We mostly avoid sub with immediate but there are a couple cases that can create them. One is the add 128, %rax -> sub -128, %rax trick in isel. The other is when a SUB immediate gets created for a compare where both the flags and the subtract value is used. If we are unable to linearize the SelectionDAG to satisfy the flag user and the sub result user from the same instruction, we will clone the sub immediate for the two uses. The one that produces flags will eventually become a compare. The other will have its flag output dead, and could then be considered for LEA creation.
I added additional test cases to add.ll to show the the sub -128 trick gets converted to LEA and a case where we don't need to convert it.
This showed up in the current codegen for PR42571.
Differential Revision: https://reviews.llvm.org/D64574
llvm-svn: 366151
This will ensure IMUL64ri8 is tried before IMUL64ri32. For IMUL32 and IMUL16 the
order doesn't really matter because only the ri8 versions use a predicate. That
automatically gives them priority.
llvm-svn: 358360
Under optsize we try to avoid folding immediates into instructions under optsize. But if the immediate is 16-bits or 32 bits, but can be encoded as an 8-bit immediate we don't save enough from disabling the folding unless the immediate has enough uses to make up for the size of the move which is either 3 bytes or 5 bytes since there are no sign extended 8-bit moves. We would also save something if the immediate was a live out of the basic block and thus a move was unavoidable, but that would require a more advanced heuristic than just counting uses.
Note we only avoid folding multiple use immediates into the patterns that use X86ISD::ADD/SUB/XOR/OR/AND/CMP/ADC/SBB nodes and not the more common ISD::ADD/SUB/XOR/OR/AND nodes.
Differential Revision: https://reviews.llvm.org/D59522
llvm-svn: 356688
We already do this for 16/32/64 as well as 8-bit add with register/immediate. Might as well do it for 8-bit INC/DEC too.
Differential Revision: https://reviews.llvm.org/D58869
llvm-svn: 355424
to reflect the new license.
We understand that people may be surprised that we're moving the header
entirely to discuss the new license. We checked this carefully with the
Foundation's lawyer and we believe this is the correct approach.
Essentially, all code in the project is now made available by the LLVM
project under our new license, so you will see that the license headers
include that license only. Some of our contributors have contributed
code under our old license, and accordingly, we have retained a copy of
our old license notice in the top-level files in each project and
repository.
llvm-svn: 351636
INC/DEC are pretty much the same as ADD/SUB except that they don't update the C flag.
This patch removes the special nodes and just pattern matches from ADD/SUB during isel if the C flag isn't being used.
I had to avoid selecting DEC is the result isn't used. This will become a SUB immediate which will turned into a CMP later by optimizeCompareInstr. This lead to the one test change where we use a CMP instead of a DEC for an overflow intrinsic since we only checked the flag.
This also exposed a hole in our RMW flag matching use of hasNoCarryFlagUses. Our root node for the match is a store and there's no guarantee that all the flag users have been selected yet. So hasNoCarryFlagUses needs to check copyToReg and machine opcodes, but it also needs to check for the pre-match SETCC, SETCC_CARRY, BRCOND, and CMOV opcodes.
Differential Revision: https://reviews.llvm.org/D55975
llvm-svn: 350245
Remove the TESTmr isel patterns and add another postprocessing combine for TESTrr+ANDrm->TESTmr. We already have a postprocessing combine for TESTrr+ANDrr->TESTrr. With this we can give ANDN a chance to match first. And clean it up during post processing if we ended up with just a regular AND.
This is another step towards my plan to gut EmitTest and do more flag handling during isel matching or by using optimizeCompare.
llvm-svn: 350038
The (cmp (and X, Y) 0) pattern is greedy and ends up forming a TESTrr and consuming the and when it might be better to use one of the BMI/TBM like BLSR or BLSI.
This patch moves removes the pattern from isel and adds a post processing check to combine TESTrr+ANDrr into just a TESTrr. With this patch we are able to select the BMI/TBM instructions, but we'll also emit a TESTrr when the result is compared to 0. In many cases the peephole pass will be able to use optimizeCompareInstr to remove the TEST, but its probably not perfect.
Differential Revision: https://reviews.llvm.org/D55870
llvm-svn: 349661
This extends the code that handles 16-bit add promotion to form LEA to also allow 8-bit adds.
That allows us to combine add ops with register moves and save some instructions. This is
another step towards allowing add truncation in generic DAGCombiner (see D54640).
Differential Revision: https://reviews.llvm.org/D55494
llvm-svn: 348946
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
Split WriteIMul by size and also by IMUL multiply-by-imm and multiply-by-reg cases.
This removes all the scheduler overrides for gpr multiplies and stops WriteMULH being ignored for BMI2 MULX instructions.
llvm-svn: 342892
There's no advantage to this instruction unless you need to avoid touching other flag bits. It's encoding is longer, it can't fold an immediate, it doesn't write all the flags.
I don't think gcc will generate this instruction either.
Fixes PR38852.
Differential Revision: https://reviews.llvm.org/D51754
llvm-svn: 342059
ADC is commutable and the load could be in either operand, but we were only checking operand 0.
Ideally we'd mark X86adc_flag as commutable and tablegen would automatically do this, but the EFLAGS register mention is preventing it.
llvm-svn: 341606
The peephole pass likely gets this normally, but we should be doing it during isel.
Ideally we'd just make the X86adc_flag pattern SDNPCommutable, but the tablegen doesn't handle that when one of the operands is a register reference.
llvm-svn: 341596
I believe isProfitableToFold will stop the load folding that this was intended to overcome.
