Summary: X86 has instructions to calculate fma and fneg at the same time. But we combine the fneg and fma only when fneg is the source operand under strict FP.
Reviewers: craig.topper, andrew.w.kaylor, uweigand, RKSimon, LiuChen3
Subscribers: LuoYuanke, llvm-commits, cfe-commits, jdoerfert, hiraditya
Tags: #llvm
Differential Revision: https://reviews.llvm.org/D72824
Many of our instructions have both a _Int form used by intrinsics and a form
used by other IR constructs. In the EVEX space the _Int versions usually cover
all the capabilities include broadcasting and rounding. While the other version
only covers simple register/register or register/load forms. For this reason
in EVEX, the non intrinsic form is usually marked isCodeGenOnly=1.
In the VEX encoding space we were less consistent, but usually the _Int version
was the isCodeGenOnly version.
This commit makes the VEX instructions match the EVEX instructions. This was
done by manually studying the AsmMatcher table so its possible I missed some
cases, but we should be closer now.
I'm thinking about using the isCodeGenOnly bit to simplify the EVEX2VEX
tablegen code that disambiguates the _Int and non _Int versions. Currently it
checks register class sizes and Record the memory operands come from. I have
some other changes I was looking into for D59266 that may break the memory check.
I had to make a few scheduler hacks to keep the _Int versions from being treated
differently than the non _Int version.
Differential Revision: https://reviews.llvm.org/D60441
llvm-svn: 358138
to reflect the new license.
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repository.
llvm-svn: 351636
Currently we hardcode instructions with ReadAfterLd if the register operands don't need to be available until the folded load has completed. This doesn't take into account the different load latencies of different memory operands (PR36957).
This patch adds a ReadAfterFold def into X86FoldableSchedWrite to replace ReadAfterLd, allowing us to specify the load latency at a scheduler class level.
I've added ReadAfterVec*Ld classes that match the XMM/Scl, XMM and YMM/ZMM WriteVecLoad classes that we currently use, we can tweak these values in future patches once this infrastructure is in place.
Differential Revision: https://reviews.llvm.org/D52886
llvm-svn: 343868
This allows us to use 231 form to fold an insertelement on the add input to the fma. There is technically no software intrinsic that can use this until AVX512F, but it can be manually built up from other intrinsics.
llvm-svn: 337223
This unfortunately requires a bunch of bitcasts to be added added to SUBREG_TO_REG, COPY_TO_REGCLASS, and instructions in output patterns. Otherwise tablegen seems to default to picking f128 and then we fail when something tries to get the register class for f128 which isn't always valid.
The test changes are because we were previously mixing fr128 and vr128 due to contrainRegClass finding FR128 first and passes like live range shrinking weren't handling that well.
llvm-svn: 337147
We now use llvm.fma.f32/f64 or llvm.x86.fmadd.f32/f64 intrinsics that use scalar types rather than vector types. So we don't these special ISD nodes that operate on the lowest element of a vector.
llvm-svn: 336883
This converts them to what clang is now using for codegen. Unfortunately, there seem to be a few kinks to work out still. I'll try to address with follow up patches.
llvm-svn: 336871
Some added 20 and some added 15. Its unclear when to use which value and whether they are required at all.
This patch removes them all. If we start finding real world issues we may need to add them back with proper tests.
llvm-svn: 336735
We've removed the legacy FMA3 intrinsics and are now using llvm.fma and extractelement/insertelement. So we don't need patterns for the nodes that could only be created by the old intrinscis. Those ISD opcodes still exist because we haven't dropped the AVX512 intrinsics yet, but those should go to EVEX instructions.
llvm-svn: 336457
The intrinsics can be implemented with a f32/f64 llvm.fma intrinsic and an insert into a zero vector.
There are a couple regressions here due to SelectionDAG not being able to pull an fneg through an extract_vector_elt. I'm not super worried about this though as InstCombine should be able to do it before we get to SelectionDAG.
llvm-svn: 336416
We only need the extractelt that corresponds to the register we're trying to insert back into. We can't guarantee the others haven't been optimized out depending on how those operands were produced.
