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Commit Graph

647 Commits

Author SHA1 Message Date
Andrea Di Biagio
57fcc40fb8 [llvm-mca][View] Improved Retire Control Unit Statistics.
RetireControlUnitStatistics now reports extra information about the ROB and the
avg/maximum number of entries consumed over the entire simulation.

Example:
  Retire Control Unit - number of cycles where we saw N instructions retired:
  [# retired], [# cycles]
   0,           109  (17.9%)
   1,           102  (16.7%)
   2,           399  (65.4%)

  Total ROB Entries:                64
  Max Used ROB Entries:             35  ( 54.7% )
  Average Used ROB Entries per cy:  32  ( 50.0% )

Documentation in llvm/docs/CommandGuide/llvmn-mca.rst has been updated to
reflect this change.

llvm-svn: 347493
2018-11-23 12:12:57 +00:00
Fedor Sergeev
ff5d61a8ad [FileCheck] fixing docs buildbot - use proper code-block type
llvm-svn: 346740
2018-11-13 05:47:01 +00:00
Fedor Sergeev
559b91886f [FileCheck] fixing small formatting error in docs
llvm-svn: 346725
2018-11-13 01:12:19 +00:00
Fedor Sergeev
82854f2e28 [FileCheck] introduce CHECK-COUNT-<num> repetition directive
In some cases it is desirable to match the same pattern repeatedly
many times. Currently the only way to do it is to copy the same
check pattern as many times as needed. And that gets pretty unwieldy
when its more than count is big.

Introducing CHECK-COUNT-<num> directive which acts like a plain CHECK
directive yet matches the same pattern exactly <num> times.

Extended FileCheckType to a struct to add Count there.
Changed some parsing routines to handle non-fixed length of directive
(all currently existing directives were fixed-length).

The code is generic enough to allow future support for COUNT in more
than just PlainCheck directives.

See motivating example for this feature in reviews.llvm.org/D54223.

Reviewed By: chandlerc, dblaikie
Differential Revision: https://reviews.llvm.org/D54336

llvm-svn: 346722
2018-11-13 00:46:13 +00:00
Max Moroz
60087383d9 [llvm-cov] Add lcov tracefile export format.
Summary:
lcov tracefiles are used by various coverage reporting tools and build
systems (e.g., Bazel). It is a simple text-based format to parse and
more convenient to use than the JSON export format, which needs
additional processing to map regions/segments back to line numbers.

It's a little unfortunate that "text" format is now overloaded to refer
specifically to JSON for export, but I wanted to avoid making any
breaking changes to the UI of the llvm-cov tool at this time.

Patch by Tony Allevato (@allevato).

Reviewers: Dor1s, vsk

Reviewed By: Dor1s, vsk

Subscribers: mgorny, llvm-commits

Differential Revision: https://reviews.llvm.org/D54266

llvm-svn: 346506
2018-11-09 16:10:44 +00:00
Joel E. Denny
3e75c39923 [FileCheck] Parse command-line options from FILECHECK_OPTS
This feature makes it easy to tune FileCheck diagnostic output when
running the test suite via ninja, a bot, or an IDE.  For example:

```
$ FILECHECK_OPTS='-color -v -dump-input-on-failure' \
  LIT_FILTER='OpenMP/for_codegen.cpp' ninja check-clang \
  | less -R
```

Reviewed By: probinson

Differential Revision: https://reviews.llvm.org/D53517

llvm-svn: 346272
2018-11-06 22:07:03 +00:00
Clement Courbet
dc9ae03db9 [MCSched] Bind PFM Counters to the CPUs instead of the SchedModel.
Summary:
The pfm counters are now in the ExegesisTarget rather than the
MCSchedModel (PR39165).

This also compresses the pfm counter tables (PR37068).

Reviewers: RKSimon, gchatelet

Subscribers: mgrang, llvm-commits

Differential Revision: https://reviews.llvm.org/D52932

llvm-svn: 345243
2018-10-25 07:44:01 +00:00
Joel E. Denny
f5d23d3609 [SourceMgr][FileCheck] Obey -color by extending WithColor
(Relands r344930, reverted in r344935, and now hopefully fixed for
Windows.)

While this change specifically targets FileCheck, it affects any tool
using the same SourceMgr facilities.

Previously, -color was documented in FileCheck's -help output, but
-color had no effect.  Now, -color obeys its documentation: it forces
colors to be used in FileCheck diagnostics even when stderr is not a
terminal.

