https://llvm.org/bugs/show_bug.cgi?id=28944
Bug ID: 28944
Summary: IRCE breaks loop-info
Product: libraries
Version: trunk
Hardware: PC
OS: All
Status: NEW
Severity: normal
Priority: P
Component: Loop Optimizer
Assignee: unassignedb...@nondot.org
Reporter: michael.v.zolotuk...@gmail.com
CC: llvm-bugs@lists.llvm.org
Classification: Unclassified
When trying to improve LoopInfo verifier, I found that one of IRCE tests
started to fail. Looks like it doesn't update LI as it creates new loops, or
something like this.
To reproduce apply a patch from https://reviews.llvm.org/D23437 and then:
$ cat fail.ll
define void @inner_loop(i32* %arr, i32* %a_len_ptr, i32 %n) {
entry:
%len = load i32, i32* %a_len_ptr, !range !0
%first.itr.check = icmp sgt i32 %n, 0
br i1 %first.itr.check, label %loop, label %exit
loop: ; preds = %in.bounds, %entry
%idx = phi i32 [ 0, %entry ], [ %idx.next, %in.bounds ]
%idx.next = add i32 %idx, 1
%abc = icmp slt i32 %idx, %len
br i1 %abc, label %in.bounds, label %out.of.bounds
in.bounds: ; preds = %loop
%addr = getelementptr i32, i32* %arr, i32 %idx
store i32 0, i32* %addr
%next = icmp slt i32 %idx.next, %n
br i1 %next, label %loop, label %exit
out.of.bounds: ; preds = %loop
ret void
exit: ; preds = %in.bounds, %entry
ret void
}
!0 = !{i32 0, i32 2147483647}
$ opt -verify-loop-info -irce-print-changed-loops -irce < ww.ll -S
irce: in function inner_loop: constrained Loop at depth 1 containing:
%loop<header><exiting>,%in.bounds<latch><exiting>
Assertion failed: (LoopHeaders1.size() == LoopHeaders2.size() && "LoopInfo is
incorrect."), function verifyByRecomputation, file
/Users/mvzolotu/devel/trunk/llvm/include/llvm/Analysis/LoopInfoImpl.h, line
600.
Stack dump:
0. Program arguments: bin/opt -verify-loop-info -irce-print-changed-loops
-irce -S
1. Running pass 'Function Pass Manager' on module '<stdin>'.
2. Running pass 'Loop Pass Manager' on function '@inner_loop'
Abort trap: 6
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