Summary:
Before this change, LLVM would always describe locals on the stack as
being relative to some specific register, RSP, ESP, EBP, ESI, etc.
Variables in stack memory are pretty common, so there is a special
S_DEFRANGE_FRAMEPOINTER_REL symbol for them. This change uses it to
reduce the size of our debug info.
On top of the size savings, there are cases on 32-bit x86 where local
variables are addressed from ESP, but ESP changes across the function.
Unlike in DWARF, there is no FPO data to describe the stack adjustments
made to push arguments onto the stack and pop them off after the call,
which makes it hard for the debugger to find the local variables in
frames further up the stack.
To handle this, CodeView has a special VFRAME register, which
corresponds to the $T0 variable set by our FPO data in 32-bit. Offsets
to local variables are instead relative to this value.
This is part of PR38857.
Reviewers: hans, zturner, javed.absar
Subscribers: aprantl, hiraditya, JDevlieghere, llvm-commits
Differential Revision: https://reviews.llvm.org/D52217
llvm-svn: 343543
Spill/reload instructions are artificially generated by the compiler and
have no relation to the original source code. So the best thing to do is
not attach any debug location to them (instead of just taking the next
debug location we find on following instructions).
Differential Revision: https://reviews.llvm.org/D52125
llvm-svn: 343520
In some senario, LLVM will remove llvm.dbg.labels in IR. For example,
when the labels are in unreachable blocks, these labels will not
be generated in LLVM IR. In the case, these debug labels will have
address zero as their address. It is not legal address for debugger to
set breakpoints or query sources. So, the patch inhibits the address info
(DW_AT_low_pc) of removed labels.
Fix build failed in BuildBot, clang-stage1-cmake-RA-incremental, on macOS.
Differential Revision: https://reviews.llvm.org/D51908
llvm-svn: 343062
Currently, we emit DW_AT_addr_base that points to the beginning of
the .debug_addr section. That is not correct for the DWARF5 case because address
table contains the header and the attribute should point to the first entry
following the header.
This is currently the reason why LLDB does not work with such executables correctly.
Patch fixes the issue.
Differential revision: https://reviews.llvm.org/D52168
llvm-svn: 342635
Enable enableMultipleCopyHints() on X86.
Original Patch by @jonpa:
While enabling the mischeduler for SystemZ, it was discovered that for some reason a test needed one extra seemingly needless COPY (test/CodeGen/SystemZ/call-03.ll). The handling for that is resulted in this patch, which improves the register coalescing by providing not just one copy hint, but a sorted list of copy hints. On SystemZ, this gives ~12500 less register moves on SPEC, as well as marginally less spilling.
Instead of improving just the SystemZ backend, the improvement has been implemented in common-code (calculateSpillWeightAndHint(). This gives a lot of test failures, but since this should be a general improvement I hope that the involved targets will help and review the test updates.
Differential Revision: https://reviews.llvm.org/D38128
llvm-svn: 342578
This patch fixes the debug info handling for SelectionDAG legalization
of DAG nodes with two results. When an replaced SDNode has more than
one result, transferDbgValues was always copying the SDDbgValue from
the first result and attaching them to all members. In reality
SelectionDAG::ReplaceAllUsesWith() is given an array of SDNodes
(though the type signature doesn't make this obvious (cf. the call
site code in ReplaceNode()).
rdar://problem/44162227
Differential Revision: https://reviews.llvm.org/D52112
llvm-svn: 342264
In r319995, we fixed the line table format to version 2 on Darwin
because dsymutil didn't yet understand the new format which caused test
failures for the LLDB bots. This has been resolved in the meantime so
there's no reason to keep this limitation.
rdar://problem/35968332
llvm-svn: 342136
Eliminating some duplication of rangelist dumping code at the expense of
some version-dependent code in dump and extract routines.
Reviewer: dblaikie, JDevlieghere, vleschuk
Differential revision: https://reviews.llvm.org/D51081
llvm-svn: 342048
Normalize common kinds of DWARF sub-expressions to make debug info
encoding a bit more compact:
DW_OP_constu [X < 32] -> DW_OP_litX
DW_OP_constu [all ones] -> DW_OP_lit0, DW_OP_not (64-bit only)
Differential revision: https://reviews.llvm.org/D51640
llvm-svn: 341457
In lib/CodeGen/LiveDebugVariables.cpp, it uses std::prev(MBBI) to
get DebugValue's SlotIndex. However, the previous instruction may be
also a debug instruction. It could not use a debug instruction to query
SlotIndex in mi2iMap.
Scan all debug instructions and use the first debug instruction to query
SlotIndex for following debug instructions. Only handle DBG_VALUE in
handleDebugValue().
Differential Revision: https://reviews.llvm.org/D50621
llvm-svn: 341446
In lib/CodeGen/LiveDebugVariables.cpp, it uses std::prev(MBBI) to
get DebugValue's SlotIndex. However, the previous instruction may be
also a debug instruction. It could not use a debug instruction to query
SlotIndex in mi2iMap.
Scan all debug instructions and use the first debug instruction to query
SlotIndex for following debug instructions. Only handle DBG_VALUE in
handleDebugValue().
Differential Revision: https://reviews.llvm.org/D50621
llvm-svn: 341289
My previoust test case had skipped CUs from one TU out of a two-TU LTO
scenario, which meant the CU index wasn't needed (as it was unambiguous
which CU a table entry applied to) - expanding the test to use 3 TUs,
skipping one (so long as it's not the last one) shows the indexes are
miscomputed. Fix that with a little indirection for the index.
llvm-svn: 340646
Fix a set of related bugs:
* Considering two locations as equivalent when their lines are the same
but their scopes are different causes erroneous debug info that
attributes a commoned call to be attributed to one of the two calls it
was commoned from.
* The previous code to compute a new location's scope was inaccurate and
would use the inlinedAt that was the /parent/ of the inlinedAt that is
the nearest common one, and also used that parent scope instead of the
nearest common scope.
