Commit Graph

181 Commits

Author SHA1 Message Date
Adrian Prantl d3f9f2138d llvm-dwarfdump: implement --recurse-depth=<N>
This patch implements the Darwin dwarfdump option --recurse-depth=<N>,
which limits the recursion depth when selectively printing DIEs at an
offset.

Differential Revision: https://reviews.llvm.org/D38064

llvm-svn: 313778
2017-09-20 17:44:00 +00:00
Jonas Devlieghere 27476ce24b [dwarfdump] Rename Brief to Verbose in DIDumpOptions
This patches renames "brief" to "verbose" in de DIDumpOptions and
inverts the logic to match the new behavior where brief is the default.
Changing the default value uncovered some bugs related to the
DIDumpOptions not being propagated and have been fixed as well.

Differential revision: https://reviews.llvm.org/D37745

llvm-svn: 313139
2017-09-13 09:43:05 +00:00
Jonas Devlieghere d9063658c8 [dsymutil] Don't mark forward declarations as canonical.
This patch completes the work done by Frederic Riss to addresses
dsymutil incorrectly considering forward declaration as canonical during
uniquing. This resulted in references to the forward declaration even
after the definition was encountered.

In addition to the test provided by Alexander Shaposhnikov in D29609, I
added another test to cover several scenarios that were mentioned in his
conversation with Fred. We now also check that uniquing still occurs
after the definition was encountered.

For more context please refer to D29609

Differential revision: https://reviews.llvm.org/D37127

llvm-svn: 312274
2017-08-31 20:22:31 +00:00
Jonas Devlieghere 3aefe872c5 Revert "[dsymutil] Don't mark forward declarations as canonical."
This reverts commit r312264.

llvm-svn: 312271
2017-08-31 19:36:26 +00:00
Jonas Devlieghere e200f9bae6 [dsymutil] Don't mark forward declarations as canonical.
This patch completes the work done by Frederic Riss to addresses
dsymutil incorrectly considering forward declaration as canonical during
uniquing. This resulted in references to the forward declaration even
after the definition was encountered.

In addition to the test provided by Alexander Shaposhnikov in D29609, I
added another test to cover several scenarios that were mentioned in his
conversation with Fred. We now also check that uniquing still occurs
after the definition was encountered.

For more context please refer to D29609

Differential revision: https://reviews.llvm.org/D37127

llvm-svn: 312264
2017-08-31 18:06:44 +00:00
Adrian Prantl acdc3a7bff dsymutil: don't copy compile units without children from PCM files
rdar://problem/33830532

llvm-svn: 311416
2017-08-22 01:10:48 +00:00
Adrian Prantl e502f00538 dsymutil: support dwarf version mismatches between object and clang module
This adds a missing call to maybeUpdateMaxDwarfVersion when visitng a
clang module. Failing to do so will cause a failure when emitting
DWARF 4 forms into a CU that AsmPrinter believes to be DWARF 2.

rdar://problem/33666528

llvm-svn: 310392
2017-08-08 18:26:12 +00:00
Rafael Espindola 9f92995781 Don't pass the code model to MC
I was surprised to see the code model being passed to MC. After all,
it assembles code, it doesn't create it.

The one place it is used is in the expansion of .cfi directives to
handle .eh_frame being more that 2gb away from the code.

As far as I can tell, gnu assembler doesn't even have an option to
enable this. Compiling a c file with gcc -mcmodel=large produces a
regular looking .eh_frame. This is probably because in practice linker
parse and recreate .eh_frames.

In llvm this is used because the JIT can place the code and .eh_frame
very far apart. Ideally we would fix the jit and delete this
option. This is hard.

Apart from confusion another problem with the current interface is
that most callers pass CodeModel::Default, which is bad since MC has
no way to map it to the target default if it actually needed to.

This patch then replaces the argument with a boolean with a default
value. The vast majority of users don't ever need to look at it. In
fact, only CodeGen and llvm-mc use it and llvm-mc just to enable more
testing.

llvm-svn: 309884
2017-08-02 20:32:26 +00:00
Adrian Prantl 5f16f54af3 De-brief doxygen comments
llvm-svn: 308757
2017-07-21 16:51:17 +00:00
Adrian Prantl 6f87d1147a Use default initializers (NFC)
llvm-svn: 308756
2017-07-21 16:51:16 +00:00
Adrian Prantl 4af0a865e0 Canonicalize the spelling of RefDie (NFC)
llvm-svn: 308755
2017-07-21 16:51:09 +00:00
Adrian Prantl 98dc599790 dsymutil: strip unused types from imported DW_TAG_modules
This patch teaches dsymutil to strip types from the imported
DW_TAG_module inside of an object file (not inside the PCM) if they
can be resolved to the full definition inside the PCM. This reduces
the size of the .dSYM from WebCore from webkit.org by almost 2/3.

