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This is closer to what we really want. 

llvm-svn: 30451
This commit is contained in:
Chris Lattner 2006-09-18 04:54:35 +00:00
parent 420c4bcc8d
commit 4a13d3b391
1 changed files with 3 additions and 2 deletions
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5
llvm/lib/Target/README.txt
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@ -260,12 +260,13 @@ quantum_sigma_x in 462.libquantum contains the following loop:
Where MAX_UNSIGNED/state is a 64-bit int. On a 32-bit platform it would be just
so cool to turn it into something like:
long long Res = ((MAX_UNSIGNED) 1 << target);
if (target < 32) {
for(i=0; i<reg->size; i++)
reg->node[i].state ^= ((int) (1 << target));
reg->node[i].state ^= Res & 0xFFFFFFFFULL;
} else {
for(i=0; i<reg->size; i++)
reg->node[i].state ^= (long long)((int) (1 << (target-32))) << 32;
reg->node[i].state ^= Res & 0xFFFFFFFF00000000ULL
}
... which would only do one 32-bit XOR per loop iteration instead of two.