COMMON blocks are a feature of Fortran that has no direct analog in C languages, but they are similar to data sections in assembly language programming. A COMMON block is a named area of memory that holds a collection of variables. Fortran subprograms may map the COMMON block memory area to their own, possibly distinct, non-empty list of variables. A Fortran COMMON block might look like the following example.
COMMON /ALPHA/ I, J
For this construct, the compiler generates a new scope-like DI construct (!DICommonBlock) into which variables (see I, J above) can be placed. As the common block implies a range of storage with global lifetime, the !DICommonBlock refers to a !DIGlobalVariable. The Fortran variable that comprise the COMMON block are also linked via metadata to offsets within the global variable that stands for the entire common block.
@alpha_ = common global %alphabytes_ zeroinitializer, align 64, !dbg !27, !dbg !30, !dbg !33!14 = distinct !DISubprogram(…)
!20 = distinct !DICommonBlock(scope: !14, declaration: !25, name: "alpha")
!25 = distinct !DIGlobalVariable(scope: !20, name: "common alpha", type: !24)
!27 = !DIGlobalVariableExpression(var: !25, expr: !DIExpression())
!29 = distinct !DIGlobalVariable(scope: !20, name: "i", file: !3, type: !28)
!30 = !DIGlobalVariableExpression(var: !29, expr: !DIExpression())
!31 = distinct !DIGlobalVariable(scope: !20, name: "j", file: !3, type: !28)
!32 = !DIExpression(DW_OP_plus_uconst, 4)
!33 = !DIGlobalVariableExpression(var: !31, expr: !32)
The DWARF generated for this is as follows.
DW_TAG_common_block:
DW_AT_name: alpha
DW_AT_location: @alpha_+0
DW_TAG_variable:
DW_AT_name: common alpha
DW_AT_type: array of 8 bytes
DW_AT_location: @alpha_+0
DW_TAG_variable:
DW_AT_name: i
DW_AT_type: integer*4
DW_AT_location: @Alpha+0
DW_TAG_variable:
DW_AT_name: j
DW_AT_type: integer*4
DW_AT_location: @Alpha+4
Patch by Eric Schweitz!
Differential Revision: https://reviews.llvm.org/D54327
llvm-svn: 357934
Moving subprogram specific flags into DISPFlags makes IR code more readable.
In addition, we provide free space in DIFlags for other
'non-subprogram-specific' debug info flags.
Patch by Djordje Todorovic.
Differential Revision: https://reviews.llvm.org/D59288
llvm-svn: 356454
Summary:
The AliasSummary previously contained the AliaseeGUID, which was only
populated when reading the summary from bitcode. This patch changes it
to instead hold the ValueInfo of the aliasee, and always populates it.
This enables more efficient access to the ValueInfo (specifically in the
recent patch r352438 which needed to perform an index hash table lookup
using the aliasee GUID).
As noted in the comments in AliasSummary, we no longer technically need
to keep a pointer to the corresponding aliasee summary, since it could
be obtained by walking the list of summaries on the ValueInfo looking
for the summary in the same module. However, I am concerned that this
would be inefficient when walking through the index during the thin
link for various analyses. That can be reevaluated in the future.
By always populating this new field, we can remove the guard and special
handling for a 0 aliasee GUID when dumping the dot graph of the summary.
An additional improvement in this patch is when reading the summaries
from LLVM assembly we now set the AliaseeSummary field to the aliasee
summary in that same module, which makes it consistent with the behavior
when reading the summary from bitcode.
Reviewers: pcc, mehdi_amini
Subscribers: inglorion, eraman, steven_wu, dexonsmith, arphaman, llvm-commits
Differential Revision: https://reviews.llvm.org/D57470
llvm-svn: 356268
This indicates an intrinsic parameter is required to be a constant,
and should not be replaced with a non-constant value.
Add the attribute to all AMDGPU and generic intrinsics that comments
indicate it should apply to. I scanned other target intrinsics, but I
don't see any obvious comments indicating which arguments are intended
to be only immediates.
