MIPS64R6 compact branch support. As the MIPS LLVM backend uses distinct
MachineInstrs for certain 32 and 64 bit instructions (e.g. BEQ & BEQ64) that
map to the same instruction, extend compact branch support for the
corresponding 64bit branches.
Reviewers: dsanders
Differential Revision: https://reviews.llvm.org/D20164
llvm-svn: 276739
Summary:
The backend has no reason to behave like a driver and should generally do
as it's told (and error out if it can't) instead of trying to figure out
what the API user meant. The default ABI is still derived from the arch
component as a concession to backwards compatibility.
API-users that previously passed an explicit CPU and a triple that was
inconsistent with the CPU (e.g. mips-linux-gnu and mips64r2) may get a
different ABI to what they got before. However, it's expected that there
are no such users on the basis that CodeGen has been asserting that the
triple is consistent with the selected ABI for several releases. API-users
that were consistent or passed '' or 'generic' as the CPU will see no
difference.
Reviewers: sdardis, rafael
Subscribers: rafael, dsanders, sdardis, llvm-commits
Differential Revision: http://reviews.llvm.org/D21466
llvm-svn: 273557
Summary:
The Mips implementation only covers the feature bits described by the ELF
e_flags so far. Mips stores additional feature bits such as MSA in the
.MIPS.abiflags section.
Also fixed a small bug this revealed where microMIPS wouldn't add the
EF_MIPS_MICROMIPS flag when using -filetype=obj.
Reviewers: echristo, rafael
Subscribers: rafael, mehdi_amini, dsanders, sdardis, llvm-commits
Differential Revision: http://reviews.llvm.org/D21125
llvm-svn: 272880
beqc and bnec cannot have $rs == $rt. Inhibit compact branch creation
if that would occur.
Reviewers: vkalintiris, dsanders
Differential Revision: http://reviews.llvm.org/D20624
llvm-svn: 271260
Restrict the creation of compact branches so that they meet the ISA encoding
requirements. Notably do not permit $zero to be used as a operand for compact
branches and ensure that some other branches fulfil the requirement that
rs != rt.
Fixup cases where $rs > $rt for bnec and beqc.
Reviewers: dsanders, vkalintiris
Differential Review: http://reviews.llvm.org/D20284
llvm-svn: 269893
This patch adds the commandline option -mips-compact-branches={never,optimal,always),
which controls how LLVM generates compact branches for MIPS targets. By
default, the compact branch policy is 'optimal' where LLVM will (hopefully)
pick the optimal branch for any situation. The 'never' policy will disable
the generation of compact branches and 'always' will generate compact branches
wherever possible.
Reviewers: dsanders
Differential Review: http://reviews.llvm.org/D20167
llvm-svn: 269753
Alias 'jic $reg, 0' to 'jrc $reg' and 'jialc $reg, 0' to 'jalrc $reg' like
binutils.
This patch was previous committed as r266055 as seemed to have caused some spurious
test failures. They did not reappear after further local testing.
llvm-svn: 266301
Summary:
Alias 'jic $reg, 0' to 'jrc $reg' and 'jialc $reg, 0' to 'jalrc $reg' like
binutils.
Reviewers: dsanders
Differential Revision: http://reviews.llvm.org/D18856
llvm-svn: 266055
This patch adds support for compact jumps similiar to the previous compact
branch support for MIPSR6. Unlike compact branches, compact jumps do not
have a forbidden slot.
As MipsInstrInfo::getEquivalentCompactForm can determine the correct
expansion for jumps and branches for both microMIPS and MIPSR6, remove the
unnecessary distinction in the delay slot filler.
Reviewers: vkalintiris
Subscribers: llvm-commits, dsanders
llvm-svn: 265390
Summary:
MIPSR6 introduces a class of branches called compact branches. Unlike the
traditional MIPS branches which have a delay slot, compact branches do not
have a delay slot. The instruction following the compact branch is only
executed if the branch is not taken and must not be a branch.
It works by generating compact branches for MIPS32R6 when the delay slot
filler cannot fill a delay slot. Then, inspecting the generated code for
forbidden slot hazards (a compact branch with an adjacent branch or other
CTI) and inserting nops to clear this hazard.
Patch by Simon Dardis.
Reviewers: vkalintiris, dsanders
Subscribers: MatzeB, dsanders, llvm-commits
Differential Revision: http://reviews.llvm.org/D16353
llvm-svn: 263444
Simon Dardis