commit 71ff44e46c230e1232403af17d1a06047685ad34
author Chris Lattner <sabre@nondot.org> Tue Apr 12 01:46:05 2005 +0000
committer Chris Lattner <sabre@nondot.org> Tue Apr 12 01:46:05 2005 +0000
tree 0d8ef7001eba1227c86069caea87d3be33ec1998
parent 87bd69884a2f658b7809a326722065532721b805

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.

llvm-svn: 21242