* Not generating new locations generally seemed like a lower quality
choice
There was some risk that generating more new locations could hurt object
size by making more fine grained line table entries, but it looks like
that was offset by the decrease in line table (& address & ranges) size
caused by more accurately computing the scope - which likely lead to
fewer range entries (more contiguous ranges) & reduced size that way.
All up with these changes I saw minor reductions (-1.21%, -1.77%) in
.rela.debug_ranges and .rela.debug_addr (in a fission, compressed debug
info build) as well as other minor size changes (generally reductinos)
across the board (-1.32% debug_info.dwo, -1.28% debug_loc.dwo). Measured
in an optimized (-O2) build of the clang binary.
If you are investigating a size regression in an optimized debug builds,
this is certainly a patch to look into - and I'd be happy to look into
any major regressions found & see what we can do to address them.
llvm-svn: 340583
This is preparation for landing a use-before-def verifier for debug
intrinsics (D46100).
As a drive-by, remove `tail` from debug intrinsic calls because it
doesn't mean anything in that context.
llvm-svn: 340366
In cases where the debugger load time is a worthwhile tradeoff (or less
costly - such as loading from a DWP instead of a variety of DWOs
(possibly over a high-latency/distributed filesystem)) against object
file size, it can be reasonable to disable pubnames and corresponding
gdb-index creation in the linker.
A backend-flag version of this was implemented for NVPTX in
D44385/r327994 - which was fine for NVPTX which wouldn't mix-and-match
CUs. Now that it's going to be a user-facing option (likely powered by
"-gno-pubnames", the same as GCC) it should be encoded in the
DICompileUnit so it can vary per-CU.
After this, likely the NVPTX support should be migrated to the metadata
& the previous flag implementation should be removed.
Reviewers: aprantl
Differential Revision: https://reviews.llvm.org/D50213
llvm-svn: 339939
Summary:
This prefix was added in r333421, and it changed our dumper output to
say things like "CVRegEAX" instead of just "EAX". That's a functional
change that I'd rather avoid.
I tested GCC, Clang, and MSVC, and all of them support #pragma
push_macro. They don't issue warnings whem the macro is not defined
either.
I don't have a Mac so I can't test the real termios.h header, but I
looked at the termios.h sources online and looked for other conflicts.
I saw only the CR* macros, so those are the ones we work around.
Reviewers: zturner, JDevlieghere
Subscribers: hiraditya, llvm-commits
Differential Revision: https://reviews.llvm.org/D50851
llvm-svn: 339907
When using APPLE extensions, don't duplicate the compiler invocation's
flags both in AT_producer and AT_APPLE_flags.
Differential revision: https://reviews.llvm.org/D50453
llvm-svn: 339268
Summary:
The accelerator tables use the debug_str section to store their strings.
However, they do not support the indirect method of access that is
available for the debug_info section (DW_FORM_strx et al.).
Currently our code is assuming that all strings can/will be referenced
indirectly, and puts all of them into the debug_str_offsets section.
This is generally true for regular (unsplit) dwarf, but in the DWO case,
most of the strings in the debug_str section will only be used from the
accelerator tables. Therefore the contents of the debug_str_offsets
section will be largely unused and bloating the main executable.
This patch rectifies this by teaching the DwarfStringPool to
differentiate between strings accessed directly and indirectly. When a
user inserts a string into the pool it has to declare whether that
string will be referenced directly or not. If at least one user requsts
indirect access, that string will be assigned an index ID and put into
debug_str_offsets table. Otherwise, the offset table is skipped.
This approach reduces the overall binary size (when compiled with
-gdwarf-5 -gsplit-dwarf) in my tests by about 2% (debug_str_offsets is
shrunk by 99%).
Reviewers: probinson, dblaikie, JDevlieghere
Subscribers: aprantl, mgrang, llvm-commits
Differential Revision: https://reviews.llvm.org/D49493
llvm-svn: 339122
We don't expect module names to be present in the index. This patch adds
DW_TAG_module to the blacklist.
Differential revision: https://reviews.llvm.org/D50237
llvm-svn: 338878
Getting the DWARF types section is only implemented for ELF object
files. We already disabled emitting debug types in clang (r337717), but
now we also report an fatal error (rather than crashing) when trying to
obtain this section in MC. Additionally we ignore the generate debug
types flag for unsupported target triples.
See PR38190 for more information.
Differential revision: https://reviews.llvm.org/D50057
llvm-svn: 338527
This revision implements support for generating DWARFv5 .debug_addr section.
The implementation is pretty straight-forward: we just check the dwarf version
and emit section header if needed.
Reviewers: aprantl, dblaikie, probinson
Reviewed by: dblaikie
Differential Revision: https://reviews.llvm.org/D50005
llvm-svn: 338487
The test failure was caused by the compiler not emitting a __debug_ranges section with DWARF 4 and
earlier when no ranges are needed. The test checks for the existence regardless.
llvm-svn: 338081
LowerDbgDeclare inserts a dbg.value before each use of an address
described by a dbg.declare. When inserting a dbg.value before a CallInst
use, however, it fails to append DW_OP_deref to the DIExpression.
The DW_OP_deref is needed to reflect the fact that a dbg.value describes
a source variable directly (as opposed to a dbg.declare, which relies on
pointer indirection).
This patch adds in the DW_OP_deref where needed. This results in the
correct values being shown during a debug session for a program compiled
with ASan and optimizations (see https://reviews.llvm.org/D49520). Note
that ConvertDebugDeclareToDebugValue is already correct -- no changes
there were needed.
One complication is that SelectionDAG is unable to distinguish between
direct and indirect frame-index (FRAMEIX) SDDbgValues. This patch also
fixes this long-standing issue in order to not regress integration tests
relying on the incorrect assumption that all frame-index SDDbgValues are
indirect. This is a necessary fix: the newly-added DW_OP_derefs cannot
be lowered properly otherwise. Basically the fix prevents a direct
SDDbgValue with DIExpression(DW_OP_deref) from being dereferenced twice
by a debugger. There were a handful of tests relying on this incorrect
"FRAMEIX => indirect" assumption which actually had incorrect
DW_AT_locations: these are all fixed up in this patch.