This breaks one questionable testcase for the autoupgrade. I'm unclear
on whether the autoupgrade is supposed to really handle declarations
which were never valid. The verifier fails because the attributes now
refer to a parameter past the end of the argument list.
llvm-svn: 355981
This patch accompanies the RFC posted here:
http://lists.llvm.org/pipermail/llvm-dev/2018-October/127239.html
This patch adds a new CallBr IR instruction to support asm-goto
inline assembly like gcc as used by the linux kernel. This
instruction is both a call instruction and a terminator
instruction with multiple successors. Only inline assembly
usage is supported today.
This also adds a new INLINEASM_BR opcode to SelectionDAG and
MachineIR to represent an INLINEASM block that is also
considered a terminator instruction.
There will likely be more bug fixes and optimizations to follow
this, but we felt it had reached a point where we would like to
switch to an incremental development model.
Patch by Craig Topper, Alexander Ivchenko, Mikhail Dvoretckii
Differential Revision: https://reviews.llvm.org/D53765
llvm-svn: 353563
This cleans up all GetElementPtr creation in LLVM to explicitly pass a
value type rather than deriving it from the pointer's element-type.
Differential Revision: https://reviews.llvm.org/D57173
llvm-svn: 352913
This cleans up all LoadInst creation in LLVM to explicitly pass the
value type rather than deriving it from the pointer's element-type.
Differential Revision: https://reviews.llvm.org/D57172
llvm-svn: 352911
This cleans up all InvokeInst creation in LLVM to explicitly pass a
function type rather than deriving it from the pointer's element-type.
Differential Revision: https://reviews.llvm.org/D57171
llvm-svn: 352910
Summary:
UBSan wants to detect when unreachable code is actually reached, so it
adds instrumentation before every `unreachable` instruction. However,
the optimizer will remove code after calls to functions marked with
`noreturn`. To avoid this UBSan removes `noreturn` from both the call
instruction as well as from the function itself. Unfortunately, ASan
relies on this annotation to unpoison the stack by inserting calls to
`_asan_handle_no_return` before `noreturn` functions. This is important
for functions that do not return but access the the stack memory, e.g.,
unwinder functions *like* `longjmp` (`longjmp` itself is actually
"double-proofed" via its interceptor). The result is that when ASan and
UBSan are combined, the `noreturn` attributes are missing and ASan
cannot unpoison the stack, so it has false positives when stack
unwinding is used.
Changes:
# UBSan now adds the `expect_noreturn` attribute whenever it removes
the `noreturn` attribute from a function
# ASan additionally checks for the presence of this attribute
Generated code:
```
call void @__asan_handle_no_return // Additionally inserted to avoid false positives
call void @longjmp
call void @__asan_handle_no_return
call void @__ubsan_handle_builtin_unreachable
unreachable
```
The second call to `__asan_handle_no_return` is redundant. This will be
cleaned up in a follow-up patch.
rdar://problem/40723397
Reviewers: delcypher, eugenis
Tags: #sanitizers
Differential Revision: https://reviews.llvm.org/D56624
llvm-svn: 352003
This broke the RISCV build, and even with that fixed, one of the RISCV
tests behaves surprisingly differently with asserts than without,
leaving there no clear test pattern to use. Generally it seems bad for
hte IR to differ substantially due to asserts (as in, an alloca is used
with asserts that isn't needed without!) and nothing I did simply would
fix it so I'm reverting back to green.
This also required reverting the RISCV build fix in r351782.
llvm-svn: 351796
to reflect the new license.
We understand that people may be surprised that we're moving the header
entirely to discuss the new license. We checked this carefully with the
Foundation's lawyer and we believe this is the correct approach.
