This is an alternative to D66980, which was reverted. Instead of
inserting a pseudo instruction that optionally expands to nothing, add a
pass that inserts int3 when appropriate after basic block layout.
Reviewers: hans
Differential Revision: https://reviews.llvm.org/D67201
llvm-svn: 371466
Summary:
Add zero-materializing XORs to X86's describeLoadedValue() hook in order
to produce call site values.
I have had to change the defs logic in collectCallSiteParameters() a bit
to be able to describe the XORs. The XORs implicitly define $eflags,
which would cause them to never be considered, due to a guard condition
that I->getNumDefs() is one. I have changed that condition so that we
now only consider instructions where a forwarded register overlaps with
the instruction's single explicit define. We still need to collect the implicit
defines of other forwarded registers to remove them from the work list.
I'm not sure how to move towards supporting instructions with multiple
explicit defines, cases where forwarded register are implicitly defined,
and/or cases where an instruction produces values for multiple forwarded
registers. Perhaps the describeLoadedValue() hook should take a register
argument, and we then leave it up to the hook to describe the loaded
value in that register? I have not yet encountered a situation where
that would be necessary though.
Reviewers: aprantl, vsk, djtodoro, NikolaPrica
Reviewed By: vsk
Subscribers: ychen, hiraditya, llvm-commits
Tags: #debug-info, #llvm
Differential Revision: https://reviews.llvm.org/D67225
llvm-svn: 371333
Summary:
The value operand in DW_OP_plus_uconst/DW_OP_constu value can be
large (it uses uint64_t as representation internally in LLVM).
This means that in the uint64_t to int conversions, previously done
by DwarfExpression::addMachineRegExpression, could lose information.
Also, the negation done in "-Offset" was undefined behavior in case
Offset was exactly INT_MIN.
To avoid the above problems, we now avoid transformation like
[Reg, DW_OP_plus_uconst, Offset] --> [DW_OP_breg, Offset]
and
[Reg, DW_OP_constu, Offset, DW_OP_plus] --> [DW_OP_breg, Offset]
when Offset > INT_MAX.
And we avoid to transform
[Reg, DW_OP_constu, Offset, DW_OP_minus] --> [DW_OP_breg,-Offset]
when Offset > INT_MAX+1.
The patch also adjusts DwarfCompileUnit::constructVariableDIEImpl
to make sure that "DW_OP_constu, Offset, DW_OP_minus" is used
instead of "DW_OP_plus_uconst, Offset" when creating DIExpressions
with negative frame index offsets.
Notice that this might just be the tip of the iceberg. There
are lots of fishy handling related to these constants. I think both
DIExpression::appendOffset and DIExpression::extractIfOffset may
trigger undefined behavior for certain values.
Reviewers: sdesmalen, rnk, JDevlieghere
Reviewed By: JDevlieghere
Subscribers: jholewinski, aprantl, hiraditya, ychen, uabelho, llvm-commits
Tags: #debug-info, #llvm
Differential Revision: https://reviews.llvm.org/D67263
llvm-svn: 371304
This currently triggers undefined behavior if executed with an
ubsan build. It is just a precommit of the test case to show that
we got a problem.
Fix is proposed in https://reviews.llvm.org/D67263 and plan is to
commit the fix directly after this patch.
llvm-svn: 371303
If a stack spill location is overwritten by another spill instruction,
any variable locations pointing at that slot should be terminated. We
cannot rely on spills always being restored to registers or variable
locations being moved by a DBG_VALUE: the register allocator is entitled
to spill a value and then forget about it when it goes out of liveness.
To address this, scan for memory writes to spill locations, even those we
don't consider to be normal "spills". isSpillInstruction and
isLocationSpill distinguish the two now. After identifying spill
overwrites, terminate the open range, and insert a $noreg DBG_VALUE for
that variable.
Differential Revision: https://reviews.llvm.org/D66941
llvm-svn: 371193
Summary:
This patch renames functions that takes or returns alignment as log2, this patch will help with the transition to llvm::Align.
The renaming makes it explicit that we deal with log(alignment) instead of a power of two alignment.
A few renames uncovered dubious assignments:
- `MirParser`/`MirPrinter` was expecting powers of two but `MachineFunction` and `MachineBasicBlock` were using deal with log2(align). This patch fixes it and updates the documentation.
