Commit Graph

241 Commits

Author SHA1 Message Date
Djordje Todorovic 44642505ce [NFC][llvm-dwarfdump] Avoid passing std::string by value in collectStatsForDie() 2021-05-12 01:29:37 -07:00
Djordje Todorovic 1ed2963600 [llvm-dwarfdump] Fix abstract origin vars location stats calculation
There are cases where a concrete DIE with DW_TAG_subprogram can have
abstract_origin attribute, so we handle that situation as well.

Differential Revision: https://reviews.llvm.org/D101025
2021-05-11 01:04:51 -07:00
Djordje Todorovic 9ad9f0c731 [NFC][llvm-dwarfdump] Code clean up for inlined var loc stats
This is preparation for the https://reviews.llvm.org/D101025.
The D101025 will start calculating var locstats for concrete fns
that refere to an abstract origin as well.
2021-05-10 05:50:16 -07:00
gbreynoo f0762fc42f [llvm-dwarfdump] Help option output should be consistent with the command guide
The dwarfdump command guide shows the short options used as aliases but
these are not found in the help text unless --show-hidden is used.
Investigating other tools some follow this pattern, others like
llvm-objdump show aliases with --help. This change fixes the help output
to be consistent with the command guide. This includes updating alias
descriptions in the help output to use "--".

As part of this change I updated cmdline.test, including some options
that were missing testing.

Differential Revision: https://reviews.llvm.org/D101646
2021-05-07 11:23:05 +01:00
Djordje Todorovic 6ba150dbb4 [llvm-dwarfdump] Fix split-dwarf bug in stats for inlined var loc cov
Initial (D96045) patch didn't handle split dwarf cases,
so this fixes that bug.

In addition, before applying this patch, we had a slowdown
that happened after the D96045. With this patch,
the slowdown will be fixed as well.

Differential Revision: https://reviews.llvm.org/D100951
2021-04-26 01:56:15 -07:00
Abhina Sreeskantharajan 82b3e28e83 [SystemZ][z/OS][Windows] Add new OF_TextWithCRLF flag and use this flag instead of OF_Text
Problem:
On SystemZ we need to open text files in text mode. On Windows, files opened in text mode adds a CRLF '\r\n' which may not be desirable.

Solution:
This patch adds two new flags

  - OF_CRLF which indicates that CRLF translation is used.
  - OF_TextWithCRLF = OF_Text | OF_CRLF indicates that the file is text and uses CRLF translation.

Developers should now use either the OF_Text or OF_TextWithCRLF for text files and OF_None for binary files. If the developer doesn't want carriage returns on Windows, they should use OF_Text, if they do want carriage returns on Windows, they should use OF_TextWithCRLF.

So this is the behaviour per platform with my patch:

z/OS:
OF_None: open in binary mode
OF_Text : open in text mode
OF_TextWithCRLF: open in text mode

Windows:
OF_None: open file with no carriage return
OF_Text: open file with no carriage return
OF_TextWithCRLF: open file with carriage return

The Major change is in llvm/lib/Support/Windows/Path.inc to only set text mode if the OF_CRLF is set.
```
  if (Flags & OF_CRLF)
    CrtOpenFlags |= _O_TEXT;
```

These following files are the ones that still use OF_Text which I left unchanged. I modified all these except raw_ostream.cpp in recent patches so I know these were previously in Binary mode on Windows.
./llvm/lib/Support/raw_ostream.cpp
./llvm/lib/TableGen/Main.cpp
./llvm/tools/dsymutil/DwarfLinkerForBinary.cpp
./llvm/unittests/Support/Path.cpp
./clang/lib/StaticAnalyzer/Core/HTMLDiagnostics.cpp
./clang/lib/Frontend/CompilerInstance.cpp
./clang/lib/Driver/Driver.cpp
./clang/lib/Driver/ToolChains/Clang.cpp

Reviewed By: MaskRay

Differential Revision: https://reviews.llvm.org/D99426
2021-04-06 07:23:31 -04:00
Fangrui Song 599711dce5 [llvm-dwarfdump] StringMap -> MapVector to make iteration order stable
Exposed by D97396
2021-02-25 20:05:05 -08:00
Djordje Todorovic 52113451fb [NFC][llvm-dwarfdump] Don't calculate unnecessary stats
Small optimization of the code -- No need to calculate any stats
for NULL nodes, and also no need to call the collectStatsForDie()
if it is the CU itself.

