Adds an LTO option to indicate that whether we are linking with an
allocator that supports hot/cold operator new interfaces. If not,
at the start of the LTO backends any existing memprof hot/cold
attributes are removed from the IR, and we also remove memprof metadata
so that post-LTO inlining doesn't add any new attributes.
This is done via setting a new flag in the module summary index. It is
important to communicate via the index to the LTO backends so that
distributed ThinLTO handles this correctly, as they are invoked by
separate clang processes and the combined index is how we communicate
information from the LTO link. Specifically, for distributed ThinLTO the
LTO related processes look like:
```
# Thin link:
$ lld --thinlto-index-only obj1.o ... objN.o -llib ...
# ThinLTO backends:
$ clang -x ir obj1.o -fthinlto-index=obj1.o.thinlto.bc -c -O2
...
$ clang -x ir objN.o -fthinlto-index=objN.o.thinlto.bc -c -O2
```
It is during the thin link (lld --thinlto-index-only) that we have
visibility into linker dependences and want to be able to pass the new
option via -Wl,-supports-hot-cold-new. This will be recorded in the
summary indexes created for the distributed backend processes
(*.thinlto.bc) and queried from there, so that we don't need to know
during those individual clang backends what allocation library was
linked. Since in-process ThinLTO and regular LTO also use a combined
index, for consistency we query the flag out of the index in all LTO
backends.
Additionally, when the LTO option is disabled, exit early from the
MemProfContextDisambiguation handling performed during LTO, as this is
unnecessary.
Depends on D149117 and D149192.
Differential Revision: https://reviews.llvm.org/D149215
Now that the runtime tracks the lifetime access density directly, we can
use that directly in the threshold checks instead of less accurately
computing from other statistics.
Differential Revision: https://reviews.llvm.org/D149684
This restores commit d6ad4f01c3dafcab335bca66dac6e36d9eac8421, which was
reverted in commit 883dbb9c86be87593a58ef10b070b3a0564c7fee, along with
a fix for gcc 12.2 build errors in the original commit.
Support for building, printing, and displaying CallsiteContextGraph
which represents the MemProf metadata contexts. Uses CRTP to enable
support for both IR (regular LTO) and summary (ThinLTO). This patch
includes the support for building it in regular LTO mode (from
memprof and callsite metadata), and the next patch will add the
handling for building it from ThinLTO summaries.
Also includes support for dumping the graph to text and to dot files.
Follow-on patches will contain the support for cloning on the graph and
in the IR.
The graph represents the call contexts in all memprof metadata on
allocation calls, with nodes for the allocations themselves, as well as
for the calls in each context. The graph is initially built from the
allocation memprof metadata (or summary) MIBs. It is then updated to
match calls with callsite metadata onto the nodes, updating it to
reflect any inlining performed on those calls.
Each MIB (representing an allocation's call context with allocation
behavior) is assigned a unique context id during the graph build. The
edges and nodes in the graph are decorated with the context ids they
carry. This is used to correctly update the graph when cloning is
performed so that we can uniquify the context for a single (possibly
cloned) allocation.
Differential Revision: https://reviews.llvm.org/D140908
Support for building, printing, and displaying CallsiteContextGraph
which represents the MemProf metadata contexts. Uses CRTP to enable
support for both IR (regular LTO) and summary (ThinLTO). This patch
includes the support for building it in regular LTO mode (from
memprof and callsite metadata), and the next patch will add the
handling for building it from ThinLTO summaries.
Also includes support for dumping the graph to text and to dot files.
Follow-on patches will contain the support for cloning on the graph and
in the IR.
The graph represents the call contexts in all memprof metadata on
allocation calls, with nodes for the allocations themselves, as well as
for the calls in each context. The graph is initially built from the
allocation memprof metadata (or summary) MIBs. It is then updated to
match calls with callsite metadata onto the nodes, updating it to
reflect any inlining performed on those calls.
Each MIB (representing an allocation's call context with allocation
behavior) is assigned a unique context id during the graph build. The
edges and nodes in the graph are decorated with the context ids they
carry. This is used to correctly update the graph when cloning is
performed so that we can uniquify the context for a single (possibly
cloned) allocation.
Depends on D140786.
Differential Revision: https://reviews.llvm.org/D140908