- `MachineBlockPlacement` exposes two flags (`align-all-blocks` and `align-all-nofallthru-blocks`) supposedly interpreted as power of two alignments, internally these values are interpreted as log2(align). This patch updates the documentation,
- `MachineFunctionexposes` exposes `align-all-functions` also interpreted as power of two alignment, internally this value is interpreted as log2(align). This patch updates the documentation,
Reviewers: lattner, thegameg, courbet
Subscribers: dschuff, arsenm, jyknight, dylanmckay, sdardis, nemanjai, jvesely, nhaehnle, javed.absar, hiraditya, kbarton, fedor.sergeev, asb, rbar, johnrusso, simoncook, apazos, sabuasal, niosHD, jrtc27, MaskRay, zzheng, edward-jones, atanasyan, rogfer01, MartinMosbeck, brucehoult, the_o, dexonsmith, PkmX, jocewei, jsji, Jim, s.egerton, llvm-commits, courbet
Tags: #llvm
Differential Revision: https://reviews.llvm.org/D65945
llvm-svn: 371045
As DW_AT_rnglists_base points after the header and headers have
different sizes for DWARF32 and DWARF64, we have to use the format
of the CU to adjust the offset correctly in order to extract
the referenced range list table.
The patch also changes the type of RangeSectionBase because in DWARF64
it is 8-bytes long.
Differential Revision: https://reviews.llvm.org/D67098
llvm-svn: 371016
SROA pass processes debug info incorrecly if applied twice.
Specifically, after SROA works first time, instcombine converts dbg.declare
intrinsics into dbg.value. Inlining creates new opportunities for SROA,
so it is called again. This time it does not handle correctly previously
inserted dbg.value intrinsics.
Differential Revision: https://reviews.llvm.org/D64595
llvm-svn: 370906
the test is building a 64-bit executable, so the addresses should be
64-bit too. The test was still passing even with smaller address size,
but it was hitting the "unexpected end of data" error sooner than it
should.
llvm-svn: 370882
When comparing variable locations, LiveDebugValues currently considers only
the machine location, ignoring any DIExpression applied to it. This is a
problem because that DIExpression can do pretty much anything to the machine
location, for example dereferencing it.
This patch adds DIExpressions to that comparison; now variables based on the
same register/memory-location but with different expressions will compare
differently, and be dropped if we attempt to merge them between blocks. This
reduces variable coverage-range a little, but only because we were producing
broken locations.
Differential Revision: https://reviews.llvm.org/D66942
llvm-svn: 370877
Summary:
While fixing the handling of some error cases, r370363 introduced new
problems -- assertion failures due to unchecked errors (my excuse is that a very
early version of that patch used Optional<T> instead of Expected).
This patch adds proper handling of parsing errors encountered when
dumping location lists from inside DWARF DIEs, and adds a bunch of
additional tests.
I reorder the arguments of the location list dumping functions to make
them consistent, and also be able to dump the two kinds of location
lists generically.
Reviewers: JDevlieghere, dblaikie, probinson
Subscribers: aprantl, llvm-commits
Tags: #llvm
Differential Revision: https://reviews.llvm.org/D67102
llvm-svn: 370868
This reverts r370525 (git commit 0bb1630685)
Also reverts r370543 (git commit 185ddc08ee)
The approach I took only works for functions marked `noreturn`. In
general, a call that is not known to be noreturn may be followed by
unreachable for other reasons. For example, there could be multiple call
sites to a function that throws sometimes, and at some call sites, it is
known to always throw, so it is followed by unreachable. We need to
insert an `int3` in these cases to pacify the Windows unwinder.
I think this probably deserves its own standalone, Win64-only fixup pass
that runs after block placement. Implementing that will take some time,
so let's revert to TrapUnreachable in the mean time.
llvm-svn: 370829
The missing line added by this patch ensures that only spilt variable
locations are candidates for being restored from the stack. Otherwise,
register or constant-value information can be interpreted as a spill
location, through a union.
The added regression test replicates a scenario where this occurs: the
stack load from [rsp] causes the register-location DBG_VALUE to be
"restored" to rsi, when it should be left alone. See PR43058 for details.
Un x-fail a test that was suffering from this from a previous patch.
Differential Revision: https://reviews.llvm.org/D66895
llvm-svn: 370648
Users have complained llvm.trap produce two ud2 instructions on Win64,
one for the trap, and one for unreachable. This change fixes that.
TrapUnreachable was added and enabled for Win64 in r206684 (April 2014)
to avoid poorly understood issues with the Windows unwinder.
There seem to be two major things in play:
- the unwinder
- C++ EH, _CxxFrameHandler3 & co
The unwinder disassembles forward from the return address to scan for
epilogues. Inserting a ud2 had the effect of stopping the unwinder, and
ensuring that it ran the EH personality function for the current frame.
