We've had several bugs(PR32256, PR32241) recently that resulted from usages of AH/BH/CH/DH either before or after a copy to/from a mask register.
This ultimately occurs because we create COPY_TO_REGCLASS with VK1 and GR8. Then in CopyToFromAsymmetricReg in X86InstrInfo we find a 32-bit super register for the GR8 to emit the KMOV with. But as these tests are demonstrating, its possible for the GR8 register to be a high register and we end up doing an accidental extra or insert from bits 15:8.
I think the best way forward is to stop making copies directly between mask registers and GR8/GR16. Instead I think we should restrict to only copies between mask registers and GR32/GR64 and use EXTRACT_SUBREG/INSERT_SUBREG to handle the conversion from GR32 to GR16/8 or vice versa.
Unfortunately, this complicates fastisel a bit more now to create the subreg extracts where we used to create GR8 copies. We can probably make a helper function to bring down the repitition.
This does result in KMOVD being used for copies when BWI is available because we don't know the original mask register size. This caused a lot of deltas on tests because we have to split the checks for KMOVD vs KMOVW based on BWI.
Differential Revision: https://reviews.llvm.org/D30968
llvm-svn: 298928
VZEROUPPER should not be issued on Knights Landing (KNL), but on Skylake-avx512 it should be.
Differential Revision: https://reviews.llvm.org/D29874
llvm-svn: 296859
Choosing a "cfi" name makes the intend a bit clearer in an assembly dump
and more importantly the assembly dumps are slightly more stable as the
numbers don't move around anymore when unrelated code calls
createTempSymbol() more or less often.
As they are temp labels the name doesn't influence the generated object
code.
Differential Revision: https://reviews.llvm.org/D27244
llvm-svn: 288290
Previously we were extending to copying the whole ZMM register. The register allocator shouldn't use XMM16-31 or YMM16-31 in this configuration as the instructions to spill them aren't available.
llvm-svn: 280648
An identity COPY like this:
%AL = COPY %AL, %EAX<imp-def>
has no semantic effect, but encodes liveness information: Further users
of %EAX only depend on this instruction even though it does not define
the full register.
Replace the COPY with a KILL instruction in those cases to maintain this
liveness information. (This reverts a small part of r238588 but this
time adds a comment explaining why a KILL instruction is useful).
llvm-svn: 274952
This re-applies r268760, reverted in r268794.
Fixes http://llvm.org/PR27670
The original imp-defs assertion was way overzealous: forward all
implicit operands, except imp-defs of the new super-reg def (r268787
for GR64, but also possible for GR16->GR32), or imp-uses of the new
super-reg use.
While there, mark the source use as Undef, and add an imp-use of the
old source reg: that should cover any case of dead super-regs.
At the stage the pass runs, flags are unlikely to matter anyway;
still, let's be as correct as possible.
Also add MIR tests for the various interesting cases.
Original commit message:
Codesize is less (16) or equal (8), and we avoid partial
dependencies.
Differential Revision: http://reviews.llvm.org/D19999
llvm-svn: 268831
Enable truncate 128/256bit packed byte/word with AVX512BW but without AVX512VL, use 512bit instructions.
Differential Revision: http://reviews.llvm.org/D16531
llvm-svn: 259044
Fix TRUNCATE lowering vector to vector i1, use LSB and not MSB.
Implement VPMOVB/W/D/Q2M intrinsic.
Differential Revision: http://reviews.llvm.org/D15675
llvm-svn: 256470
i1 type is a legal type on AVX-512 and can be passed as parameter or return value.
i1 is promoted to i8 on return and to i32 for call arguments (i8 is also promoted to i32 here).
The result code is similar to the previous X86 targets, where i1 is allways promoted to i8.
llvm-svn: 237350
Craig Topper