[Bug optimization/11708] Non-Optimal jump code generation.

["naveens at noida dot hcltech dot com" <gcc-bugzilla at gcc dot gnu dot org>]

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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=11708



------- Additional Comments From naveens at noida dot hcltech dot com  2003-07-29 14:10 -------
It seems, delay slot scheduling has the responsibility of generating 
optimal code here. 

In fact, it is able to do the required transformation in some cases. e.g.

Consider this part of the assembler 
with -fno-delayed-branch -O2 -ml -m4 -S -dA

        ! basic block 25
        cmp/pl  r3
        mov.w   .L147,r1
        bt      .L203
        bra     .L93
        nop
.L203:
.L36:
        ! basic block 26

   ..... snipped ...

.L93:
        ! basic block 69
        mov     #0,r1
        bra     .L36
        nop
        .align 5

With -fdelayed-branch, this is optimized to:

         ! basic block 25
        cmp/pl  r3
        mov.w   .L147,r1
        bt      .L36
        mov     #0,r1
.L36:
        ! basic block 26
        mov.w   .L136,r3
        mov.w   .L149,r2
        add     r1,r3
        mov.w   .L150,r1
        cmp/gt  r1,r3

So, it seems that delayed branch scheduling is able to 
optimize some cases, but misses some. I will try to 
confirm the reason.