[llvm-bugs] [Bug 27138] New: PowerPC code gen bug in 3.8. invalid elimination of store

[via llvm-bugs]

https://llvm.org/bugs/show_bug.cgi?id=27138

            Bug ID: 27138
           Summary: PowerPC code gen bug in 3.8. invalid elimination of
                    store
           Product: new-bugs
           Version: 3.8
          Hardware: Other
                OS: Linux
            Status: NEW
          Severity: normal
          Priority: P
         Component: new bugs
          Assignee: unassignedbugs at nondot.org
          Reporter: eric.schweitz at pgroup.com
                CC: llvm-bugs at lists.llvm.org
    Classification: Unclassified

Created attachment 16132
  --> https://llvm.org/bugs/attachment.cgi?id=16132&action=edit
code that exposes a store elimination bug

The bugged .ll example shows a floating-point value of 4.0 being stored,
loaded, and multiplied by 0.2. The value 0.8 is then printed as output by LLVM
3.7.  In LLVM 3.8, the output is 0.0. It appears that the store of 4.0 is
erroneously eliminated.

To expose the bug the following commands were used:

  llc -O0 -o bug.s bug.ll
  as bug.s -o bug.o
  clang bug.o -O0 -o bug.out
  ./bug.out

  0.000000

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