The height on an instruction is the minimum number of cycles from the
instruction is issued to the end of the trace. Heights are computed for
all instructions in and below the trace center block.
The method for computing heights is different from the depth
computation. As we visit instructions in the trace bottom-up, heights of
used instructions are pushed upwards. This way, we avoid scanning long
use lists, looking for uses in the current trace.
At each basic block boundary, a list of live-in registers and their
minimum heights is saved in the trace block info. These live-in lists
are used when restarting depth computations on a trace that
converges with an already computed trace. They will also be used to
accurately compute the critical path length.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@161138 91177308-0d34-0410-b5e6-96231b3b80d8
Assuming infinite issue width, compute the earliest each instruction in
the trace can issue, when considering the latency of data dependencies.
The issue cycle is record as a 'depth' from the beginning of the trace.
This is half the computation required to find the length of the critical
path through the trace. Heights are next.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@161074 91177308-0d34-0410-b5e6-96231b3b80d8
One motivating example is to sink an instruction from a basic block which has
two successors: one outside the loop, the other inside the loop. We should try
to sink the instruction outside the loop.
rdar://11980766
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@161062 91177308-0d34-0410-b5e6-96231b3b80d8
We are extending live ranges, so kill flags are not accurate. They
aren't needed until they are recomputed after RA anyway.
<rdar://problem/11950722>
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@161023 91177308-0d34-0410-b5e6-96231b3b80d8
We branch to the successor with higher edge weight first.
Convert from
je LBB4_8 --> to outer loop
jmp LBB4_14 --> to inner loop
to
jne LBB4_14
jmp LBB4_8
PR12750
rdar: 11393714
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@161018 91177308-0d34-0410-b5e6-96231b3b80d8
This lets traces include the final iteration of a nested loop above the
center block, and the first iteration of a nested loop below the center
block.
We still don't allow traces to contain backedges, and traces are
truncated where they would leave a loop, as seen from the center block.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@161003 91177308-0d34-0410-b5e6-96231b3b80d8
When computing a trace, all the candidates for pred/succ must have been
visited. Filter out back-edges first, though. The PO traversal ignores
them.
Thanks to Andy for spotting this in review.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@160995 91177308-0d34-0410-b5e6-96231b3b80d8
This is a cleaned up version of the isFree() function in
MachineTraceMetrics.cpp.
Transient instructions are very unlikely to produce any code in the
final output. Either because they get eliminated by RegisterCoalescing,
or because they are pseudo-instructions like labels and debug values.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@160977 91177308-0d34-0410-b5e6-96231b3b80d8
The MachineTraceMetrics analysis must be invalidated before modifying
the CFG. This will catch some of the violations of that rule.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@160969 91177308-0d34-0410-b5e6-96231b3b80d8
A->isPredecessor(B) is the same as B->isSuccessor(A), but it can
tolerate a B that is null or dangling. This shouldn't happen normally,
but it it useful for verification code.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@160968 91177308-0d34-0410-b5e6-96231b3b80d8
Machine CSE and other optimizations can remove instructions so folding
is possible at peephole while not possible at ISel.
rdar://10554090 and rdar://11873276
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@160919 91177308-0d34-0410-b5e6-96231b3b80d8
A value number is a PHI def if and only if it begins at a block
boundary. This can be derived from the def slot, a separate flag is not
necessary.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@160893 91177308-0d34-0410-b5e6-96231b3b80d8
This option replaces the existing live interval computation with one
based on LiveRangeCalc.cpp. The new algorithm does not depend on
LiveVariables, and it can be run at any time, before or after leaving
SSA form.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@160892 91177308-0d34-0410-b5e6-96231b3b80d8
This is still a work in progress.
Out-of-order CPUs usually execute instructions from multiple basic
blocks simultaneously, so it is necessary to look at longer traces when
estimating the performance effects of code transformations.
The MachineTraceMetrics analysis will pick a typical trace through a
given basic block and provide performance metrics for the trace. Metrics
will include:
- Instruction count through the trace.
- Issue count per functional unit.
- Critical path length, and per-instruction 'slack'.
These metrics can be used to determine the performance limiting factor
when executing the trace, and how it will be affected by a code
transformation.
Initially, this will be used by the early if-conversion pass.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@160796 91177308-0d34-0410-b5e6-96231b3b80d8
It is redundant; RegisterCoalescer will do the remat if it can't eliminate
the copy. Collected instruction counts before and after this. A few extra
instructions are generated due to spilling but it is normal to see these kinds
of changes with almost any small codegen change, according to Jakob.
