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git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@27473 91177308-0d34-0410-b5e6-96231b3b80d8
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Evan Cheng 2006-04-06 23:21:24 +00:00
parent c04766a228
commit 573cb7c506
1 changed files with 56 additions and 0 deletions
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56
lib/Target/X86/README.txt
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@ -704,3 +704,59 @@ intrisic call and select. 2) The intrinsic is expected to produce a i32 value
so a any extend (which becomes a zero extend) is added.
We probably need some kind of target DAG combine hook to fix this.
//===---------------------------------------------------------------------===//
How to decide when to use the "floating point version" of logical ops? Here are
some code fragments:
movaps LCPI5_5, %xmm2
divps %xmm1, %xmm2
mulps %xmm2, %xmm3
mulps 8656(%ecx), %xmm3
addps 8672(%ecx), %xmm3
andps LCPI5_6, %xmm2
andps LCPI5_1, %xmm3
por %xmm2, %xmm3
movdqa %xmm3, (%edi)
movaps LCPI5_5, %xmm1
divps %xmm0, %xmm1
mulps %xmm1, %xmm3
mulps 8656(%ecx), %xmm3
addps 8672(%ecx), %xmm3
andps LCPI5_6, %xmm1
andps LCPI5_1, %xmm3
orps %xmm1, %xmm3
movaps %xmm3, 112(%esp)
movaps %xmm3, (%ebx)
Due to some minor source change, the later case ended up using orps and movaps
instead of por and movdqa. Does it matter?
//===---------------------------------------------------------------------===//
Use movddup to splat a v2f64 directly from a memory source. e.g.
#include <emmintrin.h>
void test(__m128d *r, double A) {
*r = _mm_set1_pd(A);
}
llc:
_test:
movsd 8(%esp), %xmm0
unpcklpd %xmm0, %xmm0
movl 4(%esp), %eax
movapd %xmm0, (%eax)
ret
icc:
_test:
movl 4(%esp), %eax
movddup 8(%esp), %xmm0
movapd %xmm0, (%eax)
ret