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, 36 insertions, 0 deletions

diff --git a/source/slang/slang-ir-util.cpp b/source/slang/slang-ir-util.cpp
index f7a93dca6..f6b0acaed 100644
--- a/source/slang/slang-ir-util.cpp
+++ b/source/slang/slang-ir-util.cpp
@@ -1743,5 +1743,41 @@ IRType* dropNormAttributes(IRType* const t)
     return t;
 }
 
+void verifyComputeDerivativeGroupModifiers(
+    DiagnosticSink* sink,
+    SourceLoc errorLoc,
+    bool quadAttr,
+    bool linearAttr,
+    IRNumThreadsDecoration* numThreadsDecor)
+{
+    if (!numThreadsDecor)
+        return;
+
+    if (quadAttr && linearAttr)
+    {
+        sink->diagnose(errorLoc, Diagnostics::onlyOneOfDerivativeGroupLinearOrQuadCanBeSet);
+    }
+
+    IRIntegerValue x = 1;
+    IRIntegerValue y = 1;
+    IRIntegerValue z = 1;
+    if (numThreadsDecor->getX())
+        x = numThreadsDecor->getX()->getValue();
+    if (numThreadsDecor->getY())
+        y = numThreadsDecor->getY()->getValue();
+    if (numThreadsDecor->getZ())
+        z = numThreadsDecor->getZ()->getValue();
+
+    if (quadAttr)
+    {
+        if (x % 2 != 0 || y % 2 != 0)
+            sink->diagnose(errorLoc, Diagnostics::derivativeGroupQuadMustBeMultiple2ForXYThreads);
+    }
+    else if (linearAttr)
+    {
+        if ((x * y * z) % 4 != 0)
+            sink->diagnose(errorLoc, Diagnostics::derivativeGroupLinearMustBeMultiple4ForTotalThreadCount);
+    }
+}
 
 }