Rework command-line options handling for entry points and targets (#697)

* Rework command-line options handling for entry points and targets

Overview:

* The biggest functionality change is that the implicit ordering constraints when multiple `-entry` options are reversed: any `-stage` option affects the `-entry` to its *left* instead of to its *right* as it used to. This is technically a breaking change, but I expect most users aren't using this feature.

* The options parsing tries to handle profile versions and stages as distinct data (rather than using the combined `Profile` type all over), and treats a `-profile` option that specifies both a profile version and a stage (e.g., `-profile ps_5_0`) as if it were sugar for both a `-profile` and a `-stage` (e.g., `-profile sm_5_0 -stage fragment`).

* We now technically handle multiple `-target` options in one invocation of `-slangc`, but do not advertise that fact in the documentation because it might be confusing for users. Similar to the relationship between `-stage` and `-entry`, any `-profile` option affects the most recent `-target` option unless there is only one `-target`.

* The logic for associating `-o` options with corresponding entry points and targets has been beefed up. The rule is that a `-o` option for a compiled kernel binds to the entry point to its left, unless there is only one entry point (just like for `-stage`). The associated target for a `-o` option is found via a search, however, because otherwise it would be impossible to specify `-o` options for both SPIR-V and DXIL in one pass.

* The handling of output paths for entry points in the internal compiler structures was changed, because previously it could only handle one output path per entry point (even when there are multiple targets). The new logic builds up a per-target mapping from an entry point to its desired output path (if any).

Details:

* Support for formatting profile versions, stages, and compile targets (formats) was added to diagnostic printing, so that we can make better error messages. This is fairly ad hoc, and it would be nice to have all of the string<->enum stuff be more data-driven throughout the codebase.

* Test cases were added for (almost) all of the error conditions in the current options validation. The main one that is missing is around specifying an `-entry` option before any source file when compiling multiple files. This is because the test runner is putting the source file name first on the command line automatically, so we can't reproduce that case.

* Several reflection-related tests now reflect entry points where they didn't before, because the logic for detecting when to infer a default `main` entry point have been made more loose

* On the dxc path, beefed up the handling of mapping from Slang `Profile`s to the coresponding string to use when invoking dxc.

* A bunch of tests cases were in violation of the newly imposed rules, so those needed to be cleaned up.

* There were also a bunch of test cases that had accidentally gotten "disabled" at some point because there were comparing output from `slangc` both with and without a `-pass-through` option, but that meant that any errors in command-line parsing produced the *same* error output in both the Slang and pass-through cases. This change updates `slang-test` to always expect a successful run for these tests, and then manually updates or disables the various test cases that are affected.

* When merging the updated test for matrix layout mode, I found that the new command-line logic was failing to propagate a matrix layout mode passed to `render-test` into the compiler. This was because the `-matrix-layout*` options were implemented as per-target, but the target was being set by API while the option came in via command line (passed through the API). It seems like we want matrix layout mode to be a global option anyway (rather than per-target), so I made that change here.

* Add missing expected output files

* A 64-bit fix

* Remove commented-out code noted in review

1 files changed, 26 insertions, 1 deletions

diff --git a/source/slang/check.cpp b/source/slang/check.cpp
index 278ba7b61..dbf2b294c 100644
--- a/source/slang/check.cpp
+++ b/source/slang/check.cpp
@@ -8427,10 +8427,19 @@ namespace Slang
         //   that function is specific to the fragment profile/stage.
         //
 
+        auto sink = &entryPoint->compileRequest->mSink;
+
+        // Every entry point needs to have a stage specified either via
+        // command-line/API options, or via an explicit `[shader("...")]` attribute.
+        //
+        if( entryPoint->getStage() == Stage::Unknown )
+        {
+            sink->diagnose(entryPoint->decl, Diagnostics::entryPointHasNoStage, entryPoint->name);
+        }
+
         if (entryPoint->getStage() == Stage::Hull)
         {
             auto translationUnit = entryPoint->getTranslationUnit();
-            auto sink = &entryPoint->compileRequest->mSink;
             auto translationUnitSyntax = translationUnit->SyntaxNode;
 
             auto attr = entryPoint->decl->FindModifier<PatchConstantFuncAttribute>();
@@ -8554,6 +8563,22 @@ namespace Slang
             return;
         }
 
+        // If the entry point specifies a stage via a `[shader("...")]` attribute,
+        // then we might be able to infer a stage for the entry point request if
+        // it didn't have one, *or* issue a diagnostic if there is a mismatch.
+        //
+        if( auto entryPointAttribute = entryPointFuncDecl->FindModifier<EntryPointAttribute>() )
+        {
+            if( entryPoint->getStage() == Stage::Unknown )
+            {
+                entryPoint->profile.setStage(entryPointAttribute->stage);
+            }
+            else if( entryPointAttribute->stage != entryPoint->getStage() )
+            {
+                sink->diagnose(entryPointFuncDecl, Diagnostics::specifiedStageDoesntMatchAttribute, entryPoint->name, entryPoint->getStage(), entryPointAttribute->stage);
+            }
+        }
+
         // TODO: it is possible that the entry point was declared with
         // profile or target overloading. Is there anything that we need
         // to do at this point to filter out declarations that aren't