Commit Graph

87 Commits

Author SHA1 Message Date
Matthias Braun c65e904be8 MachineCopyPropagation: Introduce Reg2MIMap typedef; NFC
llvm-svn: 261408
2016-02-20 03:56:41 +00:00
Matthias Braun bd18d751de MachineCopyPropagation: Move variables from function to pass
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
2016-02-20 03:56:39 +00:00
Matthias Braun 273575dcbe MachineCopyPropagation: Use ranged for, cleanup; NFC
llvm-svn: 261406
2016-02-20 03:56:36 +00:00
Matthias Braun 57b5f11aa7 MachineCopyPropagation: Use assert() instead of if{report_error()} for 'impossible' condition
llvm-svn: 261405
2016-02-20 03:56:33 +00:00
Jun Bum Lim 59df5e89c2 [MachineCopyPropagation] Fix comment. NFC
Reviewers: MatzeB, qcolombet, jmolloy, mcrosier

Subscribers: llvm-commits, mcrosier

Differential Revision: http://reviews.llvm.org/D16806

llvm-svn: 259656
2016-02-03 15:56:27 +00:00
Alexander Kornienko f00654e31b Revert r240137 (Fixed/added namespace ending comments using clang-tidy. NFC)
Apparently, the style needs to be agreed upon first.

llvm-svn: 240390
2015-06-23 09:49:53 +00:00
Alexander Kornienko 70bc5f1398 Fixed/added namespace ending comments using clang-tidy. NFC
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
2015-06-19 15:57:42 +00:00
Matthias Braun 165d467125 MachineCopyPropagation: Remove the copies instead of using KILL instructions.
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
2015-05-29 18:19:25 +00:00
Quentin Colombet 75afbfd4a1 [MachineCopyPropagation] Fix a bug with undef handling when the value is actualy alive.
Test case will follow.

llvm-svn: 238518
2015-05-28 22:38:40 +00:00
Quentin Colombet 796d906e06 [MachineCopyPropagation] Handle undef flags conservatively so that we do not
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
2015-04-23 21:17:39 +00:00
Hao Liu 04183242b3 [MachineCopyPropagation] Fix a bug causing incorrect removal for the instruction sequences as follows
%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
2015-03-13 05:15:23 +00:00
Eric Christopher fc6de428c8 Have MachineFunction cache a pointer to the subtarget to make lookups
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
2014-08-05 02:39:49 +00:00
Eric Christopher d913448b38 Remove the TargetMachine forwards for TargetSubtargetInfo based
information and update all callers. No functional change.

llvm-svn: 214781
2014-08-04 21:25:23 +00:00
Chandler Carruth 1b9dde087e [Modules] Remove potential ODR violations by sinking the DEBUG_TYPE
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
2014-04-22 02:02:50 +00:00
Paul Robinson 7c99ec5b99 Disable each MachineFunctionPass for 'optnone' functions, unless that
pass normally runs at optimization level None, or is part of the
register allocation pipeline.

llvm-svn: 205228
2014-03-31 17:43:35 +00:00
Craig Topper 4584cd54e3 [C++11] Add 'override' keyword to virtual methods that override their base class.
llvm-svn: 203220
2014-03-07 09:26:03 +00:00
James Molloy d787d3e593 MachineCopyPropagation has special logic for removing COPY instructions. It will remove plain COPYs using eraseFromParent(), but if the COPY has imp-defs/imp-uses it will convert it to a KILL, to keep the imp-def around.
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
2014-01-22 09:12:27 +00:00
Chad Rosier abdb1d69ab Simplify logic now that r182490 is in place. No functional change intended.
llvm-svn: 182531
2013-05-22 23:17:36 +00:00
Chandler Carruth ed0881b2a6 Use the new script to sort the includes of every file under lib.
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
2012-12-03 16:50:05 +00:00
Jakob Stoklund Olesen bb1e98318f Convert COPY instructions into KILLs if they have implicit defs.
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
2012-11-30 23:53:00 +00:00
Jakub Staszak 508888e446 Remove unneeded #include.
llvm-svn: 168664
2012-11-27 01:22:15 +00:00
Jakob Stoklund Olesen c30a9af2d7 Switch most getReservedRegs() clients to the MRI equivalent.
Using the cached bit vector in MRI avoids comstantly allocating and
recomputing the reserved register bit vector.

llvm-svn: 165983
2012-10-15 21:57:41 +00:00
Jakob Stoklund Olesen 54038d796c Switch all register list clients to the new MC*Iterator interface.
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
2012-06-01 23:28:30 +00:00
Jakob Stoklund Olesen 92a0083944 Switch some getAliasSet clients to MCRegAliasIterator.
MCRegAliasIterator can optionally visit the register itself, allowing
for simpler code.

llvm-svn: 157837
2012-06-01 20:36:54 +00:00
Lang Hames 5544bf1b8a Use a SmallVector and linear lookup instead of a DenseSet - SourceMap values
will always be tiny sets, so DenseSet is overkill (SmallSet won't work as we
need iteration support). 

llvm-svn: 153529
2012-03-27 19:10:45 +00:00
Lang Hames 551662bf5d During MachineCopyPropagation a register may be the source operand of multiple
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
2012-03-27 00:44:47 +00:00
Craig Topper 4b02a29eba Convert more GenRegisterInfo tables from unsigned to uint16_t to reduce static data size.
llvm-svn: 152016
2012-03-05 05:37:41 +00:00
Craig Topper 1d32658877 Use uint16_t to store register overlaps to reduce static data.
llvm-svn: 152001
2012-03-04 10:43:23 +00:00
Evan Cheng ddeb9d11fe Fix for PR12090: clear def maps of aliases when visiting a copy. e.g.
%S5<def> = COPY %S0<kill>
First clear def map of Q1, etc.

No small test case available.

llvm-svn: 151574
2012-02-27 21:46:42 +00:00
Evan Cheng 63618f9ba6 Fix machine-cp by having it to check sub-register indicies. e.g.
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
2012-02-20 23:28:17 +00:00
Jakob Stoklund Olesen 938b4d26f1 Erase dead copies that are clobbered by a call.
This does make a difference, at least when using RABasic.

llvm-svn: 150118
2012-02-09 00:19:08 +00:00
Jakob Stoklund Olesen 8610a59de1 Handle register masks in MachineCopyPropagation.
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
2012-02-08 22:37:35 +00:00
Andrew Trick 1fa5bcbe2a Codegen pass definition cleanup. No functionality.
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
2012-02-08 21:23:13 +00:00
Andrew Trick 9e761997d8 whitespace
llvm-svn: 150094
2012-02-08 21:22:43 +00:00
Jakob Stoklund Olesen 8c139a5125 Clear kill flags before propagating a copy.
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
2012-01-26 17:52:15 +00:00
Evan Cheng 520730ff23 Avoid eraseing copies from a reserved register unless the definition can be
safely proven not to have been clobbered. No small test case possible.

llvm-svn: 147751
2012-01-08 19:52:28 +00:00
Evan Cheng 00b1a3cd7e Added a late machine instruction copy propagation pass. This catches
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
2012-01-07 03:02:36 +00:00