Working on better handling of builtin functions in IR (#196)

The main change I was working on here was to start having more of the builtin functions (in this case, `cos`, `sin`, and `saturate`) just lower to the IR as calls to builtin functions (with declarations but no definition), rather than expect/require them to map to individual IR opcodes in every case.
The main change there was the removal of some `intrinsic_op` modifiers in the stdlib. This then requires the `isTargetInstrinsic` logic in IR-based code emit to avoid emitting declarations for these intrinsics.
The corresponding logic for emitting *calls* to these intrinsics is currently being skipped.

Along the way, a variety of fixups were added:

- In order to support lowering to GLSL, we need to handle cases where a variable/function name uses a GLSL reserved word. The right long-term fix there is to always use generated or mangled names, but for now I'm hacking it by adding a `_s` prefix to all names during IR-based emit.

  - This needs a flag to disable it, since some of our tests currently rely on checking binding information from generated HLSL/SPIR-V that will include these mangled/modified names.

- Emit matrix layout modifiers appropriately for GLSL

- Specialize IR parameter-block emission between GLSL and HLSL

- Fix up argument count/index logic for a couple of opcodes that weren't fixed when removing the types from the explicit operand list

- Fix up IR generation for calls to declarations with generic arguments. We were briefly adding the generic args to the ordinary argument list, which added complexity in several places. We now rely on the declaration-reference nodes in the IR to carry that extra info.

  - TODO: We actually need to make sure that this is the case, since we don't currently correctly generated specialized decl-refs when building IR for function calls

The main test that would have been affected by this is `cross-compile-entry-point`, but I was not able to get that working fully with the IR. The main problem in this case was that when emitting GLSL we will need to perform certain required transformations on the IR to get legal code for GLSL. Notably:

- We need to hoist entry-point parameters away from being function parameters, and make them be global variables. This is currently being hand-waved during the emit logic, but it seems way better to have it all get cleaned up in the IR first.

- We need to scalarize entry-point parameters, because structure input/output is not supported as vertex input or fragment output (and it may be best to always scalarize anyway, to match HLSL semantics). (Note: "scalarize" here means to bust up structures, but not matrices/vectors)

1 files changed, 11 insertions, 77 deletions

diff --git a/source/slang/lower-to-ir.cpp b/source/slang/lower-to-ir.cpp
index 7fce0c385..502d63320 100644
--- a/source/slang/lower-to-ir.cpp
+++ b/source/slang/lower-to-ir.cpp
@@ -81,7 +81,6 @@ struct BoundSubscriptInfo : ExtendedValueInfo
     DeclRef<SubscriptDecl>  declRef;
     RefPtr<Type>            type;
     List<IRValue*>          args;
-    UInt                    genericArgCount;
 };
 
 // Some cases of `ExtendedValueInfo` need to
@@ -445,9 +444,7 @@ LoweredValInfo emitCallToDeclRef(
     IRType*         type,
     DeclRef<Decl>   funcDeclRef,
     UInt            argCount,
-    IRValue* const* args,
-    // How many of the arguments are generic args?
-    UInt            genericArgCount)
+    IRValue* const* args)
 {
     auto builder = context->irBuilder;
 
@@ -490,7 +487,6 @@ LoweredValInfo emitCallToDeclRef(
             boundSubscript->declRef = subscriptDeclRef;
             boundSubscript->type = type;
             boundSubscript->args.AddRange(args, argCount);
-            boundSubscript->genericArgCount = genericArgCount;
 
             context->shared->extValues.Add(boundSubscript);
 
@@ -506,12 +502,6 @@ LoweredValInfo emitCallToDeclRef(
     auto funcDecl = funcDeclRef.getDecl();
     if(auto intrinsicOpModifier = funcDecl->FindModifier<IntrinsicOpModifier>())
     {
-        // We don't want to include generic arguments when calling an
-        // intrinsic for now, because we assume that they already
-        // handle the parameterization internally.
-        args += genericArgCount;
-        argCount -= genericArgCount;
-
         auto op = getIntrinsicOp(funcDecl, intrinsicOpModifier);
 
         if (Int(op) < 0)
@@ -572,10 +562,6 @@ LoweredValInfo emitCallToDeclRef(
         // TODO: these should all either be intrinsic operations,
         // or calls to library functions.
 