So instead just look for an FR32/FR64 input and emit a COPY_TO_REGCLASS to VR128 in the output pattern. This matches what we do for ADD/SUB/MUL/DIV.
llvm-svn: 333473
1. Introduction of mask scalar TableGen patterns.
2. Introduction of new scalar move TableGen patterns
and refactoring of existing ones.
3. Folding of pattern created by introducing scalar
masking in Clang header files.
Patch by tkrupa
Differential Revision: https://reviews.llvm.org/D47012
llvm-svn: 333419
Sometimes the operand comes after the memory operand so we need 5 ReadDefaults first.
I suspect we also need to do something for the mask operand for masked avx512 instructions? I'm not sure if the mask should be ReadAfterLd or not since it can mask faults. If it shouldn't be ReadAfterLd then we're probably wrong for zero masking instructions already.
Differential Revision: https://reviews.llvm.org/D44726
llvm-svn: 328834
As mentioned on PR17367, many instructions are missing scheduling tags preventing us from setting 'CompleteModel = 1' for better instruction analysis. This patch deals with FMA/FMA4 which is one of the bigger offenders (along with AVX512 in general).
Annoyingly all scheduler models need to define WriteFMA (now that its actually used), even for older targets without FMA/FMA4 support, but that is an existing problem shared by other schedule classes.
Differential Revision: https://reviews.llvm.org/D40351
llvm-svn: 319016
Summary:
These instructions zero the non-scalar part of the lower 128-bits which makes them different than the FMA3 instructions which pass through the non-scalar part of the lower 128-bits.
I've only added fmadd because we should be able to derive all other variants using operand negation in the intrinsic header like we do for AVX512.
I think there are still some missed negate folding opportunities with the FMA4 instructions in light of this behavior difference that I hadn't noticed before.
I've split the tests so that we can use different intrinsics for scalar testing between the two. I just copied the tests split the RUN lines and changed out the scalar intrinsics.
fma4-fneg-combine.ll is a new test to make sure we negate the fma4 intrinsics correctly though there are a couple TODOs in it.
Reviewers: RKSimon, spatel
Reviewed By: RKSimon
Subscribers: llvm-commits
Differential Revision: https://reviews.llvm.org/D39851
llvm-svn: 318984
No existing processor has both so it doesn't really matter what we do here. But we were previously just relying on pattern order which gave FMA4 priority.
llvm-svn: 317775
This matches what we already do for AVX512. The peephole pass makes up for this in most if not all cases. But this makes isel behavior for these consistent with every other instruction.
llvm-svn: 312613
This uses the capability introduced in r312464 to make SDNode patterns commutable on the first two operands.
This allows us to remove some of the extra FMA patterns that have to put loads and mask operands in different places to cover all cases. This even includes patterns that were missing to support match a load in the first operand with FMA4. Non-broadcast loads with masking for AVX512.
I believe this is causing us to generate some duplicate patterns because tablegen's isomorphism checks don't catch isomorphism between the patterns as written in the td. It only detects isomorphism in the commuted variants it tries to create. The the unmasked 231 and 132 memory forms are isomorphic as written in the td file so we end up keeping both. I think we precommute the 132 pattern to fix this.
We also need a follow up patch to go back to the legacy FMA3 instructions and add patterns to the 231 and 132 forms which we currently don't have.
llvm-svn: 312469
There's no reason to have a target specific node with the same semantics as a target independent opcode.
This should simplify D36335 so that it doesn't need to touch X86ISelDAGToDAG.cpp
Differential Revision: https://reviews.llvm.org/D36983
llvm-svn: 311568
Some register-register instructions can be encoded in 2 different ways, this happens when 2 register operands can be folded (separately).
For example if we look at the MOV8rr and MOV8rr_REV, both instructions perform exactly the same operation, but are encoded differently. Here is the relevant information about these instructions from Intel's 64-ia-32-architectures-software-developer-manual:
Opcode Instruction Op/En 64-Bit Mode Compat/Leg Mode Description
8A /r MOV r8,r/m8 RM Valid Valid Move r/m8 to r8.
