Support derivative functions in compute & capabilities adjustments (#4014)

* Support derivative functions in compute & capabilities adjustments

fixes #4000

PR implements derivative functions in compute shaders properly so we have the functionality for SPIR-V & GLSL. Tests reflect fragment and compute paths.

PR also adjusts capabilities to correct wrong SPRI-V target capabilities for when using textures.

Remarks:
1. __requireComputeDerivative(); is a intrinsic_op and not modifier since inlining will destroy the modifier.
2. Derivative mode is tied to an entry point decoration `[DerivativeGroupQuad]`/`[DerivativeGroupLinear]` or GLSL syntax ``derivative_group_linearNV`. Default is to set the mode to `[DerivativeGroupQuad]`

* remove -emit-spirv-directly

* fixes

1. fix minor issue fwidth change where I returned the wrong type
2. fix issue where glslang{glsl->spirv} is wrong, so we don't run that test and just run the glsl test & direct spir-v test for intrinsic-texture.slang

* adjust as per review and refine code

1. add test to ensure multi-diverging-in-logic entry points work -- 2 functions which may cause computeDerivatives + 1 that uses, 1 that does not.
2. naming
3. use entry point ref graph for c-like-targets
4. reordered some code to util's and removed `static linline` since that was just for ease of coding on my end (should not have been pushed).

* Grammer

* split up source file + issolate GLSL emit path change.

---------

Co-authored-by: Yong He <yonghe@outlook.com>

1 files changed, 9 insertions, 0 deletions

diff --git a/docs/gpu-feature/derivatives-in-compute/derivatives-in-compute.md b/docs/gpu-feature/derivatives-in-compute/derivatives-in-compute.md
new file mode 100644
index 000000000..8319202f4
--- /dev/null
+++ b/docs/gpu-feature/derivatives-in-compute/derivatives-in-compute.md
@@ -0,0 +1,9 @@
+### Derivatives In Compute 
+An entry point may be decorated with `[DerivativeGroupQuad]` or `[DerivativeGroupLinear]` to specifiy how to use derivatives in compute shaders. 
+
+GLSL syntax may also be used, but is not reccomended (`derivative_group_quadsNV`/`derivative_group_linearNV`).
+
+Targets:
+* **_SPIRV:_** Enables `DerivativeGroupQuadsNV` or `DerivativeGroupLinearNV`.
+* **_GLSL:_** Enables `derivative_group_quadsNV` or `derivative_group_LinearNV`.
+* **_HLSL:_** Does nothing. sm_6_6 is required to use derivatives in compute shaders. HLSL uses an equivlent of `DerivativeGroupQuad`.
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