Given an (xor load, -1), isProfitableToFold will see that the immediate can be folded with the xor using a one byte immediate since it can be sign extended. It doesn't know about NOT, but the one byte immediate check is enough to stop the fold.
llvm-svn: 336712
This fixes a couple of BtVer2 missing instructions that weren't been handled in the override.
NOTE: There are still a lot of overrides that still need cleaning up!
llvm-svn: 331770
I've created the necessary classes but there are still a lot of overrides that need cleaning up.
NOTE: The Znver1 model was missing some div/idiv variants in the instregex patterns and wasn't setting the resource cycles at all in the overrides.
llvm-svn: 331767
Summary:
This patch removes InstRW overrides for basic arithmetic/logic instructions. To do this I've added the store address port to RMW. And used a WriteSequence to make the latency additive. It does not cover ADC/SBB because they have different latency.
Apparently we were inconsistent about whether the store has latency or not thus the test changes.
I've also left out Sandy Bridge because the load latency there is currently 4 cycles and should be 5.
Reviewers: RKSimon, andreadb
Reviewed By: andreadb
Subscribers: llvm-commits
Differential Revision: https://reviews.llvm.org/D45351
llvm-svn: 329416
Give them both the same itineraries. Add hasSideEffects = 0 to ADOX since they don't have patterns. Rename source operands to $src1 and $src2 instead of $src0 and $src. Add ReadAfterLd to the memory form SchedRW.
llvm-svn: 328952
This also moves to define it in the same way as ADCX which seems to use
constraints a bit better.
This is pulled out of the review for reducing the use of popf for
restoring EFLAGS, but is independent. There are still more problems with
our definitions for these instructions that Craig is going to look at
but this is at least less broken and he can start from this to improve
them more fully.
Thanks to Craig for the review here.
llvm-svn: 328945
They were incorrectly marked as RMW operations. Some of the CMP instrucions worked, but the ones that use a similar encoding as RMW form of ADD ended up marked as RMW.
TEST used the same tablegen class as some of the CMPs.
llvm-svn: 327947
Sometimes we used the same itinerary for MEM and REG forms, but that seems inconsistent with our usual usage.
We also used the MUL8 itinerary for MULX32/64 which was also weird.
The test changes are because we were using IIC_IMUL32_RR and IIC_IMUL64_RR instead of IIC_IMUL32_REG/IIC_IMUL64_REG for the 32 and 64 bit multiplies that produce double width result.
llvm-svn: 327866
This allows the immediate to folded into the and instead of being forced to move into a register. This can sometimes result in shorter encodings since the and can sign extend an immediate.
This also allows us to match an and to a movzx after a not.
This can cause an extra move if the input to the separate NOT has an additional user which requires a copy before the NOT.
llvm-svn: 324260
Summary:
It seems it's main effect is to create addition copies when values are inr register that do not support this trick, which increase register pressure and makes the code bigger.
Reviewers: craig.topper, niravd, spatel, hfinkel
Subscribers: llvm-commits
Differential Revision: https://reviews.llvm.org/D42646
llvm-svn: 323888
Summary:
It seems it's main effect is to create addition copies when values are inr register that do not support this trick, which increase register pressure and makes the code bigger.
The main noteworthy regression I was able to observe was pattern of the type (setcc (trunc (and X, C)), 0) where C is such as it would benefit from the hi register trick. To prevent this, a new pattern is added to materialize such pattern using a 32 bits test. This has the added benefit of working with any constant that is materializable as a 32bits immediate, not just the ones that can leverage the high register trick, as demonstrated by the test case in test-shrink.ll using the constant 2049 .
Reviewers: craig.topper, niravd, spatel, hfinkel
Subscribers: llvm-commits
Differential Revision: https://reviews.llvm.org/D42646
llvm-svn: 323690
The asm parser wasn't preventing these from being accepted in 32-bit mode. Instructions that use a GR64 register are protected by the parser rejecting the register in 32-bit mode.
llvm-svn: 320846
Summary:
Intel documentation shows the memory operand as the first operand. But we currently treat it as the second operand. Conceptually the order doesn't matter since it doesn't write memory. We have aliases to parse with the operands in either order and the isel matching is commutable.
For the register®ister form order does matter for the assembly parser. PR22995 was previously filed and fixed by changing the register®ister form from MRMSrcReg to MRMDestReg to match gas. Ideally the memory form should match by using MRMDestMem.
I believe this supercedes D38025 which was trying to switch the register®ister form back to pre-PR22995.
Reviewers: aymanmus, RKSimon, zvi
Reviewed By: aymanmus
Subscribers: llvm-commits
Differential Revision: https://reviews.llvm.org/D38120
llvm-svn: 314639
Summary:
Just because INC/DEC is a little slow on some processors doesn't mean we shouldn't prefer it when optimizing for size.
This appears to match gcc behavior.
Reviewers: chandlerc, zvi, RKSimon, spatel
Reviewed By: RKSimon
Subscribers: llvm-commits
Differential Revision: https://reviews.llvm.org/D37177
llvm-svn: 312866
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 patch handles 64-bit constants which can be encoded as 32-bit immediates.
It extends the functionality added by https://reviews.llvm.org/D11363 for 32-bit constants to 64-bit constants.
Patch by Sunita Marathe!
Differential Revision: https://reviews.llvm.org/D23391
llvm-svn: 278857
First step in preventing immediates that occur more than once within a single
basic block from being pulled into their users, in order to prevent unnecessary
large instruction encoding .Currently enabled only when optimizing for size.
Patch by: zia.ansari@intel.com
Differential Revision: http://reviews.llvm.org/D11363
llvm-svn: 244601
Overall this seems simpler. It reduces duplication of patterns between both modes and it simplifies the memory folding/unfolding tables as they don't need to create fake instructions just to keep track of 64-bitness.
llvm-svn: 225252
Craig Topper