argument of the llvm.dbg.declare/llvm.dbg.value intrinsics.
Previously, DIVariable was a variable-length field that has an optional
reference to a Metadata array consisting of a variable number of
complex address expressions. In the case of OpPiece expressions this is
wasting a lot of storage in IR, because when an aggregate type is, e.g.,
SROA'd into all of its n individual members, the IR will contain n copies
of the DIVariable, all alike, only differing in the complex address
reference at the end.
By making the complex address into an extra argument of the
dbg.value/dbg.declare intrinsics, all of the pieces can reference the
same variable and the complex address expressions can be uniqued across
the CU, too.
Down the road, this will allow us to move other flags, such as
"indirection" out of the DIVariable, too.
The new intrinsics look like this:
declare void @llvm.dbg.declare(metadata %storage, metadata %var, metadata %expr)
declare void @llvm.dbg.value(metadata %storage, i64 %offset, metadata %var, metadata %expr)
This patch adds a new LLVM-local tag to DIExpressions, so we can detect
and pretty-print DIExpression metadata nodes.
What this patch doesn't do:
This patch does not touch the "Indirect" field in DIVariable; but moving
that into the expression would be a natural next step.
http://reviews.llvm.org/D4919
rdar://problem/17994491
Thanks to dblaikie and dexonsmith for reviewing this patch!
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r218702 disabled a -gmlt optimization for darwin, but this means the
non-darwin test isn't working there anymore.
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This allows proper disambiguation of unbounded arrays and arrays of zero
bound ("struct foo { int x[]; };" and "struct foo { int x[0]; }"). GCC
instead produces an upper bound of -1 in the latter situation, but count
seems tidier. This way lower_bound is provided if it's not the language
default and count is provided if the count is known, otherwise it's
omitted. Simple.
If someone wants to look at rdar://problem/12566646 and see if this
change is acceptable to that bug/fix, that might be helpful (see the
empty-and-one-elem-array.ll test case which cites that radar).
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r218129 omits DW_TAG_subprograms which have no inlined subroutines when
emitting -gmlt data. This makes -gmlt very low cost for -O0 builds.
Darwin's dsymutil reasonably considers a CU empty if it has no
subprograms (which occurs with the above optimization in -O0 programs
without any force_inline function calls) and drops the line table, CU,
and everything in this situation, making backtraces impossible.
Until dsymutil is modified to account for this, disable this
optimization on Darwin to preserve the desired functionality.
(see r218545, which should be reverted after this patch, for other
discussion/details)
Footnote:
In the long term, it doesn't look like this scheme (of simplified debug
info to describe inlining to enable backtracing) is tenable, it is far
too size inefficient for optimized code (the DW_TAG_inlined_subprograms,
even once compressed, are nearly twice as large as the line table
itself (also compressed)) and we'll be considering things like Cary's
two level line table proposal to encode all this information directly in
the line table.
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This change replaces the brittle if/else chain of string comparisons
with a switch statement on the detected target triple, removing the
need for testing arbitrary architecture names returned from
getFileFormatName, whose primary purpose seems to be for display
(user-interface) purposes. The visitor now takes a reference to the
object file, rather than its arbitrary file format name to figure out
whether the file is a 32 or 64-bit object file and what the detected
target triple is.
A set of tests have been added to help show that the refactoring processes
relocations for the same targets as the original code.
Patch by Charlie Turner.
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This reverts commit faac033f7364bb4226e22c8079c221c96af10d02.
The test depends on all targets to be enabled in llc in order to pass,
and needs to be rewritten/refactored to not have that dependency.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@218393 91177308-0d34-0410-b5e6-96231b3b80d8
This change replaces the brittle if/else chain of string comparisons
with a switch statement on the detected target triple, removing the
need for testing arbitrary architecture names returned from
getFileFormatName, whose primary purpose seems to be for display
(user-interface) purposes. The visitor now takes a reference to the
object file, rather than its arbitrary file format name to figure out
whether the file is a 32 or 64-bit object file and what the detected
target triple is.
A set of tests have been added to help show that the refactoring processes
relocations for the same targets as the original code.
Patch by Charlie Turner.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@218388 91177308-0d34-0410-b5e6-96231b3b80d8
Fix a null pointer dereference when trying to swap the endianness of
fixups in the .eh_frame section in the AArch64 backend.
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Summary: getSubroutineName is currently only used by llvm-symbolizer, thus add a binary test containing a cross-cu inlining example.
Reviewers: samsonov, dblaikie
Subscribers: llvm-commits
Differential Revision: http://reviews.llvm.org/D5394
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To reduce the size of -gmlt data, skip the subprograms without any
inlined subroutines. Since we've now got the ability to make these
determinations in the backend (funnily enough - we added the flag so we
wouldn't produce ranges under -gmlt, but with this change we use the
flag, but go back to producing ranges under -gmlt).
Instead, just produce CU ranges to inform the consumer which parts of
the code are described by this CU's line table. Tools could inspect the
line table directly to compute the range, but the CU ranges only seem to
be about 0.5% of object/executable size, so I'm not too worried about
teaching llvm-symbolizer that trick just yet - it's certainly a possible
piece of future work.