-        // Skip the generic arguments, so they don't screw up
-        // other logic.
-        args += genericArgCount;
-        argCount -= genericArgCount;
         return LoweredValInfo::simple(builder->emitConstructorInst(type, argCount, args));
     }
 
@@ -588,10 +574,9 @@ LoweredValInfo emitCallToDeclRef(
     IRGenContext*           context,
     IRType*                 type,
     DeclRef<Decl>           funcDeclRef,
-    List<IRValue*> const&   args,
-    UInt                    genericArgCount)
+    List<IRValue*> const&   args)
 {
-    return emitCallToDeclRef(context, type, funcDeclRef, args.Count(), args.Buffer(), genericArgCount);
+    return emitCallToDeclRef(context, type, funcDeclRef, args.Count(), args.Buffer());
 }
 
 IRValue* getSimpleVal(IRGenContext* context, LoweredValInfo lowered)
@@ -620,8 +605,7 @@ top:
                     context,
                     boundSubscriptInfo->type,
                     getter,
-                    boundSubscriptInfo->args,
-                    boundSubscriptInfo->genericArgCount);
+                    boundSubscriptInfo->args);
                 goto top;
             }
 
@@ -1119,53 +1103,6 @@ struct ExprLoweringVisitorBase : ExprVisitor<Derived, LoweredValInfo>
         }
     }
 
-    // In the context of a call, we need to add the generic
-    // arguments to the call to the list of IR-level arguments
-    // we are going to pass through. We do that by looking
-    // at the specializations attached to the declaration
-    // reference itself.
-    //
-    void addGenericArgs(
-        InvokeExpr*     expr,
-        DeclRef<Decl>   declRef,
-        List<IRValue*>* ioArgs)
-    {
-        auto subst = declRef.substitutions;
-        if(!subst)
-            return;
-
-        auto genericDecl = subst->genericDecl;
-
-        // If there is an outer layer of generic arguments
-        // (e.g., we are calling a generic method nested
-        // inside a generic type) then we need to add
-        // the outer arguments *before* those from  the
-        // inner context.
-        //
-        DeclRef<Decl> outerDeclRef;
-        outerDeclRef.decl = genericDecl;
-        outerDeclRef.substitutions = subst->outer;
-        addGenericArgs(expr, outerDeclRef, ioArgs);
-
-        // Okay, now we can process the argument list at this
-        // level.
-        //
-        // TODO: there could be a sticking point here because
-        // this logic needs to agree with the logic that adds
-        // generic *parameters* to the callee, and right now
-        // we have a mismatch that constraint witnesses are
-        // explicit in the parmaeter list, but not in
-        // declaration references as currently constructed
-        // inside the front-end.
-        //
-        for(auto arg : subst->args)
-        {
-            auto loweredVal = lowerVal(context, arg);
-            addArgs(context, ioArgs, loweredVal);
-        }
-    }
-
-
     // After a call to a function with `out` or `in out`
     // parameters, we may need to copy data back into
     // the l-value locations used for output arguments.
@@ -1409,11 +1346,7 @@ struct ExprLoweringVisitorBase : ExprVisitor<Derived, LoweredValInfo>
             auto funcDeclRef = resolvedInfo.funcDeclRef;
             auto baseExpr = resolvedInfo.baseExpr;
 
-            // First come any generic arguments:
-            addGenericArgs(expr, funcDeclRef, &irArgs);
-            UInt genericArgCount = irArgs.Count();
-
-            // Next comes the `this` argument if we are calling
+            // First comes the `this` argument if we are calling
             // a member function:
             if( baseExpr )
             {
@@ -1426,7 +1359,7 @@ struct ExprLoweringVisitorBase : ExprVisitor<Derived, LoweredValInfo>
             // require "fixup" work on the other side.
             //
             addDirectCallArgs(expr, funcDeclRef, &irArgs, &argFixups);
-            auto result = emitCallToDeclRef(context, type, funcDeclRef, irArgs, genericArgCount);
+            auto result = emitCallToDeclRef(context, type, funcDeclRef, irArgs);
             applyOutArgumentFixups(argFixups);
             return result;
         }
@@ -2053,8 +1986,7 @@ top:
                     context,
                     context->getSession()->getVoidType(),
                     setterDeclRef,
-                    allArgs,
-                    subscriptInfo->genericArgCount);
+                    allArgs);
                 return;
             }
 
@@ -2709,8 +2641,10 @@ struct DeclLoweringVisitor : DeclVisitor<DeclLoweringVisitor, LoweredValInfo>
         UInt genericParamCounter = 0;
         for( auto genericParamDecl : parameterLists.genericParams )
         {
-            UInt genericParamIndex = genericParamCounter++;
+            irFunc->genericParams.Add(genericParamDecl);
+
 #if 0
+            UInt genericParamIndex = genericParamCounter++;
             if( auto genericTypeParamDecl = dynamic_cast<GenericTypeParamDecl*>(genericParamDecl) )
             {
                 // In the logical type for the function, a generic
@@ -2728,11 +2662,11 @@ struct DeclLoweringVisitor : DeclVisitor<DeclLoweringVisitor, LoweredValInfo>
                 subContext->shared->declValues[makeDeclRef(genericTypeParamDecl)] = LoweredValInfo;
             }
             else
-#endif
             {
                 // TODO: handle the other cases here.
                 SLANG_UNEXPECTED("generic parameter kind");
             }
+#endif
         }
 
         for( auto paramInfo : parameterLists.params )