diff options
| -rw-r--r-- | lib/Target/X86/README-SSE.txt | 14 |
1 files changed, 14 insertions, 0 deletions
diff --git a/lib/Target/X86/README-SSE.txt b/lib/Target/X86/README-SSE.txt index 40404e5..cb857fb 100644 --- a/lib/Target/X86/README-SSE.txt +++ b/lib/Target/X86/README-SSE.txt @@ -630,3 +630,17 @@ _bar: ret //===---------------------------------------------------------------------===// + +We should materialize vecetor constants like "all ones" and "signbit" with +code like: + + cmpeqps xmm1, xmm1 ; xmm1 = all-ones + +and: + cmpeqps xmm1, xmm1 ; xmm1 = all-ones + psrlq xmm1, 31 ; xmm1 = all 100000000000... + +instead of using a load from the constant pool. The later is important for +ABS/NEG/copysign etc. + +//===---------------------------------------------------------------------===// |