To match the cost of other scheduling models. This is expected to
schedule mov instructions around INLINEASM less frequently for the
default machineschedule (pre-RA scheduling).
Suggested by Craig Topper.
Link: https://github.com/llvm/llvm-project/issues/41914
Reviewed By: RKSimon
Differential Revision: https://reviews.llvm.org/D122350
This patch contains following enhancements to SrcRegMap and DstRegMap:
1 In findOnlyInterestingUse not only check if the Reg is two address usage,
but also check after commutation can it be two address usage.
2 If a physical register is clobbered, remove SrcRegMap entries that are
mapped to it.
3 In processTiedPairs, when create a new COPY instruction, add a SrcRegMap
entry only when the COPY instruction is coalescable. (The COPY src is
killed)
With these enhancements isProfitableToCommute can do better commute decision,
and finally more register copies are removed.
Differential Revision: https://reviews.llvm.org/D108731
Other <math>_finite calls are marked as unavailable except on GNU/Linux;
it looks like the sqrt set was just overlooked.
Differential Revision: https://reviews.llvm.org/D110418
According to IR LangRef, the FMF flag:
contract
Allow floating-point contraction (e.g. fusing a multiply followed by an
addition into a fused multiply-and-add).
reassoc
Allow reassociation transformations for floating-point instructions.
This may dramatically change results in floating-point.
My understanding is that these two flags shouldn't imply each other,
as we might have a SDNode that can be reassociated with others, but
not contractble.
eg: We may want following fmul/fad/fsub to freely reassoc, but don't
want fma being generated here.
%F = fmul reassoc double %A, %B ; <double> [#uses=1]
%G = fmul reassoc double %C, %D ; <double> [#uses=1]
%H = fadd reassoc double %F, %G ; <double> [#uses=1]
%I = fsub reassoc double %H, %E ; <double> [#uses=1]
Before https://reviews.llvm.org/D45710, `reassoc` flag actually
did not imply isContratable either.
The current implementation also only check the flag in fadd node,
ignoring fmul node, this patch update that as well.
Reviewed By: spatel, qiucf
Differential Revision: https://reviews.llvm.org/D104247
The motivation is that the update script has at least two deviations
(`<...>@GOT`/`<...>@PLT`/ and not hiding pointer arithmetics) from
what pretty much all the checklines were generated with,
and most of the tests are still not updated, so each time one of the
non-up-to-date tests is updated to see the effect of the code change,
there is a lot of noise. Instead of having to deal with that each
time, let's just deal with everything at once.
This has been done via:
```
cd llvm-project/llvm/test/CodeGen/X86
grep -rl "; NOTE: Assertions have been autogenerated by utils/update_llc_test_checks.py" | xargs -L1 <...>/llvm-project/llvm/utils/update_llc_test_checks.py --llc-binary <...>/llvm-project/build/bin/llc
```
Not all tests were regenerated, however.
We are checking the unsafe-fp-math for sqrt but not for fpow, which behaves inconsistent.
As the direction is to remove this global option, we need to remove the unsafe-fp-math
check for sqrt and update the test with afn fast-math flags.
Reviewed By: Spatel
Differential Revision: https://reviews.llvm.org/D93891
I tried to fix this in:
rG716e35a0cf53
...but that patch depends on the order that we encounter the
magic "x/sqrt(x)" expression in the combiner's worklist.
This patch should improve that by waiting until we walk the
user list to decide if there's a use to skip.
The AArch64 test reveals another (existing) ordering problem
though - we may try to create an estimate for plain sqrt(x)
before we see that it is part of a 1/sqrt(x) expression.
In general, we probably want to try the multi-use reciprocal
transform before sqrt transforms, but x/sqrt(x) is a special-case
because that will always reduce to plain sqrt(x) or an estimate.
The AArch64 tests show that the transform is limited by TLI
hook to patterns where there are 3 or more uses of the divisor.
So this change can result in an extra division compared to
what we had, but that's the intended behvior based on the
current setting of that hook.
With FMF ( "nsz" and " reassoc") fold X/Sqrt(X) to Sqrt(X).