Differential Revision: https://reviews.llvm.org/D96871
2021-02-22 00:31:29 -08:00
Djordje Todorovic b6db47d7e0 [llvm-dwarfdump][locstats] Unify handling of inlined vars with no loc
The presence or absence of an inline variable (as well as formal
parameter) with only an abstract_origin ref (without DW_AT_location)
should not change the location coverage.

It means, for both:

DW_TAG_inlined_subroutine
  DW_AT_abstract_origin (0x0000004e "f")
  DW_AT_low_pc  (0x0000000000000010)
  DW_AT_high_pc (0x0000000000000013)
  DW_TAG_formal_parameter
    DW_AT_abstract_origin       (0x0000005a "b")

and,

DW_TAG_inlined_subroutine
   DW_AT_abstract_origin (0x0000004e "f")
   DW_AT_low_pc  (0x0000000000000010)
   DW_AT_high_pc (0x0000000000000013)

we should report 0% location coverage. If we add DW_AT_location,
for both cases the coverage should be improved.

Differential Revision: https://reviews.llvm.org/D96045
2021-02-19 05:38:01 -08:00
Kazu Hirata 441650d589 [tools] Use llvm::append_range (NFC) 2021-01-05 21:15:56 -08:00
serge-sans-paille 9218ff50f9 llvmbuildectomy - replace llvm-build by plain cmake
No longer rely on an external tool to build the llvm component layout.

Instead, leverage the existing `add_llvm_componentlibrary` cmake function and
introduce `add_llvm_component_group` to accurately describe component behavior.

These function store extra properties in the created targets. These properties
are processed once all components are defined to resolve library dependencies
and produce the header expected by llvm-config.

Differential Revision: https://reviews.llvm.org/D90848
2020-11-13 10:35:24 +01:00
David Blaikie 5b346fd8c9 llvm-dwarfdump: Exit non-zero on an error path 2020-10-14 22:10:43 -07:00
OCHyams 3ff4d75c9c [llvm-dwarfdump] Fix misleading scope byte coverage statistics
Fixes PR46575.

Bump statistics version to 6.

Without this patch, for a variable described with a location list the stat
'sum_all_variables(#bytes in parent scope covered by DW_AT_location)' is
calculated by summing all bytes covered by the location ranges in the list and
capping the result to the number of bytes in the parent scope. With the patch,
only bytes which overlap with the parent DIE scope address ranges contribute to
the stat. A new stat 'sum_all_variables(#bytes in any scope covered by
DW_AT_location)' has been added which displays the total bytes covered when
ignoring scopes.
2020-08-25 06:40:11 +01:00
Fangrui Song 481c3b8c94 [llvm-dwarfdump] --statistics: break lines and indent by 2
so that the user does not have to pipe the output to `jq` or `python -m json.tool`.
This change makes testing more convenient because `-NEXT` patterns can be used.
The "prettify by default" is a good tradeoff to make. The output size increases a bit.

Differential Revision: https://reviews.llvm.org/D86318
2020-08-22 13:58:18 -07:00
Fangrui Song 2b0f40b049 [llvm-dwarfdump] Fix a typo: witin -> within 2020-08-20 14:12:37 -07:00
Fangrui Song ddde8bebb0 [llvm-dwarfdump] --statistics: switch to json::OStream. NFC
Then it is trivial to make the output indented (the second parameter of
json::OStream::OStream specifies the indentation).

Reviewed By: jhenderson, echristo

Differential Revision: https://reviews.llvm.org/D86045
2020-08-20 12:24:06 -07:00
Jonas Devlieghere fd9f5f9c1b [llvm] Remove full stop frome error message
Address post-commit feedback from James Henderson in D80959.
2020-06-24 09:41:17 -07:00
Fangrui Song 030897523d [Support] Don't tie errs() to outs() by default
This reverts part of D81156.

Accessing errs() concurrently was safe before and racy after D81156.
(`errs() << 'a'` is always racy)

Accessing outs() and errs() concurrently was safe before and racy after D81156.

