Summary:
It was previously not possible for tools to use solely the stackmap
information emitted to reconstruct the return addresses of callsites in
the map, which is necessary to use the information to walk a stack. This
patch adds per-function callsite counts when emitting the stackmap
section in order to resolve the problem. Note that this slightly alters
the stackmap format, so external tools parsing these maps will need to
be updated.

**Problem Details:**
Records only store their offset from the beginning of the function they
belong to. While these records and the functions are output in program
order, it is not possible to determine where the end of one function's
records are without the callsite count when processing the records to
compute return addresses.

Patch by Kavon Farvardin!

Reviewers: atrick, ributzka, sanjoy

Subscribers: nemanjai

Differential Revision: https://reviews.llvm.org/D23487

llvm-svn: 281532

Not having this documented led to some confusion in a recent review thread.

llvm-svn: 242441

We used to take the address specified as the direct target of the patchpoint
and did no TOC-pointer handling.  This, however, as not all that useful,
because MCJIT tends to create a lot of modules, and they have their own TOC
sections. Thus, to call from the generated code to other generated code, you
really need to switch TOC pointers. Make this work as expected, and under
ELFv1, tread the address as the function descriptor address so that the correct
TOC pointer can be loaded.

llvm-svn: 242217

Bill Schmidt pointed out that some adjustments would be needed to properly
support powerpc64le (using the ELF V2 ABI). For one thing, R11 is not available
as a scratch register, so we need to use R12. R12 is also available under ELF
V1, so to maintain consistency, I flipped the order to make R12 the first
scratch register in the array under both ABIs.

llvm-svn: 226247

This re-applies r225808, fixed to avoid problems with SDAG dependencies along
with the preceding fix to ScheduleDAGSDNodes::RegDefIter::InitNodeNumDefs.
These problems caused the original regression tests to assert/segfault on many
(but not all) systems.

Original commit message:

This commit does two things:

 1. Refactors PPCFastISel to use more of the common infrastructure for call
    lowering (this lets us take advantage of this common code for lowering some
    common intrinsics, stackmap/patchpoint among them).

 2. Adds support for stackmap/patchpoint lowering. For the most part, this is
    very similar to the support in the AArch64 target, with the obvious differences
    (different registers, NOP instructions, etc.). The test cases are adapted
    from the AArch64 test cases.

One difference of note is that the patchpoint call sequence takes 24 bytes, so
you can't use less than that (on AArch64 you can go down to 16). Also, as noted
in the docs, we take the patchpoint address to be the actual code address
(assuming the call is local in the TOC-sharing sense), which should yield
higher performance than generating the full cross-DSO indirect-call sequence
and is likely just as useful for JITed code (if not, we'll change it).

StackMaps and Patchpoints are still marked as experimental, and so this support
is doubly experimental. So go ahead and experiment!

llvm-svn: 225909

Reverting this while I investiage buildbot failures (segfaulting in
GetCostForDef at ScheduleDAGRRList.cpp:314).

llvm-svn: 225811

This commit does two things:

 1. Refactors PPCFastISel to use more of the common infrastructure for call
    lowering (this lets us take advantage of this common code for lowering some
    common intrinsics, stackmap/patchpoint among them).

 2. Adds support for stackmap/patchpoint lowering. For the most part, this is
    very similar to the support in the AArch64 target, with the obvious differences
    (different registers, NOP instructions, etc.). The test cases are adapted
    from the AArch64 test cases.

One difference of note is that the patchpoint call sequence takes 24 bytes, so
you can't use less than that (on AArch64 you can go down to 16). Also, as noted
in the docs, we take the patchpoint address to be the actual code address
(assuming the call is local in the TOC-sharing sense), which should yield
higher performance than generating the full cross-DSO indirect-call sequence
and is likely just as useful for JITed code (if not, we'll change it).

StackMaps and Patchpoints are still marked as experimental, and so this support
is doubly experimental. So go ahead and experiment!

llvm-svn: 225808

llvm-svn: 205515

llvm-svn: 205513

[Stackmaps] Update the stackmap format to use 64-bit relocations for the function address and properly align all entries.

This commit updates the stackmap format to version 1 to indicate the
reorganizaion of several fields. This was done in order to align stackmap
entries to their natural alignment and to minimize padding.

Fixes <rdar://problem/16005902>

llvm-svn: 205254

Re-applying the patch, but this time without using AsmPrinter methods.

Reviewed by Andy

llvm-svn: 200481

Revert "[Stackmaps] Record the stack size of each function that contains a stackmap/patchpoint intrinsic."

This reverts commit r200444 to unbreak buildbots.

llvm-svn: 200445

Reviewed by Andy

llvm-svn: 200444

These still have "experimental" status, meaning we don't guarantee
backward compatibility. However, they are already actively used by the
open source WebKit project, and have started to be adopted by other
projects.

llvm-svn: 197930