This is done after targets have the chance to produce a
reciprocal sqrt estimate sequence because that expansion
is probably more efficient than an expansion of a
non-reciprocal sqrt. That is also why we deferred doing
this transform in IR (D85709).
Differential Revision: https://reviews.llvm.org/D86403
Follow-up to D82716 / rGea71ba11ab11
We do not have the fabs removal fold in IR yet for the case
where the sqrt operand is repeated, so that's another potential
improvement.
X / (fabs(A) * sqrt(Z)) --> X / sqrt(A*A*Z) --> X * rsqrt(A*A*Z)
In the motivating case from PR46406:
https://bugs.llvm.org/show_bug.cgi?id=46406
...this is restoring the sequence that was originally in the source code.
We extracted a term from within the sqrt because we do not know in
instcombine whether a target will expand a sqrt call.
Note: we could say that the transform in IR should be restricted, but
that would not solve the problem if the source was originally in the
pattern shown here.
This is a gray area for fast-math-flag requirements. I think we should at
least check fast-math-flags on the fdiv and fmul because I view this
transform as 2 pieces: reassociate the fmul operands and form reciprocal
from the fdiv (as with the existing transform). We could argue that the
sqrt also needs FMF, but that was not required before, so we should change
that in a follow-up patch if that seems better.
We don't currently have a way to check that the target will produce a sqrt
or recip estimate without actually creating nodes (the APIs are SDValue
getSqrtEstimate() and SDValue getRecipEstimate()), so we clean up
speculatively created nodes if we are not able to create an estimate.
The x86 test with doubles verifies that we are not changing a test with
no estimate sequence.
Differential Revision: https://reviews.llvm.org/D82716
Currently, DAG combiner uses (fmul (rsqrt x) x) to estimate square
root of x. However, this method would return NaN if x is +Inf, which
is incorrect.
Reviewed By: spatel
Differential Revision: https://reviews.llvm.org/D76853
The code changes here are hopefully straightforward:
1. Use MachineInstruction flags to decide if FP ops can be reassociated
(use both "reassoc" and "nsz" to be consistent with IR transforms;
we probably don't need "nsz", but that's a safer interpretation of
the FMF).
2. Check that both nodes allow reassociation to change instructions.
This is a stronger requirement than we've usually implemented in
IR/DAG, but this is needed to solve the motivating bug (see below),
and it seems unlikely to impede optimization at this late stage.
3. Intersect/propagate MachineIR flags to enable further reassociation
in MachineCombiner.
We managed to make MachineCombiner flexible enough that no changes are
needed to that pass itself. So this patch should only affect x86
(assuming no other targets have implemented the hooks using MachineIR
flags yet).
The motivating example in PR43609 is another case of fast-math transforms
interacting badly with special FP ops created during lowering:
https://bugs.llvm.org/show_bug.cgi?id=43609
The special fadd ops used for converting int to FP assume that they will
not be altered, so those are created without FMF.
However, the MachineCombiner pass was being enabled for FP ops using the
global/function-level TargetOption for "UnsafeFPMath". We managed to run
instruction/node-level FMF all the way down to MachineIR sometime in the
last 1-2 years though, so we can do better now.
The test diffs require some explanation:
1. llvm/test/CodeGen/X86/fmf-flags.ll - no target option for unsafe math was
specified here, so MachineCombiner kicks in where it did not previously;
to make it behave consistently, we need to specify a CPU schedule model,
so use the default model, and there are no code diffs.
2. llvm/test/CodeGen/X86/machine-combiner.ll - replace the target option for
unsafe math with the equivalent IR-level flags, and there are no code diffs;
we can't remove the NaN/nsz options because those are still used to drive
x86 fmin/fmax codegen (special SDAG opcodes).
3. llvm/test/CodeGen/X86/pow.ll - similar to #1
4. llvm/test/CodeGen/X86/sqrt-fastmath.ll - similar to #1, but MachineCombiner
does some reassociation of the estimate sequence ops; presumably these are
perf wins based on latency/throughput (and we get some reduction of move
instructions too); I'm not sure how it affects numerical accuracy, but the
test reflects reality better now because we would expect MachineCombiner to
be enabled if the IR was generated via something like "-ffast-math" with clang.
