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llvm-svn: 34101
This commit is contained in:
Chris Lattner 2007-02-09 17:38:01 +00:00
parent 82f223475d
commit c9088b4c8e
1 changed files with 29 additions and 0 deletions
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29
llvm/lib/Target/PowerPC/README.txt
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@ -596,3 +596,32 @@ _test:
This sort of thing occurs a lot due to globalopt.
===-------------------------------------------------------------------------===
We currently compile 32-bit bswap:
declare i32 @llvm.bswap.i32(i32 %A)
define i32 @test(i32 %A) {
%B = call i32 @llvm.bswap.i32(i32 %A)
ret i32 %B
}
to:
_test:
rlwinm r2, r3, 24, 16, 23
slwi r4, r3, 24
rlwimi r2, r3, 8, 24, 31
rlwimi r4, r3, 8, 8, 15
rlwimi r4, r2, 0, 16, 31
mr r3, r4
blr
it would be more efficient to produce:
_foo: mr r0,r3
rlwinm r3,r3,8,0xffffffff
rlwimi r3,r0,24,0,7
rlwimi r3,r0,24,16,23
blr
===-------------------------------------------------------------------------===