Re: [PATCH] if-to-switch: Don't skip the first condition bb when find_conditions in if-to-switch [PR105740]

Xionghu Luo via Gcc-patches Mon, 20 Jun 2022 20:44:21 -0700

Correct the format...

 test2:
.LFB0:
        .cfi_startproc
        xorl    %edx, %edx
        cmpl    $3, (%rdi)
        jle     .L1
        movl    16(%rdi), %eax
        cmpl    $1, %eax
        je      .L4
        subl    $2, %eax
        cmpl    $4, %eax
        ja      .L1
        movl    CSWTCH.1(,%rax,4), %edx
.L1:
        movl    %edx, %eax
        ret
        .p2align 4,,10
        .p2align 3
.L4:
        movl    $12, %edx
        jmp     .L1
        .cfi_endproc
.LFE0:
        .size   test2, .-test2
        .section        .rodata
        .align 16
        .type   CSWTCH.1, @object
        .size   CSWTCH.1, 20
CSWTCH.1:
        .long   27
        .long   38
        .long   18
        .long   58
        .long   68




With the patch attatched:


 test2:
.LFB0:
        .cfi_startproc
        xorl    %edx, %edx
        cmpl    $3, (%rdi)
        jle     .L1
        movl    16(%rdi), %eax
        subl    $1, %eax
        cmpl    $5, %eax
        jbe     .L6
.L1:
        movl    %edx, %eax
        ret
        .p2align 4,,10
        .p2align 3
.L6:
        movl    CSWTCH.1(,%rax,4), %edx
        movl    %edx, %eax
        ret
        .cfi_endproc
.LFE0:
        .size   test2, .-test2
        .section        .rodata
        .align 16
        .type   CSWTCH.1, @object
        .size   CSWTCH.1, 24
CSWTCH.1:
        .long   12
        .long   27
        .long   38
        .long   18
        .long   58
        .long   68




On 2022/6/21 11:05, xionghuluo(罗雄虎) via Gcc-patches wrote:

Current GCC generates:


&nbsp;test2:
.LFB0:
&nbsp; &nbsp; &nbsp; &nbsp; .cfi_startproc
&nbsp; &nbsp; &nbsp; &nbsp; xorl &nbsp; &nbsp;%edx, %edx
&nbsp; &nbsp; &nbsp; &nbsp; cmpl &nbsp; &nbsp;$3, (%rdi)
&nbsp; &nbsp; &nbsp; &nbsp; jle &nbsp; &nbsp; .L1
&nbsp; &nbsp; &nbsp; &nbsp; movl &nbsp; &nbsp;16(%rdi), %eax
&nbsp; &nbsp; &nbsp; &nbsp; cmpl &nbsp; &nbsp;$1, %eax
&nbsp; &nbsp; &nbsp; &nbsp; je &nbsp; &nbsp; &nbsp;.L4
&nbsp; &nbsp; &nbsp; &nbsp; subl &nbsp; &nbsp;$2, %eax
&nbsp; &nbsp; &nbsp; &nbsp; cmpl &nbsp; &nbsp;$4, %eax
&nbsp; &nbsp; &nbsp; &nbsp; ja &nbsp; &nbsp; &nbsp;.L1
&nbsp; &nbsp; &nbsp; &nbsp; movl &nbsp; &nbsp;CSWTCH.1(,%rax,4), %edx
.L1:
&nbsp; &nbsp; &nbsp; &nbsp; movl &nbsp; &nbsp;%edx, %eax
&nbsp; &nbsp; &nbsp; &nbsp; ret
&nbsp; &nbsp; &nbsp; &nbsp; .p2align 4,,10
&nbsp; &nbsp; &nbsp; &nbsp; .p2align 3
.L4:
&nbsp; &nbsp; &nbsp; &nbsp; movl &nbsp; &nbsp;$12, %edx
&nbsp; &nbsp; &nbsp; &nbsp; jmp &nbsp; &nbsp; .L1
&nbsp; &nbsp; &nbsp; &nbsp; .cfi_endproc
.LFE0:
&nbsp; &nbsp; &nbsp; &nbsp; .size &nbsp; test2, .-test2
&nbsp; &nbsp; &nbsp; &nbsp; .section &nbsp; &nbsp; &nbsp; &nbsp;.rodata
&nbsp; &nbsp; &nbsp; &nbsp; .align 16
&nbsp; &nbsp; &nbsp; &nbsp; .type &nbsp; CSWTCH.1, @object
&nbsp; &nbsp; &nbsp; &nbsp; .size &nbsp; CSWTCH.1, 20
CSWTCH.1:
&nbsp; &nbsp; &nbsp; &nbsp; .long &nbsp; 27
&nbsp; &nbsp; &nbsp; &nbsp; .long &nbsp; 38
&nbsp; &nbsp; &nbsp; &nbsp; .long &nbsp; 18
&nbsp; &nbsp; &nbsp; &nbsp; .long &nbsp; 58
&nbsp; &nbsp; &nbsp; &nbsp; .long &nbsp; 68




