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, 15 insertions, 0 deletions

diff --git a/source/slang/options.cpp b/source/slang/options.cpp
index 79832a9c3..971d17b51 100644
--- a/source/slang/options.cpp
+++ b/source/slang/options.cpp
@@ -223,6 +223,11 @@ struct OptionsParser
 
 #undef CASE
 
+        else if (path.EndsWith(".slang-module"))
+        {
+            spSetOutputContainerFormat(compileRequest, SLANG_CONTAINER_FORMAT_SLANG_MODULE);
+            requestImpl->containerOutputPath = path;
+        }
         else
         {
             // Allow an unknown-format `-o`, assuming we get a target format
@@ -600,6 +605,16 @@ struct OptionsParser
             }
         }
 
+        // If the user is requesting multiple targets, *and* is asking
+        // for direct output files for entry points, that is an error.
+        if (rawOutputPaths.Count() != 0 && requestImpl->targets.Count() > 1)
+        {
+            requestImpl->mSink.diagnose(
+                SourceLoc(),
+                Diagnostics::explicitOutputPathsAndMultipleTargets);
+        }
+
+
         // Did the user try to specify output path(s)?
         if (rawOutputPaths.Count() != 0)
         {