The expansion code creates a copy to RBX before the real LCMPXCHG16B.
It's possible this copy uses a register that is also used by the
real LCMPXCHG16B. If we set the kill flag on the use in the copy,
then we'll fail the machine verifier on the use on the LCMPXCHG16B.
Differential Revision: https://reviews.llvm.org/D89151
We need to use LCMPXCHG16B_SAVE_RBX if RBX/EBX is being used as
the frame pointer. We previously checked for this during type
legalization, but that's too early to know for sure if the base
pointer is needed.
This patch adds a new pseudo instruction to emit from isel that
uses a virtual register for the RBX input. Then we use the custom
inserter hook to emit LCMPXCHG16B if RBX isn't needed as a base
pointer or LCMPXCHG16B_SAVE_RBX if it is.
Fixes PR42064.
Reviewed By: pengfei
Differential Revision: https://reviews.llvm.org/D88808
This and its friend X86ISD::LCMPXCHG8_SAVE_RBX_DAG are used if we need to avoid clobbering the frame pointer in EBX/RBX. EBX/RBX are only used a frame pointer in 64-bit mode. In 64-bit mode we don't use CMPXCHG8B since we have a GR64 cmpxchg available. So we don't need special handling for LCMPXCHG8B.
Split from D88808
Differential Revision: https://reviews.llvm.org/D88853
ebx/rbx only needs to be saved when 64-bit registers are supported
anyway. It should be fine to save/restore the whole rbx register
even in gnux32 where the base is technically just ebx.
This matches what we do for cmpxchg16b where rbx is saved/restored
regardless of gnux32.
pointer.
mwaitx uses EBX as one of its argument.
Using this instruction clobbers RBX as it is defined to hold one of the
input. When the backend uses dynamically allocated stack, RBX is used as
a reserved register for the base pointer.
This patch is adapted from @qcolombet patch for cmpxchg at r263325.
This fixes PR43528.
Reviewed By: craig.topper
Differential Revision: https://reviews.llvm.org/D73475
It makes more sense to turn these into real instructions
a little earlier in the pipeline.
I've made sure to adjust the memoperand so the spill/reload
comments are printed correctly.
Use the isCandidateForCallSiteEntry().
This should mostly be an NFC, but there are some parts ensuring
the moveCallSiteInfo() and copyCallSiteInfo() operate with call site
entry candidates (both Src and Dest should be the call site entry
candidates).
Differential Revision: https://reviews.llvm.org/D74122
The CATCHPAD node mostly existed to be selected into the EH_RESTORE
instruction, which sets the frame back up when 32-bit Windows exceptions
return to the parent function. However, creating this MachineInstr early
increases the risk that other passes will come along and insert
instructions that use the stack before ESP and EBP are restored. That
happened in PR44697.
Instead of representing these in the instruction stream early, delay it
until PEI. Mark the blocks where this needs to happen as EHPads, but not
funclet entry blocks. Passes after PEI have to be careful not to hoist
instructions that can use stack across frame setup instructions, so this
should be relatively reliable.
Fixes PR44697
Reviewed By: hans
Differential Revision: https://reviews.llvm.org/D73752
During the If-Converter optimization pay attention when copying or
deleting call instructions in order to keep call site information in
valid state.
Reviewers: aprantl, vsk, efriedma
Reviewed By: vsk, efriedma
Differential Revision: https://reviews.llvm.org/D66955
llvm-svn: 374068
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
We previously marked all the tests with branch funnels as
`-verify-machineinstrs=0`.
This is an attempt to fix it.
1) `ICALL_BRANCH_FUNNEL` has no defs. Mark it as `let OutOperandList =
(outs)`
2) After that we hit an assert: ``` Assertion failed: (Op.getValueType()
!= MVT::Other && Op.getValueType() != MVT::Glue && "Chain and glue
operands should occur at end of operand list!"), function AddOperand,
file
/Users/francisvm/llvm/llvm/lib/CodeGen/SelectionDAG/InstrEmitter.cpp,
line 461. ```
The chain operand was added at the beginning of the operand list. Move
that to the end.
