If the tied use is undef value, fastregalloc should free the def
register. There is no reload needed for the undef value.
Reviewed By: MatzeB
Differential Revision: https://reviews.llvm.org/D124834
Changes from commit 1db137b185
added iteration over hash map that can result in non-deterministic
order. Fix that by using a SmallMapVector to preserve the order.
Differential Revision: https://reviews.llvm.org/D113468
AMDGPU normally spills SGPRs to VGPRs. Previously, since all register
classes are handled at the same time, this was problematic. We don't
know ahead of time how many registers will be needed to be reserved to
handle the spilling. If no VGPRs were left for spilling, we would have
to try to spill to memory. If the spilled SGPRs were required for exec
mask manipulation, it is highly problematic because the lanes active
at the point of spill are not necessarily the same as at the restore
point.
Avoid this problem by fully allocating SGPRs in a separate regalloc
run from VGPRs. This way we know the exact number of VGPRs needed, and
can reserve them for a second run. This fixes the most serious
issues, but it is still possible using inline asm to make all VGPRs
unavailable. Start erroring in the case where we ever would require
memory for an SGPR spill.
This is implemented by giving each regalloc pass a callback which
reports if a register class should be handled or not. A few passes
need some small changes to deal with leftover virtual registers.
In the AMDGPU implementation, a new pass is introduced to take the
place of PrologEpilogInserter for SGPR spills emitted during the first
run.
One disadvantage of this is currently StackSlotColoring is no longer
used for SGPR spills. It would need to be run again, which will
require more work.
Error if the standard -regalloc option is used. Introduce new separate
-sgpr-regalloc and -vgpr-regalloc flags, so the two runs can be
controlled individually. PBQB is not currently supported, so this also
prevents using the unhandled allocator.
STATEPOINT is a fancy and complex pseudo instruction which
has both tied defs and regmask operand.
Basic FastRA algorithm is as follows:
1. Mark registers used by defs as free
2. If instruction has regmask operand displace clobbered registers
according to regmask.
3. Assign registers for use operands.
In case of tied defs step 1 is replaced with allocation of registers
for them. But regmask is still processed, which may displace already
allocated registers. As a result, tied use and def will get assigned
to different registers.
This patch makes FastRA to process instruction's RegMask (if any) when
checking for physical registers interference.
That way tied operands won't get registers clobbered by regmask.
Reviewed By: arsenm, skatkov
Differential Revision: https://reviews.llvm.org/D99284
Some liveins *can* come from this block (e.g. any SSA value except the call),
it's only the ones that produce `landingpad` values that can't and I didn't
think it through properly.
These registers get defined by the runtime, not the block being allocated, and
treating them as preassigned in RegAllocFast adds extra pressure, sometimes
enough to make the function unallocatable.
This patch adds handling for DBG_VALUE_LIST in the MIR-passes (after
finalize-isel), excluding the debug liveness passes and DWARF emission. This
most significantly affects MachineSink, which now needs to consider all used
registers of a debug value when sinking, but for most passes this change is
simply replacing getDebugOperand(0) with an iteration over all debug operands.
Differential Revision: https://reviews.llvm.org/D92578
Rewrites test to use correct architecture triple; fixes incorrect
reference in SourceLevelDebugging doc; simplifies `spillReg` behaviour
so as to not be dependent on changes elsewhere in the patch stack.
This reverts commit d2000b45d0.
This patch adds a new instruction that can represent variadic debug values,
DBG_VALUE_VAR. This patch alone covers the addition of the instruction and a set
of basic code changes in MachineInstr and a few adjacent areas, but does not
correctly handle variadic debug values outside of these areas, nor does it
generate them at any point.
The new instruction is similar to the existing DBG_VALUE instruction, with the
following differences: the operands are in a different order, any number of
values may be used in the instruction following the Variable and Expression
operands (these are referred to in code as “debug operands”) and are indexed
from 0 so that getDebugOperand(X) == getOperand(X+2), and the Expression in a
DBG_VALUE_VAR must use the DW_OP_LLVM_arg operator to pass arguments into the
expression.
The new DW_OP_LLVM_arg operator is only valid in expressions appearing in a
DBG_VALUE_VAR; it takes a single argument and pushes the debug operand at the
index given by the argument onto the Expression stack. For example the
sub-expression `DW_OP_LLVM_arg, 0` has the meaning “Push the debug operand at
index 0 onto the expression stack.”
