tree 1e32105802b693cfbf21d19458e0963718afcdb2
parent a6e6454ef27f9c3c652d6a37281c3b9ed45d4667
author gmitrano-unity <89797527+gmitrano-unity@users.noreply.github.com> 1665066918 -0400
committer GitHub <noreply@github.com> 1665066918 -0400
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Support Narrow Types in BitCast Folding Rule (#4941)

* Support Narrow Types in BitCast Folding Rule

This change adds support for narrow types in the BitCastScalarOrVector
folding rule. According to Section 2.2.1 of the SPIR-V spec, types that
are narrower than 32 bits are automatically either sign extended, or
zero extended depending on the type. With that guaranteed, we should
be able to use the first 32-bit word of any narrow type for the folding
logic without performing any special conversions.

In order to reduce code duplication, this change moves the
GetU32BitValue and GetU64BitValue functions from IntConstant to
ScalarConstant. Without this move, we would have needed an identical
version of GetU32BitValue on FloatConstant.

* Add Tests for 16-bit BitCast Folding

This change adds several new test cases to the
IntegerInstructionFoldingTest which trigger the 16-bit BitCast logic.
The logic for half types was also added to the integer case since we
can't easily validate half float types in C++ code. It's easier to
validate them as unsigned integers instead. Pllus this also allows us
to verify the SPIR-V constant sign extension logic too.

* Add 8-Bit Folding Test Cases

This change adds a couple more test cases to the integer instruction
folding test suite in order to ensure that the BitCast logic also
works correctly with the Int8 shader capability.