Summary:
Before this change, we only emit the XRay attributes in LLVM IR when the
-fxray-instrument flag is provided. This may cause issues with thinlto
when the final binary is being built/linked with -fxray-instrument, and
the constitutent LLVM IR gets re-lowered with xray instrumentation.
With this change, we can honour the "never-instrument "attributes
provided in the source code and preserve those in the IR. This way, even
in thinlto builds, we retain the attributes which say whether functions
should never be XRay instrumented.
This change addresses llvm.org/PR38922.
Reviewers: mboerger, eizan
Subscribers: mehdi_amini, dexonsmith, cfe-commits, llvm-commits
Differential Revision: https://reviews.llvm.org/D52015
llvm-svn: 342200
Summary: I'm not sure why they were in different files, but it's kind of harder to maintain. I create this patch partially for initiate a discussion.
Reviewers: dberris
Subscribers: nemanjai, cfe-commits
Differential Revision: https://reviews.llvm.org/D30118
llvm-svn: 295778
-fxray-instrument: enables XRay annotation of IR
-fxray-instruction-threshold: configures the threshold for function size (looking at IR instructions), and allow LLVM to decide whether to add the nop sleds later on in the process.
Also implements the related xray_always_instrument and xray_never_instrument function attributes.
Patch by Dean Michael Berris.
llvm-svn: 275330
Dean Michael Berris