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git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@39998 91177308-0d34-0410-b5e6-96231b3b80d8
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Evan Cheng 2007-07-18 08:21:49 +00:00
parent cbb7ec7396
commit b5cd24973c
1 changed files with 17 additions and 0 deletions
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17
lib/Target/X86/README.txt
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@ -1131,3 +1131,20 @@ _test:
subl 4(%esp), %eax
ret
//===---------------------------------------------------------------------===//
For code like:
phi (undef, x)
We get an implicit def on the undef side. If the phi is spilled, we then get:
implicitdef xmm1
store xmm1 -> stack
It should be possible to teach the x86 backend to "fold" the store into the
implicitdef, which just deletes the implicit def.
These instructions should go away:
#IMPLICIT_DEF %xmm1
movaps %xmm1, 192(%esp)
movaps %xmm1, 224(%esp)
movaps %xmm1, 176(%esp)