5. llvm/test/CodeGen/X86/vec_int_to_fp.ll - this is the test added to model PR43609;
the fadds are not reassociated now, so we should get the expected results.
6. llvm/test/CodeGen/X86/vector-reduce-fadd-fast.ll - similar to #1
7. llvm/test/CodeGen/X86/vector-reduce-fmul-fast.ll - similar to #1
Differential Revision: https://reviews.llvm.org/D74851
We have isel patterns that can put an IMPLICIT_DEF on one of
the sources for these instructions. So we should make sure
we break any dependencies there. This should be done by
just using one of the other sources.
llvm-svn: 373025
When the floating point constants are whole numbers they have no decimal point so look like integers, but mean something very different in something like an 'and' instruction.
Ideally we would just print a decimal point and a 0, but I couldn't see how to make APFloat::toString do that.
llvm-svn: 345488
Consistently try to use APFloat::toString for floating point constant comments to get rid of differences between Constant / ConstantDataSequential values - it should help stop some of the linux-windows buildbot failures matching NaN/INF etc. as well.
Differential Revision: https://reviews.llvm.org/D52702
llvm-svn: 343562
Summary:
The legacy VRCPPS/VRSQRTPS instructions aren't available in 512-bit versions. The new increased precision versions are. So we can use those to implement v16f32 reciprocal estimates.
For KNL CPUs we can probably use VRCP28PS/VRSQRT28PS and avoid the NR step altogether, but I leave that for a future patch.
Reviewers: spatel
Reviewed By: spatel
Subscribers: RKSimon, llvm-commits, mehdi_amini
Differential Revision: https://reviews.llvm.org/D46498
llvm-svn: 331606
Re-enable commit r323991 now that r325931 has been committed to make
MachineOperand::isRenamable() check more conservative w.r.t. code
changes and opt-in on a per-target basis.
llvm-svn: 326208
This reverts commit r323991.
This commit breaks target that don't model all the register constraints
in TableGen. So far the workaround was to set the
hasExtraXXXRegAllocReq, but it proves that it doesn't cover all the
cases.
For instance, when mutating an instruction (like in the lowering of
COPYs) the isRenamable flag is not properly updated. The same problem
will happen when attaching machine operand from one instruction to
another.
Geoff Berry is working on a fix in https://reviews.llvm.org/D43042.
llvm-svn: 325421
Summary:
This change extends MachineCopyPropagation to do COPY source forwarding
and adds an additional run of the pass to the default pass pipeline just
after register allocation.
This version of this patch uses the newly added
MachineOperand::isRenamable bit to avoid forwarding registers is such a
way as to violate constraints that aren't captured in the
Machine IR (e.g. ABI or ISA constraints).
This change is a continuation of the work started in D30751.
Reviewers: qcolombet, javed.absar, MatzeB, jonpa, tstellar
Subscribers: tpr, mgorny, mcrosier, nhaehnle, nemanjai, jyknight, hfinkel, arsenm, inouehrs, eraman, sdardis, guyblank, fedor.sergeev, aheejin, dschuff, jfb, myatsina, llvm-commits
Differential Revision: https://reviews.llvm.org/D41835
llvm-svn: 323991
As shown in the example in PR34994:
https://bugs.llvm.org/show_bug.cgi?id=34994
...we can return a very wrong answer (inf instead of 0.0) for square root when
using a reciprocal square root estimate instruction.
Here, I've conditionalized the filtering out of denorms based on the function
having "denormal-fp-math"="ieee" in its attributes. The other options for this
attribute are 'preserve-sign' and 'positive-zero'.
So we don't generate this extra code by default with just '-ffast-math' (because
then there's no denormal attribute string at all), but it works if you specify
'-ffast-math -fdenormal-fp-math=ieee' from clang.
As noted in the review, there may be other problems in clang that affect the
results depending on platform (Linux x86 at least), but this should allow
creating the desired codegen.
Differential Revision: https://reviews.llvm.org/D42323
llvm-svn: 323981
As part of the unification of the debug format and the MIR format, print
MBB references as '%bb.5'.
The MIR printer prints the IR name of a MBB only for block definitions.