Testing:
- check-llvm, and an end-to-end test using lldb to debug an optimized
program.
- Existing unit tests for DIExpression::appendToStack fully cover the
new DIExpression::append utility.
- check-debuginfo (the debug info integration tests)
Differential Revision: https://reviews.llvm.org/D49454
llvm-svn: 338069
The intent is to use it for location list tables as well. Change is almost NFC with the exception
of the spelling of some strings used during dumping (all lowercase now).
Reviewer: JDevlieghere
Differential Revision: https://reviews.llvm.org/D49500
llvm-svn: 337763
Summary:
This patch makes us generate the debug_names section in response to some
user-facing commands (previously it was only generated if explicitly
selected via the -accel-tables option).
My goal was to make this work for DWARF>=5 (as it's an official part of
that standard), and also, as an extension, for DWARF<5 if one is
explicitly tuning for lldb as a debugger (because it brings a large
performance improvement there).
This is slightly complicated by the fact that the debug_names tables are
incompatible with the DWARF v4 type units (they assume that the type
units are in the debug_info section), and unfortunately, right now we
generate DWARF v4-style type units even for -gdwarf-5. For this reason,
I disable all accelerator tables if the user requested type unit
generation. I do this even for apple tables, as they have the same
problem (in fact generating type units for apple targets makes us crash
even before we get around to emitting the accelerator tables).
Reviewers: JDevlieghere, aprantl, dblaikie, echristo, probinson
Subscribers: llvm-commits
Differential Revision: https://reviews.llvm.org/D49420
llvm-svn: 337544
This prevents gold from printing a warning when trying to export
these symbols via the asan dynamic list after ThinLTO promotes them
from private symbols to external symbols with hidden visibility.
Differential Revision: https://reviews.llvm.org/D49498
llvm-svn: 337428
Since DWARFv5 rnglists are self descriptive and have distinct encodings
for base-relative (offset_pair) and absolute (start_length) entries,
there's no need to use a base address specifier when describing a lone
address range in a section.
Use that, and improve the test coverage a bit here to include cases like
this and others.
llvm-svn: 337411
and no use of DW_FORM_rnglistx with the DW_AT_ranges attribute.
Reviewer: aprantl
Differential Revision: https://reviews.llvm.org/D49214
llvm-svn: 336927
Summary:
In some cases, these operands lacked the IsDebug property, which is meant to signal that
they should not affect codegen. This patch adds a check for this property in the
MachineVerifier and adds it where it was missing.
This includes refactorings to use MachineInstrBuilder construction functions instead of
manually setting up the intrinsic everywhere.
Patch by: JesperAntonsson
Reviewers: aprantl, rnk, echristo, javed.absar
Reviewed By: aprantl
Subscribers: qcolombet, sdardis, nemanjai, JDevlieghere, atanasyan, llvm-commits
Differential Revision: https://reviews.llvm.org/D48319
llvm-svn: 335214
Summary:
Fixes PR36579.
For cases where we had e.g.
DBG_VALUE 42
[...]
DBG_VALUE undef
LiveDebugVariables would discard all undef DBG_VALUEs and then it would
look like the variable had the value 42 throughout the rest of the
function, which is incorrect.
With this patch we don't remove all undef DBG_VALUEs in LiveDebugVariables
so they will be kept after register allocation just like other DBG_VALUEs
which will yield more correct debug information.
Reviewers: aprantl
Reviewed By: aprantl
Subscribers: bjope, Ka-Ka, JDevlieghere, llvm-commits
Differential Revision: https://reviews.llvm.org/D48277
llvm-svn: 335205
Errors found processing the DW_AT_ranges attribute are propagated by lower level
routines and reported by their callers.
Reviewer: JDevlieghere
Differential Revision: https://reviews.llvm.org/D48344
llvm-svn: 335188
This is r334704 (which was reverted in r334732) with a fix for
types like x86_fp80. We need to use getTypeAllocSizeInBits and
not getTypeStoreSizeInBits to avoid dropping debug info for
such types.
Original commit msg:
> Summary:
> Do not convert a DbgDeclare to DbgValue if the store
> instruction only refer to a fragment of the variable
> described by the DbgDeclare.
>
> Problem was seen when for example having an alloca for an
> array or struct, and there were stores to individual elements.
> In the past we inserted a DbgValue intrinsics for each store,
> just as if the store wrote the whole variable.
>
> When handling store instructions we insert a DbgValue that
> indicates that the variable is "undefined", as we do not know
> which part of the variable that is updated by the store.
>
> When ConvertDebugDeclareToDebugValue is used with a load/phi
> instruction we assert that the referenced value is large enough
> to cover the whole variable. Afaict this should be true for all
> scenarios where those methods are used on trunk. If the assert
> blows in the future I guess we could simply skip to insert a
> dbg.value instruction.
>
> In the future I think we should examine which part of the variable
> that is accessed, and add a DbgValue instrinsic with an appropriate
> DW_OP_LLVM_fragment expression.
>
> Reviewers: dblaikie, aprantl, rnk
>
> Reviewed By: aprantl
>
> Subscribers: JDevlieghere, llvm-commits
>
> Tags: #debug-info
>
> Differential Revision: https://reviews.llvm.org/D48024
llvm-svn: 334830
In r333801 I added a test for a dump method that, for reasons I don't
understand, fails on an msvc bot:
http://lab.llvm.org:8011/builders/clang-x86-windows-msvc2015/builds/12306/
I'll remove the test for now to unblock the bot and try to look into why
there's a discrepancy on this platform later.
llvm-svn: 333807
Summary:
"Unknown" for platforms that were not manually added into the switch
did not make sense at all. Now it prints Target + addend for all
elf-machines that were not explicitly mentioned.
Addresses PR21059 and PR25124.