-color is especially helpful when combined with FileCheck's -v, which
can produce a long series of diagnostics that you might wish to pipe
to a pager, such as less -R.  The WithColor extensions here will also
help to clean up color usage in FileCheck's annotated dump of input,
which is proposed in D52999.

Reviewed By: JDevlieghere, zturner

Differential Revision: https://reviews.llvm.org/D53419

llvm-svn: 345202
2018-10-24 21:46:42 +00:00
Aaron Ballman
f8047f57bb Revert r344930 as it broke some of the bots on Windows.
http://lab.llvm.org:8011/builders/clang-x64-windows-msvc/builds/739

llvm-svn: 344935
2018-10-22 18:51:29 +00:00
Joel E. Denny
92bb73aa3f [SourceMgr][FileCheck] Obey -color by extending WithColor
While this change specifically targets FileCheck, it affects any tool
using the same SourceMgr facilities.

Previously, -color was documented in FileCheck's -help output, but
-color had no effect.  Now, -color obeys its documentation: it forces
colors to be used in FileCheck diagnostics even when stderr is not a
terminal.

-color is especially helpful when combined with FileCheck's -v, which
can produce a long series of diagnostics that you might wish to pipe
to a pager, such as less -R.  The WithColor extensions here will also
help to clean up color usage in FileCheck's annotated dump of input,
which is proposed in D52999.

Reviewed By: JDevlieghere

Differential Revision: https://reviews.llvm.org/D53419

llvm-svn: 344930
2018-10-22 18:00:49 +00:00
Clement Courbet
988121fb86 [llvm-exegesis] Allow measuring several instructions in a single run.
Summary:
We try to recover gracefully on instructions that would crash the
program.

This includes some refactoring of runMeasurement() implementations.

Reviewers: gchatelet

Subscribers: tschuett, llvm-commits

Differential Revision: https://reviews.llvm.org/D53371

llvm-svn: 344695
2018-10-17 15:04:15 +00:00
Simon Pilgrim
13b9387d93 The llvm-exegesis output file is a html file not a txt file.
llvm-svn: 343215
2018-09-27 13:49:52 +00:00
Clement Courbet
519dab966b [llvm-exegesis] Fix doc in r342947.
llvm-exegesis.rst was using invalid indentation for bullet points.

llvm-svn: 342948
2018-09-25 07:48:38 +00:00
Clement Courbet
0301f9855d [llvm-exegesis] Allow benchmarking arbitrary code snippets.
Summary:

This is a step towards fixing PR38048.

Note that right now the measurements are given per instruction. We'll
need to give measurements a per code snippet and update the analysis (PR38731).

Reviewers: gchatelet

Subscribers: tschuett, llvm-commits

Differential Revision: https://reviews.llvm.org/D52041

llvm-svn: 342947
2018-09-25 07:31:44 +00:00
Richard Smith
0fc962508b Add flag to llvm-profdata to allow symbols in profile data to be remapped, and
add a tool to generate symbol remapping files.

Summary:
The new tool llvm-cxxmap builds a symbol mapping table from a file containing
a description of partial equivalences to apply to mangled names and files
containing old and new symbol tables.

Reviewers: davidxl

Subscribers: mgorny, llvm-commits

Differential Revision: https://reviews.llvm.org/D51470

llvm-svn: 342168
2018-09-13 20:22:02 +00:00
Andrea Di Biagio
7e5d9331c7 [llvm-mca] Report the number of dispatched micro opcodes in the DispatchStatistics view.
This patch introduces the following changes to the DispatchStatistics view:
 * DispatchStatistics now reports the number of dispatched opcodes instead of
   the number of dispatched instructions.
 * The "Dynamic Dispatch Stall Cycles" table now also reports the percentage of
   stall cycles against the total simulated cycles.

This change allows users to easily compare dispatch group sizes with the
processor DispatchWidth.
Before this change, it was difficult to correlate the two numbers, since
DispatchStatistics view reported numbers of instructions (instead of opcodes).
DispatchWidth defines the maximum size of a dispatch group in terms of number of
micro opcodes.

The other change introduced by this patch is related to how DispatchStage
generates "instruction dispatch" events.
In particular:
 * There can be multiple dispatch events associated with a same instruction
 * Each dispatch event now encapsulates the number of dispatched micro opcodes.