<rdar://problem/33047213>

llvm-svn: 308710
2017-07-21 02:07:33 +00:00
Rafael Espindola c398e67fed Use delegation instead of inheritance.
This changes DwarfContext to delegate to DwarfObject instead of having
pure virtual methods.

With this DwarfContextInMemory is replaced with an implementation of
DwarfObject that is local to a .cpp file.

llvm-svn: 308543
2017-07-19 22:27:28 +00:00
Paul Robinson 17536b935a [DWARF] NFC: DWARFDataExtractor combines relocs with DataExtractor.
Requires callers to directly associate relocations with a DataExtractor
used to read data from a DWARF section, which helps a callee not make
assumptions about which section it is reading.
This is the next step in reducing DWARFFormValue's dependence on DWARFUnit.

Differential Revision: https://reviews.llvm.org/D34704

llvm-svn: 306699
2017-06-29 16:52:08 +00:00
Paul Robinson 75c068c50b [DWARF] NFC: Collect info used by DWARFFormValue into a helper.
Some forms have sizes that depend on the DWARF version, DWARF format
(32/64-bit), or the size of an address.  Collect these into a struct
to simplify passing them around.  Require callers to provide one when
they query a form's size.

Differential Revision: http://reviews.llvm.org/D34570

llvm-svn: 306315
2017-06-26 18:43:01 +00:00
Zachary Turner 264b5d9e88 Move Object format code to lib/BinaryFormat.
This creates a new library called BinaryFormat that has all of
the headers from llvm/Support containing structure and layout
definitions for various types of binary formats like dwarf, coff,
elf, etc as well as the code for identifying a file from its
magic.

Differential Revision: https://reviews.llvm.org/D33843

llvm-svn: 304864
2017-06-07 03:48:56 +00:00
George Rimar ca53211beb [DWARF] - Take relocations in account when extracting ranges from .debug_ranges
I found this when investigated "Bug 32319 - .gdb_index is broken/incomplete" for LLD.

When we have object file with .debug_ranges section it may be filled with zeroes.
Relocations are exist in file to relocate this zeroes into real values later, but until that
a pair of zeroes is treated as terminator. And DWARF parser thinks there is no ranges at all
when I am trying to collect address ranges for building .gdb_index.

Solution implemented in this patch is to take relocations in account when parsing ranges.

Differential revision: https://reviews.llvm.org/D32228

llvm-svn: 301170
2017-04-24 10:19:45 +00:00
David Blaikie c0bb21f38e Remove the unnecessary virtual dtor from the DIEUnit hierarchy (in favor of protected dtor in the base, final derived classes with public non-virtual dtors)
These objects are never polymorphically owned/destroyed, so the virtual
dtor was unnecessary.

llvm-svn: 301068
2017-04-22 02:18:00 +00:00
Paul Robinson 70b34533c2 [DWARF] Versioning for DWARF constants; verify FORMs
Associate the version-when-defined with definitions of standard DWARF
constants.  Identify the "vendor" for DWARF extensions.
Use this information to verify FORMs in .debug_abbrev are defined as
of the DWARF version specified in the associated unit.
Removed two tests that had specified DWARF v1 (which essentially does
not exist).

Differential Revision: http://reviews.llvm.org/D30785

llvm-svn: 300875
2017-04-20 19:16:51 +00:00
Simon Pilgrim 68168d17b9 Spelling mistakes in comments. NFCI.
Based on corrections mentioned in patch for clang for PR27635

llvm-svn: 299072
2017-03-30 12:59:53 +00:00
Frederic Riss 1488766bdf [dsymutil] Fix handling of empty CUs in LTO links.
r288399 introduced the DIEUnit class, and in the process broke
the corner case where dsymutil generates an empty CU during an
LTO link. This restores the logic and adds a test for the corner
case.

llvm-svn: 294618
2017-02-09 19:41:55 +00:00
Daniel Jasper 26648828e7 Fix un-initialized error introduced by r291959.
This is uncovered when running tools/dsymutil/X86/empty_range.s.test
with ASAN. Haven't investigate yet, whether that means there is an ODR
violation in that test.

llvm-svn: 292065
2017-01-15 16:42:36 +00:00
Greg Clayton c109bbea57 Add a variant of DWARFDie::find() and DWARFDie::findRecursively() that takes a llvm::ArrayRef<dwarf::Attribute>.
This allows us efficiently look for more than one attribute, something that is quite common in DWARF consumption.