Original author: fedor.sergeev
Reviewers: jyknight, espindola, fedor.sergeev
Reviewed By: jyknight
Subscribers: eraman, dcederman, jfb, dschuff, aheejin, llvm-commits
Differential Revision: https://reviews.llvm.org/D36464
llvm-svn: 333726
When a GEP with all zero indices is converted to bitcast, its DI wasn't
copied over to the newly created instruction. This patch fixes that bug.
Patch by Kareem Ergawy!
Differential Revision: https://reviews.llvm.org/D47347
llvm-svn: 333235
In DWARF v5, the DWO ID is in the (split/skeleton) CU header, not an
attribute on the CU DIE.
This changes the size of those headers, so use the parsed size whenever
we have one, for simplicitly.
Differential Revision: https://reviews.llvm.org/D47158
llvm-svn: 333004
Summary:
The correct spelling is "DWARF", the debugging format, not "DWARG".
The typo is in a (not executed by lit) comment in a test file, so
fixing it does not result in any functional change.
Test Plan: check-llvm, just in case
llvm-svn: 332878
Rather than relying on the user to do the address calculating in
DW_AT_location we should just dump the absolute address.
rdar://problem/38513870
Differential revision: https://reviews.llvm.org/D47152
llvm-svn: 332873
length excluding the table header. Instead it must encode the contribution length minus the length
field itself.
Reviewer: JDevliegehere
Differential Revision: https://reviews.llvm.org/D45922
llvm-svn: 332030
Reviewed by: dblaikie, JDevlieghere, espindola
Differential Revision: https://reviews.llvm.org/D44560
Summary:
The .debug_line parser previously reported errors by printing to stderr and
return false. This is not particularly helpful for clients of the library code,
as it prevents them from handling the errors in a manner based on the calling
context. This change switches to using llvm::Error and callbacks to indicate
what problems were detected during parsing, and has updated clients to handle
the errors in a location-specific manner. In general, this means that they
continue to do the same thing to external users. Below, I have outlined what
the known behaviour changes are, relating to this change.
There are two levels of "errors" in the new error mechanism, to broadly
distinguish between different fail states of the parser, since not every
failure will prevent parsing of the unit, or of subsequent unit. Malformed
table errors that prevent reading the remainder of the table (reported by
returning them) and other minor issues representing problems with parsing that
do not prevent attempting to continue reading the table (reported by calling a
specified callback funciton). The only example of this currently is when the
last sequence of a unit is unterminated. However, I think it would be good to
change the handling of unrecognised opcodes to report as minor issues as well,
rather than just printing to the stream if --verbose is used (this would be a
subsequent change however).
I have substantially extended the DwarfGenerator to be able to handle
custom-crafted .debug_line sections, allowing for comprehensive unit-testing
of the parser code. For now, I am just adding unit tests to cover the basic
error reporting, and positive cases, and do not currently intend to test every
part of the parser, although the framework should be sufficient to do so at a
later point.
Known behaviour changes:
- The dump function in DWARFContext now does not attempt to read subsequent
tables when searching for a specific offset, if the unit length field of a
table before the specified offset is a reserved value.
- getOrParseLineTable now returns a useful Error if an invalid offset is
encountered, rather than simply a nullptr.
- The parse functions no longer use `WithColor::warning` directly to report
errors, allowing LLD to call its own warning function.
- The existing parse error messages have been updated to not specifically
include "warning" in their message, allowing consumers to determine what
severity the problem is.
- If the line table version field appears to have a value less than 2, an
informative error is returned, instead of just false.
- If the line table unit length field uses a reserved value, an informative
error is returned, instead of just false.
- Dumping of .debug_line.dwo sections is now implemented the same as regular
.debug_line sections.
- Verbose dumping of .debug_line[.dwo] sections now prints the prologue, if
there is a prologue error, just like non-verbose dumping.
As a helper for the generator code, I have re-added emitInt64 to the
AsmPrinter code. This previously existed, but was removed way back in r100296,
presumably because it was dead at the time.
This change also requires a change to LLD, which will be committed separately.
llvm-svn: 331971
In order to set breakpoints on labels and list source code around
labels, we need collect debug information for labels, i.e., label
name, the function label belong, line number in the file, and the
address label located. In order to keep these information in LLVM
IR and to allow backend to generate debug information correctly.
We create a new kind of metadata for labels, DILabel. The format
of DILabel is
!DILabel(scope: !1, name: "foo", file: !2, line: 3)
We hope to keep debug information as much as possible even the
code is optimized. So, we create a new kind of intrinsic for label
metadata to avoid the metadata is eliminated with basic block.
The intrinsic will keep existing if we keep it from optimized out.
The format of the intrinsic is
llvm.dbg.label(metadata !1)
It has only one argument, that is the DILabel metadata. The
intrinsic will follow the label immediately. Backend could get the
label metadata through the intrinsic's parameter.
We also create DIBuilder API for labels to be used by Frontend.
Frontend could use createLabel() to allocate DILabel objects, and use
insertLabel() to insert llvm.dbg.label intrinsic in LLVM IR.
Differential Revision: https://reviews.llvm.org/D45024
Patch by Hsiangkai Wang.
llvm-svn: 331841
Summary:
This reverts SVN r331441 (reapplies r331337), together with a fix
in to handle an already existing fragment expression in the
dbg.value that must be fragmented due to a split PHI node.
This should solve the problem seen in PR37321, which was the
reason for the revert of r331337.