The number of micro opcodes declared by an instruction may exceed the processor
DispatchWidth. Therefore, we cannot assume that instructions are always fully
dispatched in a single cycle.
DispatchStage knows already how to handle instructions declaring a number of
opcodes bigger that DispatchWidth. However, DispatchStage always emitted a
single instruction dispatch event (during the first simulated dispatch cycle)
for instructions dispatched.

With this patch, DispatchStage now correctly notifies multiple dispatch events
for instructions that cannot be dispatched in a single cycle.

A few views had to be modified. Views can no longer assume that there can only
be one dispatch event per instruction.

Tests (and docs) have been updated.

Differential Revision: https://reviews.llvm.org/D51430

llvm-svn: 341055
2018-08-30 10:50:20 +00:00
Andrea Di Biagio
80b01d0203 [llvm-mca] Add fields "Total uOps" and "uOps Per Cycle" to the report generated by the SummaryView.
This patch adds two new fields to the perf report generated by the SummaryView.
Fields are now logically organized into two small groups; only the second group
contains throughput indicators.

Example:
```
Iterations:        100
Instructions:      300
Total Cycles:      414
Total uOps:        700

Dispatch Width:    4
uOps Per Cycle:    1.69
IPC:               0.72
Block RThroughput: 4.0
```

This patch also updates the docs for llvm-mca.
Due to the nature of this change, several tests in the tools/llvm-mca directory
were affected, and had to be updated using script `update_mca_test_checks.py`.

llvm-svn: 340946
2018-08-29 17:56:39 +00:00
Andrea Di Biagio
f707cd4166 [llvm-mca] Improved report generated by the SchedulerStatistics view.
Before this patch, the SchedulerStatistics only printed the maximum number of
buffer entries consumed in each scheduler's queue at a given point of the
simulation.

This patch restructures the reported table, and adds an extra field named
"Average number of used buffer entries" to it.
This patch also uses different colors to help identifying bottlenecks caused by
high scheduler's buffer pressure.

llvm-svn: 340746
2018-08-27 14:52:52 +00:00
Kuba Mracek
66b411671f [llvm] Document "%T" as deprecated in CommandGuide/lit.rst
Differential Revision: https://reviews.llvm.org/D48842

llvm-svn: 340677
2018-08-25 01:27:48 +00:00
David Green
61ff754920 [AArch64] Add Tiny Code Model for AArch64
This adds the plumbing for the Tiny code model for the AArch64 backend. This,
instead of loading addresses through the normal ADRP;ADD pair used in the Small
model, uses a single ADR. The 21 bit range of an ADR means that the code and
its statically defined symbols need to be within 1MB of each other.

This makes it mostly interesting for embedded applications where we want to fit
as much as we can in as small a space as possible.

Differential Revision: https://reviews.llvm.org/D49673

llvm-svn: 340397
2018-08-22 11:31:39 +00:00
Michael Trent
85dcf4ad23 Add a CommandGuide for llvm-objdump
Summary:
Add a CommandGuide for llvm-objdump summarizing its usage along with some
general context.

Reviewers: beanz

Reviewed By: beanz

Subscribers: Eugene.Zelenko, llvm-commits

Differential Revision: https://reviews.llvm.org/D50034

llvm-svn: 339250
2018-08-08 14:39:22 +00:00
Chandler Carruth
d64990a158 [docs] Fix an LLVM-syntax code block to actually be valid LLVM synatx.
Hopefully fixes an issue on the docs build bot.

llvm-svn: 338980
2018-08-06 01:41:25 +00:00
Matt Davis
b0535f09cc [llvm-mca][docs] Move the code marker text into its own subsection. NFC.
Also fixed a few undecorated 'llvm-mca' references to be highlighted
with the 'program' emphasis.

llvm-svn: 338900
2018-08-03 15:56:07 +00:00
Andrea Di Biagio
3d390604c7 [llvm-mca] Speed up the computation of the wait/ready/issued sets in the Scheduler.
This patch is a follow-up to r338702.

We don't need to use a map to model the wait/ready/issued sets. It is much more
efficient to use a vector instead.

This patch gives us an average 7.5% speedup (on top of the ~12% speedup obtained
after r338702).

llvm-svn: 338883
2018-08-03 12:55:28 +00:00
Andrea Di Biagio
1aca2c2e82 [llvm-mca][docs] Improve the CommandLine documentation.
This patch replaces all the remaining occurrences of string "MCA" with
":program:`llvm-mca`".  Somehow I missed those strings when I committed r338394.

