This summarizes two recent llvm-dev discussions. Most of the text provided by David Chisnall and Benoit Belley with minor editting by me.
llvm-svn: 247301
This change extends the bitset lowering pass to support bitsets that may
contain either functions or global variables. A function bitset is lowered to
a jump table that is laid out before one of the functions in the bitset.
Also add support for non-string bitset identifier names. This allows for
distinct metadata nodes to stand in for names with internal linkage,
as done in D11857.
Differential Revision: http://reviews.llvm.org/D11856
llvm-svn: 247080
* ``the value cannot fit within the destination type`` is ambiguous.
It could mean overflow, underflow (not in the IEEE-754 sense) or a
result that cannot be exactly represented and requires rounding or it
could mean some combination of these. The semantics now state it means
overflow **only**.
* Using "truncation" in the semantics is very misleading given that it
doesn't necessarily truncate (i.e. round to zero). For example on
x86_64 with SSE2 this is currently mapped to cvtsd2ss instruction
who's rounding behaviour is dependent on the MXCSR register which
is usually set to round to nearest even by default. The semantics
now state that the rounding mode is undefined.
llvm-svn: 246792
Summary:
This intrinsic can be used to extract a pointer to the exception caught by
a given catchpad. Its argument has token type and must be a `catchpad`.
Also clarify ExtendingLLVM documentation regarding overloaded intrinsics.
Reviewers: majnemer, andrew.w.kaylor, sanjoy, rnk
Subscribers: llvm-commits
Differential Revision: http://reviews.llvm.org/D12533
llvm-svn: 246752
Summary:
Add a `cleanupendpad` instruction, used to mark exceptional exits out of
cleanups (for languages/targets that can abort a cleanup with another
exception). The `cleanupendpad` instruction is similar to the `catchendpad`
instruction in that it is an EH pad which is the target of unwind edges in
the handler and which itself has an unwind edge to the next EH action.
The `cleanupendpad` instruction, similar to `cleanupret` has a `cleanuppad`
argument indicating which cleanup it exits. The unwind successors of a
`cleanuppad`'s `cleanupendpad`s must agree with each other and with its
`cleanupret`s.
Update WinEHPrepare (and docs/tests) to accomodate `cleanupendpad`.
Reviewers: rnk, andrew.w.kaylor, majnemer
Subscribers: llvm-commits
Differential Revision: http://reviews.llvm.org/D12433
llvm-svn: 246751
This patch defines 'unpredictable' metadata. This metadata can be used to signal to the optimizer
or backend that a branch or switch is unpredictable, and therefore, it's probably better to not
split a compound predicate into multiple branches such as in CodeGenPrepare::splitBranchCondition().
This was discussed in:
https://llvm.org/bugs/show_bug.cgi?id=23827
Dependent patches to alter codegen and expose this in clang to follow.
Differential Revision; http://reviews.llvm.org/D12341
llvm-svn: 246688
As a follow-up to r246098, require `DISubprogram` definitions
(`isDefinition: true`) to be 'distinct'. Specifically, add an assembler
check, a verifier check, and bitcode upgrading logic to combat testcase
bitrot after the `DIBuilder` change.
While working on the testcases, I realized that
test/Linker/subprogram-linkonce-weak-odr.ll isn't relevant anymore. Its
purpose was to check for a corner case in PR22792 where two subprogram
definitions match exactly and share the same metadata node. The new
verifier check, requiring that subprogram definitions are 'distinct',
precludes that possibility.
I updated almost all the IR with the following script:
git grep -l -E -e '= !DISubprogram\(.* isDefinition: true' |
grep -v test/Bitcode |
xargs sed -i '' -e 's/= \(!DISubprogram(.*, isDefinition: true\)/= distinct \1/'
Likely some variant of would work for out-of-tree testcases.
llvm-svn: 246327
Expand the information on base pointers to include an example, the assumptions a collector is allowed to make, legal optimizations over gc.relocates, and the assumptions made by RewriteStatepointsForGC. This is the result of a recent conversation with folks from LLIC and the confusions that came to light therein.
llvm-svn: 246103
This commit switches the underlying JIT for the Kaleidoscope tutorials from
MCJIT to a custom ORC-based JIT, KaleidoscopeJIT. This fixes a lot of the bugs
in Kaleidoscope that were introduced when we deleted the legacy JIT. The
documentation for Chapter 4, which introduces the JIT APIs, is updated to
reflect the change.