Essentially, all code in the project is now made available by the LLVM
project under our new license, so you will see that the license headers
include that license only. Some of our contributors have contributed
code under our old license, and accordingly, we have retained a copy of
our old license notice in the top-level files in each project and
repository.
llvm-svn: 351636
Summary:
If LTOUnit splitting is disabled, the module summary analysis computes
the summary information necessary to perform single implementation
devirtualization during the thin link with the index and no IR. The
information collected from the regular LTO IR in the current hybrid WPD
algorithm is summarized, including:
1) For vtable definitions, record the function pointers and their offset
within the vtable initializer (subsumes the information collected from
IR by tryFindVirtualCallTargets).
2) A record for each type metadata summarizing the vtable definitions
decorated with that metadata (subsumes the TypeIdentiferMap collected
from IR).
Also added are the necessary bitcode records, and the corresponding
assembly support.
The index-based WPD will be sent as a follow-on.
Depends on D53890.
Reviewers: pcc
Subscribers: mehdi_amini, Prazek, inglorion, eraman, steven_wu, dexonsmith, arphaman, llvm-commits
Differential Revision: https://reviews.llvm.org/D54815
llvm-svn: 351453
Summary:
Records in the module summary index whether the bitcode was compiled
with the option necessary to enable splitting the LTO unit
(e.g. -fsanitize=cfi, -fwhole-program-vtables, or -fsplit-lto-unit).
The information is passed down to the ModuleSummaryIndex builder via a
new module flag "EnableSplitLTOUnit", which is propagated onto a flag
on the summary index.
This is then used during the LTO link to check whether all linked
summaries were built with the same value of this flag. If not, an error
is issued when we detect a situation requiring whole program visibility
of the class hierarchy. This is the case when both of the following
conditions are met:
1) We are performing LowerTypeTests or Whole Program Devirtualization.
2) There are type tests or type checked loads in the code.
Note I have also changed the ThinLTOBitcodeWriter to also gate the
module splitting on the value of this flag.
Reviewers: pcc
Subscribers: ormris, mehdi_amini, Prazek, inglorion, eraman, steven_wu, dexonsmith, arphaman, dang, llvm-commits
Differential Revision: https://reviews.llvm.org/D53890
llvm-svn: 350948
That is, remove many of the calls to Type::getNumContainedTypes(),
Type::subtypes(), and Type::getContainedType(N).
I'm not intending to remove these accessors -- they are
useful/necessary in some cases. However, removing the pointee type
from pointers would potentially break some uses, and reducing the
number of calls makes it easier to audit.
llvm-svn: 350835
Summary:
This patch computes the synthetic function entry count on the whole
program callgraph (based on module summary) and writes the entry counts
to the summary. After function importing, this count gets attached to
the IR as metadata. Since it adds a new field to the summary, this bumps
up the version.
Reviewers: tejohnson
Subscribers: mehdi_amini, inglorion, llvm-commits
Differential Revision: https://reviews.llvm.org/D43521
llvm-svn: 349076
`Saver` is a StringSaver, which has a few overloads of `save` that all
ultimately just call `StringRef save(StringRef)`. Just take a StringRef
here instead of building up a std::string to convert it to a StringRef.
llvm-svn: 348650
Packing the flags into one bitcode word will save effort in
adding new flags in the future.
Differential Revision: https://reviews.llvm.org/D54755
llvm-svn: 347806
This will hold flags specific to subprograms. In the future
we could potentially free up scarce bits in DIFlags by moving
subprogram-specific flags from there to the new flags word.
This patch does not change IR/bitcode formats, that will be
done in a follow-up.
Differential Revision: https://reviews.llvm.org/D54597
llvm-svn: 347239
An attempt to recommit r346584 after failure on OSX build bot.
Fixed cache key computation in ThinLTOCodeGenerator and added
test case
llvm-svn: 347033
Summary:
Followup from D53596/r346891. Remove the getMDNodeFwdRefOrNull interface
to the MDLoader since it is no longer used. Also improve error messages
when the internal implementation is used within the MDLoader.
Reviewers: steven_wu
Subscribers: llvm-commits
Differential Revision: https://reviews.llvm.org/D54542
llvm-svn: 346899
This is a revised version of D41474.
