Replace old notion of "intrinsic" operations

The code previously had an enumerated type for "intrinsic" operations, and allowed functions to be marked `__intrinsic_op(...)` to indicate the operation they map to.
The nature of the IR meant that each of these intrinsic ops had to have a corresponding IR opcode, but the `enum` types weren't the same.
This change cleans things up a bit by deciding that the `__intrinsic_op(...)` modifier names an actual IR opcode, and so the `IntrinsicOp` enum is gone.

The biggest source of complexity here is that there are certain operations that need to be "intrinsic"-ish for the purposes of the current AST-based translation path, because we need them to round-trip from source to AST and back.
Right now this is being handled by defining a bunch of "pseudo-ops" which can be used in the `__intrinsic_op` modifier, but which are *not* meant to be represented in the IR.
Currently I don't actually handle this during IR generation.
In the long run, once we are using IR for everything that needs cross-compilation, we should be able to eliminate the pseudo-ops in favor of just having these be ordinary (inline) functions defined in the stdlib (e.g., the `+=` operator can just have a direct definition).

There was a second category of modifier that gets a little caught up in this, which is the `__intrinsic` modifier, which got used in two ways:

1. A function marked `__intrinsic(glsl, ...)` had what I call a "target intrinsic" modifier, which specified how to lower it for a specific target (e.g., GLSL).

2. A function just marked `__intrinsic` was supposed to be a marker for "this function shouldn't be emitted in the output, because the implementation is expected to be provided"

The latter category of function should really be an `__intrinsic_op`, so I translated all those uses. I added a tiny bit of sugar so that `__intrinsic_op` without an explicit opcode will look up an opcode based on the name of the function being called, so that an operation like `sin` can automatically be plumbed through to an equivalent IR op. (The first category is a stopgap for the AST-based cross-compilation, and will hopefully be replaced by something better  as we get the IR-based path working).

Getting the switch from `__intrinsic` to `__intrinsic_op` working required shuffling around some code in `emit.cpp` that handles looking up those modifiers and emitting builtin operations appropriately during cross-compilation.

Depending on where we go with things, a possible extension of this approach is to allow multiple operands to `__intrinsic_op` so that the first specifies the opcode, and then the rest are literal arguments to specify "sub-ops." This could help us handle stuff like texture-fetch operations without an explosion in the number of opcodes. I still need to think about whether this is a good idea or not.

1 files changed, 37 insertions, 15 deletions

diff --git a/source/slang/parser.cpp b/source/slang/parser.cpp
index 9c0d692e6..8ea41641d 100644
--- a/source/slang/parser.cpp
+++ b/source/slang/parser.cpp
@@ -3766,29 +3766,51 @@ namespace Slang
     {
         RefPtr<IntrinsicOpModifier> modifier = new IntrinsicOpModifier();
 
-        parser->ReadToken(TokenType::LParent);
-        if (parser->LookAheadToken(TokenType::IntegerLiteral))
-        {
-            modifier->op = (IntrinsicOp)StringToInt(parser->ReadToken().Content);
-        }
-        else
+        // We allow a few difference forms here:
+        //
+        // First, we can specify the intrinsic op `enum` value directly:
+        //
+        //     __intrinsic_op(<integer literal>)
+        //
+        // Second, we can specify the operation by name:
+        //
+        //     __intrinsic_op(<identifier>)
+        //
+        // Finally, we can leave off the specification, so that the
+        // op name will be derived fromthe function name:
+        //
+        //     __intrinsic_op
+        //
+        if (AdvanceIf(parser, TokenType::LParent))
         {
-            modifier->opToken = parser->ReadToken(TokenType::Identifier);
+            if (AdvanceIf(parser, TokenType::OpSub))
+            {
+                modifier->op = IROp(-StringToInt(parser->ReadToken().Content));
+            }
+            else if (parser->LookAheadToken(TokenType::IntegerLiteral))
+            {
+                modifier->op = IROp(StringToInt(parser->ReadToken().Content));
+            }
+            else
+            {
+                modifier->opToken = parser->ReadToken(TokenType::Identifier);
 
-            modifier->op = findIntrinsicOp(modifier->opToken.Content.Buffer());
+                modifier->op = findIROp(modifier->opToken.Content.Buffer());
 
-            if (modifier->op == IntrinsicOp::Unknown)
-            {
-                parser->sink->diagnose(modifier->opToken, Diagnostics::unimplemented, "unknown intrinsic op");
+                if (modifier->op == kIROp_Invalid)
+                {
+                    parser->sink->diagnose(modifier->opToken, Diagnostics::unimplemented, "unknown intrinsic op");
+                }
             }
+
+            parser->ReadToken(TokenType::RParent);
         }
 
-        parser->ReadToken(TokenType::RParent);
 
         return modifier;
     }
 
-    static RefPtr<RefObject> parseIntrinsicModifier(Parser* parser, void* /*userData*/)
+    static RefPtr<RefObject> parseTargetIntrinsicModifier(Parser* parser, void* /*userData*/)
     {
         auto modifier = new TargetIntrinsicModifier();
 
@@ -4027,8 +4049,8 @@ namespace Slang
 
         MODIFIER(layout,            parseLayoutModifier);
 
-        MODIFIER(__intrinsic_op,    parseIntrinsicOpModifier);
-        MODIFIER(__intrinsic,       parseIntrinsicModifier);
+        MODIFIER(__intrinsic_op,        parseIntrinsicOpModifier);
+        MODIFIER(__target_intrinsic,    parseTargetIntrinsicModifier);
         MODIFIER(__glsl_extension,  parseGLSLExtensionModifier);
         MODIFIER(__glsl_version,    parseGLSLVersionModifier);