The situation in PR37321 is that we have a PHI node like this
%u.sroa = phi i80 [ %u.sroa.x, %if.x ],
[ %u.sroa.y, %if.y ],
[ %u.sroa.z, %if.z ]
and a dbg.value like this
call void @llvm.dbg.value(metadata i80 %u.sroa,
metadata !13,
metadata !DIExpression(DW_OP_LLVM_fragment, 0, 80))
The phi node is split into three 32-bit PHI nodes
%30:gr32 = PHI %11:gr32, %bb.4, %14:gr32, %bb.5, %27:gr32, %bb.8
%31:gr32 = PHI %12:gr32, %bb.4, %15:gr32, %bb.5, %28:gr32, %bb.8
%32:gr32 = PHI %13:gr32, %bb.4, %16:gr32, %bb.5, %29:gr32, %bb.8
but since the original value only is 80 bits we need to adjust the size
of the last fragment expression, and with this patch we get
DBG_VALUE debug-use %30:gr32, debug-use $noreg, !"u", !DIExpression(DW_OP_LLVM_fragment, 0, 32)
DBG_VALUE debug-use %31:gr32, debug-use $noreg, !"u", !DIExpression(DW_OP_LLVM_fragment, 32, 32)
DBG_VALUE debug-use %32:gr32, debug-use $noreg, !"u", !DIExpression(DW_OP_LLVM_fragment, 64, 16)
Reviewers: vsk, aprantl, mstorsjo
Reviewed By: aprantl
Subscribers: llvm-commits
Differential Revision: https://reviews.llvm.org/D46384
llvm-svn: 331464
Summary:
This is a follow up to rL331182. A PHI node can be split up into
several MIR PHI nodes when being selected. When there is a
dbg.value intrinsic that uses the result of such a PHI node we
need to select several DBG_VALUE instructions, with fragment
expressions, in order to do a correct selection.
Reviewers: rnk, aprantl, vsk
Reviewed By: vsk
Subscribers: mattd, llvm-commits, JDevlieghere, aprantl, gbedwell, rnk
Tags: #debug-info
Differential Revision: https://reviews.llvm.org/D46329
llvm-svn: 331337
Summary:
This patch will introduce copying of DBG_VALUE instructions
from an otherwise empty basic block to predecessor/successor
blocks in case the empty block is eliminated/bypassed. It
is currently only done in one identified situation in the
BranchFolding pass, before optimizing on empty block.
It can be seen as a light variant of the propagation done
by the LiveDebugValues pass, which unfortunately is executed
after the BranchFolding pass.
We only propagate (copy) DBG_VALUE instructions in a limited
number of situations:
a) If the empty BB is the only predecessor of a successor
we can copy the DBG_VALUE instruction to the beginning of
the successor (because the DBG_VALUE instruction is always
part of the flow between the blocks).
b) If the empty BB is the only successor of a predecessor
we can copy the DBG_VALUE instruction to the end of the
predecessor (because the DBG_VALUE instruction is always
part of the flow between the blocks). In this case we add
the DBG_VALUE just before the first terminator (assuming
that the terminators do not impact the DBG_VALUE).
A future solution, to handle more situations, could perhaps
be to run the LiveDebugValues pass before branch folding?
This fix is related to PR37234. It is expected to resolve
the problem seen, when applied together with the fix in
SelectionDAG from here: https://reviews.llvm.org/D46129
Reviewers: #debug-info, aprantl, rnk
Reviewed By: #debug-info, aprantl
Subscribers: ormris, gbedwell, llvm-commits
Differential Revision: https://reviews.llvm.org/D46184
llvm-svn: 331183
Summary:
When building the selection DAG at ISel all PHI nodes are
selected and lowered to Machine Instruction PHI nodes before
we start to create any SDNodes. So there are no SDNodes for
values produced by the PHI nodes.
In the past when selecting a dbg.value intrinsic that uses
the value produced by a PHI node we have been handling such
dbg.value intrinsics as "dangling debug info". I.e. we have
not created a SDDbgValue node directly, because there is
no existing SDNode for the PHI result, instead we deferred
the creationg of a SDDbgValue until we found the first use
of the PHI result.
The old solution had a couple of flaws. The position of the
selected DBG_VALUE instruction would end up quite late in a
basic block, and for example not directly after the PHI node
as in the LLVM IR input. And in case there were no use at all
in the basic block the dbg.value could be dropped completely.
This patch introduces a new VREG kind of SDDbgValue nodes.
It is similar to a SDNODE kind of node, but it refers directly
to a virtual register and not a SDNode. When we do selection
for a dbg.value that is using the result of a PHI node we
can do a lookup of the virtual register directly (as it already
is determined for the PHI node) and create a SDDbgValue node
immediately instead of delaying the selection until we find a
use.
This should fix a problem with losing debug info at ISel
as seen in PR37234 (https://bugs.llvm.org/show_bug.cgi?id=37234).
It does not resolve PR37234 completely, because the debug info
is dropped later on in the BranchFolder (see D46184).
Reviewers: #debug-info, aprantl
Reviewed By: #debug-info, aprantl
Subscribers: rnk, gbedwell, aprantl, JDevlieghere, llvm-commits
Differential Revision: https://reviews.llvm.org/D46129
llvm-svn: 331182
For local variables the first DW_OP_deref is consumed by turning the
location kind into a memeory location, but that only makes sense for
values that are in a register to begin with, which cannot happen for
global variables that are attached to a symbol.
rdar://problem/39741860
This reapplies r330970 after fixing an uncovered bug in r331086 and
working around the situation caused by it.
llvm-svn: 331090
For local variables the first DW_OP_deref is consumed by turning the
location kind into a memeory location, but that only makes sense for
values that are in a register to begin with, which cannot happen for
global variables that are attached to a symbol.
rdar://problem/39741860
llvm-svn: 330970
Debug var, expr and loc were only supported for non-fixed stack objects.
This patch adds the following fields to the "fixedStack:" entries, and
renames the ones from "stack:" to:
* debug-info-variable
* debug-info-expression
* debug-info-location
Differential Revision: https://reviews.llvm.org/D46032
llvm-svn: 330859
Updated two more debug line related warnings to use WithColor. This was
necessary to ensure consistent output order of the warnings on Windows
for debug line tests.
Differential Revision: https://reviews.llvm.org/D45871
llvm-svn: 330440
On Windows, %llc_dwarf automatically adds -mtriple causing this test to
error. Changed %llc_dwarf to llc.
Differential Revision: https://reviews.llvm.org/D45869
llvm-svn: 330414
It seems llc crashes when targetting darwin with split-dwarf (pr37164).