* find . \( -name "*.mir" -o -name "*.cpp" -o -name "*.h" -o -name "*.ll" \) -type f -print0 | xargs -0 sed -i '' -E 's/BB#" << ([a-zA-Z0-9_]+)->getNumber\(\)/" << printMBBReference(*\1)/g'
* find . \( -name "*.mir" -o -name "*.cpp" -o -name "*.h" -o -name "*.ll" \) -type f -print0 | xargs -0 sed -i '' -E 's/BB#" << ([a-zA-Z0-9_]+)\.getNumber\(\)/" << printMBBReference(\1)/g'
* find . \( -name "*.txt" -o -name "*.s" -o -name "*.mir" -o -name "*.cpp" -o -name "*.h" -o -name "*.ll" \) -type f -print0 | xargs -0 sed -i '' -E 's/BB#([0-9]+)/%bb.\1/g'
* grep -nr 'BB#' and fix
Differential Revision: https://reviews.llvm.org/D40422
llvm-svn: 319665
Issues addressed since original review:
- Avoid bug in regalloc greedy/machine verifier when forwarding to use
in an instruction that re-defines the same virtual register.
- Fixed bug when forwarding to use in EarlyClobber instruction slot.
- Fixed incorrect forwarding to register definitions that showed up in
explicit_uses() iterator (e.g. in INLINEASM).
- Moved removal of dead instructions found by
LiveIntervals::shrinkToUses() outside of loop iterating over
instructions to avoid instructions being deleted while pointed to by
iterator.
- Fixed ARMLoadStoreOptimizer bug exposed by this change in r311907.
- The pass no longer forwards COPYs to physical register uses, since
doing so can break code that implicitly relies on the physical
register number of the use.
- The pass no longer forwards COPYs to undef uses, since doing so
can break the machine verifier by creating LiveRanges that don't
end on a use (since the undef operand is not considered a use).
[MachineCopyPropagation] Extend pass to do COPY source forwarding
This change extends MachineCopyPropagation to do COPY source forwarding.
This change also extends the MachineCopyPropagation pass to be able to
be run during register allocation, after physical registers have been
assigned, but before the virtual registers have been re-written, which
allows it to remove virtual register COPY LiveIntervals that become dead
through the forwarding of all of their uses.
llvm-svn: 314729
Issues addressed since original review:
- Moved removal of dead instructions found by
LiveIntervals::shrinkToUses() outside of loop iterating over
instructions to avoid instructions being deleted while pointed to by
iterator.
- Fixed ARMLoadStoreOptimizer bug exposed by this change in r311907.
- The pass no longer forwards COPYs to physical register uses, since
doing so can break code that implicitly relies on the physical
register number of the use.
- The pass no longer forwards COPYs to undef uses, since doing so
can break the machine verifier by creating LiveRanges that don't
end on a use (since the undef operand is not considered a use).
[MachineCopyPropagation] Extend pass to do COPY source forwarding
This change extends MachineCopyPropagation to do COPY source forwarding.
This change also extends the MachineCopyPropagation pass to be able to
be run during register allocation, after physical registers have been
assigned, but before the virtual registers have been re-written, which
allows it to remove virtual register COPY LiveIntervals that become dead
through the forwarding of all of their uses.
llvm-svn: 312328
It caused PR34387: Assertion failed: (RegNo < NumRegs && "Attempting to access record for invalid register number!")
> Issues identified by buildbots addressed since original review:
> - Fixed ARMLoadStoreOptimizer bug exposed by this change in r311907.
> - The pass no longer forwards COPYs to physical register uses, since
> doing so can break code that implicitly relies on the physical
> register number of the use.
> - The pass no longer forwards COPYs to undef uses, since doing so
> can break the machine verifier by creating LiveRanges that don't
> end on a use (since the undef operand is not considered a use).
>
> [MachineCopyPropagation] Extend pass to do COPY source forwarding
>
> This change extends MachineCopyPropagation to do COPY source forwarding.
>
> This change also extends the MachineCopyPropagation pass to be able to
> be run during register allocation, after physical registers have been
> assigned, but before the virtual registers have been re-written, which
> allows it to remove virtual register COPY LiveIntervals that become dead
> through the forwarding of all of their uses.
llvm-svn: 312178
Issues identified by buildbots addressed since original review:
- Fixed ARMLoadStoreOptimizer bug exposed by this change in r311907.