This also fixed rdar://11830760 where xor is expected instead of movi0.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@160749 91177308-0d34-0410-b5e6-96231b3b80d8
When a live range splits into multiple connected components, we would
arbitrarily assign <undef> uses to component 0. This is wrong when the
use is tied to a def that gets assigned to a different component:
%vreg69<def> = ADD8ri %vreg68<undef>, 1
The use and def must get the same virtual register.
Fix this by assigning <undef> uses to the same component as the value
defined by the instruction, if any:
%vreg69<def> = ADD8ri %vreg69<undef>, 1
This fixes PR13402. The PR has a test case which I am not including
because it is unlikely to keep exposing this behavior in the future.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@160739 91177308-0d34-0410-b5e6-96231b3b80d8
that do not support it (X86 does not lower select_cc).
PR: 13428
Together with Michael Kuperstein <michael.m.kuperstein@intel.com>
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@160619 91177308-0d34-0410-b5e6-96231b3b80d8
LiveRangeEdit::foldAsLoad() can eliminate a register by folding a load
into its only use. Only do that when the load is safe to move, and it
won't extend any live ranges.
This fixes PR13414.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@160575 91177308-0d34-0410-b5e6-96231b3b80d8
PHIElimination splits critical edges when it predicts it can resolve
interference and eliminate copies. It doesn't split the edge if the
interference wouldn't be resolved anyway because the phi-use register is
live in the critical edge anyway.
Teach PHIElimination to split loop exiting edges with interference, even
if it wouldn't resolve the interference. This removes the necessary
copies from the loop, which is still an improvement from injecting the
copies into the loop.
The test case demonstrates the improvement. Before:
LBB0_1:
cmpb $0, (%rdx)
leaq 1(%rdx), %rdx
movl %esi, %eax
je LBB0_1
After:
LBB0_1:
cmpb $0, (%rdx)
leaq 1(%rdx), %rdx
je LBB0_1
movl %esi, %eax
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@160571 91177308-0d34-0410-b5e6-96231b3b80d8
LiveIntervals due to the two-addr pass generating bogus MI code.
The crux of the issue was a loop nesting problem. The intent of the code
which attempts to transform instructions before converting them to
two-addr form is to defer and reprocess any transformed instructions as
the second processing is likely to have more opportunities to coalesce
copies, etc. Unfortunately, there was one section of processing that was
not deferred -- the INSERT_SUBREG rewriting. Due to quirks of how this
rewriting proceeded, not only did it occur early, it removed the bits of
information needed for the deferred processing to correctly generate the
necessary two address form (specifically inserting a copy), but didn't
trigger any immediate assertions and produced what appeared to be
already valid two-address from code. Thus, the assertion only fired much
later in the pipeline.
The fix is to hoist the transformation logic up layer to where it can
more firmly defer all further processing, and to teach the normal
processing to handle an edge case previously handled as part of the
transformation logic. This edge case (already matched tied register
operands) needs to *not* defer any steps.
As has been brought up repeatedly in the process: wow does this code
need refactoring. I *may* squeeze in some time to at least bring sanity
to this loop... but wow... =]
Thanks to Jakob for helpful hints on the way here, and the review.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@160443 91177308-0d34-0410-b5e6-96231b3b80d8
When truncating a result of a vector that is split we need
to use the result of the split vector, and not re-split the dead node.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@160357 91177308-0d34-0410-b5e6-96231b3b80d8
large immediates. Add dag combine logic to recover in case the large
immediates doesn't fit in cmp immediate operand field.
int foo(unsigned long l) {
return (l>> 47) == 1;
}
we produce
%shr.mask = and i64 %l, -140737488355328
%cmp = icmp eq i64 %shr.mask, 140737488355328
%conv = zext i1 %cmp to i32
ret i32 %conv
which codegens to
movq $0xffff800000000000,%rax
andq %rdi,%rax
movq $0x0000800000000000,%rcx
cmpq %rcx,%rax
sete %al
movzbl %al,%eax
ret
TargetLowering::SimplifySetCC would transform
(X & -256) == 256 -> (X >> 8) == 1
if the immediate fails the isLegalICmpImmediate() test. For x86,
that's immediates which are not a signed 32-bit immediate.
Based on a patch by Eli Friedman.
