Reapply r226071 with fixes. Two fixes:
1. We need to manually remove the old and create the new 'deaf defs'
associated with physical register definitions when we move the definition of
the physical register from the copy point to the point of the original vreg def.
This problem was picked up by the machinstr verifier, and could trigger a
verification failure on test/CodeGen/X86/2009-02-12-DebugInfoVLA.ll, so I've
turned on the verifier in the tests.
2. When moving the def point of the phys reg up, we need to make sure that it
is neither defined nor read in between the two instructions. We don't, however,
extend the live ranges of phys reg defs to cover uses, so just checking for
live-range overlap between the pair interval and the phys reg aliases won't
pick up reads. As a result, we manually iterate over the range and check for
reads.
A test soon to be committed to the PowerPC backend will test this change.
Original commit message:
[RegisterCoalescer] Remove copies to reserved registers
This allows the RegisterCoalescer to join "non-flipped" range pairs with a
physical destination register -- which allows the RegisterCoalescer to remove
copies like this:
<vreg> = something (maybe a load, for example)
... (things that don't use PHYSREG)
PHYSREG = COPY <vreg>
(with all of the restrictions normally applied by the RegisterCoalescer: having
compatible register classes, etc. )
Previously, the RegisterCoalescer handled only the opposite case (copying
*from* a physical register). I don't handle the problem fully here, but try to
get the common case where there is only one use of <vreg> (the COPY).
An upcoming commit to the PowerPC backend will make this pattern much more
common on PPC64/ELF systems.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@226200 91177308-0d34-0410-b5e6-96231b3b80d8
Reverting this while I investigate some bad behavior this is causing. As a
possibly-related issue, adding -verify-machineinstrs to one of the test cases
now fails because of this change:
llc test/CodeGen/X86/2009-02-12-DebugInfoVLA.ll -march=x86-64 -o - -verify-machineinstrs
*** Bad machine code: No instruction at def index ***
- function: foo
- basic block: BB#0 return (0x10007e21f10) [0B;736B)
- liverange: [128r,128d:9)[160r,160d:8)[176r,176d:7)[336r,336d:6)[464r,464d:5)[480r,480d:4)[624r,624d:3)[752r,752d:2)[768r,768d:1)[78
4r,784d:0) 0@784r 1@768r 2@752r 3@624r 4@480r 5@464r 6@336r 7@176r 8@160r 9@128r
- register: %DS
Valno #3 is defined at 624r
*** Bad machine code: Live segment doesn't end at a valid instruction ***
- function: foo
- basic block: BB#0 return (0x10007e21f10) [0B;736B)
- liverange: [128r,128d:9)[160r,160d:8)[176r,176d:7)[336r,336d:6)[464r,464d:5)[480r,480d:4)[624r,624d:3)[752r,752d:2)[768r,768d:1)[78
4r,784d:0) 0@784r 1@768r 2@752r 3@624r 4@480r 5@464r 6@336r 7@176r 8@160r 9@128r
- register: %DS
[624r,624d:3)
LLVM ERROR: Found 2 machine code errors.
where 624r corresponds exactly to the interval combining change:
624B %RSP<def> = COPY %vreg16; GR64:%vreg16
Considering merging %vreg16 with %RSP
RHS = %vreg16 [608r,624r:0) 0@608r
updated: 608B %RSP<def> = MOV64rm <fi#3>, 1, %noreg, 0, %noreg; mem:LD8[%saved_stack.1]
Success: %vreg16 -> %RSP
Result = %RSP
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@226086 91177308-0d34-0410-b5e6-96231b3b80d8
This allows the RegisterCoalescer to join "non-flipped" range pairs with a
physical destination register -- which allows the RegisterCoalescer to remove
copies like this:
<vreg> = something (maybe a load, for example)
... (things that don't use PHYSREG)
PHYSREG = COPY <vreg>
(with all of the restrictions normally applied by the RegisterCoalescer: having
compatible register classes, etc. )
Previously, the RegisterCoalescer handled only the opposite case (copying
*from* a physical register). I don't handle the problem fully here, but try to
get the common case where there is only one use of <vreg> (the COPY).