Don't tie errs() to outs() by default to fix the fallout.
llvm-dwarfdump is single-threaded and opting in the tie behavior is safe.
2020-06-11 15:19:56 -07:00
Jonas Devlieghere 5b460fb15e [llvm-dwarfdump] Print [=<offset>] after --debug-* options in help output.
Some of the --debug-* options can take an optional offset. Although the
man page does a good job of making that clear, it's much harder to
discover from the help output.

Currently the only reference to this is the following sentence:

> Where applicable these parameters take an optional =<offset> argument
> to dump only the entry at the specified offset.

This patch changes the help output from to print [=<offset>] after the
options that take an offset.

  --debug-info[=<offset>]    - Dump the .debug_info section

rdar://problem/63150066

Differential revision: https://reviews.llvm.org/D80959
2020-06-02 11:06:11 -07:00
Simon Pilgrim 84be4278e7 llvm-dwarfdump.h - remove unnecessary WithColor.h include. NFC. 2020-05-28 13:03:18 +01:00
Xing GUO 2974b3c566 [llvm-dwarfdump] Make commandline arguments consistent.
Currently, llvm-dwarfdump's help message has two issues.

1. Most long options are printed in `--long-option`, except for some section dumping options, e.g., `-apple-names`, `-debug-addr`.

2. Most options are printed with consistent indention, except for some section dumping options.

This patch helps resolve these two issues.

Reviewed By: jhenderson

Differential Revision: https://reviews.llvm.org/D79618
2020-05-14 17:34:50 +08:00
Fangrui Song befbc99a7f Reland D79501 "[DebugInfo] Fix handling DW_OP_call_ref in DWARF64 units."
With a fix to uninitialized EndOffset.

DW_OP_call_ref is the only operation that has an operand which depends
on the DWARF format. The patch fixes handling that operation in DWARF64
units.

Differential Revision: https://reviews.llvm.org/D79501
2020-05-08 09:35:54 -07:00
Krasimir Georgiev c5e0967e4c Revert "[DebugInfo] Fix handling DW_OP_call_ref in DWARF64 units."
This reverts commit 989ae9e848.

Newly added test fails:
FAIL: LLVM::DW_OP_call_ref_unexpected.s

http://lab.llvm.org:8011/builders/clang-x86_64-debian-fast/builds/28298
2020-05-08 17:24:32 +02:00
Igor Kudrin 989ae9e848 [DebugInfo] Fix handling DW_OP_call_ref in DWARF64 units.
DW_OP_call_ref is the only operation that has an operand which depends
on the DWARF format. The patch fixes handling that operation in DWARF64
units.

Differential Revision: https://reviews.llvm.org/D79501
2020-05-08 15:14:42 +07:00
Djordje Todorovic 0a4defe8c8 [llvm-dwarfdump][Stats] Clean up
This addresses:
  -Clean up the source code
  -Refactor the JSON fields
  -Fix the test cases
  -Improve the docs for the stats output

Differential Revision: https://reviews.llvm.org/D77789
2020-05-04 09:35:40 +02:00
David Blaikie 12489b5474 llvm-dwarfdump: Fix UB (unsequenced writes) introduced in e0fd87cc64
Unsequenced write due to "x &= f()" where 'f()' modifies 'x'.

Detected by the llvm-clang-x86_64-expensive-checks-win buildbot.
Investigated/identified by Galina - thanks!
2020-04-19 21:35:04 -07:00
David Blaikie 208a11ab3a Reapply "llvm-dwarfdump: Report errors when failing to parse loclist/debug_loc entries""
Originally committed as 416fa7720e
Reverted (due to buildbot failure - breaking lldb) in 7a45aeacf3.

I still can't seem to build lldb locally, but Pavel Labath has kindly
provided a potential fix to preserve the old behavior in lldb by
registering a simple recoverable error handler there that prints to the
desired stream in lldb, rather than stderr.
2020-04-14 14:44:32 -07:00
David Blaikie 7a45aeacf3 Revert "llvm-dwarfdump: Report errors when failing to parse loclist/debug_loc entries"
Broke an LLDB build bot & I can't seem to build LLDB locally to fix
forward...
http://lab.llvm.org:8011/builders/lldb-x64-windows-ninja/builds/15567/steps/test/logs/stdio

This reverts commit 416fa7720e.
2020-04-11 16:54:49 -07:00
David Blaikie 416fa7720e llvm-dwarfdump: Report errors when failing to parse loclist/debug_loc entries
This probably isn't ideal - the error was being printed specifically
inline with the dumping that was more legible - but then the error
wasn't reported to stderr and didn't produce a non-zero exit code.