PR10328
rdar://9758774
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@160346 91177308-0d34-0410-b5e6-96231b3b80d8
In the added testcase the constant 55 was behind an AssertZext of type i1, and ComputeDemandedBits
reported that some of the bits were both known to be one and known to be zero.
Together with Michael Kuperstein <michael.m.kuperstein@intel.com>
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@160305 91177308-0d34-0410-b5e6-96231b3b80d8
Add a micro-optimization to getNode of CONCAT_VECTORS when both operands are undefs.
Can't find a testcase for this because VECTOR_SHUFFLE already handles undef operands, but Duncan suggested that we add this.
Together with Michael Kuperstein <michael.m.kuperstein@intel.com>
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@160229 91177308-0d34-0410-b5e6-96231b3b80d8
The notable fix is to look at any dependencies attached to the kill
instruction (or other instructions between MI nad the kill) where the
dependencies are specific to the register in question.
The old code implicitly handled this by rejecting the transform if *any*
other uses were found within the block, but after the start point. The
new code directly finds the kill, and has to re-use the existing
dependency scan to check for non-kill uses.
This was caught by self-host, but I found the bug via inspection and use
of absurd assert scaffolding to compute the kills in two ways and
compare them. So I have no useful testcase for this other than
"bootstrap". I'd work harder to reduce a test case if this particular
code were likely to live for a long time.
Thanks to Benjamin Kramer for reviewing the fix itself.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@160228 91177308-0d34-0410-b5e6-96231b3b80d8
Catch uses of undefined physregs that haven't been added to basic block
live-in lists. Run the verifier to pinpoint the problem.
Also run the verifier when a virtual register use is not jointly
dominated by defs.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@160207 91177308-0d34-0410-b5e6-96231b3b80d8
removes the largest scaling problem in the test cases from PR13225 when
ASan is switched to insert basic blocks in the natural CFG order.
It may also solve some scaling problems for more normal code with large
numbers of basic blocks and variables.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@160194 91177308-0d34-0410-b5e6-96231b3b80d8
When dumping the DAG for a fatal 'Cannot select' back-end error, also
provide the name of the function the construct is in. Useful when dealing
with large testcases, as the next step is to llvm-extract the function
in question to get a small(er) testcase.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@160152 91177308-0d34-0410-b5e6-96231b3b80d8
the input vector, it can be bigger (this is helpful for powerpc where <2 x i16>
is a legal vector type but i16 isn't a legal type, IIRC). However this wasn't
being taken into account by ExpandRes_EXTRACT_VECTOR_ELT, causing PR13220.
Lightly tweaked version of a patch by Michael Liao.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@160116 91177308-0d34-0410-b5e6-96231b3b80d8
r1025 = s/zext r1024, 4
r1026 = extract_subreg r1025, 4
to a copy:
r1026 = copy r1024
This is correct. However it uses TII->isCoalescableExtInstr() which can return
true for instructions which essentially does a sext_in_reg so this can end up
with an illegal copy where the source and destination register classes do not
match. Add a check to avoid it. Sorry, no test case possible at this time.
rdar://11849816
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@160059 91177308-0d34-0410-b5e6-96231b3b80d8
generalizing its implementation sufficiently to support this value
number scenario as well.
This cuts out another significant performance hit in large functions
(over 10k basic blocks, etc), especially those with "natural" CFG
structures.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@160026 91177308-0d34-0410-b5e6-96231b3b80d8
This ordering allows nested if-conversion without using a work list, and
it makes it possible to update the dominator tree on the fly as well.
Any erased basic blocks will always be dominated by the current
post-order position, so the domtree can be pruned without invalidating
the iterator.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@160025 91177308-0d34-0410-b5e6-96231b3b80d8
back of it.
I don't have anything even remotely close to a test case for this. It
only broke two build bots, both of them doing bootstrap builds, one of
them a dragonegg bootstrap. It doesn't break for me when I bootstrap
either. It doesn't reproduce every time or on many machines during the
bootstrap. Many thanks to Duncan Sands who got the exact command (and
stage of the bootstrap) which failed on the dragonegg bootstrap and
managed to get it to trigger under valgrind with debug symbols. The fix
was then found by inspection.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@159993 91177308-0d34-0410-b5e6-96231b3b80d8
multiple scalars and insert them into a vector. Next, we shuffle the elements
into the correct places, as before.
