New renaming strategy for when minifying multiple files

src/renamer.fs

@@ -125,12 +125,21 @@ module private RenamerImpl =
         let newName = sprintf "%04d" !numberOfUsedIdents
         env.Rename(id, newName), newName
 
-    // FIXME: handle 2-letter names
+    // A renaming strategy that considers how a variable is used. It optimizes the frequency of
+    // adjacent characters, which can make the output more compression-friendly. This is best
+    // suited when minifying a single file.
     let optimizeContext contextTable env id =
         let cid = char (1000 + int id)
         let newName = chooseIdent contextTable cid env.availableNames
         env.Rename(id, newName), newName
 
+    // A renaming strategy that always picks the first available name. This optimizes the
+    // frequency of a few variables. It also ensures that two identical functions will use the
+    // same names for local variables, which can be very important in some multifile scenarios.
+    let optimizeNameFrequency (env: Env) id =
+        let newName = env.availableNames.Head
+        env.Rename(id, newName), newName
+
     let dontRename (env: Env) name =
         env.Rename(name, name)
 
@@ -336,17 +345,20 @@ module private RenamerImpl =
     let rename shaders =
         let exportedNames = assignUniqueIds shaders
 
-        // Get data about the context
-        let text = [for shader in shaders -> Printer.printText shader.code] |> String.concat "\0"
-        let names = computeListOfNames text
-        let contextTable = computeContextTable text
-
         // TODO: combine from all shaders
         let forbiddenNames = (Seq.head shaders).forbiddenNames
 
-        let names = names |> List.filter (fun x -> not <| List.exists ((=) x) forbiddenNames)
-
-        let mutable env = Env.Create(names, true, optimizeContext contextTable, shadowVariables)
+        // Compute the list of variable names to use
+        let text = [for shader in shaders -> Printer.printText shader.code] |> String.concat "\0"
+        let names = computeListOfNames text
+                 |> List.filter (fun x -> not <| List.exists ((=) x) forbiddenNames)
+
+        let mutable env =
+            if Array.length shaders > 1 then
+                Env.Create(names, true, optimizeNameFrequency, shadowVariables)
+            else
+                let contextTable = computeContextTable text
+                Env.Create(names, true, optimizeContext contextTable, shadowVariables)
         env <- dontRenameList env options.noRenamingList
         env.exportedNames := exportedNames
         renameAsts shaders env

tests/unit/inout.expected

@@ -3,66 +3,66 @@
  */
 #ifndef INOUT_EXPECTED_
 # define INOUT_EXPECTED_
-# define VAR_AMBIENTLIGHT "r"
-# define VAR_DIFFUSECOLOR "n"
-# define VAR_EMISSIVECOLOR "t"
-# define VAR_FRAGMENTCOLOR "f"
-# define VAR_MEDIUMDENSITY "s"
-# define VAR_NORMAL "m"
-# define VAR_SPECULARCOLOR "c"
-# define VAR_TEXTURE0 "v"
-# define VAR_VIEWVEC "d"
+# define VAR_AMBIENTLIGHT "a"
+# define VAR_DIFFUSECOLOR "m"
+# define VAR_EMISSIVECOLOR "l"
+# define VAR_FRAGMENTCOLOR "o"
+# define VAR_MEDIUMDENSITY "t"
+# define VAR_NORMAL "c"
+# define VAR_SPECULARCOLOR "i"
+# define VAR_TEXTURE0 "e"
+# define VAR_VIEWVEC "v"
 