However, it's not clear what the unwinder does when the return address
happens to be the last address of one function and the first address of
the next function.
The Visual C++ EH personality, _CxxFrameHandler3, needs to figure out
what the current EH state number is. It does this by consulting the
ip2state table, which maps from PC to state number. This seems to go
wrong when the return address is the last PC of the function or catch
funclet.
I'm not sure precisely which system is involved here, but in order to
address these real or hypothetical problems, I believe it is enough to
insert int3 after a call site if it would otherwise be the last
instruction in a function or funclet. I was able to reproduce some
similar problems locally by arranging for a noreturn call to appear at
the end of a catch block immediately before an unrelated function, and I
confirmed that the problems go away when an extra trailing int3
instruction is added.
MSVC inserts int3 after every noreturn function call, but I believe it's
only necessary to do it if the call would be the last instruction. This
change inserts a pseudo instruction that expands to int3 if it is in the
last basic block of a function or funclet. I did what I could to run the
Microsoft compiler EH tests, and the ones I was able to run showed no
behavior difference before or after this change.
Differential Revision: https://reviews.llvm.org/D66980
llvm-svn: 370525
Summary:
Change LiveDebugValues so that it inserts entry values after the bundle
which contains the clobbering instruction. Previously it would insert
the debug value after the bundle head using insertAfter(), breaking the
bundle.
Reviewers: djtodoro, NikolaPrica, aprantl, vsk
Reviewed By: vsk
Subscribers: hiraditya, llvm-commits
Tags: #debug-info, #llvm
Differential Revision: https://reviews.llvm.org/D66888
llvm-svn: 370448
Summary:
While examining this class for possible use in lldb, I noticed two
things:
- it spits out parsing errors directly to stderr
- the loclists parser can incorrectly return valid location lists when
parsing malformed (truncated) data
I improve the stderr situation by making the parseOneLocationList
functions return Expected<T>s. The errors are still dumped to stderr by
their callers, so this is only a partial fix, but it is enough for my
use case, as I intend to parse the locations lists one by one.
I fix the behavior in the truncated scenario by using the newly
introduced DataExtractor Cursor API.
I also add tests for handling the error cases, as they currently have no
coverage.
Reviewers: dblaikie, JDevlieghere, probinson
Subscribers: lldb-commits, llvm-commits
Tags: #llvm
Differential Revision: https://reviews.llvm.org/D63591
llvm-svn: 370363
The missing line added by this patch ensures that only spilt variable
locations are candidates for being restored from the stack. Otherwise,
register or constant-value information can be interpreted as a spill
location, through a union.
The added regression test replicates a scenario where this occurs: the
stack load from [rsp] causes the register-location DBG_VALUE to be
"restored" to rsi, when it should be left alone. See PR43058 for details.
Un x-fail a test that was suffering from this from a previous patch.
Differential Revision: https://reviews.llvm.org/D66895
llvm-svn: 370334
The "join" method in LiveDebugValues does not attempt to join unseen
predecessor blocks if their out-locations aren't yet initialized, instead
the block should be re-visited later to see if any locations have changed
validity. However, because the set of blocks were all being "process"'d
once before "join" saw them, that logic in "join" was actually ignoring
legitimate out-locations on the first pass through. This meant that some
invalidated locations were not removed from the head of loops, allowing
illegal locations to persist.
Fix this by removing the run of "process" before the main join/process loop
in ExtendRanges. Now the unseen predecessors that "join" skips truly are
uninitialized, and we come back to the block at a later time to re-run
"join", see the @baz function added.
This also fixes another fault where stack/register transfers in the entry
block (or any other before-any-loop-block) had their tranfers initially
ignored, and were then never revisited. The MIR test added tests for this
behaviour.
XFail a test that exposes another bug; a fix for this is coming in D66895.
Differential Revision: https://reviews.llvm.org/D66663
llvm-svn: 370328
This implements the DWARF 5 feature described in:
http://dwarfstd.org/ShowIssue.php?issue=141212.1
To support recognizing anonymous structs:
struct A {
struct { // Anonymous struct
int y;
};
} a
This patch adds support for the new flag in constructTypeDIE(...) and test to verify this change.
Differential Revision: https://reviews.llvm.org/D66605
llvm-svn: 369969
The test case used invalid source operands as input
to BTS64rr instructions (feeding register operands with
immediates). This patch changes those instruction into
using BTS64ri8 instead, which seems to better match the
operand types.