When the debug location is parsed in BitcodeReader::parseFunction, the
scope and inlinedAt MDNodes are obtained via MDLoader->getMDNodeFwdRefOrNull(),
which will create a forward ref if they were not yet loaded.
Specifically, if one of these MDNodes is in the module level metadata
block, and this is during ThinLTO importing, that metadata block is
lazily loaded.
Most places in that invoke getMDNodeFwdRefOrNull have a corresponding call
to resolveForwardRefsAndPlaceholders which will take care of resolving them.
E.g. places that call getMetadataFwdRefOrLoad, or at the end of parsing a
function-level metadata block, or at the end of the initial lazy load of
module level metadata in order to handle invocations of getMDNodeFwdRefOrNull
for named metadata and global object attachments. However, the calls for
the scope/inlinedAt of debug locations are not backed by any such call to
resolveForwardRefsAndPlaceholders.
To fix this, change the scope and inlinedAt parsing to instead use
getMetadataFwdRefOrLoad, which will ensure the forward refs to lazily
loaded metadata are resolved.
Fixes PR35472.
llvm-svn: 346891
Summary:
Ranges base address specifiers can save a lot of object size in
relocation records especially in optimized builds.
For an optimized self-host build of Clang with split DWARF and debug
info compression in object files, but uncompressed debug info in the
executable, this change produces about 18% smaller object files and 6%
larger executable.
While it would've been nice to turn this on by default, gold's 32 bit
gdb-index support crashes on this input & I don't think there's any
perfect heuristic to implement solely in LLVM that would suffice - so
we'll need a flag one way or another (also possible people might want to
aggressively optimized for executable size that contains debug info
(even with compression this would still come at some cost to executable
size)) - so let's plumb it through.
Differential Revision: https://reviews.llvm.org/D54242
llvm-svn: 346788
The IEEE-754 Standard makes it clear that fneg(x) and
fsub(-0.0, x) are two different operations. The former is a bitwise
operation, while the latter is an arithmetic operation. This patch
creates a dedicated FNeg IR Instruction to model that behavior.
Differential Revision: https://reviews.llvm.org/D53877
llvm-svn: 346774
This patch allows internalising globals if all accesses to them
(from live functions) are from non-volatile load instructions
Differential revision: https://reviews.llvm.org/D49362
llvm-svn: 346584
Summary:
The NotEligibleToImport flag on the GlobalValueSummary was set if it
isn't legal to import (e.g. because it references unpromotable locals)
and when it can't be inlined (in which case importing is pointless).
I split out the inlinable piece into a separate flag on the
FunctionSummary (doesn't make sense for aliases or global variables),
because in the future we may want to import for reasons other than
inlining.
Reviewers: davidxl
Subscribers: mehdi_amini, inglorion, eraman, steven_wu, dexonsmith, arphaman, llvm-commits
Differential Revision: https://reviews.llvm.org/D53345
llvm-svn: 346261
Summary:
This is a revised version of D41474.
When the debug location is parsed in BitcodeReader::parseFunction, the
scope and inlinedAt MDNodes are obtained via MDLoader->getMDNodeFwdRefOrNull(),
which will create a forward ref if they were not yet loaded.
Specifically, if one of these MDNodes is in the module level metadata
block, and this is during ThinLTO importing, that metadata block is
lazily loaded.
Most places in that invoke getMDNodeFwdRefOrNull have a corresponding call
to resolveForwardRefsAndPlaceholders which will take care of resolving them.
E.g. places that call getMetadataFwdRefOrLoad, or at the end of parsing a
function-level metadata block, or at the end of the initial lazy load of
module level metadata in order to handle invocations of getMDNodeFwdRefOrNull
for named metadata and global object attachments. However, the calls for
the scope/inlinedAt of debug locations are not backed by any such call to
resolveForwardRefsAndPlaceholders.
To fix this, change the scope and inlinedAt parsing to instead use
getMetadataFwdRefOrLoad, which will ensure the forward refs to lazily
loaded metadata are resolved.
Fixes PR35472.
