Address glslang ordering requirments for 'derivative_group_*NV' (#4323)

* Address glslang ordering requirments for 'derivative_group_*NV'

fixes: #4305

The solution is to emit some `layout`s after a module source is emitted.

Added to slangs gfx backend code to enable the compute shader derivative extension for testing purposes.

* address review

* enable removed test

---------

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

1 files changed, 5 insertions, 2 deletions

diff --git a/source/slang/slang-emit-c-like.cpp b/source/slang/slang-emit-c-like.cpp
index d85c72ae5..6412ff730 100644
--- a/source/slang/slang-emit-c-like.cpp
+++ b/source/slang/slang-emit-c-like.cpp
@@ -129,9 +129,12 @@ void CLikeSourceEmitter::emitPreModuleImpl()
         m_writer->emit(prelude->getStringSlice());
         m_writer->emit("\n");
     }
-    for (auto prelude : m_requiredPreludesRaw)
+}
+void CLikeSourceEmitter::emitPostModuleImpl()
+{   
+    if(m_requiredAfter.requireComputeDerivatives.getLength() > 0)
     {
-        m_writer->emit(prelude);
+        m_writer->emit(m_requiredAfter.requireComputeDerivatives);
         m_writer->emit("\n");
     }
 }