[llvm-bugs] [Bug 49464] New: [InstCombiner] WRONG code

[via llvm-bugs]

https://bugs.llvm.org/show_bug.cgi?id=49464

            Bug ID: 49464
           Summary: [InstCombiner]  WRONG code
           Product: libraries
           Version: trunk
          Hardware: PC
                OS: Linux
            Status: NEW
          Severity: normal
          Priority: P
         Component: Scalar Optimizations
          Assignee: unassignedbugs at nondot.org
          Reporter: paulsson at linux.vnet.ibm.com
                CC: llvm-bugs at lists.llvm.org

Created attachment 24598
  --> https://bugs.llvm.org/attachment.cgi?id=24598&action=edit
reduced testcase

The reduced program has a loop which executes only two iterations.
LoopVectorizer makes a loop with VF=2, but then InstCombiner removes most
relevant parts of both the scalar and vectorized loop.

clang -march=z14 wrong0.i -o a.out -Os -fno-vectorize -w && ./a.out
1
clang -march=z14 wrong0.i -o a.out -Os -w && ./a.out
0

The program is supposed to print '1'.

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