Also included are a number of C++11 modernizations and general cleanup. Where
appropriate, the docs have been updated to reflect these changes too.
llvm-svn: 246002
- Fix some grammatical and typographical errors.
- Try to improve upon some awkward/nonstandard phrasings.
- Expand slightly the treatment of how you specify arguments to cmake.
- Update the list of possible LLVM_BUILD_TESTS and state where to find the
definitive list.
- Correct the name of llvm-tblgen.
- Expand slightly the treatment of several build options, including
LLVM_LIT_TOOLS_DIR, LLVM_ENABLE_FFI, and LLVM_EXTERNAL_project_SOURCE_DIR.
Patch by Brian R. Gaeke!
Differential Revision: http://reviews.llvm.org/D11862
llvm-svn: 245911
Arranging the language specific property section into readable groupings and adding a couple of notes about pass order, extensions, and the like.
For the record, suggestion for word smithing are welcomed. I'm happy to revise; I'm just trying to get *something* in place.
llvm-svn: 245855
This change just groups the suggestions by broad topic. I'm planning a couple of follow on changes to improve the readability of this document.
llvm-svn: 245854
Summary:
WinEHPrepare is going to require that cleanuppad and catchpad produce values
of token type which are consumed by any cleanupret or catchret exiting the
pad. This change updates the signatures of those operators to require/enforce
that the type produced by the pads is token type and that the rets have an
appropriate argument.
The catchpad argument of a `CatchReturnInst` must be a `CatchPadInst` (and
similarly for `CleanupReturnInst`/`CleanupPadInst`). To accommodate that
restriction, this change adds a notion of an operator constraint to both
LLParser and BitcodeReader, allowing appropriate sentinels to be constructed
for forward references and appropriate error messages to be emitted for
illegal inputs.
Also add a verifier rule (noted in LangRef) that a catchpad with a catchpad
predecessor must have no other predecessors; this ensures that WinEHPrepare
will see the expected linear relationship between sibling catches on the
same try.
Lastly, remove some superfluous/vestigial casts from instruction operand
setters operating on BasicBlocks.
Reviewers: rnk, majnemer
Subscribers: llvm-commits
Differential Revision: http://reviews.llvm.org/D12108
llvm-svn: 245797
such as std::equal on the third argument. This reverts previous workarounds.
Predefining _DEBUG_POINTER_IMPL disables Visual C++ 2013 headers from defining
it to a function performing the null pointer check. In practice, it's not that
bad since any function actually using the nullptr will seg fault. The other
iterator sanity checks remain enabled in the headers.
Reviewed by Aaron Ballmanþ and Duncan P. N. Exon Smith.
llvm-svn: 245711
Some personality routines require funclet exit points to be clearly
marked, this is done by producing a token at the funclet pad and
consuming it at the corresponding ret instruction. CleanupReturnInst
already had a spot for this operand but CatchReturnInst did not.
Other personality routines don't need to use this which is why it has
been made optional.
llvm-svn: 245149
This introduces the basic functionality to support "token types".
The motivation stems from the need to perform operations on a Value
whose provenance cannot be obscured.
There are several applications for such a type but my immediate
motivation stems from WinEH. Our personality routine enforces a
single-entry - single-exit regime for cleanups. After several rounds of
optimizations, we may be left with a terminator whose "cleanup-entry
block" is not entirely clear because control flow has merged two
cleanups together. We have experimented with using labels as operands
inside of instructions which are not terminators to indicate where we
came from but found that LLVM does not expect such exotic uses of
BasicBlocks.
Instead, we can use this new type to clearly associate the "entry point"
and "exit point" of our cleanup. This is done by having the cleanuppad
yield a Token and consuming it at the cleanupret.
The token type makes it impossible to obscure or otherwise hide the
Value, making it trivial to track the relationship between the two
points.
What is the burden to the optimizer? Well, it turns out we have already
paid down this cost by accepting that there are certain calls that we
are not permitted to duplicate, optimizations have to watch out for
such instructions anyway. There are additional places in the optimizer
that we will probably have to update but early examination has given me
the impression that this will not be heroic.
Differential Revision: http://reviews.llvm.org/D11861
llvm-svn: 245029