3) After that we hit another verifier issue in the pseudo expansion
where the registers used in the cmps and jmps are not added to the
livein lists. Add the `EFLAGS` to all the new MBBs that we create.
PR39436
Differential Review: https://reviews.llvm.org/D54155
llvm-svn: 365058
Handle call instruction replacements and deletions in order to preserve
valid state of the call site info of the MachineFunction.
NOTE: If the call site info is enabled for a new target, the assertion from
the MachineFunction::DeleteMachineInstr() should help to locate places
where the updateCallSiteInfo() should be called in order to preserve valid
state of the call site info.
([10/13] Introduce the debug entry values.)
Co-authored-by: Ananth Sowda <asowda@cisco.com>
Co-authored-by: Nikola Prica <nikola.prica@rt-rk.com>
Co-authored-by: Ivan Baev <ibaev@cisco.com>
Differential Revision: https://reviews.llvm.org/D61062
llvm-svn: 364536
The expansion of TCRETURNri(64) would not keep operand flags like
undef/renamable/etc. which can result in machine verifier issues.
Also add plumbing to be able to use `-run-pass=x86-pseudo`.
llvm-svn: 357808
Summary:
This avoids needing an isel pattern for each condition code. And it removes translation switches for converting between Jcc instructions and condition codes.
Now the printer, encoder and disassembler take care of converting the immediate. We use InstAliases to handle the assembly matching. But we print using the asm string in the instruction definition. The instruction itself is marked IsCodeGenOnly=1 to hide it from the assembly parser.
Reviewers: spatel, lebedev.ri, courbet, gchatelet, RKSimon
Reviewed By: RKSimon
Subscribers: MatzeB, qcolombet, eraman, hiraditya, arphaman, llvm-commits
Tags: #llvm
Differential Revision: https://reviews.llvm.org/D60228
llvm-svn: 357802
to reflect the new license.
We understand that people may be surprised that we're moving the header
entirely to discuss the new license. We checked this carefully with the
Foundation's lawyer and we believe this is the correct approach.
Essentially, all code in the project is now made available by the LLVM
project under our new license, so you will see that the license headers
include that license only. Some of our contributors have contributed
code under our old license, and accordingly, we have retained a copy of
our old license notice in the top-level files in each project and
repository.
llvm-svn: 351636
The retpoline mitigation for variant 2 of CVE-2017-5715 inhibits the
branch predictor, and as a result it can lead to a measurable loss of
performance. We can reduce the performance impact of retpolined virtual
calls by replacing them with a special construct known as a branch
funnel, which is an instruction sequence that implements virtual calls
to a set of known targets using a binary tree of direct branches. This
allows the processor to speculately execute valid implementations of the
virtual function without allowing for speculative execution of of calls
to arbitrary addresses.
This patch extends the whole-program devirtualization pass to replace
certain virtual calls with calls to branch funnels, which are
represented using a new llvm.icall.jumptable intrinsic. It also extends
the LowerTypeTests pass to recognize the new intrinsic, generate code
for the branch funnels (x86_64 only for now) and lay out virtual tables
as required for each branch funnel.
The implementation supports full LTO as well as ThinLTO, and extends the
ThinLTO summary format used for whole-program devirtualization to
support branch funnels.
For more details see RFC:
http://lists.llvm.org/pipermail/llvm-dev/2018-January/120672.html
Differential Revision: https://reviews.llvm.org/D42453
llvm-svn: 327163
The prologue-end line record must be emitted after the last
instruction that is part of the function frame setup code and before
the instruction that marks the beginning of the function body.
Patch by Carlos Alberto Enciso!
Differential Revision: https://reviews.llvm.org/D41762
llvm-svn: 325143
The original commit was reverted in r283329 due to a miscompile in
Chromium. That turned out to be the same issue as PR31257, which was
fixed in r295262.
llvm-svn: 295357
This reverts r294348, which removed support for conditional tail calls
due to the PR above. It fixes the PR by marking live registers as
implicitly used and defined by the now predicated tailcall. This is
similar to how IfConversion predicates instructions.