This patch also improves section "Instruction Dispatch".

llvm-svn: 338881
2018-08-03 12:44:56 +00:00
Matt Davis
7b7e97dd13 [llvm-mca][docs] Replace "temporary" with "physical registers". NFC.
llvm-svn: 338415
2018-07-31 18:59:46 +00:00
Andrea Di Biagio
4a150d2528 [llvm-mca][docs] Improve the "How LLVM-MCA works" section.
llvm-svn: 338410
2018-07-31 18:19:15 +00:00
Andrea Di Biagio
159d252dca [llvm-mca][docs] Always use llvm-mca in place of MCA.
llvm-svn: 338394
2018-07-31 15:29:10 +00:00
Matt Davis
2fb231bb42 [llvm-mca][docs] Add instruction flow documentation. NFC.
Summary:
This patch mostly copies the existing Instruction Flow, and stage descriptions
from the mca README.  I made a few text tweaks, but no semantic changes,
and made reference to the "default pipeline."  I also removed the internals
references (e.g., reference to class names and header files).  I did leave the
LSUnit name around, but only as an abbreviated word for the load-store unit.


Reviewers: andreadb, courbet, RKSimon, gbedwell, filcab

Reviewed By: andreadb

Subscribers: tschuett, jfb, llvm-commits

Differential Revision: https://reviews.llvm.org/D49692

llvm-svn: 338319
2018-07-30 22:30:14 +00:00
Matt Davis
c79a134b78 [llvm-mca][docs] Define IPC where it is first mentioned. NFC.
Expand the abbreviation where it is first used, and use IPC elsewhere.

llvm-svn: 337739
2018-07-23 21:10:50 +00:00
Matt Davis
9597587b97 [llvm-mca][docs] Add documentation for the statistic outputs from mca. NFC
Summary: The original text was lifted from the MCA README.  I re-ran the dot-product example and updated the output seen in the docs.  I also added a few paragraphs discussing the instruction issued and retired histograms, as well as discussing the register file stats.

Reviewers: andreadb, RKSimon, courbet, gbedwell, filcab

Reviewed By: andreadb

Subscribers: tschuett

Differential Revision: https://reviews.llvm.org/D49614

llvm-svn: 337648
2018-07-21 18:32:47 +00:00
George Karpenkov
56b2870853 [FileCheck] Provide an option for FileCheck to dump original input to stderr on failure
The option can be either set using environment variable (e.g. env
FILECHECK_DUMP_INPUT_ON_FAILURE=1 ninja check-fuzzer) or with a
FileCheck flag.

This can be extremely useful for debugging, cf.
https://groups.google.com/forum/#!topic/llvm-dev/kLrzg8OM_h8 for
discussion.

Differential Revision: https://reviews.llvm.org/D49328

llvm-svn: 337609
2018-07-20 20:21:57 +00:00
Matt Davis
3fa9be1fea [llvm-mca][docs] Add Timeline and How MCA works.
For the most part, these changes were from the RFC.  I made a few minor
word/structure changes, but nothing significant.  I also regenerated the
example output, and adjusted the text accordingly.

Differential Revision: https://reviews.llvm.org/D49527

llvm-svn: 337496
2018-07-19 20:33:59 +00:00
Matt Davis
7447fc96e1 [llvm-mca][docs] Revert mca internals docs.
We're going to work on this in a separate review focusing more on documenting
the View and probably removing some of the less-interesting/less-useful pieces.

This reverts r337219,337225

llvm-svn: 337295
2018-07-17 16:11:54 +00:00
Matt Davis
4c4b8e599d [llvm-mca][docs] Add notes about cycle and resource callbacks. NFC.
llvm-svn: 337225
2018-07-16 23:50:53 +00:00
Matt Davis
c3a63ec6c0 [llvm-mca][docs] Initial description of mca internals. NFC
This patch introduces a brief description of the components of MCA.  The main
focus is on Views.   This is a work in progress, and more descriptions will be
introduced later.  I want to flesh-out the Views section more and provide a
detailed description of eventing in MCA.  Eventually a brief code example of a
View should accompany the description.

Also, we should consider moving the MCA internals guide elsewhere at some point.

llvm-svn: 337219
2018-07-16 21:42:58 +00:00
Vedant Kumar
04073c9cdb [docs] Update usage directive for llvm-cov report -show-functions
llvm-svn: 337062
2018-07-13 22:39:31 +00:00
Joel E. Denny
460b0069e3 [FileCheck] Implement -v and -vv for tracing matches
-v prints all directive pattern matches.

