| Commit message (Collapse) | Author | Age | Files | Lines |
|---|
| |
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
| |
references in .text
Summary:
This is a re-roll of D36615 which uses PLT relocations in the back-end
to the call to __xray_CustomEvent() when building in -fPIC and
-fxray-instrument mode.
Reviewers: pcc, djasper, bkramer
Subscribers: sdardis, javed.absar, llvm-commits
Differential Revision: https://reviews.llvm.org/D37373
llvm-svn: 312466
|
| |
|
|
|
|
|
|
| |
synthetic references in .text"
Breaks builds internally. Will forward repo instructions to author.
llvm-svn: 312243
|
| |
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
| |
references in .text
Summary:
This change achieves two things:
- Redefine the Custom Event handling instrumentation points emitted by
the compiler to not require dynamic relocation of references to the
__xray_CustomEvent trampoline.
- Remove the synthetic reference we emit at the end of a function that
we used to keep auxiliary sections alive in favour of SHF_LINK_ORDER
associated with the section where the function is defined.
To achieve the custom event handling change, we've had to introduce the
concept of sled versioning -- this will need to be supported by the
runtime to allow us to understand how to turn on/off the new version of
the custom event handling sleds. That change has to land first before we
change the way we write the sleds.
To remove the synthetic reference, we rely on a relatively new linker
feature that preserves the sections that are associated with each other.
This allows us to limit the effects on the .text section of ELF
binaries.
Because we're still using absolute references that are resolved at
runtime for the instrumentation map (and function index) maps, we mark
these sections write-able. In the future we can re-define the entries in
the map to use relative relocations instead that can be statically
determined by the linker. That change will be a bit more invasive so we
defer this for later.
Depends on D36816.
Reviewers: dblaikie, echristo, pcc
Subscribers: llvm-commits
Differential Revision: https://reviews.llvm.org/D36615
llvm-svn: 311525
|
|
|
Summary:
This is an implementation of the loop detection logic that XRay needs to
determine whether a function might take time at runtime. Without this
heuristic, XRay will tend to not instrument short functions that have
loops that might have runtime dependent on inputs or external values.
While this implementation doesn't do any further analysis than just
figuring out whether there is a loop in the MachineFunction being
code-gen'ed, we're paving the way for being able to perform more
sophisticated analysis of the function in the future (for example to
determine whether the trip count for the loop might be constant, and
make a decision on that instead). This enables us to cover more
functions with the default heuristics, and potentially identify ones
that have variable runtime latency just by looking for the presence of
loops.
Reviewers: chandlerc, rnk, pelikan
Subscribers: llvm-commits
Differential Revision: https://reviews.llvm.org/D32274
llvm-svn: 302103
|