Reviewers: dexonsmith, Sunil_Srivastava, vsk
Subscribers: inglorion, eraman, steven_wu, sebpop, mehdi_amini, dmikulin, vsk, hiraditya, llvm-commits
Differential Revision: https://reviews.llvm.org/D53596
llvm-svn: 345095
Summary:
In D49565/r337503, the type id record writing was fixed so that only
referenced type ids were emitted into each per-module index for ThinLTO
distributed builds. However, this still left an efficiency issue: each
per-module index checked all type ids for membership in the referenced
set, yielding O(M*N) performance (M indexes and N type ids).
Change the TypeIdMap in the summary to be indexed by GUID, to facilitate
correlating with type identifier GUIDs referenced in the function
summary TypeIdInfo structures. This allowed simplifying other
places where a map from type id GUID to type id map entry was previously
being used to aid this correlation.
Also fix AsmWriter code to handle the rare case of type id GUID
collision.
For a large internal application, this reduced the thin link time by
almost 15%.
Reviewers: pcc, vitalybuka
Subscribers: mehdi_amini, inglorion, steven_wu, dexonsmith, llvm-commits
Differential Revision: https://reviews.llvm.org/D51330
llvm-svn: 343021
https://reviews.llvm.org/D42082 introduced variant parts to debug info
in LLVM. Subsequent work on the Rust compiler has found a bug in that
patch; namely, there is a path in MetadataLoader that fails to restore
the discriminator.
This patch fixes the bug.
Patch by: Tom Tromey
Differential revision: https://reviews.llvm.org/D52340
llvm-svn: 342725
r342631 expanded bitc::METADATA_LOCATION by one element. The bitcode
metadata loader was changed in a backwards-incompatible way, leading to
crashes when disassembling old bitcode:
assertion: empty() && "PlaceholderQueue hasn't been flushed before being destroyed"
Assertion failed: (empty() && "PlaceholderQueue hasn't been flushed before being destroyed")
This commit teaches the metadata loader to assume that the newly-added
IsImplicitCode bit is 'false' when not present in old bitcode. I've added a
bitcode compat regression test.
rdar://44645820
llvm-svn: 342678
Summary:
Some lines have a hit counter where they should not have one.
For example, in C++, some cleanup is adding at the end of a scope represented by a '}'.
So such a line has a hit counter where a user expects to not have one.
The goal of the patch is to add this information in DILocation which is used to get the covered lines in GCOVProfiling.cpp.
A following patch in clang will add this information when generating IR (https://reviews.llvm.org/D49916).
Reviewers: marco-c, davidxl, vsk, javed.absar, rnk
Reviewed By: rnk
Subscribers: eraman, xur, danielcdh, aprantl, rnk, dblaikie, #debug-info, vsk, llvm-commits, sylvestre.ledru
Tags: #debug-info
Differential Revision: https://reviews.llvm.org/D49915
llvm-svn: 342631
Summary:
ThinLTO imports alias as a copy of a aliasee, so when we import such functions with type tests we will
need type ids used by function. However after D49565 we pick types only during processing of
FunctionSummary which is not happening for such aliesees.
Example:
Unit U1 with a type, a functions F with the type check, and an alias A to the function.
Unit U2 with only call to the alias A.
In particular, this happens when we use -mconstructor-aliases, which is default.
So if c++ unit only creates instance of the class, without calling any other methods it will lack of
necessary type ids, which will result in false CFI reports.
Reviewers: tejohnson, eugenis
Subscribers: pcc, mehdi_amini, inglorion, eraman, hiraditya, steven_wu, dexonsmith, llvm-commits
Differential Revision: https://reviews.llvm.org/D52201
llvm-svn: 342574
Load Hardening.
Wires up the existing pass to work with a proper IR attribute rather
than just a hidden/internal flag. The internal flag continues to work
for now, but I'll likely remove it soon.
Most of the churn here is adding the IR attribute. I talked about this
Kristof Beyls and he seemed at least initially OK with this direction.