-vv additionally prints info that might be noise to users but that can
be helpful to FileCheck developers.

To maximize code reuse and to make diagnostics more consistent, this
patch also adjusts and extends some of the existing diagnostics.
CHECK-NOT failures now report variables uses.  Many more diagnostics
now report the check prefix and kind of directive.

Reviewed By: probinson

Differential Revision: https://reviews.llvm.org/D47114

llvm-svn: 336967
2018-07-13 03:08:23 +00:00
Joel E. Denny
a6c7ce37b0 [FileCheck] Don't permit overlapping CHECK-DAG
That is, make CHECK-DAG skip matches that overlap the matches of any
preceding consecutive CHECK-DAG directives.  This change makes
CHECK-DAG more consistent with other directives, and there is evidence
it makes CHECK-DAG more intuitive and less error-prone.  See the RFC
discussion starting at:

  http://lists.llvm.org/pipermail/llvm-dev/2018-May/123010.html

Moreover, this behavior enables CHECK-DAG groups for unordered,
non-unique strings or patterns.  For example, it is useful for
verifying output or logs from a parallel program, such as the OpenMP
runtime.

This patch also implements the command-line option
-allow-deprecated-dag-overlap, which reverts CHECK-DAG to the old
overlapping behavior.  This option should not be used in new tests.
It is meant only for the existing tests that are broken by this change
and that need time to update.

See the following bugzilla issue for tracking of such tests:

  https://bugs.llvm.org/show_bug.cgi?id=37532

Patches to add -allow-deprecated-dag-overlap to those tests will
follow immediately.

Reviewed By: probinson

Differential Revision: https://reviews.llvm.org/D47106

llvm-svn: 336847
2018-07-11 20:27:27 +00:00
Joel E. Denny
71e616812c Revert r336830: [FileCheck] Don't permit overlapping CHECK-DAG
Companion patches are failing to commit, and this patch alone breaks
many tests.

llvm-svn: 336833
2018-07-11 19:03:00 +00:00
Joel E. Denny
e3515ea4e8 [FileCheck] Don't permit overlapping CHECK-DAG
That is, make CHECK-DAG skip matches that overlap the matches of any
preceding consecutive CHECK-DAG directives.  This change makes
CHECK-DAG more consistent with other directives, and there is evidence
it makes CHECK-DAG more intuitive and less error-prone.  See the RFC
discussion starting at:

  http://lists.llvm.org/pipermail/llvm-dev/2018-May/123010.html

Moreover, this behavior enables CHECK-DAG groups for unordered,
non-unique strings or patterns.  For example, it is useful for
verifying output or logs from a parallel program, such as the OpenMP
runtime.

This patch also implements the command-line option
-allow-deprecated-dag-overlap, which reverts CHECK-DAG to the old
overlapping behavior.  This option should not be used in new tests.
It is meant only for the existing tests that are broken by this change
and that need time to update.

See the following bugzilla issue for tracking of such tests:

  https://bugs.llvm.org/show_bug.cgi?id=37532

Patches to add -allow-deprecated-dag-overlap to those tests will
follow immediately.

Reviewed By: probinson

Differential Revision: https://reviews.llvm.org/D47106

llvm-svn: 336830
2018-07-11 18:42:58 +00:00
Simon Tatham
7aeb5f145e [TableGen] Add a general-purpose JSON backend.
The aim of this backend is to output everything TableGen knows about
the record set, similarly to the default -print-records backend. But
where -print-records produces output in TableGen's input syntax
(convenient for humans to read), this backend produces it as
structured JSON data, which is convenient for loading into standard
scripting languages such as Python, in order to extract information
from the data set in an automated way.

The output data contains a JSON representation of the variable
definitions in output 'def' records, and a few pieces of metadata such
as which of those definitions are tagged with the 'field' prefix and
which defs are derived from which classes. It doesn't dump out
absolutely every piece of knowledge it _could_ produce, such as type
information and complicated arithmetic operator nodes in abstract
superclasses; the main aim is to allow consumers of this JSON dump to
essentially act as new backends, and backends don't generally need to
depend on that kind of data.

The new backend is implemented as an EmitJSON() function similar to
all of llvm-tblgen's other EmitFoo functions, except that it lives in
lib/TableGen instead of utils/TableGen on the basis that I'm expecting
to add it to clang-tblgen too in a future patch.

