[LLVMbugs] [Bug 10963] New: [AVX] incorrect code generated for <8 x i8> vector shuffle

[bugzilla-daemon at llvm.org]

http://llvm.org/bugs/show_bug.cgi?id=10963

           Summary: [AVX] incorrect code generated for <8 x i8> vector
                    shuffle
           Product: new-bugs
           Version: trunk
          Platform: PC
        OS/Version: All
            Status: NEW
          Severity: normal
          Priority: P
         Component: new bugs
        AssignedTo: unassignedbugs at nondot.org
        ReportedBy: matt at pharr.org
                CC: llvmbugs at cs.uiuc.edu


Created an attachment (id=7297)
 --> (http://llvm.org/bugs/attachment.cgi?id=7297)
test case, part 1

The attached test case loads a vector of i8 values from memory
(0,1,2,3,4,5,6,7) and does a shuffle of them with shuffle indices
(2,3,4,5,6,7,0,1) (such that the result should be the same as the shuffle
indices).  If I compile with a regular SSE target, I get the expected result:

% llc bug.ll -o bug.s && clang bug.c bug.s && ./a.out
2 3 4 5 6 7 0 1

But with avx, all of the values are wrong.

% llc -mattr=+avx bug.ll -o bug.s && clang bug.c bug.s && ./a.out
0 2 3 4 5 6 7 0

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