Differential Revision: https://reviews.llvm.org/D29856
llvm-svn: 295262
They are currently modelled incorrectly (as calls, which clobber
registers, confusing e.g. Machine Copy Propagation).
Reverting until we figure out the proper solution.
llvm-svn: 294348
Rename from addOperand to just add, to match the other method that has been
added to MachineInstrBuilder for adding more than just 1 operand.
See https://reviews.llvm.org/D28057 for the whole discussion.
Differential Revision: https://reviews.llvm.org/D28556
llvm-svn: 291891
We can't use Jcc to leave a Win64 function in general, because that
confuses the unwinder. However, for "leaf" functions, that is, functions
where the return address is always on top of the stack and which don't
have unwind info, it's OK.
Differential Revision: https://reviews.llvm.org/D24836
llvm-svn: 282920
This extends the optimization in r280832 to also work for 64-bit. The only
quirk is that we can't do this for 64-bit Windows (yet).
Differential Revision: https://reviews.llvm.org/D24423
llvm-svn: 281113
The REX prefix should be used on indirect jmps, but not direct ones.
For direct jumps, the unwinder looks at the offset to determine if
it's inside the current function.
Differential Revision: https://reviews.llvm.org/D24359
llvm-svn: 281003
When branching to a block that immediately tail calls, it is possible to fold
the call directly into the branch if the call is direct and there is no stack
adjustment, saving one byte.
Example:
define void @f(i32 %x, i32 %y) {
entry:
%p = icmp eq i32 %x, %y
br i1 %p, label %bb1, label %bb2
bb1:
tail call void @foo()
ret void
bb2:
tail call void @bar()
ret void
}
before:
f:
movl 4(%esp), %eax
cmpl 8(%esp), %eax
jne .LBB0_2
jmp foo
.LBB0_2:
jmp bar
after:
f:
movl 4(%esp), %eax
cmpl 8(%esp), %eax
jne bar
.LBB0_1:
jmp foo
I don't expect any significant size savings from this (on a Clang bootstrap I
saw 288 bytes), but it does make the code a little tighter.
This patch only does 32-bit, but 64-bit would work similarly.
Differential Revision: https://reviews.llvm.org/D24108
llvm-svn: 280832
Rename AllVRegsAllocated to NoVRegs. This avoids the connotation of
running after register and simply describes that no vregs are used in
a machine function. With that we can simply compute the property and do
not need to dump/parse it in .mir files.
Differential Revision: http://reviews.llvm.org/D23850
llvm-svn: 279698
Avoid implicit conversions from MachineInstrBundleIterator to
MachineInstr*, mainly by preferring MachineInstr& over MachineInstr* and
using range-based for loops.
llvm-svn: 275149
This bug (llvm.org/PR28124) was introduced by r237977, which refactored
the tail call sequence to be generated in two passes instead of one.
Unfortunately, the stack adjustment produced by the first pass was not
recognized by X86FrameLowering::mergeSPUpdates() in all cases, causing
code such as the following, which clobbers the return address, to be
generated:
popl %edi
popl %edi
pushl %eax
jmp tailcallee # TAILCALL
To fix the problem, the entire stack adjustment is performed in
X86ExpandPseudo::ExpandMI() for tail calls.
Patch by Magnus Lång <margnus1@gmail.com>
Differential Revision: http://reviews.llvm.org/D21325
llvm-svn: 275103
Summary:
This adds the same checks that were added in r264593 to all
target-specific passes that run after register allocation.
Reviewers: qcolombet
Subscribers: jyknight, dsanders, llvm-commits
Differential Revision: http://reviews.llvm.org/D18525
llvm-svn: 265313
cmpxchg[8|16]b uses RBX as one of its argument.
In other words, using this instruction clobbers RBX as it is defined to hold one
the input. When the backend uses dynamically allocated stack, RBX is used as a
reserved register for the base pointer.
Reserved registers have special semantic that only the target understands and
enforces, because of that, the register allocator don’t use them, but also,
don’t try to make sure they are used properly (remember it does not know how
they are supposed to be used).