Differential Revision: https://reviews.llvm.org/D28704

llvm-svn: 291967
2017-01-13 22:32:12 +00:00
Greg Clayton 97d22187d0 Cleanup how DWARFDie attributes are accessed and decoded.
Removed all DWARFDie::getAttributeValueAs*() calls.
Renamed:
  Optional<DWARFFormValue> DWARFDie::getAttributeValue(dwarf::Attribute);
To:
  Optional<DWARFFormValue> DWARFDie::find(dwarf::Attribute);
Added:
  Optional<DWARFFormValue> DWARFDie::findRecursively(dwarf::Attribute);
  
All decoding of Optional<DWARFFormValue> values are now done using the dwarf::to*() functions from DWARFFormValue.h:

Old code:
  
  auto DeclLine = DWARFDie.getAttributeValueAsSignedConstant(DW_AT_decl_line).getValueOr(0);
  
New code:

  auto DeclLine = toUnsigned(DWARFDie.find(DW_AT_decl_line), 0);
  
This composition helps us since we can now easily do:

  auto DeclLine = toUnsigned(DWARFDie.findRecursively(DW_AT_decl_line), 0);
  
This allows us to easily find attribute values in the current DIE only (the first new code above) or in any DW_AT_abstract_origin or DW_AT_specification Dies using the line above. Note that the code line length is shorter and more concise.

Differential Revision: https://reviews.llvm.org/D28581

llvm-svn: 291959
2017-01-13 21:08:18 +00:00
Greg Clayton d1efea89c9 Remove all variants of DWARFDie::getAttributeValueAs...() that had parameters that specified default values.
Now we only support returning Optional<> values and have changed all clients over to use Optional::getValueOr().

Differential Revision: https://reviews.llvm.org/D28569

llvm-svn: 291686
2017-01-11 17:43:37 +00:00
Greg Clayton 93e4fe8aad Add iterator support to DWARFDie to allow child DIE iteration.
Differential Revision: https://reviews.llvm.org/D28303

llvm-svn: 291194
2017-01-05 23:47:37 +00:00
Greg Clayton 2520c9ebee Make a function to correctly extract the DW_AT_high_pc given the low pc value.
DWARF 4 and later supports encoding the PC as an address or as as offset from the low PC. Clients using DWARFDie should be insulated from how to extract the high PC value. This function takes care of extracting the form value and looking for the correct form.

Differential Revision: https://reviews.llvm.org/D27885

llvm-svn: 290131
2016-12-19 20:36:41 +00:00
Greg Clayton 52fe1f68c8 Add the ability to get attribute values as Optional<T>
When getting attributes it is sometimes nicer to use Optional<T> some of the time instead of magic values. I tried to cut over to only using the Optional values but it made many of the call sites very messy, so it makes sense the leave in the calls that can return a default value. Otherwise code that looks like this:

uint64_t CallColumn = Die.getAttributeValueAsAddress(DW_AT_call_line, 0);

Has to be turned into:

uint64_t CallColumn = 0;
if (auto CallColumnValue = Die.getAttributeValueAsAddress(DW_AT_call_line))
    CallColumn = *CallColumnValue;

The first snippet of code looks much better. But in cases where you want an offset that may or may not be there, the following code looks better:

if (auto StmtOffset = Die.getAttributeValueAsSectionOffset(DW_AT_stmt_list)) {
  // Use StmtOffset
}

Differential Revision: https://reviews.llvm.org/D27772

llvm-svn: 289731
2016-12-14 22:38:08 +00:00
Greg Clayton 1cbf3fa94a Switch functions that returned bool and filled in a DWARFFormValue arg with ones that return Optional<DWARFFormValue>
Differential Revision: https://reviews.llvm.org/D27737

llvm-svn: 289611
2016-12-13 23:20:56 +00:00
Greg Clayton c8c1032c0c Make a DWARFDIE class that can help avoid using the wrong DWARFUnit when extracting attributes
Many places pass around a DWARFDebugInfoEntryMinimal and a DWARFUnit. It is easy to get things wrong by using the wrong DWARFUnit with a DWARFDebugInfoEntryMinimal. This patch creates a DWARFDie class that contains the DWARFUnit and DWARFDebugInfoEntryMinimal objects so that they can't get out of sync. All attribute extraction has been moved out of DWARFDebugInfoEntryMinimal and into DWARFDie. DWARFDebugInfoEntryMinimal was also renamed to DWARFDebugInfoEntry.

