[PATCH] D37570: [XRay][CodeGen][PowerPC] Fix tail exit codegen for XRay in PPC

[Dean Michael Berris via Phabricator via llvm-commits]

dberris created this revision.
Herald added subscribers: kbarton, nemanjai.

This fixes code-gen for XRay in PPC. The regression wasn't caught by
codegen tests  which we add in this change.

What happened was the following:

- For tail exits, we used to unconditionally prepend the returns/exits with a pseudo-instruction that gets lowered to the instrumentation sled (and leave the actual return/exit instruction as-is).
- Changes to the XRay instrumentation pass caused the tail exits to suddenly also emit the tail exit pseudo-instruction, since the check for whether a return instruction was also a call instruction meant it was a tail exit instruction.
- None of the tests caught the regression either due to non-existent tests, or the tests being disabled/removed for continuous breakage.

This change re-introduces some of the basic tests and verifies that
we're back to a state that allows the back-end to generate appropriate
XRay instrumented binaries for PPC in the presence of tail exits.


https://reviews.llvm.org/D37570

Files:
  lib/CodeGen/XRayInstrumentation.cpp
  lib/Target/PowerPC/PPCAsmPrinter.cpp
  test/CodeGen/PowerPC/xray-attribute-instrumentation.ll
  test/CodeGen/PowerPC/xray-tail-call-hidden.ll
  test/CodeGen/PowerPC/xray-tail-call-sled.ll

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