diff options
Diffstat (limited to 'lib/Target/X86/README.txt')
| -rw-r--r-- | lib/Target/X86/README.txt | 44 |
1 files changed, 44 insertions, 0 deletions
diff --git a/lib/Target/X86/README.txt b/lib/Target/X86/README.txt index 845da38..56dc29c 100644 --- a/lib/Target/X86/README.txt +++ b/lib/Target/X86/README.txt @@ -1612,3 +1612,47 @@ The coalescer could coalesce "edx" with "eax" to avoid the movl in LBB1_2 if it commuted the addl in LBB1_1. //===---------------------------------------------------------------------===// + +See rdar://4653682. + +From flops: + +LBB1_15: # bb310 + cvtss2sd LCPI1_0, %xmm1 + addsd %xmm1, %xmm0 + movsd 176(%esp), %xmm2 + mulsd %xmm0, %xmm2 + movapd %xmm2, %xmm3 + mulsd %xmm3, %xmm3 + movapd %xmm3, %xmm4 + mulsd LCPI1_23, %xmm4 + addsd LCPI1_24, %xmm4 + mulsd %xmm3, %xmm4 + addsd LCPI1_25, %xmm4 + mulsd %xmm3, %xmm4 + addsd LCPI1_26, %xmm4 + mulsd %xmm3, %xmm4 + addsd LCPI1_27, %xmm4 + mulsd %xmm3, %xmm4 + addsd LCPI1_28, %xmm4 + mulsd %xmm3, %xmm4 + addsd %xmm1, %xmm4 + mulsd %xmm2, %xmm4 + movsd 152(%esp), %xmm1 + addsd %xmm4, %xmm1 + movsd %xmm1, 152(%esp) + incl %eax + cmpl %eax, %esi + jge LBB1_15 # bb310 +LBB1_16: # bb358.loopexit + movsd 152(%esp), %xmm0 + addsd %xmm0, %xmm0 + addsd LCPI1_22, %xmm0 + movsd %xmm0, 152(%esp) + +Rather than spilling the result of the last addsd in the loop, we should have +insert a copy to split the interval (one for the duration of the loop, one +extending to the fall through). The register pressure in the loop isn't high +enough to warrant the spill. + +Also check why xmm7 is not used at all in the function. |