[LLVMbugs] [Bug 9569] New: DSE is non-deterministic

[bugzilla-daemon at llvm.org]

http://llvm.org/bugs/show_bug.cgi?id=9569

           Summary: DSE is non-deterministic
           Product: libraries
           Version: trunk
          Platform: PC
        OS/Version: Linux
            Status: NEW
          Severity: normal
          Priority: P
         Component: Scalar Optimizations
        AssignedTo: unassignedbugs at nondot.org
        ReportedBy: benny.kra at gmail.com
                CC: llvmbugs at cs.uiuc.edu


DSE is non-determinstic on LLVM's XCoreRegisterInfo.cpp leading to bootstrap
miscompares.

The attached archive contains
- x.ii: preprocessed source of XCoreRegisterInfo.cpp
- big.ll, small.ll: bitcode of the two possible states
- diff.sh: script to compile x.ii until it produces different assembly. On my
ALSR-enabled linux box it usually finds a difference in less than 10
iterations.

diff output of -stats:
-  11 dse                          - Number of other instrs removed
-  11 dse                          - Number of stores deleted
+  27 dse                          - Number of other instrs removed
+  23 dse                          - Number of stores deleted

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