Probably the error message could be improved by adding more context now
that it isn't printed in-situ of the DIE dumping as much.
2020-04-10 17:28:09 -07:00
Fangrui Song b184923151 [llvm-dwarfdump] Interface cleanup. NFC
This patch moves interface declarations into llvm-dwarfdump.h and wrap
declarations in anonymous namespaces as appropriate. At the same time,
the externals are moved into the `llvm::dwarfdump` namespace`.

Reviewed By: djtodoro

Differential Revision: https://reviews.llvm.org/D77848
2020-04-10 09:22:56 -07:00
David Blaikie e0fd87cc64 llvm-dwarfdump: Return non-zero on error
Makes it easier to test "this doesn't produce an error" (& indeed makes
that the implied default so we don't accidentally write tests that have
silent/sneaky errors as well as the positive behavior we're testing for)

Though the support for applying relocations is patchy enough that a
bunch of tests treat lack of relocation application as more of a warning
than an error - so rather than me trying to figure out how to add
support for a bunch of relocation types, let's degrade that to a warning
to match the usage (& indeed, it's sort of more of a tool warning anyway
- it's not that the DWARF is wrong, just that the tool can't fully cope
with it - and it's not like the tool won't dump the DWARF, it just won't
follow/render certain relocations - I guess in the most general case it
might try to render an unrelocated value & instead render something
bogus... but mostly seems to be about interesting relocations used in
eh_frame (& honestly it might be nice if we were lazier about doing this
relocation resolution anyway - if you're not dumping eh_frame, should we
really be erroring about the relocations in it?))
2020-04-09 20:53:58 -07:00
Djordje Todorovic 5e508b9bac [llvm-dwarfdump] Add the --show-sections-sizes option
Add an option to llvm-dwarfdump to calculate the bytes within
the debug sections. Dump this numbers when using --statistics
option as well.

This is an initial patch (e.g. we should support other units,
since we only support 'bytes' now).

Differential Revision: https://reviews.llvm.org/D74205
2020-04-02 13:14:30 +02:00
Djordje Todorovic 3e47f87e64 [NFC][llvm-dwarfdump] Always use 'const Twine &'
According to the Twine.h comment, the Twines should only
be used as const references in arguments.

Differential Revision: https://reviews.llvm.org/D75727
2020-03-10 12:58:59 +01:00
Djordje Todorovic d180899cb7 [llvm-dwarfdump][Stats] Fix the License header
Fix the added License.

Differential Revision: https://reviews.llvm.org/D74207
2020-02-10 08:01:56 +01:00
Djordje Todorovic d173cb1db7 [llvm-dwarfdump][Stats] Add the license header
Add the License header into the Statistics.cpp.

Differential Revision: https://reviews.llvm.org/D74207
2020-02-07 12:37:32 +01:00
Benjamin Kramer adcd026838 Make llvm::StringRef to std::string conversions explicit.
This is how it should've been and brings it more in line with
std::string_view. There should be no functional change here.

This is mostly mechanical from a custom clang-tidy check, with a lot of
manual fixups. It uncovers a lot of minor inefficiencies.

This doesn't actually modify StringRef yet, I'll do that in a follow-up.
2020-01-28 23:25:25 +01:00
Kristina Bessonova 4b0a7fe008 [llvm-dwarfdump][Statistics] Make calculations of vars in global scope more accurate
It isn't known how many times we've seen the same variable or member in
the global scope (unlike in functions), but there still can be some duplicates
among different CUs.
So, this patch proposes to count variables in the global scope just as a sum of
the number of vars, constant members and artificial entities.

Reviewed by: aprantl

Differential Revision: https://reviews.llvm.org/D73004
2020-01-28 20:52:20 +02:00
Kristina Bessonova 5499e2f455 [llvm-dwarfdump][Statistics] Distinguish parameters with same name or w/o a name
A few DW_TAG_formal_parameter's of the same function may have the same
name (e.g. variadic (template) functions) or don't have a name at all
(if the parameter isn't used inside the function body), but we still
need to be able to distinguish between them to get correct number of 'total vars'
and 'availability' metric.