 const char *inout_frag =
  "#version 330\n"
- "uniform samplerCube v;"
- "in vec3 m,d;"
- "out vec4 f;"
+ "uniform samplerCube e;"
+ "in vec3 c,v;"
+ "out vec4 o;"
  "void main()"
  "{"
-   "vec3 r=normalize(d),n=normalize(m),c=vec3(.1,.2,.3),t=vec3(.5,.5,.5);"
-   "float s=1.5;"
-   "vec3 z=texture(v,reflect(-r,n)).xyz,e=texture(v,refract(-r,n,1./s)).xyz,p=mix(c*e,z,.1);"
-   "f=vec4(p,1.);"
+   "vec3 r=normalize(v),t=normalize(c),a=vec3(.1,.2,.3),m=vec3(.5,.5,.5);"
+   "float l=1.5;"
+   "vec3 i=texture(e,reflect(-r,t)).xyz,n=texture(e,refract(-r,t,1./l)).xyz,f=mix(a*n,i,.1);"
+   "o=vec4(f,1.);"
  "}"
- "vec3 e(vec3 v,vec3 m,vec3 f)"
+ "vec3 r(vec3 e,vec3 c,vec3 v)"
  "{"
-   "float s=1.-clamp(dot(m,f),0.,1.);"
-   "return s*s*s*s*s*(1.-v)+v;"
+   "float o=1.-clamp(dot(c,v),0.,1.);"
+   "return o*o*o*o*o*(1.-e)+e;"
  "}"
- "vec3 e(vec3 v,vec3 m,vec3 r,vec3 n,vec3 d,float s)"
+ "vec3 r(vec3 e,vec3 c,vec3 v,vec3 o,vec3 r,float t)"
  "{"
-   "vec3 f=normalize(v+m);"
-   "float c=1.+2048.*(1.-s)*(1.-s);"
-   "vec3 z=n,t=vec3(pow(clamp(dot(f,r),0.,1.),c)*(c+4.)/8.),e=x(d,v,f);"
-   "return mix(z,t,e);"
+   "vec3 a=normalize(e+c);"
+   "float m=1.+2048.*(1.-t)*(1.-t);"
+   "vec3 l=o,i=vec3(pow(clamp(dot(a,v),0.,1.),m)*(m+4.)/8.),f=n(r,e,a);"
+   "return mix(l,i,f);"
  "}";
 
 const char *inout2_frag =
  "#version 330\n"
- "uniform samplerCube v;"
- "uniform float s;"
- "uniform vec3 r,n,t,c;"
- "in vec3 m,d;"
- "out vec4 f;"
- "vec3 x(vec3 v,vec3 m,vec3 f)"
+ "uniform samplerCube e;"
+ "uniform float t;"
+ "uniform vec3 a,m,l,i;"
+ "in vec3 c,v;"
+ "out vec4 o;"
+ "vec3 n(vec3 e,vec3 c,vec3 v)"
  "{"
-   "float s=1.-clamp(dot(m,f),0.,1.);"
-   "return s*s*s*s*s*(1.-v)+v;"
+   "float o=1.-clamp(dot(c,v),0.,1.);"
+   "return o*o*o*o*o*(1.-e)+e;"
  "}"
  "void main()"
  "{"
-   "vec3 s=normalize(d),v=normalize(m),e=n,z=c;"
-   "float p=.5;"
-   "vec3 x=t+mix(e*r,r,p);"
-   "f=vec4(x,1.);"
+   "vec3 e=normalize(v),r=normalize(c),t=m,n=i;"
+   "float f=.5;"
+   "vec3 u=l+mix(t*a,a,f);"
+   "o=vec4(u,1.);"
  "}"
- "vec3 x(vec3 v,vec3 m,vec3 f,vec3 n,vec3 d,float s)"
+ "vec3 n(vec3 e,vec3 c,vec3 v,vec3 o,vec3 r,float t)"
  "{"
-   "vec3 r=normalize(v+m);"
-   "float c=1.+2048.*(1.-s)*(1.-s);"
-   "vec3 z=n,e=vec3(pow(clamp(dot(r,f),0.,1.),c)*(c+4.)/8.),t=x(d,v,r);"
-   "return mix(z,e,t);"
+   "vec3 a=normalize(e+c);"
+   "float m=1.+2048.*(1.-t)*(1.-t);"
+   "vec3 l=o,i=vec3(pow(clamp(dot(a,v),0.,1.),m)*(m+4.)/8.),f=n(r,e,a);"
+   "return mix(l,i,f);"
  "}";
 
 #endif // INOUT_EXPECTED_