Fixes problems seen in https://reviews.llvm.org/D63973.
llvm-svn: 369866
LiveDebugValues gives variable locations to blocks, but it should also take
away. There are various circumstances where a variable location is known
until a loop backedge with a different location is detected. In those
circumstances, where there's no agreement on the variable location, it
should be undef / removed, otherwise we end up picking a location that's
valid on some loop iterations but not others.
However, LiveDebugValues doesn't currently do this, see the new testcase
attached. Without this patch, the location of !3 is assumed to be %bar
through the loop. Once it's added to the In-Locations list, it's never
removed, even though the later dbg.value(0... of !3 makes the location
un-knowable.
This patch checks during block-location-joining to see whether any
previously-present locations have been removed in a predecessor. If they
have, the live-ins have changed, and the block needs reprocessing.
Similarly, in transferTerminator, assign rather than |= the Out-Locations
after processing a block, as we may have deleted some previously valid
locations. This will mean that LiveDebugValues performs more propagation
-- but that's necessary for it being correct.
Differential Revision: https://reviews.llvm.org/D66599
llvm-svn: 369778
Patch https://reviews.llvm.org/D43256 introduced more aggressive loop layout optimization which depends on profile information. If profile information is not available, the statically estimated profile information(generated by BranchProbabilityInfo.cpp) is used. If user program doesn't behave as BranchProbabilityInfo.cpp expected, the layout may be worse.
To be conservative this patch restores the original layout algorithm in plain mode. But user can still try the aggressive layout optimization with -force-precise-rotation-cost=true.
Differential Revision: https://reviews.llvm.org/D65673
llvm-svn: 369664
LiveDebugValues propagates variable locations between blocks by creating
new DBG_VALUE insts in the successors, then interpreting them when it
passes back through the block at a later time. However, this flushes out
any extra information about the location that LiveDebugValues holds: for
example, connections between variable locations such as discussed in
D65368. And as reported in PR42772 this causes us to lose track of the
fact that a spill-location is actually a spill, not a register location.
This patch fixes that by deferring the creation of propagated DBG_VALUEs
until after propagation has completed: instead location propagation occurs
only by sharing location ID numbers between blocks.
Differential Revision: https://reviews.llvm.org/D66412
llvm-svn: 369508
Currently the machine instruction sinker identifies DBG_VALUE insts that
also need to sink by comparing register numbers. Unfortunately this isn't
safe, because (after register allocation) a DBG_VALUE may read a register
that aliases what's being sunk. To fix this, identify the DBG_VALUEs that
need to sink by recording & examining their register units. Register units
gives us the following guarantee:
"Two registers overlap if and only if they have a common register unit"
[MCRegisterInfo.h]
Thus we can always identify aliasing DBG_VALUEs if the set of register
units read by the DBG_VALUE, and the register units of the instruction
being sunk, intersect. (MachineSink already uses classes like
"LiveRegUnits" for determining sinking validity anyway).
The test added checks for super and subregister DBG_VALUE reads of a sunk
copy being sunk as well.
Differential Revision: https://reviews.llvm.org/D58191
llvm-svn: 369247
LiveDebugVariables can coalesce ranges of variable locations across
multiple basic blocks. However when it recreates DBG_VALUE instructions,
it has to recreate one DBG_VALUE per block, otherwise it doesn't
represent the pre-regalloc layout and variable assignments can go missing.
This feature works -- however while mucking around with LiveDebugVariables,
I commented the relevant code it out and no tests failed. Thus, here's a
test that checks LiveDebugVariables preserves DBG_VALUEs across block
boundaries.
Differential Revision: https://reviews.llvm.org/D66347
llvm-svn: 369243
In r369026 we disabled spill-recognition in LiveDebugValues for anything
that has a complex expression. This is because it's hard to recover the
complex expression once the spill location is baked into it.
This patch re-enables spill-recognition and slightly adjusts the DBG_VALUE
insts that LiveDebugValues tracks: instead of tracking the last DBG_VALUE
for a variable, it tracks the last _unspilt_ DBG_VALUE. The spill-restore
code is then able to access and copy the original complex expression; but
the rest of LiveDebugValues has to be aware of the slight semantic shift,
and produce a new spilt location if a spilt location is propagated between
blocks.
The test added produces an incorrect variable location (see FIXME), which
will be the subject of future work.
Differential Revision: https://reviews.llvm.org/D65368
llvm-svn: 369092
This patch avoids a crash caused by DW_OP_LLVM_fragments being dropped
from DIExpressions by LiveDebugValues spill-restore code. The appearance
of a previously unseen fragment configuration confuses LDV, as documented
in PR42773, and reproduced by the test function this patch adds (Crashes
on a x86_64 debug build).
