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| -rw-r--r-- | lib/Target/PowerPC/README_ALTIVEC.txt | 23 |
1 files changed, 23 insertions, 0 deletions
diff --git a/lib/Target/PowerPC/README_ALTIVEC.txt b/lib/Target/PowerPC/README_ALTIVEC.txt index 461b4123c7..1e4c6fb984 100644 --- a/lib/Target/PowerPC/README_ALTIVEC.txt +++ b/lib/Target/PowerPC/README_ALTIVEC.txt @@ -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; +} + |