Introduce CDataLayout & -fvk-use-c-layout (#8136)

Closes #8112. ~~The issue asks for a "C layout", but in this PR I use
the term "CPU layout" because this naming was pre-existing in the
codebase as `kCPULayoutRulesImpl_`. The primary purpose of this layout
is to match CPU-side struct definitions with the shader side. I'm open
to better naming suggestions, though.~~

Edit: switched back to using `CDataLayout` & `-fvk-use-c-layout`, as the
CPU target depends on the object layout rules of existing CPU layout
rules, but they're incompatible with actual shaders. So a new
`kCLayoutRulesImpl_` was needed anyway.

---------

Co-authored-by: Ellie Hermaszewska <ellieh@nvidia.com>

1 files changed, 7 insertions, 0 deletions

diff --git a/source/slang/slang-ir-layout.h b/source/slang/slang-ir-layout.h
index 1918f31b6..a0f144c86 100644
--- a/source/slang/slang-ir-layout.h
+++ b/source/slang/slang-ir-layout.h
@@ -56,6 +56,12 @@ struct IRTypeLayoutRules
 public:
     IRTypeLayoutRuleName ruleName;
 
+    /// This function calculates the size and alignment of the given type.
+    virtual Result calcSizeAndAlignment(
+        CompilerOptionSet& optionSet,
+        IRType* type,
+        IRSizeAndAlignment* outSizeAndAlignment);
+
     /// Align composite based on rule. Type is aligned assuming
     /// it is apart of a composite (array, struct, matrix, etc...)
     virtual IRSizeAndAlignment alignCompositeElement(IRSizeAndAlignment elementSize) = 0;
@@ -79,6 +85,7 @@ public:
     static IRTypeLayoutRules* getStd430();
     static IRTypeLayoutRules* getStd140();
     static IRTypeLayoutRules* getNatural();
+    static IRTypeLayoutRules* getC();
     static IRTypeLayoutRules* getConstantBuffer();
     static IRTypeLayoutRules* get(IRTypeLayoutRuleName name);
 };