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| author | Chris Lattner <sabre@nondot.org> | 2007-08-24 15:17:59 +0000 |
|---|---|---|
| committer | Chris Lattner <sabre@nondot.org> | 2007-08-24 15:17:59 +0000 |
| commit | b23f4c5f44203a3ebe9153ed5dc15dc08623dcbd (patch) | |
| tree | 450186dc0aa2d830f768b4e2d8b65fcb3b05fec8 | |
| parent | 4259fe3281558d129a5442d1eba03b390ed50bc8 (diff) | |
| download | external_llvm-b23f4c5f44203a3ebe9153ed5dc15dc08623dcbd.zip external_llvm-b23f4c5f44203a3ebe9153ed5dc15dc08623dcbd.tar.gz external_llvm-b23f4c5f44203a3ebe9153ed5dc15dc08623dcbd.tar.bz2 | |
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git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@41359 91177308-0d34-0410-b5e6-96231b3b80d8
| -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. + +//===---------------------------------------------------------------------===// |