Commit Graph

823 Commits

Author SHA1 Message Date
Sanjay Patel 629c411538 [IR] redefine 'UnsafeAlgebra' / 'reassoc' fast-math-flags and add 'trans' fast-math-flag
As discussed on llvm-dev:
http://lists.llvm.org/pipermail/llvm-dev/2016-November/107104.html
and again more recently:
http://lists.llvm.org/pipermail/llvm-dev/2017-October/118118.html

...this is a step in cleaning up our fast-math-flags implementation in IR to better match
the capabilities of both clang's user-visible flags and the backend's flags for SDNode.

As proposed in the above threads, we're replacing the 'UnsafeAlgebra' bit (which had the 
'umbrella' meaning that all flags are set) with a new bit that only applies to algebraic 
reassociation - 'AllowReassoc'.

We're also adding a bit to allow approximations for library functions called 'ApproxFunc' 
(this was initially proposed as 'libm' or similar).

...and we're out of bits. 7 bits ought to be enough for anyone, right? :) FWIW, I did 
look at getting this out of SubclassOptionalData via SubclassData (spacious 16-bits), 
but that's apparently already used for other purposes. Also, I don't think we can just 
add a field to FPMathOperator because Operator is not intended to be instantiated. 
We'll defer movement of FMF to another day.

We keep the 'fast' keyword. I thought about removing that, but seeing IR like this:
%f.fast = fadd reassoc nnan ninf nsz arcp contract afn float %op1, %op2
...made me think we want to keep the shortcut synonym.

Finally, this change is binary incompatible with existing IR as seen in the 
compatibility tests. This statement:
"Newer releases can ignore features from older releases, but they cannot miscompile 
them. For example, if nsw is ever replaced with something else, dropping it would be 
a valid way to upgrade the IR." 
( http://llvm.org/docs/DeveloperPolicy.html#ir-backwards-compatibility )
...provides the flexibility we want to make this change without requiring a new IR 
version. Ie, we're not loosening the FP strictness of existing IR. At worst, we will 
fail to optimize some previously 'fast' code because it's no longer recognized as 
'fast'. This should get fixed as we audit/squash all of the uses of 'isFast()'.

Note: an inter-dependent clang commit to use the new API name should closely follow 
commit.

Differential Revision: https://reviews.llvm.org/D39304

llvm-svn: 317488
2017-11-06 16:27:15 +00:00
Sean Fertile 4595a915f6 [LTO][ThinLTO] Use the linker resolutions to mark global values as dso_local.
Now that we have a way to mark GlobalValues as local we can use the symbol
resolutions that the linker plugin provides as part of lto/thinlto link
step to refine the compilers view on what symbols will end up being local.

Originally commited as r317374, but reverted in r317395 to update some missed
tests.

Differential Revision: https://reviews.llvm.org/D35702

llvm-svn: 317408
2017-11-04 17:04:39 +00:00
Sean Fertile 39770ca0a1 Revert "[LTO][ThinLTO] Use the linker resolutions to mark global values ..."
Changes more tests then expected on one of the build bots.
reverting to investigate.

This reverts https://llvm.org/svn/llvm-project/llvm/trunk@317374

llvm-svn: 317395
2017-11-04 01:54:20 +00:00
Sean Fertile 36528c2a9b [LTO][ThinLTO] Use the linker resolutions to mark global values as dso_local.
Now that we have a way to mark GlobalValues as local we can use the symbol
resolutions that the linker plugin provides as part of lto/thinlto link
step to refine the compilers view on what symbols will end up being local.

Differential Revision: https://reviews.llvm.org/D35702

llvm-svn: 317374
2017-11-03 21:45:55 +00:00
David Blaikie 526f30b8aa Modularize: Include some required headers
DenseMaps require the definition of a type to be available when using a
pointer to that type as a key to know how many bits are available for
tombstone/etc.

llvm-svn: 317360
2017-11-03 20:24:19 +00:00
Sean Fertile c70d28bff5 Represent runtime preemption in the IR.
Currently we do not represent runtime preemption in the IR, which has several
drawbacks:

  1) The semantics of GlobalValues differ depending on the object file format
     you are targeting (as well as the relocation-model and -fPIE value).
  2) We have no way of disabling inlining of run time interposable functions,
     since in the IR we only know if a function is link-time interposable.
     Because of this llvm cannot support elf-interposition semantics.
  3) In LTO builds of executables we will have extra knowledge that a symbol
     resolved to a local definition and can't be preemptable, but have no way to
     propagate that knowledge through the compiler.

