Fix smoothstep optimization trick

It was leading to things like "x--0.1", which doesn't parse. Now prints
"x+0.1" as expected.

App.config

 <?xml version="1.0" encoding="utf-8"?>
 <configuration>
   <startup>
-    <supportedRuntime version="v4.0" sku=".NETFramework,Version=v4.5" />
+    <supportedRuntime version="v4.0" sku=".NETFramework,Version=v4.0" />
   </startup>
   <runtime>
     <assemblyBinding xmlns="urn:schemas-microsoft-com:asm.v1">
       <dependentAssembly>
         <assemblyIdentity name="FSharp.Core" publicKeyToken="b03f5f7f11d50a3a" culture="neutral" />
-        <bindingRedirect oldVersion="2.0.0.0" newVersion="4.4.0.0" />
-        <bindingRedirect oldVersion="2.3.0.0" newVersion="4.4.0.0" />
-        <bindingRedirect oldVersion="2.3.5.0" newVersion="4.4.0.0" />
-        <bindingRedirect oldVersion="4.0.0.0" newVersion="4.4.0.0" />
-        <bindingRedirect oldVersion="4.3.0.0" newVersion="4.4.0.0" />
-        <bindingRedirect oldVersion="3.3.1.0" newVersion="4.4.0.0" />
-        <bindingRedirect oldVersion="2.3.5.1" newVersion="4.4.0.0" />
-        <bindingRedirect oldVersion="3.78.3.1" newVersion="4.4.0.0" />
-        <bindingRedirect oldVersion="3.259.3.1" newVersion="4.4.0.0" />
-        <bindingRedirect oldVersion="4.3.1.0" newVersion="4.4.0.0" />
-        <bindingRedirect oldVersion="3.47.4.0" newVersion="4.4.0.0" />
-        <bindingRedirect oldVersion="3.78.4.0" newVersion="4.4.0.0" />
-        <bindingRedirect oldVersion="3.259.4.0" newVersion="4.4.0.0" />
+        <bindingRedirect oldVersion="2.0.0.0" newVersion="4.3.0.0" />
+        <bindingRedirect oldVersion="2.3.0.0" newVersion="4.3.0.0" />
+        <bindingRedirect oldVersion="2.3.5.0" newVersion="4.3.0.0" />
+        <bindingRedirect oldVersion="4.0.0.0" newVersion="4.3.0.0" />
       </dependentAssembly>
     </assemblyBinding>
   </runtime>

Shader Minifier.fsproj

@@ -9,10 +9,10 @@
     <OutputType>Exe</OutputType>
     <RootNamespace>glsl_minifier</RootNamespace>
     <AssemblyName>shader_minifier</AssemblyName>
-    <TargetFrameworkVersion>v3.5</TargetFrameworkVersion>
+    <TargetFrameworkVersion>v4.0</TargetFrameworkVersion>
     <Name>Shader Minifier</Name>
     <TargetFrameworkProfile />
-    <TargetFSharpCoreVersion>2.3.0.0</TargetFSharpCoreVersion>
+    <TargetFSharpCoreVersion>4.3.0.0</TargetFSharpCoreVersion>
     <MinimumVisualStudioVersion Condition="'$(MinimumVisualStudioVersion)' == ''">11</MinimumVisualStudioVersion>
   </PropertyGroup>
   <PropertyGroup Condition=" '$(Configuration)|$(Platform)' == 'Debug|AnyCPU' ">
@@ -33,7 +33,7 @@
     <OutputPath>bin\Release\</OutputPath>
     <DefineConstants>TRACE</DefineConstants>
     <WarningLevel>3</WarningLevel>
-    <StartArguments>-o "" ../../tests\unit\1.simple.frag</StartArguments>
+    <StartArguments>-o "" ../../tests\unit\smoothstep.frag --smoothstep</StartArguments>
     <OtherFlags>--standalone</OtherFlags>
   </PropertyGroup>
   <Choose>

src/ast.fs

@@ -101,6 +101,7 @@ let foldList env fct li =
     snd x) : 'a -> 'a)
   !env, res
 
