[LoopInterchange] Check number of latch successors before accessing them.

In cases where the OuterMostLoopLatchBI only has a single successor,
accessing the second successor will fail.

This fixes a failure when building the test-suite with loop-interchange
enabled.

Reviewers: mcrosier, karthikthecool, davide

Reviewed by: karthikthecool

Differential Revision: https://reviews.llvm.org/D42906

llvm-svn: 324994
This commit is contained in:
Florian Hahn 2018-02-13 10:02:52 +00:00
parent 92e0bb5c95
commit 1f95ef1815
2 changed files with 41 additions and 1 deletions

View File

@ -541,7 +541,7 @@ struct LoopInterchange : public FunctionPass {
BasicBlock *OuterMostLoopLatch = OuterMostLoop->getLoopLatch();
BranchInst *OuterMostLoopLatchBI =
dyn_cast<BranchInst>(OuterMostLoopLatch->getTerminator());
if (!OuterMostLoopLatchBI)
if (!OuterMostLoopLatchBI || OuterMostLoopLatchBI->getNumSuccessors() != 2)
return false;
// Since we currently do not handle LCSSA PHI's any failure in loop

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@ -0,0 +1,40 @@
; RUN: opt < %s -loop-interchange -S | FileCheck %s
; BB latch1 is the loop latch, but does not exit the loop.
define void @foo() {
entry:
%dest = alloca i16*, align 8
br label %header1
header1:
%0 = phi i16* [ %2, %latch1 ], [ undef, %entry ]
br i1 false, label %inner, label %loopexit
inner:
br i1 undef, label %inner.ph, label %latch1
inner.ph:
br label %inner.body
inner.body:
%1 = load i16, i16* %0, align 2
store i16* inttoptr (i64 2 to i16*), i16** %dest, align 8
br i1 false, label %inner.body, label %inner.loopexit
inner.loopexit:
br label %latch1
latch1:
%2 = phi i16* [ %0, %inner ], [ undef, %inner.loopexit ]
br label %header1
loopexit: ; preds = %header1
unreachable
}
; CHECK-LABEL: inner.body:
; CHECK: br i1 false, label %inner.body, label %inner.loopexit
; CHECK: latch1:
; CHECK-NEXT: %2 = phi i16* [ %0, %inner ], [ undef, %inner.loopexit ]
; CHECK-NEXT: br label %header1