This patch adds preemptability specifiers to the IR with the following meaning:

dso_local --> means the compiler may assume the symbol will resolve to a
 definition within the current linkage unit and the symbol may be accessed
 directly even if the definition is not within this compilation unit.

dso_preemptable --> means that the compiler must assume the GlobalValue may be
replaced with a definition from outside the current linkage unit at runtime.

To ease transitioning dso_preemptable is treated as a 'default' in that
low-level codegen will still do the same checks it did previously to see if a
symbol should be accessed indirectly. Eventually when IR producers emit the
specifiers on all Globalvalues we can change dso_preemptable to mean 'always
access indirectly', and remove the current logic.

Differential Revision: https://reviews.llvm.org/D20217

llvm-svn: 316668
2017-10-26 15:00:26 +00:00
Aaron Ballman 615eb47035 Reverting r315590; it did not include changes for llvm-tblgen, which is causing link errors for several people.
Error LNK2019 unresolved external symbol "public: void __cdecl `anonymous namespace'::MatchableInfo::dump(void)const " (?dump@MatchableInfo@?A0xf4f1c304@@QEBAXXZ) referenced in function "public: void __cdecl `anonymous namespace'::AsmMatcherEmitter::run(class llvm::raw_ostream &)" (?run@AsmMatcherEmitter@?A0xf4f1c304@@QEAAXAEAVraw_ostream@llvm@@@Z) llvm-tblgen D:\llvm\2017\utils\TableGen\AsmMatcherEmitter.obj 1

llvm-svn: 315854
2017-10-15 14:32:27 +00:00
Don Hinton 3e0199f7eb [dump] Remove NDEBUG from test to enable dump methods [NFC]
Summary:
Add LLVM_FORCE_ENABLE_DUMP cmake option, and use it along with
LLVM_ENABLE_ASSERTIONS to set LLVM_ENABLE_DUMP.

Remove NDEBUG and only use LLVM_ENABLE_DUMP to enable dump methods.

Move definition of LLVM_ENABLE_DUMP from config.h to llvm-config.h so
it'll be picked up by public headers.

Differential Revision: https://reviews.llvm.org/D38406

llvm-svn: 315590
2017-10-12 16:16:06 +00:00
Mandeep Singh Grang 1be19e6f5b [llvm] Fix some typos. NFC.
Reviewers: mcrosier

Reviewed By: mcrosier

Subscribers: mcrosier, llvm-commits

Differential Revision: https://reviews.llvm.org/D37922

llvm-svn: 313388
2017-09-15 20:01:43 +00:00
Peter Collingbourne b52e23669c IR: Represent -ggnu-pubnames with a flag on the DICompileUnit.
This allows the flag to be persisted through to LTO.

Differential Revision: https://reviews.llvm.org/D37655

llvm-svn: 313078
2017-09-12 21:50:41 +00:00
Eugene Zelenko 975293f0e5 [Bitcode] Fix some Clang-tidy modernize-use-using and Include What You Use warnings; other minor fixes (NFC).
llvm-svn: 312760
2017-09-07 23:28:24 +00:00
Benjamin Kramer 49a49fe816 Move helper classes into anonymous namespaces.
No functionality change intended.

llvm-svn: 311288
2017-08-20 13:03:48 +00:00
Xinliang David Li 5a57b842cf Add more comment
llvm-svn: 311025
2017-08-16 17:33:43 +00:00
Xinliang David Li 71ecaa19ff [PGO] Fix ThinLTO crash
Differential Revsion: http://reviews.llvm.org/D36640

llvm-svn: 311023
2017-08-16 17:18:01 +00:00
Andrew Kaylor 53a5fbb45f Add strictfp attribute to prevent unwanted optimizations of libm calls
Differential Revision: https://reviews.llvm.org/D34163

llvm-svn: 310885
2017-08-14 21:15:13 +00:00
Charles Saternos 75da10d1b2 [ThinLTO] Add FunctionAttrs to ThinLTO index
Adds function attributes to index: ReadNone, ReadOnly, NoRecurse, NoAlias. This attributes will be used for future ThinLTO optimizations that will propagate function attributes across modules.

