llvm-6502

mirror of https://github.com/c64scene-ar/llvm-6502.git synced 2025-02-10 20:33:15 +00:00

History

Chris Lattner 08b698e38d Emit long comparison against -1 better. Instead of this (x86):

test2:
        movl 8(%esp), %eax
        notl %eax
        movl 4(%esp), %ecx
        notl %ecx
        orl %eax, %ecx
        cmpl $0, %ecx
        sete %al
        movzbl %al, %eax
        ret

or this (PPC):

_test2:
        nor r2, r4, r4
        nor r3, r3, r3
        or r2, r2, r3
        cntlzw r2, r2
        srwi r3, r2, 5
        blr

Emit this:

test2:
        movl 8(%esp), %eax
        andl 4(%esp), %eax
        cmpl $-1, %eax
        sete %al
        movzbl %al, %eax
        ret

or this:

_test2:
.LBB_test2_0:   ;
        and r2, r4, r3
        cmpwi cr0, r2, -1
        li r3, 1
        li r2, 0
        beq .LBB_test2_2        ;
.LBB_test2_1:   ;
        or r3, r2, r2
.LBB_test2_2:   ;
        blr

it seems like the PPC isel could do better for R32 == -1 case.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@21242 91177308-0d34-0410-b5e6-96231b3b80d8

2005-04-12 01:46:05 +00:00

Analysis

Don't make this require loopsimplify. It works BETTER with loop simplify

2005-04-06 21:45:00 +00:00