Reviewed by: aprantl

Differential Revision: https://reviews.llvm.org/D73003
2020-01-28 20:52:20 +02:00
Kristina Bessonova 57839e5178 [llvm-dwarfdump][Statistics] Count more than one conrete out-of-line instances of a function
Here may be more than one out-of-line instance of the same function
among different CUs. All of them should be accounted for to get an accurate
total number of variables/parameters.

Reviewed by: aprantl

Differential Revision: https://reviews.llvm.org/D73002
2020-01-28 20:52:19 +02:00
Kristina Bessonova 2e5d20bd47 [llvm-dwarfdump][Statistics] Ignore declarations of global variables
Reviewed by: djtodoro

Differential Revision: https://reviews.llvm.org/D73001
2020-01-28 19:50:46 +02:00
Kristina Bessonova e76106e01c [llvm-dwarfdump][Statistics] Ignore DW_TAG_subroutine_type in statistics
DW_TAG_subroutine_type is not really useful for statistics purposes, as it never
has location information. But it may contain DW_TAG_formal_parameter
children that generate number of parameters w/o location and decrease
'availability' metric significantly.

Reviewed by: djtodoro

Differential Revision: https://reviews.llvm.org/D72983
2020-01-28 19:50:46 +02:00
Kristina Bessonova 9806b39dae [llvm-dwarfdump][Statistics] Distinguish functions/variables with same name across different CUs
Different variables and functions might have the same name in different CU.
To calculate 'Availability' metric more accurate (i.e. to avoid getting
availability above 100%), we need to have some additional logic to
distinguish between them.

The patch introduces a DIE identifier that consists of a function/variable name
and declaration information: a filename and a line number. This allows
distinguishing different functions/variables (different means declared in
different files/lines) with the same name, keeping duplicates counted
as duplicates.

Reviewed by: aprantl, djtodoro

Differential Revision: https://reviews.llvm.org/D72797
2020-01-28 19:50:46 +02:00
Igor Kudrin 8f3d47c54a [DWARF] Do not pass Version to DWARFExpression. NFCI.
The Version was used only to determine the size of an operand of
DW_OP_call_ref. The size was 4 for all versions apart from 2, but
the DW_OP_call_ref operation was introduced only in DWARF3. Thus,
the code may be simplified and using of Version may be eliminated.

Differential Revision: https://reviews.llvm.org/D73264
2020-01-27 19:08:46 +07:00
Kristina Bessonova d5655c4d2e [llvm-dwarfdump][Statistics] Don't count coverage less than 1% as 0%
Summary:
This is a follow up for D70548.
Currently, variables with debug info coverage between 0% and 1% are put into
zero-bucket. D70548 changed the way statistics calculate a variable's coverage:
we began to use enclosing scope rather than a possible variable life range.
Thus more variables might be moved to zero-bucket despite they have some debug
info coverage.
The patch is to distinguish between a variable that has location info but
it's significantly less than its enclosing scope and a variable that doesn't
have it at all.

Reviewers: djtodoro, aprantl, dblaikie, avl

Subscribers: llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D71070
2019-12-13 17:34:58 +03:00
Kristina Bessonova 1cc4b603ba [llvm-dwarfdump][Statistics] Change the coverage buckets representation. NFC
Summary:
This changes the representation of 'coverage buckets' in llvm-dwarfdump and
llvm-locstats to one that makes more clear what the buckets contain.

See some related details in D71070.

Reviewers: djtodoro, aprantl, cmtice, jhenderson

Subscribers: llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D71366
2019-12-13 16:08:25 +03:00
Jonas Devlieghere d9466653e4 [llvm/dwarfdump] Use the architecture string to filter.
Currently dwarfdump uses the ArchType to filter out architectures, which
is problematic for architectures like arm64e and x86_64h that map back
to arm64 and x86_64 respectively. The result is that the filter doesn't
work for these architectures because it matches all the variants. This
is especially bad because usually these architectures are the reason to
use the filter in the first place.