The idea of using a full attribute here is that we *do* expect at least
some forms of this for other architectures. There isn't anything
*inherently* x86-specific about this technique, just that we only have
an implementation for x86 at the moment.
While we could potentially expose this as a Clang-level attribute as
well, that seems like a good question to defer for the moment as it
isn't 100% clear whether that or some other programmer interface (or
both?) would be best. We'll defer the programmer interface side of this
for now, but at least get to the point where the feature can be enabled
without relying on implementation details.
This also allows us to do something that was really hard before: we can
enable *just* the indirect call retpolines when using SLH. For x86, we
don't have any other way to mitigate indirect calls. Other architectures
may take a different approach of course, and none of this is surfaced to
user-level flags.
Differential Revision: https://reviews.llvm.org/D51157
llvm-svn: 341363
This is a bit awkward in a handful of places where we didn't even have
an instruction and now we have to see if we can build one. But on the
whole, this seems like a win and at worst a reasonable cost for removing
`TerminatorInst`.
All of this is part of the removal of `TerminatorInst` from the
`Instruction` type hierarchy.
llvm-svn: 340701
Most users won't have to worry about this as all of the
'getOrInsertFunction' functions on Module will default to the program
address space.
An overload has been added to Function::Create to abstract away the
details for most callers.
This is based on https://reviews.llvm.org/D37054 but without the changes to
make passing a Module to Function::Create() mandatory. I have also added
some more tests and fixed the LLParser to accept call instructions for
types in the program address space.
Reviewed By: bjope
Differential Revision: https://reviews.llvm.org/D47541
llvm-svn: 340519
In cases where the debugger load time is a worthwhile tradeoff (or less
costly - such as loading from a DWP instead of a variety of DWOs
(possibly over a high-latency/distributed filesystem)) against object
file size, it can be reasonable to disable pubnames and corresponding
gdb-index creation in the linker.
A backend-flag version of this was implemented for NVPTX in
D44385/r327994 - which was fine for NVPTX which wouldn't mix-and-match
CUs. Now that it's going to be a user-facing option (likely powered by
"-gno-pubnames", the same as GCC) it should be encoded in the
DICompileUnit so it can vary per-CU.
After this, likely the NVPTX support should be migrated to the metadata
& the previous flag implementation should be removed.
Reviewers: aprantl
Differential Revision: https://reviews.llvm.org/D50213
llvm-svn: 339939
Flags in DIBasicType will be used to pass attributes used in
DW_TAG_base_type, such as DW_AT_endianity.
Patch by Chirag Patel!
Differential Revision: https://reviews.llvm.org/D49610
llvm-svn: 339714
Summary:
Currently all type ids are emitted into the index file when it is
written. For distributed ThinLTO, that meant that all type ids were
being duplicated into every single distributed index file, regardless of
whether they were referenced, leading to huge amounts of unnecessary
duplication and size bloat.
Keep track of the type id GUIDs actually referenced by the GV summary
records being emitted, and only emit those type IDs.
Add a new test, and fix test/Assembler/thinlto-summary.ll so that all
type ids are referenced to prevent deletion in that test.
Reviewers: pcc
Subscribers: mehdi_amini, inglorion, eraman, steven_wu, dexonsmith, vitalybuka, llvm-commits
Differential Revision: https://reviews.llvm.org/D49565
llvm-svn: 337503
Summary:
To allow bitcode built by old compiler to pass the current verifer,
BitcodeReader needs to auto infer the correct runtime preemption from
linkage and visibility for GlobalValues.
Since llvm-6.0 bitcode already contains the new field but can be
incorrect in some cases, the attribute needs to be recomputed all the
time in BitcodeReader. This will make all the GVs has dso_local marked
correctly if read from bitcode, and it should still allow the verifier
to catch mistakes in optimization passes.
This should fix PR38009.
Reviewers: sfertile, vsk
Reviewed By: vsk
Subscribers: dexonsmith, llvm-commits
Differential Revision: https://reviews.llvm.org/D49039
llvm-svn: 336560
Adrian Prantl