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git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@50267 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Chris Lattner 2008-04-25 17:25:00 +00:00
parent 682f81032f
commit 7c400dcb03
1 changed files with 23 additions and 0 deletions
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23
lib/Target/PowerPC/README_ALTIVEC.txt
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@ -186,3 +186,26 @@ lowering would be:
3. lvsl 0; splat index; vcmpeq to generate a select mask
4. lvsl slot + x; vperm to rotate result into correct slot
5. vsel result together.
//===----------------------------------------------------------------------===//
Should codegen branches on vec_any/vec_all to avoid mfcr. Two examples:
#include <altivec.h>
int f(vector float a, vector float b)
{
int aa = 0;
if (vec_all_ge(a, b))
aa |= 0x1;
if (vec_any_ge(a,b))
aa |= 0x2;
return aa;
}
vector float f(vector float a, vector float b) {
if (vec_any_eq(a, b))
return a;
else
return b;
}