llvm-svn: 310061
2017-08-04 16:00:58 +00:00
Haojie Wang 1dec57d5b0 ThinLTO Minimized Bitcode File Size Reduction
Summary: Currently the ThinLTO minimized bitcode file only strip the debug info, but there is still a lot of information in the minimized bit code file that will be not used for thin linker. In this patch, most of the extra information is striped to reduce the minimized bitcode file. Now only ModuleVersion, ModuleInfo, ModuleGlobalValueSummary, ModuleHash, Symtab and Strtab are left. Now the minimized bitcode file size is reduced to 15%-30% of the debug info stripped bitcode file size.

Reviewers: danielcdh, tejohnson, pcc

Reviewed By: pcc

Subscribers: mehdi_amini, aprantl, inglorion, eraman, llvm-commits

Differential Revision: https://reviews.llvm.org/D35334

llvm-svn: 308760
2017-07-21 17:25:20 +00:00
Adrian Prantl d63bfd218b Debug Info: Add a file: field to DIImportedEntity.
DIImportedEntity has a line number, but not a file field. To determine
the decl_line/decl_file we combine the line number from the
DIImportedEntity with the file from the DIImportedEntity's scope. This
does not work correctly when the parent scope is a DINamespace or a
DIModule, both of which do not have a source file.

This patch adds a file field to DIImportedEntity to unambiguously
identify the source location of the using/import declaration.  Most
testcase updates are mechanical, the interesting one is the removal of
the FIXME in test/DebugInfo/Generic/namespace.ll.

This fixes PR33822. See https://bugs.llvm.org/show_bug.cgi?id=33822
for more context.

<rdar://problem/33357889>
https://bugs.llvm.org/show_bug.cgi?id=33822

Differential Revision: https://reviews.llvm.org/D35583

llvm-svn: 308398
2017-07-19 00:09:54 +00:00
Konstantin Zhuravlyov bb80d3e1d3 Enhance synchscope representation
OpenCL 2.0 introduces the notion of memory scopes in atomic operations to
  global and local memory. These scopes restrict how synchronization is
  achieved, which can result in improved performance.

  This change extends existing notion of synchronization scopes in LLVM to
  support arbitrary scopes expressed as target-specific strings, in addition to
  the already defined scopes (single thread, system).

  The LLVM IR and MIR syntax for expressing synchronization scopes has changed
  to use *syncscope("<scope>")*, where <scope> can be "singlethread" (this
  replaces *singlethread* keyword), or a target-specific name. As before, if
  the scope is not specified, it defaults to CrossThread/System scope.

  Implementation details:
    - Mapping from synchronization scope name/string to synchronization scope id
      is stored in LLVM context;
    - CrossThread/System and SingleThread scopes are pre-defined to efficiently
      check for known scopes without comparing strings;
    - Synchronization scope names are stored in SYNC_SCOPE_NAMES_BLOCK in
      the bitcode.

Differential Revision: https://reviews.llvm.org/D21723

llvm-svn: 307722
2017-07-11 22:23:00 +00:00
Peter Collingbourne c855615831 Bitcode: Include any strings added to the string table in the module hash.
Differential Revision: https://reviews.llvm.org/D35037

llvm-svn: 307286
2017-07-06 17:56:01 +00:00
Peter Collingbourne 2d67e3789a Add missing library dependency.
llvm-svn: 306491
2017-06-28 00:05:27 +00:00
Peter Collingbourne 92648c25a4 Bitcode: Write the irsymtab to disk.
Differential Revision: https://reviews.llvm.org/D33973

llvm-svn: 306487
2017-06-27 23:50:11 +00:00
Evgeniy Stepanov 4d4ee93d25 [cfi] CFI-ICall for ThinLTO.
Implement ControlFlowIntegrity for indirect function calls in ThinLTO.
Design follows the RFC in llvm-dev, see
https://groups.google.com/d/msg/llvm-dev/MgUlaphu4Qc/kywu0AqjAQAJ

llvm-svn: 305533
2017-06-16 00:18:29 +00:00
Florian Hahn ffc498dfcc Align definition of DW_OP_plus with DWARF spec [3/3]
Summary:
This patch is part of 3 patches that together form a single patch, but must be introduced in stages in order not to break things.
 
