[Bug target/41514] New: redundant compare instruction of consecutive conditional branches

[carrot at google dot com]

Compile the attached source code with options -Os -march=armv5te -mthumb, gcc
generates:

        push    {lr}
        cmp     r0, #63     // A
        beq     .L3
        cmp     r0, #63     // B
        bhi     .L4
        cmp     r0, #45
        beq     .L3
        cmp     r0, #47
        bne     .L5
        b       .L3
.L4:
        cmp     r0, #99
        bne     .L5
.L3:
        mov     r0, #1
        b       .L2
.L5:
        mov     r0, #0
.L2:
        @ sp needed for prologue
        pop     {pc}

Instruction B is the same as instruction A, and there are no other instructions
between them clobber condition codes. So we can remove instruction B.


-- 
           Summary: redundant compare instruction of consecutive conditional
                    branches
           Product: gcc
           Version: 4.5.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: target
        AssignedTo: unassigned at gcc dot gnu dot org
        ReportedBy: carrot at google dot com
 GCC build triplet: i686-linux
  GCC host triplet: i686-linux
GCC target triplet: arm-eabi


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=41514