DWARFDie objects are temporary objects that are used by clients and contain 2 pointers that you always need to have anyway. Keeping them grouped will avoid errors and simplify many of the attribute extracting APIs by not having to pass in a DWARFUnit.

Differential Revision: https://reviews.llvm.org/D27634

llvm-svn: 289565
2016-12-13 18:25:19 +00:00
David Blaikie 4aa8175a92 [dsymutil] Simplify a lazy-init condition/expression
llvm-svn: 288423
2016-12-01 22:04:16 +00:00
Greg Clayton 35630c3357 This change removes the dependency on DwarfDebug that was used for DW_FORM_ref_addr by making a new DIEUnit class in DIE.cpp.
The DIEUnit class represents a compile or type unit and it owns the unit DIE as an instance variable. This allows anyone with a DIE, to get the unit DIE, and then get back to its DIEUnit without adding any new ivars to the DIE class. Why was this needed? The DIE class has an Offset that is always the CU relative DIE offset, not the "offset in debug info section" as was commented in the header file (the comment has been corrected). This is great for performance because most DIE references are compile unit relative and this means most code that accessed the DIE's offset didn't need to make it into a compile unit relative offset because it already was. When we needed to emit a DW_FORM_ref_addr though, we needed to find the absolute offset of the DIE by finding the DIE's compile/type unit. This class did have the absolute debug info/type offset and could be added to the CU relative offset to compute the absolute offset. With this change we can easily get back to a DIE's DIEUnit which will have this needed offset. Prior to this is required having a DwarfDebug and required calling:

DwarfCompileUnit *DwarfDebug::lookupUnit(const DIE *CU) const;
Now we can use the DIEUnit class to do so without needing DwarfDebug. All clients now use DIEUnit objects (the DwarfDebug stack and the DwarfLinker). A follow on patch for the DWARF generator will also take advantage of this.

Differential Revision: https://reviews.llvm.org/D27170

llvm-svn: 288399
2016-12-01 18:56:29 +00:00
Greg Clayton 6f6e4dbd5d Improve DWARF parsing speed by improving DWARFAbbreviationDeclaration
This patch gets a DWARF parsing speed improvement by having DWARFAbbreviationDeclaration instances know if they have a fixed byte size. If an abbreviation has a fixed byte size that can be calculated given a DWARFUnit, then parsing a DIE becomes two steps: parse ULEB128 abbrev code, and then add constant size to the offset.

This patch also adds a fixed byte size to each DWARFAbbreviationDeclaration::AttributeSpec so that attributes can quickly skip their values if needed without the need to lookup the fixed for size.

Notable improvements:

- DWARFAbbreviationDeclaration::findAttributeIndex() now returns an Optional<uint32_t> instead of a uint32_t and we no longer have to look for the magic -1U return value
- Optional<uint32_t> DWARFAbbreviationDeclaration::findAttributeIndex(dwarf::Attribute attr) const;
- DWARFAbbreviationDeclaration now has a getAttributeValue() function that extracts an attribute value given a DIE offset that takes advantage of the DWARFAbbreviationDeclaration::AttributeSpec::ByteSize
- bool DWARFAbbreviationDeclaration::getAttributeValue(const uint32_t DIEOffset, const dwarf::Attribute Attr, const DWARFUnit &U, DWARFFormValue &FormValue) const;
- A DWARFAbbreviationDeclaration instance can return a fixed byte size for itself so DWARF parsing is faster:
- Optional<size_t> DWARFAbbreviationDeclaration::getFixedAttributesByteSize(const DWARFUnit &U) const;
- Any functions that used to take a "const DWARFUnit *U" that would crash if U was NULL now take a "const DWARFUnit &U" and are only called with a valid DWARFUnit

Differential Revision: https://reviews.llvm.org/D26567

llvm-svn: 286924
2016-11-15 01:23:06 +00:00
Pavel Labath 62d72041d4 [dsymutil] Replace TimeValue with TimePoint
Summary:
All changes are pretty straight-forward. I chose to use TimePoints with
second precision, as that is all that seems to be required here.

