This reverts commit r237210.
Also fix X86/complex-fca.ll to match the code that we used to generate
on win32 and now generate everwhere to conform to SysV.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@237639 91177308-0d34-0410-b5e6-96231b3b80d8
This commit broke an x86 test and the bots have been broken for well
over an hour now so I'm just reverting.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@237210 91177308-0d34-0410-b5e6-96231b3b80d8
Summary:
This rule was always in the old SysV i386 ABI docs and the new ones that
H.J. Lu has put together, but we never noticed:
EAX scratch register; also used to return integer and pointer values
from functions; also stores the address of a returned struct or union
Fixes PR23491.
Reviewers: majnemer
Subscribers: llvm-commits
Differential Revision: http://reviews.llvm.org/D9715
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This lets us avoid a few copies that are otherwise hard to get rid of.
The way this is done is, the custom-inserter looks at the following
instruction for another CMOV, and replaces both at the same time.
A previous version used a new CMOV2 opcode, but the custom inserter
is expected to be able to return a different basic block anyway, which
means it's OK - though far from ideal - to alter that block's contents.
Explicitly document that, in case it ever makes a difference.
Alternatives welcome!
Follow-up to r231045.
rdar://19767934
Closes http://reviews.llvm.org/D8019
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Fold and/or of setcc's to double CMOV:
(CMOV F, T, ((cc1 | cc2) != 0)) -> (CMOV (CMOV F, T, cc1), T, cc2)
(CMOV F, T, ((cc1 & cc2) != 0)) -> (CMOV (CMOV T, F, !cc1), F, !cc2)
When we can't use the CMOV instruction, it might increase branch
mispredicts. When we can, or when there is no mispredict, this
improves throughput and reduces register pressure.
These can't be catched by generic combines, because the pattern can
appear when legalizing some instructions (such as fcmp une).
rdar://19767934
http://reviews.llvm.org/D7634
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@231045 91177308-0d34-0410-b5e6-96231b3b80d8
