Add config options to control Slang

.gitignore

@@ -28,3 +28,7 @@ Framework/Externals/slang/source/**/*.natvis
 !Framework/Externals/slang/source/**/*.cpp
 !Framework/Externals/slang/source/**/*.cpp
 !Framework/Externals/slang/source/**/*.h
+
+# Ignore intermediate files that Slang dumps when
+# we ask it to preserve intermedites
+slang-dump*

Framework/Source/FalcorConfig.h

@@ -39,9 +39,5 @@
 
 #define _ENABLE_NVAPI false // Controls NVIDIA specific DX extensions. If it is set to true, make sure you have the NVAPI package in your 'Externals' directory. View the readme for more information
 
-#define FALCOR_BUILD_SPIRE                  1 /* Set this to 1 to enable Slang compiler to be built into Falcor */
-#define FALCOR_USE_SLANG_AS_PREPROCESSOR    0 /* Set this to 1 to use Slang as a source-to-source preprocessor */
-
-#if (FALCOR_USE_SLANG_AS_PREPROCESSOR) && !FALCOR_BUILD_SPIRE
-#error Trying to use Slang without building it
-#endif
+#define FALCOR_SLANG_DISABLE_LINE_DIRECTIVES 0 /* Set this to 1 to disable emission of `#line` directives in Slang-generated code */
+#define FALCOR_SLANG_DUMP_COMPILER_INTERMEDIATES 0 /* Set this to 1 to enable dumping of intermediate code generated by Slang to disk */

Framework/Source/Graphics/Program.cpp

@@ -328,6 +328,29 @@ namespace Falcor
         slangFlags |= SLANG_COMPILE_FLAG_NO_CHECKING;
         spSetCompileFlags(slangRequest, slangFlags);
 
+        // Enable this block to disable the emission of `#line` directives
+        // and hopefully make the HLSL/GLSL output by Slang a bit more
+        // readable.
+        //
+        // This is useful for diagnosing issues where Slang outputs bogus
+        // code and you need to isolate what Slang is doing wrong.
+        //
+        // This is way less useful if the user's code has a legitimate
+        // issue in it, because it will be reported at a location
+        // unrelated to the code they wrote. That is why it is off by default.
+#if FALCOR_SLANG_DISABLE_LINE_DIRECTIVES
+        spSetLineDirectiveMode(slangRequest, SLANG_LINE_DIRECTIVE_MODE_NONE);
+#endif
+
+        // Enable this block to make Slang dump intermediate HLSL/GLSL
+        // and DXBC/SPIR-V (both binary and assembly) for every shader
+        // it compiles. These will be dumped to the current working
+        // directory and named `slang-dump-*.{glsl,hlsl,spv,dxbc,spv.asm,dxbc.asm}
+#if FALCOR_SLANG_DUMP_COMPILER_INTERMEDIATES
+        spSetDumpIntermediates(slangRequest, true);
+#endif
+
+
         // Now lets add all our input shader code, one-by-one
         int translationUnitsAdded = 0;
         for(auto source : mDesc.mSources)