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
The bitset metadata currently used in LLVM has a few problems:
1. It has the wrong name. The name "bitset" refers to an implementation
detail of one use of the metadata (i.e. its original use case, CFI).
This makes it harder to understand, as the name makes no sense in the
context of virtual call optimization.
2. It is represented using a global named metadata node, rather than
being directly associated with a global. This makes it harder to
manipulate the metadata when rebuilding global variables, summarise it
as part of ThinLTO and drop unused metadata when associated globals are
dropped. For this reason, CFI does not currently work correctly when
both CFI and vcall opt are enabled, as vcall opt needs to rebuild vtable
globals, and fails to associate metadata with the rebuilt globals. As I
understand it, the same problem could also affect ASan, which rebuilds
globals with a red zone.
This patch solves both of those problems in the following way:
1. Rename the metadata to "type metadata". This new name reflects how
the metadata is currently being used (i.e. to represent type information
for CFI and vtable opt). The new name is reflected in the name for the
associated intrinsic (llvm.type.test) and pass (LowerTypeTests).
2. Attach metadata directly to the globals that it pertains to, rather
than using the "llvm.bitsets" global metadata node as we are doing now.
This is done using the newly introduced capability to attach
metadata to global variables (r271348 and r271358).
See also: http://lists.llvm.org/pipermail/llvm-dev/2016-June/100462.html
Differential Revision: http://reviews.llvm.org/D21053
llvm-svn: 273729
Removed some unused headers, replaced some headers with forward class declarations.
Found using simple scripts like this one:
clear && ack --cpp -l '#include "llvm/ADT/IndexedMap.h"' | xargs grep -L 'IndexedMap[<]' | xargs grep -n --color=auto 'IndexedMap'
Patch by Eugene Kosov <claprix@yandex.ru>
Differential Revision: http://reviews.llvm.org/D19219
From: Mehdi Amini <mehdi.amini@apple.com>
llvm-svn: 266595
This pass implements whole program optimization of virtual calls in cases
where we know (via bitset information) that the list of callees is fixed. This
includes the following:
- Single implementation devirtualization: if a virtual call has a single
possible callee, replace all calls with a direct call to that callee.
- Virtual constant propagation: if the virtual function's return type is an
integer <=64 bits and all possible callees are readnone, for each class and
each list of constant arguments: evaluate the function, store the return
value alongside the virtual table, and rewrite each virtual call as a load
from the virtual table.
- Uniform return value optimization: if the conditions for virtual constant
propagation hold and each function returns the same constant value, replace
each virtual call with that constant.
- Unique return value optimization for i1 return values: if the conditions
for virtual constant propagation hold and a single vtable's function
returns 0, or a single vtable's function returns 1, replace each virtual
call with a comparison of the vptr against that vtable's address.
Differential Revision: http://reviews.llvm.org/D16795
llvm-svn: 260312
Chandler Carruth