[LLVMbugs] [Bug 7458] New: thumb2 instruction not narrowed where expected

bugzilla-daemon at llvm.org bugzilla-daemon at llvm.org
Tue Jun 22 23:17:23 CDT 2010


http://llvm.org/bugs/show_bug.cgi?id=7458

           Summary: thumb2 instruction not narrowed where expected
           Product: new-bugs
           Version: unspecified
          Platform: PC
        OS/Version: Linux
            Status: NEW
          Severity: normal
          Priority: P
         Component: new bugs
        AssignedTo: unassignedbugs at nondot.org
        ReportedBy: sharparrow1 at yahoo.com
                CC: llvmbugs at cs.uiuc.edu


Testcase:
define void @_Z1ajj(i32 %x, i32 %y) {
entry:
  %shr10 = xor i32 %y, %x                         ; <i32> [#uses=1]
  %tmp9 = and i32 %shr10, 65280                   ; <i32> [#uses=1]
  %cmp = icmp eq i32 %tmp9, 0                     ; <i1> [#uses=1]
  br i1 %cmp, label %if.then, label %if.end
if.then:                                          ; preds = %entry
  tail call void @_Z1bv()
  ret void
if.end:                                           ; preds = %entry
  ret void
}
declare void @_Z1bv()


Output:
_Z1ajj:
@ BB#0:                                 @ %entry
    str    lr, [sp, #-4]!
    eor.w    r0, r1, r0
    tst.w    r0, #65280
    bne    .LBB0_2
@ BB#1:                                 @ %if.then
    bl    _Z1bv
.LBB0_2:                                @ %if.end
    ldr    lr, [sp], #4
    bx    lr

The eor.w should be narrowed.

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