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Clarify the use of descriptor set indices in the PAL metadata #497

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Clarify the use of descriptor set indices in the PAL metadata #497

wants to merge 2 commits into from

Commits on Mar 9, 2020

  1. Remove duplicate definitions of Llpc::{InvalidValue,SizeOfVec4} 

    There is a second set of definitions in llpcUtil.h, which could cause
conflicts going forward.
    @nhaehnle
    nhaehnle committed Mar 9, 2020
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  2. Clarify the use of descriptor set indices in the PAL metadata 

    The PAL metadata contains a userdata mapping which tells PAL the data to
load into each loaded userdata SGPR. There are two kinds of values:

1. Indices into the userdata table maintained by the client driver via
   Pal::ICmdBuffer::CmdSetUserData
2. Special "system" values as listed in Util::Abi::UserDataMapping

Pointers to descriptor sets fall into the first category. The client driver
tells the compiler which location in the userdata table will contain the
pointer to each descriptor set (via the ResourceMappingNode part of the
pipeline build info).

When compiling a partial pipeline, the layout of the userdata table may not
be known yet. The compiler can already decide which SGPR will hold the
pointer to the descriptor set (the "key" part of the metadata), but it
does not yet know the final "value" part of the metadata.

To solve this problem, introduce a new kind of value, the
VkDescriptorSetIndex, which is emitted as part of the PAL metadata during
the initial compiler. It is resolved, when linking the different parts of a
pipeline together.

The emitDescriptorSetIndexInMetadata option instructs the compiler to
generate these VkDescriptorSetIndex mapping.

Resolving any such mappings during linking happens unconditionally while
merging the metadata.

This commit integrates the "updating" of the "meta note" into the merging
of the metadata, as this is conceptually one operation. Some method names
are updated to better reflect the asymmetry in what they do.

The updateDescInElf option is renamed to emitDescriptorSetIndexInMetadata
to better reflect the purpose of the option.
    @nhaehnle
    nhaehnle committed Mar 9, 2020
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