With the patch attatched:


&nbsp;test2:
.LFB0:
&nbsp; &nbsp; &nbsp; &nbsp; .cfi_startproc
&nbsp; &nbsp; &nbsp; &nbsp; xorl &nbsp; &nbsp;%edx, %edx
&nbsp; &nbsp; &nbsp; &nbsp; cmpl &nbsp; &nbsp;$3, (%rdi)
&nbsp; &nbsp; &nbsp; &nbsp; jle &nbsp; &nbsp; .L1
&nbsp; &nbsp; &nbsp; &nbsp; movl &nbsp; &nbsp;16(%rdi), %eax
&nbsp; &nbsp; &nbsp; &nbsp; subl &nbsp; &nbsp;$1, %eax
&nbsp; &nbsp; &nbsp; &nbsp; cmpl &nbsp; &nbsp;$5, %eax
&nbsp; &nbsp; &nbsp; &nbsp; jbe &nbsp; &nbsp; .L6
.L1:
&nbsp; &nbsp; &nbsp; &nbsp; movl &nbsp; &nbsp;%edx, %eax
&nbsp; &nbsp; &nbsp; &nbsp; ret
&nbsp; &nbsp; &nbsp; &nbsp; .p2align 4,,10
&nbsp; &nbsp; &nbsp; &nbsp; .p2align 3
.L6:
&nbsp; &nbsp; &nbsp; &nbsp; movl &nbsp; &nbsp;CSWTCH.1(,%rax,4), %edx
&nbsp; &nbsp; &nbsp; &nbsp; movl &nbsp; &nbsp;%edx, %eax
&nbsp; &nbsp; &nbsp; &nbsp; ret
&nbsp; &nbsp; &nbsp; &nbsp; .cfi_endproc
.LFE0:
&nbsp; &nbsp; &nbsp; &nbsp; .size &nbsp; test2, .-test2
&nbsp; &nbsp; &nbsp; &nbsp; .section &nbsp; &nbsp; &nbsp; &nbsp;.rodata
&nbsp; &nbsp; &nbsp; &nbsp; .align 16
&nbsp; &nbsp; &nbsp; &nbsp; .type &nbsp; CSWTCH.1, @object
&nbsp; &nbsp; &nbsp; &nbsp; .size &nbsp; CSWTCH.1, 24
CSWTCH.1:
&nbsp; &nbsp; &nbsp; &nbsp; .long &nbsp; 12
&nbsp; &nbsp; &nbsp; &nbsp; .long &nbsp; 27
&nbsp; &nbsp; &nbsp; &nbsp; .long &nbsp; 38
&nbsp; &nbsp; &nbsp; &nbsp; .long &nbsp; 18
&nbsp; &nbsp; &nbsp; &nbsp; .long &nbsp; 58
&nbsp; &nbsp; &nbsp; &nbsp; .long &nbsp; 68


Bootstrap and regression tested pass on x86_64-linux-gnu, OK for master?

Re: [PATCH] if-to-switch: Don't skip the first condition bb when find_conditions in if-to-switch [PR105740]

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