+// Applies env.fExpr recursively on all nodes of an expression.
 let rec mapExpr env = function
   | FunCall(fct, args) ->
      env.fExpr env (FunCall(mapExpr env fct, List.map (mapExpr env) args))

src/main.fs

@@ -35,15 +35,13 @@ let printSize code =
       printfn "Shader size is: %d" n
 
 let rename code =
-    Renamer.renameMode <- Renamer.Unambiguous
     Printer.printMode <- Printer.SingleChar
-    let code, lastIdent = Renamer.renTopLevel code
+    let code, lastIdent = Renamer.renTopLevel code Renamer.Unambiguous
     computeFrequencyIdentTable code
     Renamer.computeContextTable code
 
     Printer.printMode <- Printer.FromTable
-    Renamer.renameMode <- Renamer.Context
-    let code, lastIdent = Renamer.renTopLevel code
+    let code, lastIdent = Renamer.renTopLevel code Renamer.Context
     vprintf "%d identifiers renamed. " Renamer.numberOfUsedIdents
     printSize code
     code
@@ -129,7 +127,6 @@ let () =
      "--smoothstep", ArgType.Unit (fun() -> Ast.smoothstepTrick<-true), "Use IQ's smoothstep trick"
      //"--macro-threshold", ArgType.Int (fun i ->
      //    printfn "Macros are disabled in the release."; Ast.macroThreshold <- i), "[disabled] Use a #define macro if it can save at least <int> bytes"
-     //"--make-elevated2", ArgType.Unit (fun () -> printfn "Please buy the commercial version."; exit 1), "Generate the 4k intro 'Elevated 2'"
      "--shader-only", ArgType.Unit (fun() -> Ast.targetOutput<-Ast.Text), "[Deprecated]"
      "--js-output", ArgType.Unit (fun() -> Ast.targetOutput<-Ast.JS), "[Deprecated]"
      "--", ArgType.Rest setFile, "Stop parsing command line"

src/renamer.fs

@@ -279,7 +279,8 @@ let rec doNotOverload env = function
       let env = {env with map = Map.add name name env.map; reusable = re}
       doNotOverload env li
 
-let rec renTopLevel li =
+let rec renTopLevel li mode =
+  renameMode <- mode
   let idents = Printer.identTable |> Array.toList
             |> List.filter (fun x -> x.Length = 1)
             |> List.filter (fun x -> not <| List.exists ((=) x) Ast.forbiddenNames)

src/rewriter.fs

@@ -70,6 +70,11 @@ let rec expr env = function
   | FunCall(Var ",", [e1; FunCall(Var ",", [e2; e3])]) ->
       FunCall(Var ",", [expr env (FunCall(Var ",", [e1; e2])); e3])
 
+  | FunCall(Var "-", [x; Float (f, s)]) when f < 0. ->
+        FunCall(Var "+", [x; Float (-f, s)]) |> expr env
+  | FunCall(Var "-", [x; Int (i, s)]) when i < 0 ->
+        FunCall(Var "+", [x; Int (-i, s)]) |> expr env
+
   // Boolean simplifications (let's ignore the suffix)
   | FunCall(Var "<",  [Int (i1, _); Int (i2, _)]) -> bool(i1 < i2)
   | FunCall(Var ">",  [Int (i1, _); Int (i2, _)]) -> bool(i1 > i2)

tests/unit/smoothstep.frag

@@ -5,5 +5,7 @@ void main()
 
     s = smoothstep(0.0,1.0,s);
 
-    ao = smoothstep(0.0,0.4,s) - smoothstep(0.4,0.7,s);
+    ao = smoothstep(0.0,0.4,s) - 1.0 * smoothstep(0.4,0.7,s);
+
+    float dom = 1.0 * smoothstep( (-0.1), (0.1), ref.y); // https://github.com/laurentlb/Shader_Minifier/issues/7
 }