Reviewers: friss, zturner

Subscribers: llvm-commits

Differential Revision: https://reviews.llvm.org/D25908

llvm-svn: 286358
2016-11-09 11:43:52 +00:00
Victor Leschuk e1156c2eb0 DebugInfo: make DW_TAG_atomic_type valid
DW_TAG_atomic_type was already included in Dwarf.defs and emitted correctly,
however Verifier didn't recognize it as valid.
Thus we introduce the following changes:

  * Make DW_TAG_atomic_type valid tag for IR and DWARF (enabled only with -gdwarf-5)
  * Add it to related docs
  * Add DebugInfo tests

Differential Revision: https://reviews.llvm.org/D26144

llvm-svn: 285624
2016-10-31 19:09:38 +00:00
Greg Clayton cddab279f6 Modify DWARFFormValue to remember the DWARFUnit that it was decoded with.
Modifying DWARFFormValue to remember the DWARFUnit that it was encoded with can simplify the usage of instances of this class. Previously users would have to try and pass in the same DWARFUnit that was used to decode the form value and there was a possibility that a different DWARFUnit might be supplied to the functions that extract values (strings, CU relative references, addresses) and cause problems. This fixes this potential issue by storing the DWARFUnit inside the DWARFFormValue so that this mistake can't be made. Instances of DWARFFormValue are not stored permanently and are used as temporary values, so the increase in size of an instance of DWARFFormValue isn't a big deal. This makes decoding form values more bullet proof and is a change that will be used by future modifications.

https://reviews.llvm.org/D26052

llvm-svn: 285594
2016-10-31 16:46:02 +00:00
Justin Bogner b03fd12cef Replace "fallthrough" comments with LLVM_FALLTHROUGH
This is a mechanical change of comments in switches like fallthrough,
fall-through, or fall-thru to use the LLVM_FALLTHROUGH macro instead.

llvm-svn: 278902
2016-08-17 05:10:15 +00:00
Joel Jones 373d7d30dd MC] Provide an MCTargetOptions to implementors of MCAsmBackendCtorTy, NFC
Some targets, notably AArch64 for ILP32, have different relocation encodings
based upon the ABI. This is an enabling change, so a future patch can use the
ABIName from MCTargetOptions to chose which relocations to use. Tested using
check-llvm.

The corresponding change to clang is in: http://reviews.llvm.org/D16538

Patch by: Joel Jones

Differential Revision: https://reviews.llvm.org/D16213

llvm-svn: 276654
2016-07-25 17:18:28 +00:00
Pete Cooper cadadaa1b3 Fix r276380 for targets without REALPATH.
This was a mistake in the layout of the code from r276380.  I moved the appropriate lines out of the #ifdef to fix it.

llvm-svn: 276382
2016-07-22 01:52:58 +00:00
Pete Cooper b2ba776aed Avoid dsymutil calls to getFileNameByIndex.
This change adds a hasFileAtIndex method. getChildDeclContext can first call this method, and if it returns true it knows it can then lookup the resolved path cache for the given file index. If we hit that cache then we don't even have to call getFileNameByIndex.

Running dsymutil against the swift executable built from github gives a 20% performance improvement without any change in the binary.

Differential Revision: https://reviews.llvm.org/D22655

Reviewed by friss.

llvm-svn: 276380
2016-07-22 01:41:32 +00:00
Benjamin Kramer c321e53402 Apply most suggestions of clang-tidy's performance-unnecessary-value-param
Avoids unnecessary copies. All changes audited & pass tests with asan.
No functional change intended.

llvm-svn: 272190
2016-06-08 19:09:22 +00:00
Petr Hosek faef3207de [MC] Rename EmitFill to emitFill
This is to match the overloaded variants as well as the new style.

Differential Revision: http://reviews.llvm.org/D20690

llvm-svn: 271359
2016-06-01 01:59:58 +00:00
Adrian Prantl 9e7e8839b2 dsymutil/modules: Reword the warning for static libraries without module caches
In addition to clarifying the warning message this contains a minor functional
change in that it now warns if the *immediate* parent directory in which the
missing PCM is expected to be isn't found.

This patch also includes a more comprehensive testcase.

rdar://problem/25860711

llvm-svn: 270269
2016-05-20 20:36:06 +00:00
Rafael Espindola 8c34dd8257 Delete Reloc::Default.
Having an enum member named Default is quite confusing: Is it distinct
from the others?