The way that LLVM interprets DW_OP_plus in DIExpression nodes is basically that of the DW_OP_plus_uconst operator since LLVM expects an unsigned constant operand. This unnecessarily restricts the DW_OP_plus operator, preventing it from being used to describe the evaluation of runtime values on the expression stack. These patches try to align the semantics of DW_OP_plus and DW_OP_minus with that of the DWARF definition, which pops two elements off the expression stack, performs the operation and pushes the result back on the stack.
 
This is done in three stages:
• The first patch (LLVM) adds support for DW_OP_plus_uconst.
• The second patch (Clang) contains changes all its uses from DW_OP_plus to DW_OP_plus_uconst.
• The third patch (LLVM) changes the semantics of DW_OP_plus and DW_OP_minus to be in line with its DWARF meaning. This patch includes the bitcode upgrade from legacy DIExpressions.

Patch by Sander de Smalen.

Reviewers: echristo, pcc, aprantl

Reviewed By: aprantl

Subscribers: fhahn, javed.absar, aprantl, llvm-commits

Differential Revision: https://reviews.llvm.org/D33894

llvm-svn: 305386
2017-06-14 13:14:38 +00:00
Peter Collingbourne e357fbd243 Write summaries for merged modules when splitting modules for ThinLTO.
This is to prepare to allow for dead stripping of globals in the
merged modules.

Differential Revision: https://reviews.llvm.org/D33921

llvm-svn: 305027
2017-06-08 23:01:49 +00:00
David Blaikie 358c012db2 BitcodeWriter: Removing unnecessary std::function in favor of template
More cleanup from post-commit discussion on r304516

llvm-svn: 304579
2017-06-02 18:25:29 +00:00
David Blaikie b6b42e018a Tidy up a bit of r304516, use SmallVector::assign rather than for loop
This might give a few better opportunities to optimize these to memcpy
rather than loops - also a few minor cleanups (StringRef-izing,
templating (to avoid std::function indirection), etc).

The SmallVector::assign(iter, iter) could be improved with the use of
SFINAE, but the (iter, iter) ctor and append(iter, iter) need it to and
don't have it - so, workaround it for now rather than bothering with the
added complexity.

(also, as noted in the added FIXME, these assign ops could potentially
be optimized better at least for non-trivially-copyable types)

llvm-svn: 304566
2017-06-02 17:24:26 +00:00
Teresa Johnson 7a27b132a8 [ThinLTO] Efficiency improvement when writing module path string table
Summary:
When writing the combined index, we are walking the entire module
path StringMap in the full index, and checking whether each one should be
included in the index being written. For distributed backends, where we
write an individual combined index for each file, each with only a few
module paths, this is incredibly inefficient. Add a method that takes
a callback and hides the details of whether we are writing the full
combined index, or just a slice, and in the latter case it walks the set
of modules to include instead of the entire index.

For a huge application with around 23K files (i.e. where we were iterating
through the 23K-entry modulePath StringMap 23K times), this change improved
the thin link time by a whopping 48%.

Reviewers: pcc

Subscribers: Prazek, inglorion, llvm-commits

Differential Revision: https://reviews.llvm.org/D33813

llvm-svn: 304516
2017-06-02 01:56:02 +00:00
Evgeniy Stepanov 56584bbf16 (NFC) Track global summary liveness in GVFlags.
Replace GVFlags::LiveRoot with GVFlags::Live and use that instead of
all the DeadSymbols sets. This is refactoring in order to make
liveness information available in the RegularLTO pipeline.

llvm-svn: 304466
2017-06-01 20:30:06 +00:00
Teresa Johnson a6a3fb57a1 [ThinLTO] Reduce unnecessary map lookups during combined summary write
Summary:
Don't assign values to undefined references, simply don't emit those
reference edges as they are not useful (we were already not emitting
call edges to undefined refs).

Also, streamline the later lookup of value ids when writing the
summaries, by combining the check for value id existence with the access
of that value id.

