diff options
Diffstat (limited to 'lib/Target/X86/README-SSE.txt')
| -rw-r--r-- | lib/Target/X86/README-SSE.txt | 20 |
1 files changed, 20 insertions, 0 deletions
diff --git a/lib/Target/X86/README-SSE.txt b/lib/Target/X86/README-SSE.txt index 71ad51c..0f3e44b 100644 --- a/lib/Target/X86/README-SSE.txt +++ b/lib/Target/X86/README-SSE.txt @@ -916,3 +916,23 @@ cheaper to do fld1 than load from a constant pool for example, so "load, add 1.0, store" is better done in the fp stack, etc. //===---------------------------------------------------------------------===// + +The X86 backend should be able to if-convert SSE comparisons like "ucomisd" to +"cmpsd". For example, this code: + +double d1(double x) { return x == x ? x : x + x; } + +Compiles into: + +_d1: + ucomisd %xmm0, %xmm0 + jnp LBB1_2 + addsd %xmm0, %xmm0 + ret +LBB1_2: + ret + +Also, the 'ret's should be shared. This is PR6032. + +//===---------------------------------------------------------------------===// + |
