Patch by Ben Gamari!
This redefines the `prefix` attribute introduced previously and
introduces a `prologue` attribute. There are a two primary usecases
that these attributes aim to serve,
1. Function prologue sigils
2. Function hot-patching: Enable the user to insert `nop` operations
at the beginning of the function which can later be safely replaced
with a call to some instrumentation facility
3. Runtime metadata: Allow a compiler to insert data for use by the
runtime during execution. GHC is one example of a compiler that
needs this functionality for its tables-next-to-code functionality.
Previously `prefix` served cases (1) and (2) quite well by allowing the user
to introduce arbitrary data at the entrypoint but before the function
body. Case (3), however, was poorly handled by this approach as it
required that prefix data was valid executable code.
Here we redefine the notion of prefix data to instead be data which
occurs immediately before the function entrypoint (i.e. the symbol
address). Since prefix data now occurs before the function entrypoint,
there is no need for the data to be valid code.
The previous notion of prefix data now goes under the name "prologue
data" to emphasize its duality with the function epilogue.
The intention here is to handle cases (1) and (2) with prologue data and
case (3) with prefix data.
References
----------
This idea arose out of discussions[1] with Reid Kleckner in response to a
proposal to introduce the notion of symbol offsets to enable handling of
case (3).
[1] http://lists.cs.uiuc.edu/pipermail/llvmdev/2014-May/073235.html
Test Plan: testsuite
Differential Revision: http://reviews.llvm.org/D6454
llvm-svn: 223189
This format is simply a regular object file with the bitcode stored in a
section named ".llvmbc", plus any number of other (non-allocated) sections.
One immediate use case for this is to accommodate compilation processes
which expect the object file to contain metadata in non-allocated sections,
such as the ".go_export" section used by some Go compilers [1], although I
imagine that in the future we could consider compiling parts of the module
(such as large non-inlinable functions) directly into the object file to
improve LTO efficiency.
[1] http://golang.org/doc/install/gccgo#Imports
Differential Revision: http://reviews.llvm.org/D4371
llvm-svn: 218078
[LLVM part]
These patches rename the loop unrolling and loop vectorizer metadata
such that they have a common 'llvm.loop.' prefix. Metadata name
changes:
llvm.vectorizer.* => llvm.loop.vectorizer.*
llvm.loopunroll.* => llvm.loop.unroll.*
This was a suggestion from an earlier review
(http://reviews.llvm.org/D4090) which added the loop unrolling
metadata.
Patch by Mark Heffernan.
llvm-svn: 211710
This replaces the old NoIntegratedAssembler with at TargetOption. This is
more flexible and will be used to forward clang's -no-integrated-as option.
llvm-svn: 201836
after the 3.4 release to the release notes. See the *lengthy* llvmdev
and cfe-dev threads on this subject. There will be more emails,
discussion and announcements, but I want to make noise in as many places
as I can to get everyone's concerns voiced and understood.
llvm-svn: 194183
This change makes test with RUN lines like
RUN: opt ... | FileCheck
fail if opt fails, even if it prints what FileCheck wants. Enabling this
found some interesting cases of broken tests that were not being noticed
because opt (or some other tool) was crashing late.
Pipefail is used when the shell supports it or when using the internal
python based tester.
llvm-svn: 187261
This change also removes a bunch of boilerplate and stuffing which made
it unnecessarily hard to navigate and see the comparatively miniscule
actual content that was added to this document during the 3.2
development period (or maybe even sticking around from earlier
releases...).
The new organization (a flat list) optimizes for making it easy for
people who know about changes to add them to the document. It's
completely trivial for anyone with basic knowledge of LLVM to come in
later (such as when preparing for the actual release) and cluster any
changes into logical groups. However, I have left some comments
indicating how to add larger descriptions, if someone is feeling
adventurous ;)
Hopefully this organization will highlight how little effort is being
put into producing accurate, high-quality release notes, prompting a
corresponding improvement for the 3.3 release.
I have preserved the changes to this document that are not present
in the 3.2 release notes. There were only two... I'm pretty sure we've
been busier than that... (version control shows +213347/-173656 raw
lines just in the LLVM repo since the 3.2 release).
llvm-svn: 172954
- This code is dead, and the "right" way to get this support is to use the
platform-specific linker-integrated LTO mechanisms, or the forthcoming LLVM
linker.
llvm-svn: 172749
Bill Schmidt