Reviewers: pcc

Subscribers: Prazek, llvm-commits, inglorion

Differential Revision: https://reviews.llvm.org/D33634

llvm-svn: 304323
2017-05-31 18:58:11 +00:00
Peter Collingbourne 2c26a18501 Bitcode: Remove some dead code. Spotted by Teresa.
Differential Revision: https://reviews.llvm.org/D33609

llvm-svn: 304046
2017-05-26 23:21:40 +00:00
Reid Kleckner 8bf67fe98f [IR] Switch AttributeList to use an array for O(1) access
Summary:
Before this change, AttributeLists stored a pair of index and
AttributeSet. This is memory efficient if most arguments do not have
attributes. However, it requires doing a search over the pairs to test
an argument or function attribute. Profiling shows that this loop was
0.76% of the time in 'opt -O2' of sqlite3.c, because LLVM constantly
tests values for nullability.

This was worth about 2.5% of mid-level optimization cycles on the
sqlite3 amalgamation. Here are the full perf results:
https://reviews.llvm.org/P7995

Here are just the before and after cycle counts:
```
$ perf stat -r 5 ./opt_before -O2 sqlite3.bc -o /dev/null
    13,274,181,184      cycles                    #    3.047 GHz                      ( +-  0.28% )
$ perf stat -r 5 ./opt_after -O2 sqlite3.bc -o /dev/null
    12,906,927,263      cycles                    #    3.043 GHz                      ( +-  0.51% )
```

This patch *does not* change the indices used to query attributes, as
requested by reviewers. Tracking whether an index is usable for array
indexing is a huge pain that affects many of the internal APIs, so it
would be good to come back later and do a cleanup to remove this
internal adjustment.

Reviewers: pete, chandlerc

Subscribers: javed.absar, llvm-commits

Differential Revision: https://reviews.llvm.org/D32819

llvm-svn: 303654
2017-05-23 17:01:48 +00:00
Javed Absar f3d7904d20 [IR] Allow attributes with global variables
This patch extends llvm-ir to allow attributes to be set on global variables.
An RFC was sent out earlier by my colleague James Molloy: http://lists.llvm.org/pipermail/cfe-dev/2017-March/053100.html
A key part of that proposal was to extend LLVM-IR to carry attributes on global variables.
This generic feature could be useful for multiple purposes.
In our present context, it would be useful to carry user specified sections for bss/rodata/data.

Reviewed by: Jonathan Roelofs, Reid Kleckner
Differential Revision: https://reviews.llvm.org/D32009

llvm-svn: 302794
2017-05-11 12:28:08 +00:00
Peter Collingbourne 9667b91b13 Re-apply r302108, "IR: Use pointers instead of GUIDs to represent edges in the module summary. NFCI."
with a fix for the clang backend.

llvm-svn: 302176
2017-05-04 18:03:25 +00:00
Eric Liu f6039f255e Revert "IR: Use pointers instead of GUIDs to represent edges in the module summary. NFCI."
This reverts commit r302108. This causes crash in clang bootstrap with LTO.

Contacted the auther in the original commit.

llvm-svn: 302140
2017-05-04 11:49:39 +00:00
Peter Collingbourne 5f85a9deda IR: Use pointers instead of GUIDs to represent edges in the module summary. NFCI.
When profiling a no-op incremental link of Chromium I found that the functions
computeImportForFunction and computeDeadSymbols were consuming roughly 10% of
the profile. The goal of this change is to improve the performance of those
functions by changing the map lookups that they were previously doing into
pointer dereferences.

This is achieved by changing the ValueInfo data structure to be a pointer to
an element of the global value map owned by ModuleSummaryIndex, and changing
reference lists in the GlobalValueSummary to hold ValueInfos instead of GUIDs.
This means that a ValueInfo will take a client directly to the summary list
for a given GUID.

Differential Revision: https://reviews.llvm.org/D32471

llvm-svn: 302108
2017-05-04 03:36:16 +00:00
Peter Collingbourne 7c2c4097a0 Bitcode: Simplify how we enumerate summaries in the index. NFCI.
Instead of defining a custom iterator class, just use a function with a
callback, which is much easier to understand and less error prone.

Differential Revision: https://reviews.llvm.org/D32470

llvm-svn: 301942
2017-05-02 17:48:39 +00:00
Adrian Prantl fed4f399d3 Remove line and file from DINamespace.
Fixes the issue highlighted in
http://lists.llvm.org/pipermail/cfe-dev/2014-June/037500.html.

