When encountering instructions with regmasks, instead of cleaning up all the
elements in MaybeDeadCopies map, remove only the instructions erased. By keeping
more instruction in MaybeDeadCopies, this change will expose more dead copies
across instructions with regmasks.
llvm-svn: 264462
This also simplifies the code by removing the overly conservative
NoInterveningSideEffect() function. This function checked:
- That the two copies belong to the same block: We only process one
block at a time and clear our maps in between it is impossible to find a
copy from a different block.
- There is no terminator between the two copy instructions: This is not
allowed anyway (the MachineVerifier would complain)
- Does not have instructions with hasUnmodeledSideEffects() or isCall()
set: Even for those instructuction we must have all clobbers/defs of
registers explicit as an operand. If the register is explicitely
clobbered we would never come to the point of checking for
NoInterveningSideEffect() anyway.
(I also checked this with a temporary build of the test-suite with all
potentially failing conditions in NoInterveningSideEffect() turned into
asserts)
Differential Revision: http://reviews.llvm.org/D17474
llvm-svn: 261965
Delete MachineInstr::getIterator(), since the term "iterator" is
overloaded when talking about MachineInstr.
- Downcast to ilist_node in iplist::getNextNode() and getPrevNode() so
that ilist_node::getIterator() is still available.
- Add it back as MachineInstr::getInstrIterator(). This matches the
naming in MachineBasicBlock.
- Add MachineInstr::getBundleIterator(). This is explicitly called
"bundle" (not matching MachineBasicBlock) to disintinguish it clearly
from ilist_node::getIterator().
- Update all calls. Some of these I switched to `auto` to remove
boiler-plate, since the new name is clear about the type.
There was one call I updated that looked fishy, but it wasn't clear what
the right answer was. This was in X86FrameLowering::inlineStackProbe(),
added in r252578 in lib/Target/X86/X86FrameLowering.cpp. I opted to
leave the behaviour unchanged, but I'll reply to the original commit on
the list in a moment.
llvm-svn: 261504
This avoids unnecessarily passing them around when calling helper
functions. It may also be slightly faster to call clear() on the
datastructures instead of freshly initializing them for each block.
llvm-svn: 261407
The patch is generated using this command:
tools/clang/tools/extra/clang-tidy/tool/run-clang-tidy.py -fix \
-checks=-*,llvm-namespace-comment -header-filter='llvm/.*|clang/.*' \
llvm/lib/
Thanks to Eugene Kosov for the original patch!
llvm-svn: 240137
For some history here see the commit messages of r199797 and r169060.
The original intent was to fix cases like:
%EAX<def> = COPY %ECX<kill>, %RAX<imp-def>
%RCX<def> = COPY %RAX<kill>
where simply removing the copies would have RCX undefined as in terms of
machine operands only the ECX part of it is defined. The machine
verifier would complain about this so 169060 changed such COPY
instructions into KILL instructions so some super-register imp-defs
would be preserved. In r199797 it was finally decided to always do this
regardless of super-register defs.
But this is wrong, consider:
R1 = COPY R0
...
R0 = COPY R1
getting changed to:
R1 = KILL R0
...
R0 = KILL R1
It now looks like R0 dies at the first KILL and won't be alive until the
second KILL, while in reality R0 is alive and must not change in this
part of the program.
As this only happens after register allocation there is not much code
still performing liveness queries so the issue was not noticed. In fact
I didn't manage to create a testcase for this, without unrelated changes
I am working on at the moment.
The fix is simple: As of r223896 the MachineVerifier allows reads from
partially defined registers, so the whole transforming COPY->KILL thing
is not necessary anymore. This patch also changes a similar (but more
benign case as the def and src are the same register) case in the
VirtRegRewriter.
Differential Revision: http://reviews.llvm.org/D10117
llvm-svn: 238588
remove copies that are useful after breaking some hardware dependencies.
In other words, handle this kind of situations conservatively by assuming reg2
is redefined by the undef flag.
reg1 = copy reg2
= inst reg2<undef>
reg2 = copy reg1
Copy propagation used to remove the last copy.
This is incorrect because the undef flag on reg2 in inst, allows next
passes to put whatever trashed value in reg2 that may help.
In practice we end up with this code:
reg1 = copy reg2
reg2 = 0
= inst reg2<undef>
reg2 = copy reg1
This fixes PR21743.
llvm-svn: 235647
%Q5_Q6<def> = COPY %Q2_Q3
%D5<def> =
%D3<def> =
%D3<def> = COPY %D6 // Incorrectly removed in MachineCopyPropagation
Using of %D3 results in incorrect result ...