Update an llvm-symbolizer test just to demonstrate that this schema is
acceptable there (if it wasn't, the compiler-rt tests would catch this,
but good to have an in-llvm-tree test for llvm-symbolizer's behavior
here)
Building the clang binary with -gmlt with this patch reduces the total
size of object files by 5.1% (5.56% without ranges) without compression
and the executable by 4.37% (4.75% without ranges).
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This omission will be done in a fancier manner once we're dealing with
"put gmlt in the skeleton CUs under fission" - it'll have to be
conditional on the kind of CU we're emitting into (skeleton or gmlt).
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It's probably not a huge deal to not do this - if we could, maybe the
address could be reused by a subprogram low_pc and avoid an extra
relocation, but it's just one per CU at best.
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DWARF address ranges contain a reference to the debug_info section. This offset
is an absolute relocation except on non-PE/COFF targets where it is section
relative. We would emit this incorrectly, and trying to map the debug info from
the address would fail.
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Forge a test case where llvm-symbolizer has to use external .dwo
file to produce the inlining information.
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This commit was reverted in r217183, but is OK to go in again now that its dependency is commited (as of r217186).
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The header contains an offset to the DWARF line table for the CU. The offset
must be section relative for COFF and absolute for others. The non-assembly
code path for the DWARF header generation already has the correct emission for
the headers. This corrects the assembly input path.
This was identified by BFD objecting to the LLVM generated DWARF information.
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This reverts commit 93c7e6161e1adbd2c7ac81fa081823183035cb64.
This commit got approved first, but was dependant on another one going in (The one pretty printing attribute values). I'll reapply when the other one is in.
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DW_TAG_lexical_scopes inform debuggers about the instruction range for
which a given variable (or imported declaration/module/etc) is valid. If
the scope doesn't itself contain any such entities, it's a waste of
space and should be omitted.
We were correctly doing this for entirely empty leaves, but not for
intermediate nodes.
Reduces total (not just debug sections) .o file size for a bootstrap
-gmlt LLVM by 22% and bootstrap -gmlt clang executable by 13%. The wins
for a full -g build will be less as a % (and in absolute terms), but
should still be substantial - with some of that win being fewer
relocations, thus more substantiall reducing link times than fewer bytes
alone would have.
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specifier and change the default behavior to only emit the
DW_AT_accessibility(public) attribute when the isPublic() is explicitly
set.
rdar://problem/18154959
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Somewhat unnoticed in the original implementation of discriminators, but
it could cause instructions to end up in new, small,
DW_TAG_lexical_blocks due to the use of DILexicalBlock to track
discriminator changes.
Instead, use DILexicalBlockFile which we already use to track file
changes without introducing new scopes, so it works well to track
discriminator changes in the same way.
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This reverts:
r215595 "[FastISel][X86] Add large code model support for materializing floating-point constants."
r215594 "[FastISel][X86] Use XOR to materialize the "0" value."
r215593 "[FastISel][X86] Emit more efficient instructions for integer constant materialization."
r215591 "[FastISel][AArch64] Make use of the zero register when possible."
r215588 "[FastISel] Let the target decide first if it wants to materialize a constant."
r215582 "[FastISel][AArch64] Cleanup constant materialization code. NFCI."
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refactoring in 215384. This way it can unique multiple entries describing
the same piece even if they don't have the exact same location.
(The same piece may get merged in and be added from OpenRanges).
There ought to be a more elegant solution for this, though.
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Due to an unnecessary special case, inlined arguments that happened to
be from the same function as they were inlined into were misclassified
as non-inline arguments and would overwrite the non-inlined arguments.
Assert that we never overwrite a function's arguments, and stop
misclassifying inlined arguments as non-inline arguments to fix this
issue.
Excuse the rather crappy test case - handcrafted IR might do better, or
someone who understands better how to tickle the inliner to create a
recursive inlining situation like this (though it may also be necessary
to tickle the variable in a particular way to cause it to be recorded in
the MMI side table and go down this particular path for location
information).
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mach-o doesn't like sections without segments, and elf is perfectly
happy with commas in section names, so use a Darwin-like section name.
Suggestion by Eric Christopher.
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Originally this test case tested the specified behavior (that -gmlt
would not produce DW_AT_ranges and that when no CU DW_AT_ranges were
produced, no debug_ranges section (not even an empty list) would be
produced) but then the ranges emission code was improved not to create
ranges of a single element (instead favoring high_pc/low_pc) and so this
test case no longer exercised the -gmlt portion of the behavior.
This caused me some confusion when reading the comments and trying to
update this test case for future changes to -gmlt. I've made this test
resilient to those changes (by using the {{DW_TAG|NULL}} pattern to
block the end of the attribute search at the end of the CU's attribute
list without mandating that it must (or must not) be followed by another
tag (the future changes to -gmlt should produce no subprograms in this
CU))
Fix the test case to have two functions in distinct sections to force
the use of DW_AT_ranges.
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