From ccea5702442a7a8303e6735a038be86939c1ce7a Mon Sep 17 00:00:00 2001
From: Tim Foley <tfoley@nvidia.com>
Date: Tue, 7 Nov 2017 10:22:53 -0800
Subject: Emit pointer-type parameters as out params

The IR encodes `out` and `in out` function parameters as pointer types, so the emit logic needs to handle it. We had code to handle translation of pointers types into `out` declarations for function *declarations* but weren't handling it for function *definitions*.

This change unifies the logic so that it is shared by function definitions and decalrations.

This change does *not* deal with the following issues that need to be addressed sometime soon-ish:

- We currently always translate pointers into `out`, even if they should be `in out`. This is obviously wrong.

- If/when we eventually have targets that support true pointers (e.g., CUDA, NVIDIA OpenGL, etc.) we'll need a way to tell the difference between an `in` pointer parameter, and an `out` parameter.

Both of these issues are meant to be addressed by having a few special cases of pointer types, for the `out` and `in out` cases, and only translating those (not all pointers). We need to plumb those through the IR more completely, but I'm not dealing with that here.
---
 source/slang/emit.cpp | 51 ++++++++++++++++++++++++++++++---------------------
 1 file changed, 30 insertions(+), 21 deletions(-)

(limited to 'source')

diff --git a/source/slang/emit.cpp b/source/slang/emit.cpp
index c67bb7b29..617e25d71 100644
--- a/source/slang/emit.cpp
+++ b/source/slang/emit.cpp
@@ -5698,7 +5698,8 @@ emitDeclImpl(decl, nullptr);
                 emit(", ");
 
             auto paramName = getIRName(pp);
-            emitIRType(ctx, pp->getType(), paramName);
+            auto paramType = pp->getType();
+            emitIRParamType(ctx, paramType, paramName);
 
             emitIRSemantics(ctx, pp);
         }
@@ -5724,6 +5725,33 @@ emitDeclImpl(decl, nullptr);
         }
     }
 
+    void emitIRParamType(
+        EmitContext*    ctx,
+        Type*           type,
+        String const&   name)
+    {
+        // An `out` or `inout` parameter will have been
+        // encoded as a parameter of pointer type, so
+        // we need to decode that here.
+        //
+        if( auto ptrType = type->As<PtrType>() )
+        {
+            // TODO: we need a way to distinguish `out`
+            // from `inout`. The easiest way to do
+            // that might be to have each be a distinct
+            // sub-case of `IRPtrType` - this would also
+            // ensure that they can be distinguished from
+            // real pointers when the user means to use
+            // them.
+
+            emit("out ");
+
+            type = ptrType->getValueType();
+        }
+
+        emitIRType(ctx, type, name);
+    }
+
     void emitIRFuncDecl(
         EmitContext*    ctx,
         IRFunc*         func)
@@ -5771,26 +5799,7 @@ emitDeclImpl(decl, nullptr);
             paramName.append(pp);
             auto paramType = funcType->getParamType(pp);
 
-            // An `out` or `inout` parameter will have been
-            // encoded as a parameter of pointer type, so
-            // we need to decode that here.
-            //
-            if( auto ptrType = paramType->As<PtrType>() )
-            {
-                // TODO: we need a way to distinguish `out`
-                // from `inout`. The easiest way to do
-                // that might be to have each be a distinct
-                // sub-case of `IRPtrType` - this would also
-                // ensure that they can be distinguished from
-                // real pointers when the user means to use
-                // them.
-
-                emit("out ");
-
-                paramType = ptrType->getValueType();
-            }
-
-            emitIRType(ctx, paramType, paramName);
+            emitIRParamType(ctx, paramType, paramName);
         }
         emit(");\n");
     }
-- 
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