Old entry-point metadata being updated. Nothing is required
to account for deprecation as nothing uses the old style

Allows MCExprs as passed values to PALMetadata. Also adds related
`DelayedMCExpr` classes which serve as a pseudo-fixup to resolve MCExprs
as late as possible (i.e., right before emit through string or blob,
where they should be resolvable).

The support library contains helpers to parse and emit YAML documents.

In the textual YAML representation, some strings need to be quoted, e.g.
when containing unprintable characters.

We already have such quoting implemented for YAML values.

This patch applies the same quoting to YAML *keys*.

One affected case is output of control registers in AMDGPU Msgpack
metadata, which are printed in a format like this:

```
   0x2cca (SPI_SHADER_PGM_RSRC1_ES): 42
```

With this patch, the key is quoted:

```
   '0x2cca (SPI_SHADER_PGM_RSRC1_ES)': 42
```

Most test changes come from this pattern.

This is part of the pertinent tests, more to follow in subsequent
patches.

Differential Revision: https://reviews.llvm.org/D94114

If no pal metadata is given, default to the msgpack format instead of
the legacy metadata. This makes tests better readable.

Differential Revision: https://reviews.llvm.org/D90035

  - Move PAL metadata definitions to AMDGPUMetadata
  - Make naming consistent with HSA metadata

Differential Revision: https://reviews.llvm.org/D38745

llvm-svn: 315523

Summary:
For the amdpal OS type:

We write an AMDGPU_PAL_METADATA record in the .note section in the ELF
(or as an assembler directive). It contains key=value pairs of 32 bit
ints. It is a merge of metadata from codegen of the shaders, and
metadata provided by the frontend as _amdgpu_pal_metadata IR metadata.
Where both sources have a key=value with the same key, the two values
are ORed together.

This .note record is part of the amdpal ABI and will be documented in
docs/AMDGPUUsage.rst in a future commit.

Eventually the amdpal OS type will stop generating the .AMDGPU.config
section once the frontend has safely moved over to using the .note
records above instead of .AMDGPU.config.

Reviewers: arsenm, nhaehnle, dstuttard

Subscribers: kzhuravl, wdng, yaxunl, llvm-commits, t-tye

Differential Revision: https://reviews.llvm.org/D37753

llvm-svn: 314829

Summary:
This commit adds comments on how the AMDPAL OS type overloads the
existing AMDGPU_ calling conventions used by Mesa, and adds a couple of
new ones.

Reviewers: arsenm, nhaehnle, dstuttard

Subscribers: mehdi_amini, kzhuravl, wdng, yaxunl, t-tye, llvm-commits

Differential Revision: https://reviews.llvm.org/D37752

llvm-svn: 314502