To avoid this, on spill restore, we now use fragment information from the
spilt-location-expression.
In addition, when spilling, we now don't spill any DBG_VALUE with a complex
expression, as it can't be safely restored and will definitely lead to an
incorrect variable location. The discussion of this is in D65368.
Differential Revision: https://reviews.llvm.org/D66284
llvm-svn: 369026
Summary: There are places where a case that debug label scope has an extra lexical block file is not considered properly. The modified test won't pass without this patch.
Reviewers: aprantl, HsiangKai
Subscribers: hiraditya, llvm-commits
Tags: #llvm
Differential Revision: https://reviews.llvm.org/D66187
llvm-svn: 368891
An incorrect verification error revealed that the list of type tags was
incomplete. This patch adds the missing types by adding a tag kind to
the Dwarf.def file, which is used by the `isType` function.
A test was added for the original verification error.
Differential revision: https://reviews.llvm.org/D65914
llvm-svn: 368718
It caused assertions to fire when building Chromium:
lib/CodeGen/LiveDebugValues.cpp:331: bool
{anonymous}::LiveDebugValues::OpenRangesSet::empty() const: Assertion
`Vars.empty() == VarLocs.empty() && "open ranges are inconsistent"' failed.
See https://crbug.com/992871#c3 for how to reproduce.
> Patch https://reviews.llvm.org/D43256 introduced more aggressive loop layout optimization which depends on profile information. If profile information is not available, the statically estimated profile information(generated by BranchProbabilityInfo.cpp) is used. If user program doesn't behave as BranchProbabilityInfo.cpp expected, the layout may be worse.
>
> To be conservative this patch restores the original layout algorithm in plain mode. But user can still try the aggressive layout optimization with -force-precise-rotation-cost=true.
>
> Differential Revision: https://reviews.llvm.org/D65673
llvm-svn: 368579
Summary:
When eliminating an unreachable block we must remove any call site
information for calls residing in the block.
This was originally found on a downstream target, and the attached x86
test case was produced by hand-modifying some MIR.
Reviewers: aprantl, asowda, NikolaPrica, djtodoro, ivanbaev, vsk
Reviewed By: NikolaPrica, vsk
Subscribers: vsk, hiraditya, llvm-commits
Tags: #debug-info, #llvm
Differential Revision: https://reviews.llvm.org/D64500
llvm-svn: 368566
This isn't the most robust error handling API, but does allow clients to
opt-in to getting Errors they can handle. I suspect the long-term
solution would be to move away from the lazy unit parsing and have an
explicit step that parses the unit and then allows access to the other
APIs that require a parsed unit.
llvm-dwarfdump could be expanded to use this (or newer/better API) to
demonstrate the benefit of it - but for now lld will use this in a
follow-up cl which ensures lld can exit non-zero on errors like this (&
provide more descriptive diagnostics including which object file the
error came from).
(error access to later errors when parsing nested DIEs would be good too
- but, again, exposing that without it being a hassle for every consumer
may be tricky)
llvm-svn: 368377
Patch https://reviews.llvm.org/D43256 introduced more aggressive loop layout optimization which depends on profile information. If profile information is not available, the statically estimated profile information(generated by BranchProbabilityInfo.cpp) is used. If user program doesn't behave as BranchProbabilityInfo.cpp expected, the layout may be worse.
To be conservative this patch restores the original layout algorithm in plain mode. But user can still try the aggressive layout optimization with -force-precise-rotation-cost=true.
Differential Revision: https://reviews.llvm.org/D65673
llvm-svn: 368339
Prevent the LoadStoreOptimizer from pairing any load/store instructions with
instructions from the prologue/epilogue if the CFI information has encoded the
operations as separate instructions. This would otherwise lead to a mismatch
of the actual prologue size from the size as recorded in the Windows CFI.
Reviewers: efriedma, mstorsjo, ssijaric
Reviewed By: efriedma
Differential Revision: https://reviews.llvm.org/D65817
llvm-svn: 368164
In debug frame information, some fields, e.g., Length in CIE/FDE and
Offset in FDE are attributes to describe the structure of CIE/FDE. They
are not related to the relaxed code. However, these attributes are
symbol differences. So, in current design, these attributes will be
filled as zero and LLVM generates relocations for them.
We only need to generate relocations for symbols in executable sections.
So, if the symbols are not located in executable sections, we still
evaluate their values under relaxation.
Differential Revision: https://reviews.llvm.org/D61584
llvm-svn: 366531
Reid Kleckner