Add a avoidWriteAfterWrite() target hook to identify register classes that
suffer from write-after-write hazards. For those register classes, try to avoid
writing the same register in two consecutive instructions.
This is currently disabled by default. We should not spill to avoid hazards!
The command line flag -avoid-waw-hazard can be used to enable waw avoidance.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@129772 91177308-0d34-0410-b5e6-96231b3b80d8
Ideally, we would match an S-register to its containing D-register, but that
requires arithmetic (divide by 2).
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@129756 91177308-0d34-0410-b5e6-96231b3b80d8
en-mass for C++ PODs. On my c++ test file, this cuts the fast isel rejects by 10x
and shrinks the generated .s file by 5%
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@129755 91177308-0d34-0410-b5e6-96231b3b80d8
when they are a truncate from something else. This eliminates fully half of all the
fastisel rejections on a test c++ file I'm working with, which should make a substantial
improvement for -O0 compile of c++ code.
This fixed rdar://9297003 - fast isel bails out on all functions taking bools
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@129752 91177308-0d34-0410-b5e6-96231b3b80d8
Before we would bail out on i1 arguments all together, now we just bail on
non-constant ones. Also, we used to emit extraneous code. e.g. test12 was:
movb $0, %al
movzbl %al, %edi
callq _test12
and test13 was:
movb $0, %al
xorl %edi, %edi
movb %al, 7(%rsp)
callq _test13f
Now we get:
movl $0, %edi
callq _test12
and:
movl $0, %edi
callq _test13f
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is, it assumes addresses are 64-bit aligned (which should be the more common
case). If the alignment is found not to be aligned, then getOperandLatency()
would adjust the operand latency computation by one to compensate for it.
rdar://9294833
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small heap-allocated SmallString because it unconditionally forces a malloc.
(Revised version of r129688, with the necessary flush() call.)
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registers for fast allocation a different way. This has us updating
used registers only when we're using that exact register.
Fixes rdar://9207598
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the generated FastISel. X86 doesn't need to generate code to match ADD16ri8
since ADD16ri will do just fine. This is a small codesize win in the generated
instruction selector.
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value constraints on them (when defined as ImmLeaf's). This is particularly important
for X86-64, where almost all reg/imm instructions take a i64immSExt32 immediate operand,
which has a value constraint. Before this patch we ended up iseling the examples into
such amazing code as:
movabsq $7, %rax
imulq %rax, %rdi
movq %rdi, %rax
ret
now we produce:
imulq $7, %rdi, %rax
ret
This dramatically shrinks the generated code at -O0 on x86-64.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@129691 91177308-0d34-0410-b5e6-96231b3b80d8
simplifying them and exposing more information to tblgen. It would be nice
if other target authors adopted this as well, particularly arm since it has fastisel.
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kind of predicate: one that is specific to imm nodes. The predicate function
specified here just checks an int64_t directly instead of messing around with
SDNode's. The virtue of this is that it means that fastisel and other things
can reason about these predicates.
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structure and fix some fixmes. We now have a TreePredicateFn class
that handles all of the decoding of these things. This is an internal
cleanup that has no impact on the code generated by tblgen.
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