Therefore, when RBX is used as a reserved register but defined by something that
is not compatible with that use, the register allocator will not fix the
surrounding code to make sure it gets saved and restored properly around the
broken code. This is the responsibility of the target to do the right thing with
its reserved register.
To fix that, when the base pointer needs to be preserved, we use a different
pseudo instruction for cmpxchg that save rbx.
That pseudo takes two more arguments than the regular instruction:
- One is the value to be copied into RBX to set the proper value for the
comparison.
- The other is the virtual register holding the save of the value of RBX as the
base pointer. This saving is done as part of isel (i.e., we emit a copy from
rbx).
cmpxchg_save_rbx <regular cmpxchg args>, input_for_rbx_reg, save_of_rbx_as_bp
This gets expanded into:
rbx = copy input_for_rbx_reg
cmpxchg <regular cmpxchg args>
rbx = save_of_rbx_as_bp
Note: The actual modeling of the pseudo is a bit more complicated to make sure
the interferes that appears after the pseudo gets expanded are properly modeled
before that expansion.
This fixes PR26883.
llvm-svn: 263325
The x86 ret instruction has a 16 bit immediate indicating how many bytes
to pop off of the stack beyond the return address.
There is a problem when extremely large structs are passed by value: we
might not be able to fit the number of bytes to pop into the return
instruction.
To fix this, expand RET_FLAG a little later and use a special sequence
to clean the stack:
pop %ecx ; return address is now in %ecx
add $n, %esp ; clean the stack
push %ecx ; bring the return address back on the stack
ret ; pop the return address and jmp to it's value
llvm-svn: 262755
Change MachineInstr API to prefer MachineInstr& over MachineInstr*
whenever the parameter is expected to be non-null. Slowly inching
toward being able to fix PR26753.
llvm-svn: 262149
The C++ EH personality automatically restores ESP from the C++ EH
registration node after a catchret. I mistakenly thought it was like
SEH, which does not restore ESP.
It makes sense for C++ EH to differ from SEH here because SEH does not
use funclets for catches, and does not allow catching inside of finally.
C++ EH may need to unwind through multiple catch funclets and eventually
catchret to some outer funclet. Therefore, the runtime has to keep track
of which ESP to use with catchret, rather than having the compiler
reload it manually.
llvm-svn: 253084
This adds the EH_RESTORE x86 pseudo instr, which is responsible for
restoring the stack pointers: EBP and ESP, and ESI if stack realignment
is involved. We only need this on 32-bit x86, because on x64 the runtime
restores CSRs for us.
Previously we had to keep the CATCHRET instruction around during SEH so
that we could convince X86FrameLowering to restore our frame pointers.
Now we can split these instructions earlier.
This was confusing, because we had a return instruction which wasn't
really a return and was ultimately going to be removed by
X86FrameLowering. This change also simplifies X86FrameLowering, which
really shouldn't be building new MBBs.
No observable functional change currently, but with the new register
mask stuff in D14407, CATCHRET will become a register allocator barrier,
and our existing tests rely on us having reasonable register allocation
around SEH.
llvm-svn: 252266
The x64 ABI requires that epilogues do not contain code other than stack
adjustments and some limited control flow. However, we'd insert code to
initialize the return address after stack adjustments. Instead, insert
EAX/RAX with the current value before we create the stack adjustments in
the epilogue.
llvm-svn: 248839
This makes catchret look more like a branch, and less like a weird use
of BlockAddress. It also lets us get away from
llvm.x86.seh.restoreframe, which relies on the old parentfpoffset label
arithmetic.
llvm-svn: 247936
Deduplicates some code and lets us use LEA on atom when adjusting the
stack around callee-cleanup calls. This is the only intended
functionality change.
llvm-svn: 240044
There is a one-to-one relationship between X86Subtarget and
X86FrameLowering, but every frame lowering method would previously pull
the subtarget off the MachineFunction and query some subtarget
properties.
Over time, these locals began to grow in complexity and it became
important to keep their names and meaning in sync across all of the
frame lowering methods, leading to duplication. We can eliminate that
duplication by computing them once in the constructor.
llvm-svn: 239948
Craig Topper