Implement notion of a "container format" (#213)

The big addition here is that the Slang "bytecode" is no longer treated as just a "code generation target" (`CodeGenTarget`) akin to DX bytecode (DXBC) or SPIR-V, but instead is a `ContainerFormat` that can be used to emit all the results of a compile request (well, currently just the IR-as-BC, but the intention is there).

Getting to this goal involved some prior checkins that eliminated bogus "targets" that weren't really akin to SPIR-V or DXBC: `-target slang-ir-asm` and `-target reflection-json`. Those targets were really in place to support testing, and so they've been made more explicit testing/debug options.

This change eliminates `-target slang-ir` and instead tries to allow the user to specify `-o foo.slang-module` as an output file name, that indicates the intention to output a "container" file that will wrap up all the generated code.

I've also gone ahead and generalized the existing `-target` option so that we are actually building up a *list* of code generation targets. This is largely just a cleanup, since it forces code to be more aware of when it is doing something target-specific vs. target independent. For example, reflection layout information lives on a requested target, and not on the compile request as a whole, and similarly output code is per-target, per-entry-point.

As a cleanup, I eliminated support for per-translation-unit output. This was vestigial code from back when I used to try and do HLSL generation for a whole translation unit instead of per-entry-point (which turned out to be a lot of complexity for little gain), and it was only being used in the `hello` example and the `render-test` test fixture - in both cases fixing it up was easy enough. I've stubbed out the old `spGetTranslationUnitSource` API, but haven't removed it yet.

1 files changed, 2 insertions, 43 deletions

diff --git a/source/slang/lower.cpp b/source/slang/lower.cpp
index 1387abc23..3e6ee9917 100644
--- a/source/slang/lower.cpp
+++ b/source/slang/lower.cpp
@@ -4556,49 +4556,8 @@ struct LoweringVisitor
 
 };
 
-static RefPtr<StructTypeLayout> getGlobalStructLayout(
-    ProgramLayout*      programLayout)
-{
-    // Layout information for the global scope is either an ordinary
-    // `struct` in the common case, or a constant buffer in the case
-    // where there were global-scope uniforms.
-    auto globalScopeLayout = programLayout->globalScopeLayout;
-    StructTypeLayout* globalStructLayout = globalScopeLayout.As<StructTypeLayout>();
-    if(globalStructLayout)
-    { }
-    else if(auto globalConstantBufferLayout = globalScopeLayout.As<ParameterBlockTypeLayout>())
-    {
-        // TODO: the `cbuffer` case really needs to be emitted very
-        // carefully, but that is beyond the scope of what a simple rewriter
-        // can easily do (without semantic analysis, etc.).
-        //
-        // The crux of the problem is that we need to collect all the
-        // global-scope uniforms (but not declarations that don't involve
-        // uniform storage...) and put them in a single `cbuffer` declaration,
-        // so that we can give it an explicit location. The fields in that
-        // declaration might use various type declarations, so we'd really
-        // need to emit all the type declarations first, and that involves
-        // some large scale reorderings.
-        //
-        // For now we will punt and just emit the declarations normally,
-        // and hope that the global-scope block (`$Globals`) gets auto-assigned
-        // the same location that we manually asigned it.
-
-        auto elementTypeLayout = globalConstantBufferLayout->elementTypeLayout;
-        auto elementTypeStructLayout = elementTypeLayout.As<StructTypeLayout>();
-
-        // We expect all constant buffers to contain `struct` types for now
-        SLANG_RELEASE_ASSERT(elementTypeStructLayout);
-
-        globalStructLayout = elementTypeStructLayout.Ptr();
-    }
-    else
-    {
-        SLANG_UNEXPECTED("unhandled type for global-scope parameter layout");
-    }
-    return globalStructLayout;
-}
-
+StructTypeLayout* getGlobalStructLayout(
+    ProgramLayout*  programLayout);
 
 // Determine if the user is just trying to "rewrite" their input file
 // into an output file. This will affect the way we approach code