Differential Revision: https://reviews.llvm.org/D82363
Fast register allocator skips bundled MIs, as the main assignment
loop uses MachineBasicBlock::iterator (= MachineInstrBundleIterator)
This was causing SIInsertWaitcnts to crash which expects all
instructions to have registers assigned.
This patch makes sure to set everything inside bundle to the same
assignments done on BUNDLE header.
Reviewed By: qcolombet
Differential Revision: https://reviews.llvm.org/D90369
This allows LiveDebugValues to insert the proper DBG_VALUEs in live
out blocks if a spill is inserted before the use of a
register. Previously, this would see the register use as the last
DBG_VALUE, even though the stack slot should be treated as the live
out value.
This avoids an lldb test regression when D52010 is re-applied.
This rewrites big parts of the fast register allocator. The basic
strategy of doing block-local allocation hasn't changed but I tweaked
several details:
Track register state on register units instead of physical
registers. This simplifies and speeds up handling of register aliases.
Process basic blocks in reverse order: Definitions are known to end
register livetimes when walking backwards (contrary when walking
forward then uses may or may not be a kill so we need heuristics).
Check register mask operands (calls) instead of conservatively
assuming everything is clobbered. Enhance heuristics to detect
killing uses: In case of a small number of defs/uses check if they are
all in the same basic block and if so the last one is a killing use.
Enhance heuristic for copy-coalescing through hinting: We check the
first k defs of a register for COPYs rather than relying on there just
being a single definition. When testing this on the full llvm
test-suite including SPEC externals I measured:
average 5.1% reduction in code size for X86, 4.9% reduction in code on
aarch64. (ranging between 0% and 20% depending on the test) 0.5%
faster compiletime (some analysis suggests the pass is slightly slower
than before, but we more than make up for it because later passes are
faster with the reduced instruction count)
Also adds a few testcases that were broken without this patch, in
particular bug 47278.
Patch mostly by Matthias Braun
This currently has no impact on code, but prevents sizeable code size
regressions after D52010. This prevents spilling and reloading all
values inside blocks that loop back. Add a baseline test which would
regress without this patch.
This seems to have caused incorrect register allocation in some cases,
breaking tests in the Zig standard library (PR47278).
As discussed on the bug, revert back to green for now.
> Record internal state based on register units. This is often more
> efficient as there are typically fewer register units to update
> compared to iterating over all the aliases of a register.
>
> Original patch by Matthias Braun, but I've been rebasing and fixing it
> for almost 2 years and fixed a few bugs causing intermediate failures
> to make this patch independent of the changes in
> https://reviews.llvm.org/D52010.
This reverts commit 66251f7e1d, and
follow-ups 931a68f26b
and 0671a4c508. It also adjust some
test expectations.
Following on from this RFC[0] from a while back, this is the first patch towards
implementing variadic debug values.
This patch specifically adds a set of functions to MachineInstr for performing
operations specific to debug values, and replacing uses of the more general
functions where appropriate. The most prevalent of these is replacing
getOperand(0) with getDebugOperand(0) for debug-value-specific code, as the
operands corresponding to values will no longer be at index 0, but index 2 and
upwards: getDebugOperand(x) == getOperand(x+2). Similar replacements have been
added for the other operands, along with some helper functions to replace
oft-repeated code and operate on a variable number of value operands.
[0] http://lists.llvm.org/pipermail/llvm-dev/2020-February/139376.html<Paste>
Differential Revision: https://reviews.llvm.org/D81852
Record internal state based on register units. This is often more
efficient as there are typically fewer register units to update
compared to iterating over all the aliases of a register.
Original patch by Matthias Braun, but I've been rebasing and fixing it
for almost 2 years and fixed a few bugs causing intermediate failures
to make this patch independent of the changes in
https://reviews.llvm.org/D52010.
This file lists every pass in LLVM, and is included by Pass.h, which is
very popular. Every time we add, remove, or rename a pass in LLVM, it
caused lots of recompilation.
I found this fact by looking at this table, which is sorted by the
number of times a file was changed over the last 100,000 git commits
multiplied by the number of object files that depend on it in the
current checkout:
recompiles touches affected_files header
342380 95 3604 llvm/include/llvm/ADT/STLExtras.h
314730 234 1345 llvm/include/llvm/InitializePasses.h
307036 118 2602 llvm/include/llvm/ADT/APInt.h
213049 59 3611 llvm/include/llvm/Support/MathExtras.h
170422 47 3626 llvm/include/llvm/Support/Compiler.h
162225 45 3605 llvm/include/llvm/ADT/Optional.h
158319 63 2513 llvm/include/llvm/ADT/Triple.h
140322 39 3598 llvm/include/llvm/ADT/StringRef.h
137647 59 2333 llvm/include/llvm/Support/Error.h
131619 73 1803 llvm/include/llvm/Support/FileSystem.h
Before this change, touching InitializePasses.h would cause 1345 files
to recompile. After this change, touching it only causes 550 compiles in
an incremental rebuild.
