Refactor D3D12 renderer root signature creation (#1779)

This change originated as an attempt to re-enable a test case, but it has ended up disabling more tests (for good reasons) than it re-enables.

The main change here is a significant overhaul of the way that the D3D12 render path extracts information from the Slang reflection API to produce a root signature.
There were also some supporting fixes in the reflection information to make sure it returns what the D3D12 back-end needed.

The big picture here is that the D3D12 path now uses the descriptor ranges stored in the reflection data more or less directly.
It still needs to use register/space offset information queried via the "old" reflection API, but it only does so at the top level now, for the program and entry points themselves.
All other layout information is derived directly from what Slang provides.

Smaller changes:

* The "flat" reflection API was expanded to include `getBindingRangeDescriptorRangeCount()` which was clearly missing.

* The "flat" reflection results for a constant buffer or parameter block that didn't contain any uniform data and was mapped to a plain constant buffer needed to be fixed up. That logic is still way to subtle to be trusted.

* Several additional tests were disabled that relied on static specialization, global/entry-point generi type parameters, structured buffers of interfaces or other features we don't officially support with shader objects right now. All of the affected tests were somehow passing by sheer luck and because they often passed in specialization arguments via explicit  `TEST_INPUT` lines.

* The `inteface-shader-param` test is re-enabled now that we can properly describe its input with the new `set` mode on `TEST_INPUT`

* `ShaderCursor::getElement()` can now be used on structure types (in addition to arrays) to support by-index access to fields

* The `TEST_INPUT` system was expanded to support both by-name and by-index setting of structure fields for aggregates

* The `TEST_INPUT` system was expanded to allow an `out` prefix to mark parts of an expression as outputs on a `set` lines

* The `TEST_INPUT` system was expanded so that anything that would be allowed on a `TEST_INPUT` line by itself (like `ubuffer(...)`) can now be used as a sub-expression on a `set` line

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

1 files changed, 9 insertions, 2 deletions

diff --git a/tools/render-test/shader-input-layout.cpp b/tools/render-test/shader-input-layout.cpp
index c5f1cb6dd..4febc4bd5 100644
--- a/tools/render-test/shader-input-layout.cpp
+++ b/tools/render-test/shader-input-layout.cpp
@@ -504,10 +504,17 @@ namespace renderer_test
                         val->contentVal = parseValExpr(parser);
                         return val;
                     }
+                    else if( parser.AdvanceIf("out") )
+                    {
+                        auto val = parseValExpr(parser);
+                        val->isOutput = true;
+                        return val;
+                    }
                     else
                     {
-                        // TODO: other named cases
-                        throw ShaderInputLayoutFormatException(String("Unexpected '") + parser.NextToken().Content + String("' at line") + String(parser.NextToken().Position.Line));
+                        // We assume that any other word is introducing one of the other
+                        // cases for a parse-able value.
+                        return parseVal(parser);
                     }
                 }
                 break;