This happens on all inputs, not just the one I added in the above
commit. Work around the issue by hardcoding the target triple to linux,
which is what all split-dwarf tests seem to be doing.
As I don't know of a way to specify the os part of the triple without
spelling out the architecture as well, I move the new test to the X86
folder.
llvm-svn: 330265
Summary:
When sinking an instruction in InstCombine we now also sink
the DbgInfoIntrinsics that are using the sunken value.
Example)
When sinking the load in this input
bb.X:
%0 = load i64, i64* %start, align 4, !dbg !31
tail call void @llvm.dbg.value(metadata i64 %0, ...)
br i1 %cond, label %for.end, label %for.body.lr.ph
for.body.lr.ph:
br label %for.body
we now also move the dbg.value, like this
bb.X:
br i1 %cond, label %for.end, label %for.body.lr.ph
for.body.lr.ph:
%0 = load i64, i64* %start, align 4, !dbg !31
tail call void @llvm.dbg.value(metadata i64 %0, ...)
br label %for.body
In the past we haven't moved the dbg.value so we got
bb.X:
tail call void @llvm.dbg.value(metadata i64 %0, ...)
br i1 %cond, label %for.end, label %for.body.lr.ph
for.body.lr.ph:
%0 = load i64, i64* %start, align 4, !dbg !31
br label %for.body
So in the past we got a debug-use before the def of %0.
And that dbg.value was also on the path jumping to %for.end, for
which %0 never was defined.
CodeGenPrepare normally comes to rescue later (when not moving
the dbg.value), since it moves dbg.value instrinsics quite
brutally, without really analysing if it is correct to move
the intrinsic (see PR31878).
So at the moment this patch isn't expected to have much impact,
besides that it is moving the dbg.value already in opt, making
the IR look more sane directly.
This can be seen as a preparation to (hopefully) make it possible
to turn off CodeGenPrepare::placeDbgValues later as a solution
to PR31878.
I also adjusted test/DebugInfo/X86/sdagsplit-1.ll to make the
IR in the test case up-to-date with this behavior in InstCombine.
Reviewers: rnk, vsk, aprantl
Reviewed By: vsk, aprantl
Subscribers: mattd, JDevlieghere, llvm-commits
Tags: #debug-info
Differential Revision: https://reviews.llvm.org/D45425
llvm-svn: 330243
As demonstrated by the regression tests added in this patch, the
following cases are valid cases:
1. A Function with no DISubprogram attached, but various debug info
related to its instructions, coming, for instance, from an inlined
function, also defined somewhere else in the same module;
2. ... or coming exclusively from the functions inlined and eliminated
from the module entirely.
The ValueMap shared between CloneFunctionInto calls within CloneModule
needs to contain identity mappings for all of the DISubprogram's to
prevent them from being duplicated by MapMetadata / RemapInstruction
calls, this is achieved via DebugInfoFinder collecting all the
DISubprogram's. However, CloneFunctionInto was missing calls into
DebugInfoFinder for functions w/o DISubprogram's attached, but still
referring DISubprogram's from within (case 1). This patch fixes that.
The fix above, however, exposes another issue: if a module contains a
DISubprogram referenced only indirectly from other debug info
metadata, but not attached to any Function defined within the module
(case 2), cloning such a module causes a DICompileUnit duplication: it
will be moved in indirecty via a DISubprogram by DebugInfoFinder first
(because of the first bug fix described above), without being
self-mapped within the shared ValueMap, and then will be copied during
named metadata cloning. So this patch makes sure DebugInfoFinder
visits DICompileUnit's referenced from DISubprogram's as it goes w/o
re-processing llvm.dbg.cu list over and over again for every function
cloned, and makes sure that CloneFunctionInto self-maps
DICompileUnit's referenced from the entire function, not just its own
DISubprogram attached that may also be missing.
The most convenient way of tesing CloneModule I found is to rely on
CloneModule call from `opt -run-twice`, instead of writing tedious
unit tests. That feature has a couple of properties that makes it hard
to use for this purpose though:
1. CloneModule doesn't copy source filename, making `opt -run-twice`
report it as a difference.
2. `opt -run-twice` does the second run on the original module, not
its clone, making the result of cloning completely invisible in opt's
actual output with and without `-run-twice` both, which directly
contradicts `opt -run-twice`s own error message.
This patch fixes this as well.
Reviewed By: aprantl
Reviewers: loladiro, GorNishanov, espindola, echristo, dexonsmith
Subscribers: vsk, debug-info, JDevlieghere, llvm-commits
Differential Revision: https://reviews.llvm.org/D45593
llvm-svn: 330069
This is causing compilation timeouts on code with long sequences of
local values and calls (i.e. foo(1); foo(2); foo(3); ...). It turns out
that code coverage instrumentation is a great way to create sequences
like this, which how our users ran into the issue in practice.
Intel has a tool that detects these kinds of non-linear compile time
issues, and Andy Kaylor reported it as PR37010.
The current sinking code scans the whole basic block once per local
value sink, which happens before emitting each call. In theory, local
values should only be introduced to be used by instructions between the
current flush point and the last flush point, so we should only need to
scan those instructions.
llvm-svn: 329822
Summary:
This type is created on-demand and used as the base type for array
ranges. Since it is "special", its construction did not go through the
createTypeDIE function and so it was never inserted into the accelerator
table, although it clearly belongs there.
I add an explicit addAccelType call to insert it into the table.
During review, we also decided to rename the type to something more
unique to avoid confusion in case the user has own "sizetype" type. The
new name for the type size __ARRAY_SIZE_TYPE__.
Reviewers: JDevlieghere, aprantl, dblaikie
Subscribers: llvm-commits
Differential Revision: https://reviews.llvm.org/D45445
llvm-svn: 329705
- MSVC was not OK with a static_assert referencing a non-static member
variable, even though it was just in a sizeof(expression). I move the
assert into the emit function, where it is probably more useful.