This patch removes that member and instead uses Optional<Reloc> in
places where we have a user input that still hasn't been maped to the
default value, which is now clear has no be one of the remaining 3
options.

llvm-svn: 269988
2016-05-18 22:04:49 +00:00
Rafael Espindola 699281cce7 Don't pass a Reloc::Model to MC.
MC only needs to know if the output is PIC or not. It never has to
decide about creating GOTs and PLTs for example. The only thing that
MC itself uses this information for is expanding "macros" in sparc and
mips. The rest I am pretty sure could be moved to CodeGen.

This is a cleanup and isolates the code from future changes to
Reloc::Model.

llvm-svn: 269909
2016-05-18 11:58:50 +00:00
Adrian Prantl e1bc3e2027 dsymutil: Fix the DWOId mismatch check for cached modules.
In verbose mode, we emit a warning if the DWOId of a skeleton CU
mismatches the DWOId of the referenced module. This patch updates the
cached DWOId after a module has been loaded to the DWOId of the module
on disk (instead of storing the DWOId we expected to load). This
allows us to correctly emit the mismatch warning for all subsequent
object files that want to import the same module. This patch also
ensures both warnings are only emitted in verbose mode.

rdar://problem/26214027

llvm-svn: 269383
2016-05-13 00:17:58 +00:00
Adrian Prantl 2c0b0ab624 dsymutil: Only warn about clang module DWO id mismatches in verbose mode.
Until PR27449 (https://llvm.org/bugs/show_bug.cgi?id=27449) is fixed in
clang this warning is pointless, since ASTFileSignatures will change
randomly when a module is rebuilt.

rdar://problem/25610919

llvm-svn: 267427
2016-04-25 17:04:32 +00:00
Kevin Enderby 81e8b7d949 Thread Expected<...> up from libObject’s getName() for symbols to allow llvm-objdump to produce a good error message.
Produce another specific error message for a malformed Mach-O file when a symbol’s
string index is past the end of the string table.  The existing test case in test/Object/macho-invalid.test
for macho-invalid-symbol-name-past-eof now reports the error with the message indicating
that a symbol at a specific index has a bad sting index and that bad string index value.
 
Again converting interfaces to Expected<> from ErrorOr<> does involve
touching a number of places. Where the existing code reported the error with a
string message or an error code it was converted to do the same.  There is some
code for this that could be factored into a routine but I would like to leave that for
the code owners post-commit to do as they want for handling an llvm::Error.  An
example of how this could be done is shown in the diff in
lib/ExecutionEngine/RuntimeDyld/RuntimeDyldImpl.h which had a Check() routine
already for std::error_code so I added one like it for llvm::Error .

Also there some were bugs in the existing code that did not deal with the
old ErrorOr<> return values.  So now with Expected<> since they must be
checked and the error handled, I added a TODO and a comment:
“// TODO: Actually report errors helpfully” and a call something like
consumeError(NameOrErr.takeError()) so the buggy code will not crash
since needed to deal with the Error.

Note there fixes needed to lld that goes along with this that I will commit right after this.
So expect lld not to built after this commit and before the next one.

llvm-svn: 266919
2016-04-20 21:24:34 +00:00
Pete Cooper 64d075ec07 Always cache resolved paths as it even saves on StringMap lookups.
Now that the resolved path cache stores the StringRef's, its
best to just always cache the results, even when realpath isn't
used.  This way we'll still avoid the StringMap hashing and lookup.

This also conveniently reorganises this code in a way I need for
a future patch.

llvm-svn: 263777
2016-03-18 05:04:04 +00:00
Pete Cooper ef4e36ad99 Use StringRef's in resolved path cache to avoid extra internString lookups. NFC.
ResolvedPaths was storing std::string's as a cache. We would then take those strings and look them up in the internString pool to get a unique StringRef for each path.

This patch changes ResolvedPaths to store the StringRef pointing in to the internString pool itself. This way, when getResolvedPath returns a string, we know we have the StringRef we would find in the pool anyway. We can avoid the duplicate memory of the std::string's, and also the time from the lookup.

Unfortunately my profiles show no runtime change here, but it should still save memory allocations which is nice.

Reviewed by Frederic Riss.

Differential Revision: http://reviews.llvm.org/D18259

llvm-svn: 263774
2016-03-18 03:48:09 +00:00