK-NEXT: br i1 [[CHECK]], label %[[ENTRY_SPLIT_US:.*]], label %[[ENTRY_SPLIT:.*]]
; CHECK: [[ENTRY_SPLIT_US]]:
; CHECK-NEXT: br label %[[BB0_US:.*]]
; CHECK: [[BB0_US]]:
; CHECK-NEXT: br label %[[LOOP0_US:.*]]
; CHECK: [[LOOP0_US]]:
; CHECK-NEXT: [[V_US:%.*]] = load atomic i32, ptr [[P]] unordered, align 8
; CHECK-NEXT: [[ADD_US:%.*]] = add i32 [[V_US]], 3
; CHECK-NEXT: br i1 true, label %[[PREHEADER_SPLIT_US:.*]], label %[[BB0_US]]
; CHECK: [[PREHEADER_SPLIT_US]]:
; CHECK-NEXT: [[ADD_LCSSA_US:%.*]] = phi i32 [ [[ADD_US]], %[[LOOP0_US]] ]
; CHECK-NEXT: br label %[[PREHEADER:.*]]
; CHECK: [[ENTRY_SPLIT]]:
; CHECK-NEXT: br label %[[BB0:.*]]
; CHECK: [[BB0]]:
; CHECK-NEXT: br label %[[LATCH:.*]]
; CHECK: [[LATCH]]:
; CHECK-NEXT: br i1 false, label %[[EXIT0:.*]], label %[[LOOP0:.*]]
; CHECK: [[EXIT0]]:
; CHECK-NEXT: ret void
; CHECK: [[LOOP0]]:
; CHECK-NEXT: [[V:%.*]] = load atomic i32, ptr [[P]] unordered, align 8
; CHECK-NEXT: [[ADD:%.*]] = add i32 [[V]], 3
; CHECK-NEXT: br i1 true, label %[[PREHEADER_SPLIT:.*]], label %[[BB0]]
; CHECK: [[PREHEADER_SPLIT]]:
; CHECK-NEXT: [[ADD_LCSSA:%.*]] = phi i32 [ [[ADD]], %[[LOOP0]] ]
; CHECK-NEXT: br label %[[PREHEADER]]
; CHECK: [[PREHEADER]]:
; CHECK-NEXT: [[DOTUS_PHI:%.*]] = phi i32 [ [[ADD_LCSSA]], %[[PREHEADER_SPLIT]] ], [ [[ADD_LCSSA_US]], %[[PREHEADER_SPLIT_US]] ]
; CHECK-NEXT: br label %[[LOOP1:.*]]
; CHECK: [[LOOP1]]:
; CHECK-NEXT: [[IV1:%.*]] = phi i32 [ [[DOTUS_PHI]], %[[PREHEADER]] ], [ [[IV1_NEXT:%.*]], %[[BACKEDGE:.*]] ]
; CHECK-NEXT: [[IV1_NEXT]] = add i32 [[IV1]], -33
; CHECK-NEXT: br label %[[LOOP2:.*]]
; CHECK: [[BACKEDGE]]:
; CHECK-NEXT: br i1 true, label %[[EXIT1:.*]], label %[[LOOP1]]
; CHECK: [[LOOP2]]:
; CHECK-NEXT: [[IV0:%.*]] = phi i32 [ [[IV1]], %[[LOOP1]] ], [ [[IV0_NEXT:%.*]], %[[LOOP2]] ]
; CHECK-NEXT: [[IV0_NEXT]] = add nsw i32 [[IV0]], 1
; CHECK-NEXT: [[CMP:%.*]] = icmp sgt i32 [[IV0_NEXT]], 0
; CHECK-NEXT: br i1 [[CMP]], label %[[BACKEDGE]], label %[[LOOP2]]
; CHECK: [[EXIT1]]:
; CHECK-NEXT: ret void
;
entry:
%check = icmp eq ptr %p, null
br label %bb0

bb0: ; preds = %loop0, %entry
br i1 %check, label %loop0, label %latch

latch: ; preds = %bb0
br i1 %check, label %exit0, label %loop0

exit0: ; preds = %latch
ret void

loop0: ; preds = %latch, %bb0
%v = load atomic i32, ptr %p unordered, align 8
%add = add i32 %v, 3
br i1 true, label %preheader, label %bb0

preheader: ; preds = %loop0
br label %loop1

loop1: ; preds = %backedge, %preheader
%iv1 = phi i32 [ %add, %preheader ], [ %iv1.next, %backedge ]
%iv1.next = add i32 %iv1, -33
br label %loop2

backedge: ; preds = %loop2
br i1 true, label %exit1, label %loop1

loop2: ; preds = %loop2, %loop1
%iv0 = phi i32 [ %iv1, %loop1 ], [ %iv0.next, %loop2 ]
%iv0.next = add nsw i32 %iv0, 1
%cmp = icmp sgt i32 %iv0.next, 0
br i1 %cmp, label %backedge, label %loop2

exit1: ; preds = %backedge
ret void
}
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