- The pass no longer forwards COPYs to physical register uses, since
doing so can break code that implicitly relies on the physical
register number of the use.
- The pass no longer forwards COPYs to undef uses, since doing so
can break the machine verifier by creating LiveRanges that don't
end on a use (since the undef operand is not considered a use).
[MachineCopyPropagation] Extend pass to do COPY source forwarding
This change extends MachineCopyPropagation to do COPY source forwarding.
This change also extends the MachineCopyPropagation pass to be able to
be run during register allocation, after physical registers have been
assigned, but before the virtual registers have been re-written, which
allows it to remove virtual register COPY LiveIntervals that become dead
through the forwarding of all of their uses.
llvm-svn: 312154
Two issues identified by buildbots were addressed:
- The pass no longer forwards COPYs to physical register uses, since
doing so can break code that implicitly relies on the physical
register number of the use.
- The pass no longer forwards COPYs to undef uses, since doing so
can break the machine verifier by creating LiveRanges that don't
end on a use (since the undef operand is not considered a use).
[MachineCopyPropagation] Extend pass to do COPY source forwarding
This change extends MachineCopyPropagation to do COPY source forwarding.
This change also extends the MachineCopyPropagation pass to be able to
be run during register allocation, after physical registers have been
assigned, but before the virtual registers have been re-written, which
allows it to remove virtual register COPY LiveIntervals that become dead
through the forwarding of all of their uses.
Reviewers: qcolombet, javed.absar, MatzeB, jonpa
Subscribers: jyknight, nemanjai, llvm-commits, nhaehnle, mcrosier, mgorny
Differential Revision: https://reviews.llvm.org/D30751
llvm-svn: 311135
This reverts commit r311038.
Several buildbots are breaking, and at least one appears to be due to
the forwarding of physical regs enabled by this change. Reverting while
I investigate further.
llvm-svn: 311062
This change extends MachineCopyPropagation to do COPY source forwarding.
This change also extends the MachineCopyPropagation pass to be able to
be run during register allocation, after physical registers have been
assigned, but before the virtual registers have been re-written, which
allows it to remove virtual register COPY LiveIntervals that become dead
through the forwarding of all of their uses.
Reviewers: qcolombet, javed.absar, MatzeB, jonpa
Subscribers: jyknight, nemanjai, llvm-commits, nhaehnle, mcrosier, mgorny
Differential Revision: https://reviews.llvm.org/D30751
llvm-svn: 311038
The motivation for the change is that we can't have pseudo-global settings for
codegen living in TargetOptions because that doesn't work with LTO.
Ideally, these reciprocal attributes will be moved to the instruction-level via
FMF, metadata, or something else. But making them function attributes is at least
an improvement over the current state.
The ingredients of this patch are:
Remove the reciprocal estimate command-line debug option.
Add TargetRecip to TargetLowering.
Remove TargetRecip from TargetOptions.
Clean up the TargetRecip implementation to work with this new scheme.
Set the default reciprocal settings in TargetLoweringBase (everything is off).
Update the PowerPC defaults, users, and tests.
Update the x86 defaults, users, and tests.
Note that if this patch needs to be reverted, the related clang patch checked in
at r283251 should be reverted too.
Differential Revision: https://reviews.llvm.org/D24816
llvm-svn: 283252
When calculating a square root using Newton-Raphson with two constants,
a naive implementation is to use five multiplications (four muls to calculate
reciprocal square root and another one to calculate the square root itself).
However, after some reassociation and CSE the same result can be obtained
with only four multiplications. Unfortunately, there's no reliable way to do
such a reassociation in the back-end. So, the patch modifies NR code itself
so that it directly builds optimal code for SQRT and doesn't rely on any
further reassociation.
Patch by Nikolai Bozhenov!
Differential Revision: http://reviews.llvm.org/D21127
llvm-svn: 272920
autogenerated.
Also update existing test cases which appear to be generated by it and
weren't modified (other than addition of the header) by rerunning it.
llvm-svn: 253917
