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| -rw-r--r-- | lib/Target/X86/README.txt | 20 |
1 files changed, 20 insertions, 0 deletions
diff --git a/lib/Target/X86/README.txt b/lib/Target/X86/README.txt index aa7bb3d978..f146ff3634 100644 --- a/lib/Target/X86/README.txt +++ b/lib/Target/X86/README.txt @@ -1868,3 +1868,23 @@ carried over to machine instructions. Asm printer (or JIT) can use this information to add the "lock" prefix. //===---------------------------------------------------------------------===// + +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. + +//===---------------------------------------------------------------------===// + |