- Tests were failing in builds which did not have the X86 target
configured. Since this functionality is not target-specific, I have
removed the target specifiers from the .ll files.
llvm-svn: 329201
Summary:
This patch adds a DwarfAccelTableEmitter class, which generates an
accelerator table, as specified in DWARF v5 standard. At the moment it
only generates a DIE offset column and (if we are indexing more than one
compile unit) a CU column.
Indexing type units is not currently supported, as we don't even have
the ability to generate DWARF v5-compatible compile units.
The implementation is not data-source agnostic like the one generating
apple tables. This was not necessary as we currently only have one user
of this code, and without a second user it was not obvious to me how to
best abstract this. (The difference between these tables and the apple
ones is that they need a lot more metadata about the debug info they are
indexing).
The generation is triggered by the --accel-tables argument, which
supersedes the --dwarf-accel-tables arg -- the latter was a simple
on-off switch, but not we can choose between two kinds of accelerator
tables we can generate.
This is tested by parsing the generated tables with llvm-dwarfdump and
the DWARFVerifier, and I've also checked that GNU readelf is able to
make sense of the tables.
Differential Revision: https://reviews.llvm.org/D43286
llvm-svn: 329179
DWARF v5 specifies that the root file (also given in the DW_AT_name
attribute of the compilation unit DIE) should be emitted explicitly to
the line table's list of files. This makes the line table more
independent of the .debug_info section.
We emit the new syntax only for DWARF v5 and later.
Fixes the bug found by asan. Also XFAIL the new test for Darwin, which
is stuck on DWARF v2, and fix up other tests so they stop failing on
Windows. Last but not least, don't break "clang -g" of an assembler
file that has .file directives in it.
Differential Revision: https://reviews.llvm.org/D44054
llvm-svn: 328805
Before this patch we were parsing the attributes as section offsets, as
that is what apple_names is doing. However, this is not correct as DWARF
v5 specifies that this attribute should use the Reference form class.
This also updates all the testcases (except the ones that deliberately
pass a different form) to use the correct form class.
llvm-svn: 328773
This reverts commit r328676.
Commit r328676 broke the -no-integrated-as flag necessary to build Linux kernel with Clang:
$ cat t.c
void foo() {}
$ clang -no-integrated-as -c t.c -g
/tmp/t-dcdec5.s: Assembler messages:
/tmp/t-dcdec5.s:8: Error: file number less than one
clang-7.0: error: assembler command failed with exit code 1 (use -v to see invocation)
llvm-svn: 328699
DWARF v5 specifies that the root file (also given in the DW_AT_name
attribute of the compilation unit DIE) should be emitted explicitly to
the line table's list of files. This makes the line table more
independent of the .debug_info section.
Fixes the bug found by asan. Also XFAIL the new test for Darwin, which
is stuck on DWARF v2, and fix up other tests so they stop failing on
Windows. Last but not least, don't break "clang -g" of an assembler
file that has .file directives in it.
Differential Revision: https://reviews.llvm.org/D44054
llvm-svn: 328676
On Hexagon "x = y" is a syntax used in most instructions, and is not
treated as a directive.
Differential Revision: https://reviews.llvm.org/D44256
llvm-svn: 328635
Summary:
Some targets does not support labels inside debug sections, but support
references in form `section+offset`. Patch adds initial support
for this.
Reviewers: echristo, probinson, jlebar
Subscribers: llvm-commits, JDevlieghere
Differential Revision: https://reviews.llvm.org/D43943
llvm-svn: 328314
Summary:
This pass sinks COPY instructions into a successor block, if the COPY is not
used in the current block and the COPY is live-in to a single successor
(i.e., doesn't require the COPY to be duplicated). This avoids executing the
the copy on paths where their results aren't needed. This also exposes
additional opportunites for dead copy elimination and shrink wrapping.
These copies were either not handled by or are inserted after the MachineSink
pass. As an example of the former case, the MachineSink pass cannot sink
COPY instructions with allocatable source registers; for AArch64 these type
of copy instructions are frequently used to move function parameters (PhyReg)
into virtual registers in the entry block..
For the machine IR below, this pass will sink %w19 in the entry into its
successor (%bb.1) because %w19 is only live-in in %bb.1.
```
%bb.0:
%wzr = SUBSWri %w1, 1
%w19 = COPY %w0
Bcc 11, %bb.2
%bb.1:
Live Ins: %w19
BL @fun
%w0 = ADDWrr %w0, %w19
RET %w0
%bb.2:
%w0 = COPY %wzr
RET %w0
```
As we sink %w19 (CSR in AArch64) into %bb.1, the shrink-wrapping pass will be
able to see %bb.0 as a candidate.
With this change I observed 12% more shrink-wrapping candidate and 13% more dead copies deleted in spec2000/2006/2017 on AArch64.
Reviewers: qcolombet, MatzeB, thegameg, mcrosier, gberry, hfinkel, john.brawn, twoh, RKSimon, sebpop, kparzysz
Reviewed By: sebpop
Subscribers: evandro, sebpop, sfertile, aemerson, mgorny, javed.absar, kristof.beyls, llvm-commits
Differential Revision: https://reviews.llvm.org/D41463
llvm-svn: 328237
This is mostly just plumbing to get a DWARFDataExtractor where we
compute abbr_offset so we can use getRelocatedValue.
This is part of PR36793.
llvm-svn: 328154
Summary:
When building the selection DAG we sometimes need to postpone
the handling of a dbg.value until the value it should refer to
is created. This is done by using the DanglingDebugInfoMap.
In the past this map has been limited to hold one dangling
dbg.value per value. This patch removes that restriction.
Reviewers: aprantl, rnk, probinson, vsk
Reviewed By: aprantl
Subscribers: Ka-Ka, llvm-commits, JDevlieghere
Tags: #debug-info
Differential Revision: https://reviews.llvm.org/D44610
llvm-svn: 328084
Summary:
Added a flag -no-dwarf-pub-sections, which allows to disable
emission of DWARF public sections.
