[LLVMbugs] [Bug 1499] NEW: Instruction Combining misoptimization

bugzilla-daemon at cs.uiuc.edu bugzilla-daemon at cs.uiuc.edu
Tue Jun 5 14:25:09 PDT 2007


           Summary: Instruction Combining misoptimization
           Product: libraries
           Version: trunk
          Platform: PC
        OS/Version: Linux
            Status: NEW
          Severity: normal
          Priority: P2
         Component: Scalar Optimizations
        AssignedTo: unassignedbugs at nondot.org
        ReportedBy: lauro.venancio at gmail.com

Instruction Combining is wrongly optimizing the following code:

        %tmp30 = load i64* %tmp10               ; <i64> [#uses=1]
        %.cast = zext i32 63 to i64             ; <i64> [#uses=1]
        %tmp31 = ashr i64 %tmp30, %.cast                ; <i64> [#uses=1]
        %tmp3132 = trunc i64 %tmp31 to i32              ; <i32> [#uses=1]
        %tmp33 = or i32 %tmp3132, 1             ; <i32> [#uses=1]
        store i32 %tmp33, i32* %tmp9
        %tmp34 = load i32* %tmp9                ; <i32> [#uses=1]
        store i32 %tmp34, i32* %retval
        br label %return.exitStub

        store i32 -1, i32* %tmp9
        store i32 -1, i32* %retval
        ret void

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