Make LValue detection more precise and more reusable

- In `arr[idx] = 1`, we now detect that arr a lvalue, while idx is not.
- LValue detection is now part of the generic map function

src/analyzer.fs

@@ -100,34 +100,20 @@ let inlineAllConsts li =
     |> mapTopLevel (mapEnv mapExpr mapStmt)
     |> List.map mapTLDecl
 
-let assignOps = Set.ofList [
-    "="; "+="; "-="; "*="; "/="; "%="
-    "<<="; ">>="; "&="; "^="; "|="
-    "++"; "--"; "$++"; "$--"
-]
-
 let markLValues li =
-    // Helpers for the bodies of functions: find any expression of the form
-    // "foo = ..." or "foo += ..." etc, then scan through all of "foo" marking
-    // any variable seen there as potentially in an lvalue position. This will
-    // over-mark things, e.g., "x[i]" both "x" and "i" will get marked even
-    // though the latter does not need to be, but it is simple.
-    let markVars env = function
-        | Var v as e ->
+
+    let findWrites (env: MapEnv) = function
+        | Var v as e when env.isLValue ->
             match env.vars.TryFind v.Name with
             | Some (_, {name = vv}) -> vv.IsLValue <- true; e
             | _ -> e
-        | e -> e
-
-    let findWrites env = function
-        | FunCall(Op o, e::args) when assignOps.Contains o ->
-            let newEnv = {env with fExpr = markVars}
-            FunCall(Op o, (mapExpr newEnv e)::args)
-        | FunCall(Var v, _) as e ->
+        | FunCall(Var v, args) as e ->
             match env.fns.TryFind v.Name with
             | Some (fct, _) when fct.fName.IsLValue ->
-                let newEnv = {env with fExpr = markVars}
-                mapExpr newEnv e
+                let newEnv = {env with isLValue = true}
+                for arg in args do
+                    (mapExpr newEnv arg: Expr) |> ignore
+                e
             | _ -> e
         | e -> e
 

src/ast.fs

@@ -132,9 +132,16 @@ type MapEnv = {
     fStmt: Stmt -> Stmt
     vars: Map<string, Type * DeclElt>
     fns: Map<string, FunctionType * Stmt>
+    isLValue: bool
 }
 
-let mapEnv fe fi = {fExpr = fe; fStmt = fi; vars = Map.empty; fns = Map.empty}
+let mapEnv fe fi = {fExpr = fe; fStmt = fi; vars = Map.empty; fns = Map.empty; isLValue = false}
+
+let assignOps = Set.ofList [
+    "="; "+="; "-="; "*="; "/="; "%="
+    "<<="; ">>="; "&="; "^="; "|="
+    "++"; "--"; "$++"; "$--"
+]
 
 let foldList env fct li =
     let mutable env = env
@@ -146,10 +153,15 @@ let foldList env fct li =
 
 // Applies env.fExpr recursively on all nodes of an expression.
 let rec mapExpr env = function
+    | FunCall(Op o as fct, first::args) when assignOps.Contains o ->
+        let first = mapExpr {env with isLValue = true} first
+        env.fExpr env (FunCall(mapExpr env fct, first :: List.map (mapExpr env) args))
     | FunCall(fct, args) ->
+        let env = {env with isLValue = false}
         env.fExpr env (FunCall(mapExpr env fct, List.map (mapExpr env) args))
     | Subscript(arr, ind) ->
-        env.fExpr env (Subscript(mapExpr env arr, Option.map (mapExpr env) ind))
+        let indexEnv = {env with isLValue = false}
+        env.fExpr env (Subscript(mapExpr env arr, Option.map (mapExpr indexEnv) ind))
     | Dot(e,  field) -> env.fExpr env (Dot(mapExpr env e, field))
     | Cast(id, e) -> env.fExpr env (Cast(id, mapExpr env e))
     | VectorExp(li) ->

tests/unit/inline-aggro.aggro.expected

@@ -36,9 +36,7 @@ float inl7()
 }
 int inl8(ivec3 x)
 {
-  int i=1;
-  x[i]+=1;
-  return x[i]+i;
+  return x[1]+=1,x[1]+1;
 }
 float noinl1()
 {

tests/unit/inline.aggro.expected

@@ -1,3 +1,5 @@
+#version 120
+
 float result;
 void main()
 {
@@ -37,6 +39,11 @@ int dont_inline_lvalue()
   a=2;
   return 3;
 }
+float arr[]=float[](3.4,4.2);
+void lvalues()
+{
+  arr[1]=2.;
+}
 uniform int time;
 in int sync;
 int dependOnConst()

tests/unit/inline.expected

@@ -1,3 +1,5 @@
+#version 120
+
 float result;
 void main()
 {
@@ -39,6 +41,11 @@ int dont_inline_lvalue()
   a=2;
   return 3;
 }
+float arr[]=float[](3.4,4.2);
+void lvalues()
+{
+  arr[1]=2.;
+}
 uniform int time;
 in int sync;
 int dependOnConst()

tests/unit/inline.frag

@@ -1,3 +1,5 @@
+#version 120
+
 float result;
 
 void main()
@@ -67,6 +69,12 @@ int dont_inline_lvalue() {
   return 3;
 }
 
+float arr[] = float[](3.4, 4.2);
+void lvalues() {
+  int a = 1;
+  arr[a] = 2.;
+}
+
 uniform int time;
 in int sync;
 

tests/unit/inline.no.expected

@@ -1,3 +1,5 @@
+#version 120
+
 float result;
 void main()
 {
@@ -43,6 +45,12 @@ int dont_inline_lvalue()
   a=2;
   return 3;
 }
+float arr[]=float[](3.4,4.2);
+void lvalues()
+{
+  int a=1;
+  arr[a]=2.;
+}
 uniform int time;
 in int sync;
 int dependOnConst()