An upcoming commit to the PowerPC backend will make this pattern much more
common on PPC64/ELF systems.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@226071 91177308-0d34-0410-b5e6-96231b3b80d8
utils/sort_includes.py.
I clearly haven't done this in a while, so more changed than usual. This
even uncovered a missing include from the InstrProf library that I've
added. No functionality changed here, just mechanical cleanup of the
include order.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@225974 91177308-0d34-0410-b5e6-96231b3b80d8
This is a fixed version of reverted r225500. It fixes the too early
if() continue; of the last patch and adds a comment to the unorthodox
loop.
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The code that eliminated additional coalescable copies in
removeCopyByCommutingDef() used MergeValueNumberInto() which internally
may merge A into B or B into A. In this case A and B had different Def
points, so we have to reset ValNo.Def to the intended one after merging.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@225503 91177308-0d34-0410-b5e6-96231b3b80d8
The register coalescer used to remove implicit_defs when they are
covered by the main range anyway. With subreg liveness tracking we can't
do that anymore in places where the IMPLICIT_DEF is required as begin of
a subregister liverange.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@225416 91177308-0d34-0410-b5e6-96231b3b80d8
I got confused and assumed SrcIdx/DstIdx of the CoalescerPair is a
subregister index in SrcReg/DstReg, but they are actually subregister
indices of the coalesced register that get you back to SrcReg/DstReg
when applied.
Fixed the bug, improved comments and simplified code accordingly.
Testcase by Tom Stellard!
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@225415 91177308-0d34-0410-b5e6-96231b3b80d8
This also fixes problems with undef copies of subregisters. I can't
attach a testcase for that as none of the targets in trunk has
subregister liveness tracking enabled.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@224560 91177308-0d34-0410-b5e6-96231b3b80d8
This fixes a problem where stripCopies() would switch to values in the
main liverange when it crossed a copy instruction. However when joining
subranges we need to stay in the respective subregister ranges.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@224461 91177308-0d34-0410-b5e6-96231b3b80d8
eliminating all uses of a vreg, update any DBG_VALUE describing that vreg
to point to the rematerialized register instead.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@223401 91177308-0d34-0410-b5e6-96231b3b80d8
- Show "Considering..." message after flipping so you actually see the final
destination vreg as destination.
- Add a message on final join, so you can grep for "Success" messages to obtain
a list of which register got merged with which.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@222382 91177308-0d34-0410-b5e6-96231b3b80d8
This is to be consistent with StringSet and ultimately with the standard
library's associative container insert function.
This lead to updating SmallSet::insert to return pair<iterator, bool>,
and then to update SmallPtrSet::insert to return pair<iterator, bool>,
and then to update all the existing users of those functions...
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@222334 91177308-0d34-0410-b5e6-96231b3b80d8
Indices into the table are stored in each MCRegisterClass instead of a pointer. A new method, getRegClassName, is added to MCRegisterInfo and TargetRegisterInfo to lookup the string in the table.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@222118 91177308-0d34-0410-b5e6-96231b3b80d8
The coalescer is very aggressive at propagating constraints on the register classes, and the register allocator doesn’t know how to split sub-registers later to recover. This patch provides an escape valve for targets that encounter this problem to limit coalescing.
This patch also implements such for ARM to lower register pressure when using lots of large register classes. This works around PR18825.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@213078 91177308-0d34-0410-b5e6-96231b3b80d8
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.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@206837 91177308-0d34-0410-b5e6-96231b3b80d8
When rematerializing an instruction that defines a super register that would be
used by a physical subregisters we use the related physical super register for
the definition.
To keep the live-range information accurate, all the defined subregisters must be
marked as dead def, otherwise the register allocation may miss some
interferences.
Working on a reduced test-case!