The DW_AT_decl_file and DW_AT_decl_line attributes on namespaces can
prevent LLVM from uniquing types that are in the same namespace. They
also don't carry any meaningful information.

rdar://problem/17484998
Differential Revision: https://reviews.llvm.org/D32648

llvm-svn: 301706
2017-04-28 22:25:46 +00:00
Matt Arsenault b19b57ea60 Add speculatable function attribute
This attribute tells the optimizer that the function may be speculated.

Patch by Tom Stellard

llvm-svn: 301680
2017-04-28 20:25:27 +00:00
Adrian Prantl 1d12b885b0 Add support for DW_TAG_thrown_type.
For Swift we would like to be able to encode the error types that a
function may throw, so the debugger can display them alongside the
function's return value when finish-ing a function.

DWARF defines DW_TAG_thrown_type (intended to be used for C++ throw()
declarations) that is a perfect fit for this purpose. This patch wires
up support for DW_TAG_thrown_type in LLVM by adding a list of thrown
types to DISubprogram.

To offset the cost of the extra pointer, there is a follow-up patch
that turns DISubprogram into a variable-length node.

rdar://problem/29481673

Differential Revision: https://reviews.llvm.org/D32559

llvm-svn: 301489
2017-04-26 22:56:44 +00:00
Reid Kleckner 63b26f0eea Make getSlotAttributes return an AttributeSet instead of a wrapper list
Remove the temporary, poorly named getSlotSet method which did the same
thing. Also remove getSlotNode, which is a hold-over from when we were
dealing with AttributeSetNode* instead of AttributeSet.

llvm-svn: 301267
2017-04-24 22:25:02 +00:00
Reid Kleckner b4a2d18777 [Bitcode] Refactor attribute group writing to avoid getSlotAttributes
Summary:
That API creates a temporary AttributeList to carry an index and a
single AttributeSet. We need to carry the index in addition to the set,
because that is how attribute groups are currently encoded.

NFC

Reviewers: pcc

Subscribers: llvm-commits

Differential Revision: https://reviews.llvm.org/D32262

llvm-svn: 301245
2017-04-24 20:38:30 +00:00
Adrian Prantl 6825fb64e9 PR32382: Fix emitting complex DWARF expressions.
The DWARF specification knows 3 kinds of non-empty simple location
descriptions:
1. Register location descriptions
  - describe a variable in a register
  - consist of only a DW_OP_reg
2. Memory location descriptions
  - describe the address of a variable
3. Implicit location descriptions
  - describe the value of a variable
  - end with DW_OP_stack_value & friends

The existing DwarfExpression code is pretty much ignorant of these
restrictions. This used to not matter because we only emitted very
short expressions that we happened to get right by accident.  This
patch makes DwarfExpression aware of the rules defined by the DWARF
standard and now chooses the right kind of location description for
each expression being emitted.

This would have been an NFC commit (for the existing testsuite) if not
for the way that clang describes captured block variables. Based on
how the previous code in LLVM emitted locations, DW_OP_deref
operations that should have come at the end of the expression are put
at its beginning. Fixing this means changing the semantics of
DIExpression, so this patch bumps the version number of DIExpression
and implements a bitcode upgrade.

There are two major changes in this patch:

I had to fix the semantics of dbg.declare for describing function
arguments. After this patch a dbg.declare always takes the *address*
of a variable as the first argument, even if the argument is not an
alloca.

When lowering a DBG_VALUE, the decision of whether to emit a register
location description or a memory location description depends on the
MachineLocation — register machine locations may get promoted to
memory locations based on their DIExpression. (Future) optimization
passes that want to salvage implicit debug location for variables may
do so by appending a DW_OP_stack_value. For example:
  DBG_VALUE, [RBP-8]                        --> DW_OP_fbreg -8
  DBG_VALUE, RAX                            --> DW_OP_reg0 +0
  DBG_VALUE, RAX, DIExpression(DW_OP_deref) --> DW_OP_reg0 +0

All testcases that were modified were regenerated from clang. I also
added source-based testcases for each of these to the debuginfo-tests
repository over the last week to make sure that no synchronized bugs
slip in. The debuginfo-tests compile from source and run the debugger.

https://bugs.llvm.org/show_bug.cgi?id=32382
<rdar://problem/31205000>

Differential Revision: https://reviews.llvm.org/D31439

llvm-svn: 300522
2017-04-18 01:21:53 +00:00
Peter Collingbourne 4cba6ecb06 Bitcode: Add missing build dep to fix shlib build.
llvm-svn: 300478
2017-04-17 18:53:27 +00:00
Peter Collingbourne a0f371a106 Bitcode: Add a string table to the bitcode format.
Add a top-level STRTAB block containing a string table blob, and start storing
strings for module codes FUNCTION, GLOBALVAR, ALIAS, IFUNC and COMDAT in
the string table.