88 /r MOV r/m8,r8 MR Valid Valid Move r8 to r/m8.
Here we can see that in order to enable the folding of the output and input registers, we had to define 2 "encodings", and as a result we got 2 move 8-bit register-register instructions.
In the X86 backend, we define both of these instructions, usually one has a regular name (MOV8rr) while the other has "_REV" suffix (MOV8rr_REV), must be marked with isCodeGenOnly flag and is not emitted from CodeGen.
Automatically generating the memory folding tables relies on matching encodings of instructions, but in these cases where we want to map both memory forms of the mov 8-bit (MOV8rm & MOV8mr) to MOV8rr (not to MOV8rr_REV) we have to somehow point from the MOV8rr_REV to the "regular" appropriate instruction which in this case is MOV8rr.
This field enable this "pointing" mechanism - which is used in the TableGen backend for generating memory folding tables.
Differential Revision: https://reviews.llvm.org/D32683
llvm-svn: 304087
This places the 132/213/231 form number in front of the SS/SD/PS/PD. Move the Y for 256-bit versions to be after the PS/PD. Change the AVX512 scalar forms to include a Z in the their name. This new format should be consistent with the general naming of instructions.
llvm-svn: 276559
generated for _mm_losd_s{s,d}() intrinsics and used in scalar FMAs generated
for FMA intrinsics _mm_f{madd,msub,nmadd,nmsub}_s{s,d}().
Reviewer: David Kreitzer
Differential Revision: http://reviews.llvm.org/D14762
llvm-svn: 254140
It made it possible to apply the memory folding optimization for the 2nd
operand of FMA*_Int instructions.
Reviewer: Quentin Colombet
Differential Revision: http://reviews.llvm.org/D14550
llvm-svn: 252973
All 3 operands of FMA3 instructions are commutable now.
Patch by Slava Klochkov
Reviewers: Quentin Colombet(qcolombet), Ahmed Bougacha(ab).
Differential Revision: http://reviews.llvm.org/D13269
llvm-svn: 252335
Patch by Slava Klochkov
The key difference between FMA* and FMA*_Int opcodes is that FMA*_Int opcodes are handled more conservatively. It is illegal to commute the 1st operand of FMA*_Int instructions as the upper bits of scalar FMA intrinsic result must be taken from the 1st operand, but such commute transformation would change those upper bits and invalidate the intrinsic's result.
Reviewers: Quentin Colombet, Elena Demikhovsky
Differential Revision: http://reviews.llvm.org/D13710
llvm-svn: 252060
The semantics of the scalar FMA intrinsics are that the high vector elements are copied from the first source.
The existing pattern switches src1 and src2 around, to match the "213" order, which ends up tying the original src2 to the dest. Since the actual scalar fma3 instructions copy the high elements from the dest register, the wrong values are copied.
This modifies the pattern to leave src1 and src2 in their original order.
Differential Revision: http://reviews.llvm.org/D9908
llvm-svn: 238131
Given a FMA family (e.g., 213, 231), not all the variants (i.e., register or
memory) are commutable.
E.g., for the 213 family (with the syntax src1, src2, src3):
fmaXXX213 A, B, reg3/mem3 == fmaXXX213 B, A, reg3/mem3
Now consider the 231 family:
fmaXXX231 A, B, reg3 == fmaXXX231 A, reg3, B
But
fmaXXX231 A, B, mem3 != fmaXXX231 A, mem3, B
Indeed, mem3 cannot be the second argument of the memory variant of fmaXXX231.
Working on a reduced test case!
<rdar://problem/16800495>
llvm-svn: 208252
on FMA3 memory operands. FMA3 instructions are VEX encoded, so they can load
from unaligned memory.
Testcase to follow, along with related patch.
<rdar://problem/16478629>
llvm-svn: 205472
Commuting the 231 and 132 variants would swap addends and
multiplicands/multipliers, which isn't valid.
I'm still trying to reduce a decent test case for this.
llvm-svn: 200792
Kazuaki Ishizaki