<rdar://problem/16582185>
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@206060 91177308-0d34-0410-b5e6-96231b3b80d8
operator* on the by-operand iterators to return a MachineOperand& rather than
a MachineInstr&. At this point they almost behave like normal iterators!
Again, this requires making some existing loops more verbose, but should pave
the way for the big range-based for-loop cleanups in the future.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@203865 91177308-0d34-0410-b5e6-96231b3b80d8
for use with C++11 range-based for-loops.
The gist of phase 1 is to remove the skipInstruction() and skipBundle()
methods from these iterators, instead splitting each iterator into a version
that walks operands, a version that walks instructions, and a version that
walks bundles. This has the result of making some "clever" loops in lib/CodeGen
more verbose, but also makes their iterator invalidation characteristics much
more obvious to the casual reader. (Making them concise again in the future is a
good motivating case for a pre-incrementing range adapter!)
Phase 2 of this undertaking with consist of removing the getOperand() method,
and changing operator*() of the operand-walker to return a MachineOperand&. At
that point, it should be possible to add range views for them that work as one
might expect.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@203757 91177308-0d34-0410-b5e6-96231b3b80d8
This compiles with no changes to clang/lld/lldb with MSVC and includes
overloads to various functions which are used by those projects and llvm
which have OwningPtr's as parameters. This should allow out of tree
projects some time to move. There are also no changes to libs/Target,
which should help out of tree targets have time to move, if necessary.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@203083 91177308-0d34-0410-b5e6-96231b3b80d8
There are two attempted optimisations in reMaterializeTrivialDef, trying to
avoid promoting the size of a register too much when rematerializing.
Unfortunately, both appear to be flawed. First, we see if the original register
would have worked, but this is inadequate. Consider:
v1 = SOMETHING (v1 is QQ)
v2:Q0 = COPY v1:Q1 (v1, v2 are QQ)
...
uses of v2
In this case even though v2 *could* be used directly as the output of
SOMETHING, this would set the wrong bits of the QQ register involved. The
correct rematerialization must be:
v2:Q0_Q1 = SOMETHING (v2 promoted to QQQ)
...
uses of v2:Q1_Q2
For the second optimisation, if the correct remat is "v2:idx = SOMETHING" then
we can't necessarily expect v2 itself to be valid for SOMETHING, but we do try
to hunt for a class between v1 and v2 that works. Unfortunately, this is also
wrong:
v1 = SOMETHING (v1 is QQ)
v2:Q0_Q1 = COPY v1 (v1 is QQ, v2 is QQQ)
...
uses of v2 as a QQQ
The canonical rematerialization here is "v2:Q0_Q1 = SOMETHING". However current
logic would decide that v2 could be a QQ (no interest is taken in later uses).
This patch, therefore, always accepts the widened register class without trying
to be clever. Generally there is no penalty to this (e.g. in the common GR32 <
GR64 case, expanding the width doesn't matter because it's not like you were
going to do anything else with the high bits of a GR32 register). It can
increase register pressure in cases like the ARM VFP regs though (multiple
non-overlapping but equivalent subregisters). This situation can be
spotted by the fact that both source and destination in the
not-quite-coalesced pair have a sub-register index and
rematerialisation is skipped in that situation.
Unfortunately, no in-tree targets actually expose this as far as I can tell
(there are so few isAsCheapAsAMove instructions for it to trigger on) so I've
been unable to produce a test. It was exposed in our ARM64 SPEC tests though,
and I will be adding a test there that we should be able to contribute
soon(TM).
rdar://problem/15775279
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@199376 91177308-0d34-0410-b5e6-96231b3b80d8
Sorry, I don't understand why the warning is generated (a gcc
bug?). Anyhow, the change should improve readablity. No functionality
change intended.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@199214 91177308-0d34-0410-b5e6-96231b3b80d8
Very sorry, this was a premature patch that I still need to investigate and
finish off (for some reason beyond me at the moment it doesn't actually fix the
issue in all cases).
This reverts commit r199091.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@199093 91177308-0d34-0410-b5e6-96231b3b80d8