Reviewers: bkramer, asbirlea, bollu, jdoerfert
Differential Revision: https://reviews.llvm.org/D70211
Summary:
This clang-tidy check is looking for unsigned integer variables whose initializer
starts with an implicit cast from llvm::Register and changes the type of the
variable to llvm::Register (dropping the llvm:: where possible).
Partial reverts in:
X86FrameLowering.cpp - Some functions return unsigned and arguably should be MCRegister
X86FixupLEAs.cpp - Some functions return unsigned and arguably should be MCRegister
X86FrameLowering.cpp - Some functions return unsigned and arguably should be MCRegister
HexagonBitSimplify.cpp - Function takes BitTracker::RegisterRef which appears to be unsigned&
MachineVerifier.cpp - Ambiguous operator==() given MCRegister and const Register
PPCFastISel.cpp - No Register::operator-=()
PeepholeOptimizer.cpp - TargetInstrInfo::optimizeLoadInstr() takes an unsigned&
MachineTraceMetrics.cpp - MachineTraceMetrics lacks a suitable constructor
Manual fixups in:
ARMFastISel.cpp - ARMEmitLoad() now takes a Register& instead of unsigned&
HexagonSplitDouble.cpp - Ternary operator was ambiguous between unsigned/Register
HexagonConstExtenders.cpp - Has a local class named Register, used llvm::Register instead of Register.
PPCFastISel.cpp - PPCEmitLoad() now takes a Register& instead of unsigned&
Depends on D65919
Reviewers: arsenm, bogner, craig.topper, RKSimon
Reviewed By: arsenm
Subscribers: RKSimon, craig.topper, lenary, aemerson, wuzish, jholewinski, MatzeB, qcolombet, dschuff, jyknight, dylanmckay, sdardis, nemanjai, jvesely, wdng, nhaehnle, sbc100, jgravelle-google, kristof.beyls, hiraditya, aheejin, kbarton, fedor.sergeev, javed.absar, asb, rbar, johnrusso, simoncook, apazos, sabuasal, niosHD, jrtc27, MaskRay, zzheng, edward-jones, atanasyan, rogfer01, MartinMosbeck, brucehoult, the_o, tpr, PkmX, jocewei, jsji, Petar.Avramovic, asbirlea, Jim, s.egerton, llvm-commits
Tags: #llvm
Differential Revision: https://reviews.llvm.org/D65962
llvm-svn: 369041
Summary:
As part of this, define DenseMapInfo for MCRegister (and Register while I'm at it)
Depends on D65599
Reviewers: arsenm
Subscribers: MatzeB, qcolombet, jvesely, wdng, nhaehnle, hiraditya, llvm-commits
Tags: #llvm
Differential Revision: https://reviews.llvm.org/D65605
llvm-svn: 367719
Setting mayLiveOut based only on use instructions after allocating the
def block did not work if the use block was allocated before the def
block, since the virtual register uses were already removed.
Fixes bug 41973.
llvm-svn: 361781
Trace through multiple COPYs when looking for a physreg source. Add
hinting for vregs that will be copied into physregs (we only hinted
for vregs getting copied to a physreg previously). Give hinted a
register a bonus when deciding which value to spill. This is part of
my rewrite regallocfast series. In fact this one doesn't even have an
effect unless you also flip the allocation to happen from back to
front of a basic block. Nonetheless it helps to split this up to ease
review of D52010
Patch by Matthias Braun
llvm-svn: 360887
When assigning the definitions of an instruction we were updating
the available registers while walking the definitions. Some of
those definitions may be from physical registers and thus, they are
not available for other definitions to take, but by the time we see
that we may have already assign these registers to another
virtual register.
Fix that by walking through all the definitions and mark as unavailable
the physical register definitions, then do the virtual register assignments.
PR41790
llvm-svn: 360278
Do not actually allocate a register for an undef use. Previously we we
would create unnecessary reload instruction for undef uses where the
register wasn't live.
Patch by Matthias Braun
llvm-svn: 356501
Luo, Yuanke