To test it, I've written a Python script that loads the JSON output
and tests properties of it based on comments in the .td source - more
or less like FileCheck, except that the CHECK: lines have Python
expressions after them instead of textual pattern matches.

Reviewers: nhaehnle

Reviewed By: nhaehnle

Subscribers: arichardson, labath, mgorny, llvm-commits

Differential Revision: https://reviews.llvm.org/D46054

llvm-svn: 336771
2018-07-11 08:40:19 +00:00
Dave Lee
1320ae98e2 nm: Add -no-weak flag for hiding weak symbols
Summary:
This adds a new -no-weak flag to nm to hide weak symbols in its output.
This also adds a -W alias for this which is analogous to -U.

Patch by Keith Smiley

Reviewers: kastiglione, enderby, compnerd

Reviewed By: kastiglione

Subscribers: llvm-commits

Differential Revision: https://reviews.llvm.org/D48751

llvm-svn: 336126
2018-07-02 17:24:37 +00:00
James Henderson
e41aa01cbe Fix doc title underlining.
llvm-svn: 335615
2018-06-26 15:29:09 +00:00
James Henderson
de9948f983 [FileCheck] Add CHECK-EMPTY directive for checking for blank lines
Prior to this change, there was no clean way of getting FileCheck to
check that a line is completely empty. The expected way of using
"CHECK: {{^$}}" does not work because the '^' matches the end of the
previous match (this behaviour may be desirable in certain instances).
For the same reason, "CHECK-NEXT: {{^$}}" will fail when the previous
match was at the end of the line, as the pattern will match there.
Using the recommended [[:space:]] to match an explicit new line could
also match a space, and thus is not always desired. Literal '\n'
matches also do not work. A workaround was suggested in the review, but
it is a little clunky.

This change adds a new directive that behaves the same as CHECK-NEXT,
except that it only matches against empty lines (nothing, not even
whitespace, is allowed). As with CHECK-NEXT, it will fail if more than
one newline occurs before the next blank line. Example usage:
; test.txt
foo

bar
; CHECK: foo
; CHECK-EMPTY:
; CHECK-NEXT: bar

Differential Revision: https://reviews.llvm.org/D28896

Reviewed by: probinson

llvm-svn: 335613
2018-06-26 15:15:45 +00:00
Fangrui Song
bbd9bdf17a [docs] Update doc after split of -gen-intrinsic in r335407
llvm-svn: 335515
2018-06-25 19:40:08 +00:00
Simon Pilgrim
d11526cd96 [docs] Fix indentation of llvm-exegesis command line arguments
llvm-svn: 334976
2018-06-18 20:05:02 +00:00
Clement Courbet
bdb322c5a1 [llvm-exegesis] Optionally ignore instructions without a sched class.
Summary: See PR37602.

Reviewers: RKSimon

Subscribers: llvm-commits, tschuett

Differential Revision: https://reviews.llvm.org/D48267

llvm-svn: 334932
2018-06-18 11:27:47 +00:00
Clement Courbet
097a2cc290 [llvm-exegesis] Fix off-by-one in llvm-exegesis documentation.
llvm-svn: 333759
2018-06-01 14:49:06 +00:00
Joel E. Denny
3204e36001 [lit] Report line number for failed RUN command
(Relands r333584, reverted in 333592.)

When debugging test failures with -vv (or -v in the case of the
internal shell), this makes it easier to locate the RUN line that
failed.  For example, clang's test/Driver/linux-ld.c has 892 total RUN
lines, and clang's test/Driver/arm-cortex-cpus.c has 424 RUN lines
after concatenation for line continuations.

When reading the generated shell script, this also makes it easier to
locate the RUN line that produced each command.

To support reporting RUN line numbers in the case of the internal
shell, this patch extends the internal shell to support the null
command, ":", except pipelines are not supported.

To support reporting RUN line numbers in the case of windows cmd.exe
as the external shell, this patch extends -vv to set "echo on" instead
of "echo off" in bat files.  (Support for windows cmd.exe as a lit
external shell will likely be dropped later, but I found out too
late.)

Reviewed By: delcypher,	asmith, stella.stamenova, jmorse, lebedev.ri, rnk

Differential Revision: https://reviews.llvm.org/D44598

llvm-svn: 333614
2018-05-31 00:55:32 +00:00