llvm-project/compiler-rt/include
Dean Michael Berris 1b09aae82a [compiler-rt][XRay] Support tail call sleds
Summary:
This change depends on D23986 which adds tail call-specific sleds. For
now we treat them first as normal exits, and in the future leave room
for implementing this as a different kind of log entry.

The reason for deferring the change is so that we can keep the naive
logging implementation more accurate without additional complexity for
reading the log. The accuracy is gained in effectively interpreting call
stacks like:

  A()
    B()
      C()

Which when tail-call merged will end up not having any exit entries for
A() nor B(), but effectively in turn can be reasoned about as:

  A()
  B()
  C()

Although we lose the fact that A() had called B() then had called C()
with the naive approach, a later iteration that adds the explicit tail
call entries would be a change in the log format and thus necessitate a
version change for the header. We can do this later to have a chance at
releasing some tools (in D21987) that are able to handle the naive log
format, then support higher version numbers of the log format too.

Reviewers: echristo, kcc, rSerge, majnemer

Subscribers: mehdi_amini, llvm-commits, dberris

Differential Revision: https://reviews.llvm.org/D23988

llvm-svn: 284178
2016-10-13 23:56:54 +00:00
..
sanitizer [sanitizer-coverage] remove stale code, second attempt after failed r282994 2016-10-04 04:18:30 +00:00
xray [compiler-rt][XRay] Support tail call sleds 2016-10-13 23:56:54 +00:00
CMakeLists.txt [compiler-rt][XRay] re-submitting r276117, with fixes for build breakage due to extraneous and missing dependencies and attempts to build on unsupported OSes 2016-07-21 07:39:55 +00:00