Get IR working for `AdaptiveTessellationCS40/Render` test

I had expected this to be the first case where control-flow instructions were needed, but it turns out that we aren't testing that entry point right now.

The real work/fix here ended up being handling of the `row_major` layout qualifier on a matrix inside a `cbuffer`. The existing AST-based code was passing it through easily (although I don't believe it was handling the layout rules right).
Getting it working in the IR involved beefing up the type-layout behavior so that it can handle explicit layout qualifiers (at least for matrix layout) which should also improve the layout computation for non-square matrices with nonstandard layout in the AST-based path.

There are still some annoying things left to do:

- The `row_major` and `column_major` layout qualifiers in HLSL/GLSL mean different things (well, they mean the reverse of one another) so I need to validate that the GLSL case is working remotely correctly.

- The layout logic isn't handling other explicit-layout cases as supported by GLSL (but of course GLSL is a far lower priority than HLSL/Slang)

- There is currently no way to pass in an explicit matrix layout flag to Slang to control the default behavior.
  - Any client who was using Slang for HLSL pass-through and then applying a non-default flag on their HLSL->* compilation will get nasty unexpected behavior when the IR goes live - and they are already dealing with nasty behavior around non-square matrices not matching layout between Slang and the downstream.

- The logic that gleans layout modes from a variable declaration is currently only being applied for fields of structure types (which applies to `cbuffer` declarations as well), and not to global-scope uniform variables.

- We need test cases for all of this.

1 files changed, 44 insertions, 1 deletions

diff --git a/source/slang/emit.cpp b/source/slang/emit.cpp
index 40366c43c..209436da4 100644
--- a/source/slang/emit.cpp
+++ b/source/slang/emit.cpp
@@ -4416,6 +4416,16 @@ emitDeclImpl(decl, nullptr);
             emit("]");
             break;
 
+        case kIROp_Mul_Vector_Matrix:
+        case kIROp_Mul_Matrix_Vector:
+        case kIROp_Mul_Matrix_Matrix:
+            emit("mul(");
+            emitIROperand(context, inst->getArg(1));
+            emit(", ");
+            emitIROperand(context, inst->getArg(2));
+            emit(")");
+            break;
+
         default:
             emit("/* uhandled */");
             break;
@@ -4575,6 +4585,34 @@ emitDeclImpl(decl, nullptr);
         emit("};\n");
     }
 
+    void emitIRVarModifiers(
+        EmitContext*    context,
+        VarLayout*      layout)
+    {
+        if (!layout)
+            return;
+
+        // We need to handle the case where the variable has
+        // a matrix type, and has been given a non-standard
+        // layout attribute (for HLSL, `row_major` is the
+        // non-standard layout).
+        //
+        if (auto matrixTypeLayout = layout->typeLayout.As<MatrixTypeLayout>())
+        {
+            switch (matrixTypeLayout->mode)
+            {
+            case kMatrixLayoutMode_ColumnMajor:
+                emit("column_major ");
+                break;
+
+            case kMatrixLayoutMode_RowMajor:
+                emit("row_major ");
+                break;
+            }
+
+        }
+    }
+
     void emitIRParameterBlock(
         EmitContext*            context,
         IRVar*                  varDecl,
@@ -4624,7 +4662,7 @@ emitDeclImpl(decl, nullptr);
 
                     auto fieldLayout = structTypeLayout->fields[fieldIndex++];
 
-
+                    emitIRVarModifiers(context, fieldLayout);
 
                     auto fieldType = ff->getFieldType();
                     emitIRType(context, fieldType, getName(ff));
@@ -4662,6 +4700,11 @@ emitDeclImpl(decl, nullptr);
             break;
         }
 
+        // Need to emit appropriate modifiers here.
+
+        auto layout = getVarLayout(context, varDecl);
+        
+        emitIRVarModifiers(context, layout);
 
         emitIRType(context, varType, getName(varDecl));