This change allows us to share names between globals and comdats as well
as between modules, and improves the efficiency of loading bitcode files by
no longer using a bit encoding for symbol names. Once we start writing the
irsymtab to the bitcode file we will also be able to share strings between
it and the module.

On my machine, link time for Chromium for Linux with ThinLTO decreases by
about 7% for no-op incremental builds or about 1% for full builds. Total
bitcode file size decreases by about 3%.

As discussed on llvm-dev:
http://lists.llvm.org/pipermail/llvm-dev/2017-April/111732.html

Differential Revision: https://reviews.llvm.org/D31838

llvm-svn: 300464
2017-04-17 17:51:36 +00:00
Chandler Carruth 927d8e610a [IR] Redesign the case iterator in SwitchInst to actually be an iterator
and to expose a handle to represent the actual case rather than having
the iterator return a reference to itself.

All of this allows the iterator to be used with common STL facilities,
standard algorithms, etc.

Doing this exposed some missing facilities in the iterator facade that
I've fixed and required some work to the actual iterator to fully
support the necessary API.

Differential Revision: https://reviews.llvm.org/D31548

llvm-svn: 300032
2017-04-12 07:27:28 +00:00
Peter Collingbourne db4cafa6c4 Bitcode: Do not create FNENTRYs for aliases of functions.
There doesn't seem to be any point in doing this.

Differential Revision: https://reviews.llvm.org/D31691

llvm-svn: 299694
2017-04-06 19:39:24 +00:00
Peter Collingbourne e935296f36 Bitcode: Remove an unused declaration. NFC.
llvm-svn: 299598
2017-04-05 22:49:52 +00:00
Adam Nemet cd847a8f30 [IR] Add AllowContract to FastMathFlags
-ffp-contract=fast does not currently work with LTO because it's passed as a
TargetOption to the backend rather than in the IR. This adds it to
FastMathFlags.

This is toward fixing PR25721

Differential Revision: https://reviews.llvm.org/D31164

llvm-svn: 298939
2017-03-28 20:11:52 +00:00
Teresa Johnson 0c6a4ff8dc [ThinLTO] Add support for emitting minimized bitcode for thin link
Summary:
The cumulative size of the bitcode files for a very large application
can be huge, particularly with -g. In a distributed build environment,
all of these files must be sent to the remote build node that performs
the thin link step, and this can exceed size limits.

The thin link actually only needs the summary along with a bitcode
symbol table. Until we have a proper bitcode symbol table, simply
stripping the debug metadata results in significant size reduction.

Add support for an option to additionally emit minimized bitcode
modules, just for use in the thin link step, which for now just strips
all debug metadata. I plan to add a cc1 option so this can be invoked
easily during the compile step.

However, care must be taken to ensure that these minimized thin link
bitcode files produce the same index as with the original bitcode files,
as these original bitcode files will be used in the backends.

Specifically:
1) The module hash used for caching is typically produced by hashing the
written bitcode, and we want to include the hash that would correspond
to the original bitcode file. This is because we want to ensure that
changes in the stripped portions affect caching. Added plumbing to emit
the same module hash in the minimized thin link bitcode file.
2) The module paths in the index are constructed from the module ID of
each thin linked bitcode, and typically is automatically generated from
the input file path. This is the path used for finding the modules to
import from, and obviously we need this to point to the original bitcode
files. Added gold-plugin support to take a suffix replacement during the
thin link that is used to override the identifier on the MemoryBufferRef
constructed from the loaded thin link bitcode file. The assumption is
that the build system can specify that the minimized bitcode file has a
name that is similar but uses a different suffix (e.g. out.thinlink.bc
instead of out.o).

Added various tests to ensure that we get identical index files out of
the thin link step.

Reviewers: mehdi_amini, pcc

Subscribers: Prazek, llvm-commits

Differential Revision: https://reviews.llvm.org/D31027

llvm-svn: 298638
2017-03-23 19:47:39 +00:00