[llvm-bugs] [Bug 19644] Miscompile with x86 hosted release compiler targeting x64

[via llvm-bugs]

https://bugs.llvm.org/show_bug.cgi?id=19644

Fangrui Song <i at maskray.me> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |i at maskray.me
         Resolution|---                         |FIXED
             Status|NEW                         |RESOLVED

--- Comment #1 from Fangrui Song <i at maskray.me> ---
Updated .ll

define void @_ZL12Test_S5303X7v() #0 {
  %1 = tail call noalias i8* @meow(i64 16)
  %2 = bitcast i8* %1 to i64*
  %3 = load i64, i64* %2, align 4
  %4 = and i64 %3, -2251799813685249
  store i64 %4, i64* %2, align 4
  ret void
}

; Function Attrs: nobuiltin
declare noalias i8* @meow(i64)

The AND immediate is -2251799813685249 = 0xfff7ffffffffffff

In CurDAG->Combine(BeforeLegalizeTypes, AA, OptLevel),
DAGCombiner::ReduceLoadOpStoreWidth optimizes 0xfff7ffffffffffff with: andb   
$0xf7, 6(%rax)

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