Instead, we should match the architecture based on the string name. This
means the filter works for the values printed by dwarfdump. It has the
unfortunate side effect of not working for aliases, like AArch64, but I
think that's worth the trade-off.

rdar://53653014

Differential revision: https://reviews.llvm.org/D71230
2019-12-09 17:17:01 -08:00
Kristina Bessonova 68f464ac2e [llvm-dwarfdump][Statistics] Unify coverage statistic computation
Summary:
The patch removes OffsetToFirstDefinition in the 'scope bytes total'
statistic computation. Thus it unifies the way the scope and the coverage
buckets are computed. The rationals behind that are the following:

1. OffsetToFirstDefinition was used to calculate the variable's life range.
However, there is no simple way to do it accurately, so the scope calculated
this way might be misleading. See D69027 for more details on the subject.
2. Both 'scope bytes total' and coverage buckets seem to be intended
to represent the same data in different ways. Otherwise, the statistics
might be controversial and confusing.

Note that the approach gives up a thorough evaluation of debug information
completeness (i.e. coverage buckets by themselves doesn't tell how good
the debug information is). Only changes in coverage over time make
a 'physical' sense.

Reviewers: djtodoro, aprantl, vsk, dblaikie, avl

Subscribers: llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D70548
2019-12-08 15:46:49 +03:00
Pavel Labath f65cfff605 dwarfdump --statistics: Use new location list api
Summary:
This patch removes manual location list handling in the statistics code
and replaces it with the new DWARFDie api, which provides access to a
"cooked" location list. This has the following effects:
- the code now properly handles split-dwarf location lists
- it will automatically support dwarf5 location lists once support for
  those is added
- it properly handles location lists with base address selection entries
- it fixes a bug where the location list code was using the first
  DW_AT_ranges range as a "base address" of the compile unit (it should
  have used DW_AT_low_pc instead. The effect of this was that the
  computation of the start address of a variable in its scope was broken
  for these kinds of compile units. This only manifested itself on
  linked files, since in object files the first DW_AT_ranges range
  normally starts at 0.

Since pretty much every kind of location list was broken in some way,
it's hard to verify that the new implementation is correct -- the output
will be different in all non-trivial cases, and mostly with good reason.

Most of the existing statistics tests continue to pass though, and a
visual inspection of the statistics for non-trivial inputs shows that
the data is more "reasonable" now. I have updated the "dwo statistics"
test to include the new numbers, as the previous ones were completely
bogus, and I have added a targeted test for the "base address" bug.

Reviewers: dblaikie, cmtice, vsk

Subscribers: aprantl, SouraVX, JDevlieghere, djtodoro, llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D70444
2019-11-21 11:55:21 +01:00
Pavel Labath 0908093977 DWARFDebugLoc(v4): Add an incremental parsing function
Summary:
This adds a visitLocationList function to the DWARF v4 location lists,
similar to what already exists for DWARF v5. It follows the approach
outlined in previous patches (D69672), where the parsed form is always
stored in the DWARF v5 format, which makes it easier for generic code to
be built on top of that. v4 location lists are "upgraded" during
parsing, and then this upgrade is undone while dumping.

Both "inline" and section-based dumping is rewritten to reuse the
existing "generic" location list dumper. This means that the output
format is consistent for all location lists (the only thing one needs to
implement is the function which prints the "raw" form of a location
list), and that debug_loc dumping correctly processes base address
selection entries, etc.

The previous existing debug_loc functionality (e.g.,
parseOneLocationList) is rewritten on top of the new API, but it is not
removed as there is still code which uses them. This will be done in
follow-up patches, after I build the API to access the "interpreted"
location lists in a generic way (as that is what those users really
want).

Reviewers: dblaikie, probinson, JDevlieghere, aprantl, SouraVX

Subscribers: hiraditya, llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D69847
2019-11-15 13:38:00 +01:00
Kai Nacke c9ddda8405 [Tools] Mark output of tools as text if it is text
Several LLVM tools write text files/streams without using OF_Text.
This can cause problems on platforms which distinguish between
text and binary output. This PR adds the OF_Text flag for the
following tools:

- llvm-dis
- llvm-dwarfdump
- llvm-mca
- llvm-mc (assembler files only)
- opt (assembler files only)
- RemarkStreamer (used e.g. by opt)

Reviewers: rnk, vivekvpandya, Bigcheese, andreadb

Differential Revision: https://reviews.llvm.org/D67696

llvm-svn: 374024
2019-10-08 08:21:20 +00:00