Also fix a small dagcombine bug in SimplifyBinOpWithSameOpcodeHands, when the
migration of bitcasts happened too late in the SelectionDAG process.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@159991 91177308-0d34-0410-b5e6-96231b3b80d8
quadratic behavior when performing pathological merges. Fixes the core
element of PR12652.
There is only one user of addRangeFrom left: join. I'm hoping to
refactor further in a future patch and have join use this merge
operation as well.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@159982 91177308-0d34-0410-b5e6-96231b3b80d8
of the trick merge routines. This adds a layer of testing that was
necessary when implementing more efficient (and complex) merge logic for
this datastructure.
No functionality changed here.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@159981 91177308-0d34-0410-b5e6-96231b3b80d8
Previously, this would become an integer extension operation, followed by a real integer->float conversion.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@159957 91177308-0d34-0410-b5e6-96231b3b80d8
subtarget CPU descriptions and support new features of
MachineScheduler.
MachineModel has three categories of data:
1) Basic properties for coarse grained instruction cost model.
2) Scheduler Read/Write resources for simple per-opcode and operand cost model (TBD).
3) Instruction itineraties for detailed per-cycle reservation tables.
These will all live side-by-side. Any subtarget can use any
combination of them. Instruction itineraries will not change in the
near term. In the long run, I expect them to only be relevant for
in-order VLIW machines that have complex contraints and require a
precise scheduling/bundling model. Once itineraries are only actively
used by VLIW-ish targets, they could be replaced by something more
appropriate for those targets.
This tablegen backend rewrite sets things up for introducing
MachineModel type #2: per opcode/operand cost model.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@159891 91177308-0d34-0410-b5e6-96231b3b80d8
DwarfDebug class could generate the same (inlined) DIVariable twice:
1) when trying to find abstract debug variable for a concrete inlined instance.
2) when explicitly collecting info for variables that were optimized out.
This change makes sure that this duplication won't happen and makes
Clang pass "gdb.opt/inline-locals" test from gdb testsuite.
Reviewed by Eric Christopher.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@159811 91177308-0d34-0410-b5e6-96231b3b80d8
hash_value overload for MachineOperands. This addresses a FIXME
sufficient for me to remove it, and cleans up the code nicely too.
The important changes to the hashing logic:
- TargetFlags are now included in all of the hashes. These were complete
missed.
- Register operands have their subregisters and whether they are a def
included in the hash.
- We now actually hash all of the operand types. Previously, many
operand types were simply *dropped on the floor*. For example:
- Floating point immediates
- Large integer immediates (>64-bit)
- External globals!
- Register masks
- Metadata operands
- It removes the offset from the block-address hash; I'm a bit
suspicious of this, but isIdenticalTo doesn't consider the offset for
black addresses.
Any patterns involving these entities could have triggered extreme
slowdowns in MachineCSE or PHIElimination. Let me know if there are PRs
you think might be closed now... I'm looking myself, but I may miss
them.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@159743 91177308-0d34-0410-b5e6-96231b3b80d8
broken. This patch fixes the superficial problems which lead to the
intractably slow compile times reported in PR13225.
The specific issue is that we were failing to include the *offset* of
a global variable in the hash code. Oops. This would in turn cause all
MIs which were only distinguishable due to operating on different
offsets of a global variable to produce identical hash functions. In
some of the test cases attached to the PR I saw hash table activity
where there were O(1000) probes-per-lookup *on average*. A very few
entries were responsible for most of these probes.
There is still quite a bit more to do here. The ad-hoc layering of data
in MachineOperands makes them *extremely* brittle to hash correctly.
We're missing quite a few other cases, the only ones I've fixed here are
the specific MO types which were allowed through the assert() in
getOffset().
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@159741 91177308-0d34-0410-b5e6-96231b3b80d8
change.
Move the "Not profitable, avoid CSE!" debug message next to where we fail the
check for profitability and use a different message for avoiding CSE due to
being in different register classes.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@159729 91177308-0d34-0410-b5e6-96231b3b80d8
Also allow trailing register mask operands on non-variadic both
MachineSDNodes and MachineInstrs.
The extra physreg RegisterSDNode operands are added to the MI as
<imp-use> operands. This makes it possible to have non-variadic call
instructions.
Call and return instructions really are non-variadic, the argument
registers should only be used implicitly - they are not part of the
encoding.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@159727 91177308-0d34-0410-b5e6-96231b3b80d8