Reviewers: probinson, echristo
Subscribers: aprantl, JDevlieghere, llvm-commits
Differential Revision: https://reviews.llvm.org/D44385
llvm-svn: 327994
Summary:
Local values are constants, global addresses, and stack addresses that
can't be folded into the instruction that uses them. For example, when
storing the address of a global variable into memory, we need to
materialize that address into a register.
FastISel doesn't want to materialize any given local value more than
once, so it generates all local value materialization code at
EmitStartPt, which always dominates the current insertion point. This
allows it to maintain a map of local value registers, and it knows that
the local value area will always dominate the current insertion point.
The downside is that local value instructions are always emitted without
a source location. This is done to prevent jumpy line tables, but it
means that the local value area will be considered part of the previous
statement. Consider this C code:
call1(); // line 1
++global; // line 2
++global; // line 3
call2(&global, &local); // line 4
Today we end up with assembly and line tables like this:
.loc 1 1
callq call1
leaq global(%rip), %rdi
leaq local(%rsp), %rsi
.loc 1 2
addq $1, global(%rip)
.loc 1 3
addq $1, global(%rip)
.loc 1 4
callq call2
The LEA instructions in the local value area have no source location and
are treated as being on line 1. Stepping through the code in a debugger
and correlating it with the assembly won't make much sense, because
these materializations are only required for line 4.
This is actually problematic for the VS debugger "set next statement"
feature, which effectively assumes that there are no registers live
across statement boundaries. By sinking the local value code into the
statement and fixing up the source location, we can make that feature
work. This was filed as https://bugs.llvm.org/show_bug.cgi?id=35975 and
https://crbug.com/793819.
This change is obviously not enough to make this feature work reliably
in all cases, but I felt that it was worth doing anyway because it
usually generates smaller, more comprehensible -O0 code. I measured a
0.12% regression in code generation time with LLC on the sqlite3
amalgamation, so I think this is worth doing.
There are some special cases worth calling out in the commit message:
1. local values materialized for phis
2. local values used by no-op casts
3. dead local value code
Local values can be materialized for phis, and this does not show up as
a vreg use in MachineRegisterInfo. In this case, if there are no other
uses, this patch sinks the value to the first terminator, EH label, or
the end of the BB if nothing else exists.
Local values may also be used by no-op casts, which adds the register to
the RegFixups table. Without reversing the RegFixups map direction, we
don't have enough information to sink these instructions.
Lastly, if the local value register has no other uses, we can delete it.
This comes up when fastisel tries two instruction selection approaches
and the first materializes the value but fails and the second succeeds
without using the local value.
Reviewers: aprantl, dblaikie, qcolombet, MatzeB, vsk, echristo
Subscribers: dotdash, chandlerc, hans, sdardis, amccarth, javed.absar, zturner, llvm-commits, hiraditya
Differential Revision: https://reviews.llvm.org/D43093
llvm-svn: 327581
Summary:
1) Make sure to discard dangling debug info if the variable (or
variable fragment) is mapped to something new before we had a
chance to resolve the dangling debug info.
2) When resolving debug info, make sure to bump the associated
SDNodeOrder to ensure that the DBG_VALUE is emitted after the
instruction that defines the value used in the DBG_VALUE.
This will avoid a debug-use before def scenario as seen in
https://bugs.llvm.org/show_bug.cgi?id=36417.
The new test case, test/DebugInfo/X86/sdag-dangling-dbgvalue.ll,
show some other limitations in how dangling debug info is
handled in the SelectionDAG. Since we currently only support
having one dangling dbg.value per Value, we will end up dropping
debug info when there are more than one variable that is described
by the same "dangling value".
Reviewers: aprantl
Reviewed By: aprantl
Subscribers: aprantl, eraman, llvm-commits, JDevlieghere
Tags: #debug-info
Differential Revision: https://reviews.llvm.org/D44369
llvm-svn: 327303
Summary:
This patch adds the DW_AT_byte_size dwarf attribute to vectors.
This fixes PR21924
LLVM will round a vector up to the next alignable address, which can result in
the vector's representation in the object file being larger than what the
debugger will calculate via NumberOfElements * ElementSize. In such a case calling sizeof(MyVec) in the source will result in a different value than what a debugger might present. This situation can occur because LLVM permits non-power of two 'vector_size' attributes.
Reviewers: echristo, dexonsmith, aprantl
Reviewed By: aprantl
Subscribers: probinson, aprantl, llvm-commits, JDevlieghere
Tags: #debug-info
Differential Revision: https://reviews.llvm.org/D44048
llvm-svn: 327072
Instead of only printing the CU-relative offset in non-verbose mode, it
makes more sense to only printed the resolved address. In verbose mode
we still print both.
Differential revision: https://reviews.llvm.org/D44148
rdar://33525475
llvm-svn: 326903
Fixes the bug found by asan. Also XFAIL the new test for Darwin,
which is stuck on DWARF v2, and fix up other tests so they stop
failing on Windows.
llvm-svn: 326839
Summary:
This is a workaround for pr36417
https://bugs.llvm.org/show_bug.cgi?id=36417
LiveDebugVariables will now verify that the DBG_VALUE instructions
are sane (prior to register allocation) by asking LIS if a virtual
register used in the DBG_VALUE is live (or dead def) in the slot
index before the DBG_VALUE. If it isn't sane the DBG_VALUE is
discarded.
One pass that was identified as introducing non-sane DBG_VALUE
instructtons, when analysing pr36417, was the DAG->DAG Instruction
Selection. It sometimes inserts DBG_VALUE instructions referring to
a virtual register that is defined later in the same basic block.
So it is a use before def kind of problem. The DBG_VALUE is
typically inserted in the beginning of a basic block when this
happens. The problem can be seen in the test case
test/DebugInfo/X86/dbg-value-inlined-parameter.ll
Reviewers: aprantl, rnk, probinson
Reviewed By: aprantl
Subscribers: vsk, davide, alexcrichton, Ka-Ka, eraman, llvm-commits, JDevlieghere
Differential Revision: https://reviews.llvm.org/D43956
llvm-svn: 326769
Reid Kleckner