Reviewed in http://reviews.llvm.org/D8242
llvm-svn: 232142
shorter/easier and have the DAG use that to do the same lookup. This
can be used in the future for TargetMachine based caching lookups from
the MachineFunction easily.
Update the MIPS subtarget switching machinery to update this pointer
at the same time it runs.
llvm-svn: 214838
define below all header includes in the lib/CodeGen/... tree. While the
current modules implementation doesn't check for this kind of ODR
violation yet, it is likely to grow support for it in the future. It
also removes one layer of macro pollution across all the included
headers.
Other sub-trees will follow.
llvm-svn: 206837
This actually totally breaks and causes the machine verifier to cry in several cases, one of which being:
%RAX<def> = COPY %RCX<kill>
%ECX<def> = COPY %EAX<kill>, %RAX<imp-use,kill>
These subregister copies are together identified as noops, so are both removed. However, the second one as it has an imp-use gets converted into a kill:
%ECX<def> = KILL %EAX<kill>, %RAX<imp-use,kill>
As the original COPY has been removed, the verifier goes into tears at the use of undefined EAX and RAX.
There are several hacky solutions to this hacky problem (which is all to do with imp-use/def weirdnesses), but the least hacky I've come up with is to *always* remove COPYs by converting to KILLs. KILLs are no-ops to the code generator so the generated code doesn't change (which is why they were partially used in the first place), but using them also keeps the def/use and imp-def/imp-use chains alive:
%RAX<def> = KILL %RCX<kill>
%ECX<def> = KILL %EAX<kill>, %RAX<imp-use,kill>
The patch passes all test cases including the ones that check the removal of MOVs in this circumstance, along with an extra test I added to check subregister behaviour (which made the machine verifier fall over before my patch).
The patch also adds some DEBUG() statements because the file hadn't got any.
llvm-svn: 199797
Sooooo many of these had incorrect or strange main module includes.
I have manually inspected all of these, and fixed the main module
include to be the nearest plausible thing I could find. If you own or
care about any of these source files, I encourage you to take some time
and check that these edits were sensible. I can't have broken anything
(I strictly added headers, and reordered them, never removed), but they
may not be the headers you'd really like to identify as containing the
API being implemented.
Many forward declarations and missing includes were added to a header
files to allow them to parse cleanly when included first. The main
module rule does in fact have its merits. =]
llvm-svn: 169131
MachineCopyPropagation doesn't understand super-register liveness well
enough to be able to remove implicit defs of super-registers.
This fixes a problem in ARM/2012-01-26-CopyPropKills.ll that is exposed
by an future TwoAddressInstructionPass change. The KILL instructions are
removed before the machine code is emitted.
llvm-svn: 169060
No functional change intended.
Sorry for the churn. The iterator classes are supposed to help avoid
giant commits like this one in the future. The TableGen-produced
register lists are getting quite large, and it may be necessary to
change the table representation.
This makes it possible to do so without changing all clients (again).
llvm-svn: 157854
copies being considered for removal. Make sure to track all of the copies,
rather than just the most recent encountered, by holding a DenseSet instead of
an unsigned in SrcMap.
No test case - couldn't reduce something with a sane size.
llvm-svn: 153487
ecx = mov eax
al = mov ch
The second copy is not a nop because the sub-indices of ecx,ch is not the
same of that of eax/al.
Re-enabled machine-cp.
PR11940
llvm-svn: 151002
For simplicity, treat calls with register masks as basic block
boundaries. This means we can't copy propagate callee-saved registers
across calls, but I don't think that is a big deal.
llvm-svn: 150108
Moving toward a uniform style of pass definition to allow easier target configuration.
Globally declare Pass ID.
Globally declare pass initializer.
Use INITIALIZE_PASS consistently.
Add a call to the initializer from CodeGen.cpp.
Remove redundant "createPass" functions and "getPassName" methods.
While cleaning up declarations, cleaned up comments (sorry for large diff).
llvm-svn: 150100
The live range of the source register may be extended when a redundant
copy is eliminated. Make sure any kill flags between the two copies are
cleared.
This fixes PR11765.
llvm-svn: 149069
opportunities that only present themselves after late optimizations
such as tail duplication .e.g.
## BB#1:
movl %eax, %ecx
movl %ecx, %eax
ret
The register allocator also leaves some of them around (due to false
dep between copies from phi-elimination, etc.)
This required some changes in codegen passes. Post-ra scheduler and the
pseudo-instruction expansion passes have been moved after branch folding
and tail merging. They were before branch folding before because it did
not always update block livein's. That's fixed now. The pass change makes
independently since we want to properly schedule instructions after
branch folding / tail duplication.
rdar://10428165
rdar://10640363
llvm-svn: 147716
Jun Bum Lim