Add debugging traces (#345)

Checker/checker-linux.fsproj

@@ -1,4 +1,4 @@
-<Project Sdk="Microsoft.NET.Sdk">
+<Project Sdk="Microsoft.NET.Sdk">
 
   <PropertyGroup>
     <OutputType>Exe</OutputType>
@@ -25,4 +25,8 @@
     </ProjectReference>
   </ItemGroup>
 
+  <PropertyGroup>
+     <RunWorkingDirectory>$(MSBuildProjectDirectory)/..</RunWorkingDirectory>
+  </PropertyGroup>
+
 </Project>

Checker/main.fs

@@ -43,8 +43,8 @@ let canBeCompiled content =
             printfn "compilation failed: %s" info
             false
 
-let doMinify content =
-    let arr = ShaderMinifier.minify [|"input", content|] |> fst |> Array.map (fun s -> s.code)
+let doMinify file content =
+    let arr = ShaderMinifier.minify [|file, content|] |> fst |> Array.map (fun s -> s.code)
     Printer.print arr.[0]
 
 let testMinifyAndCompile (file: string) =
@@ -54,7 +54,7 @@ let testMinifyAndCompile (file: string) =
             printfn "Invalid input file '%s'" file
             false
         else
-            let minified = doMinify content + "\n"
+            let minified = doMinify file content + "\n"
             if not (canBeCompiled minified) then
                 printfn "Minification broke the file '%s'" file
                 printfn "%s" minified

src/analyzer.fs

@@ -73,8 +73,12 @@ module private VariableInlining =
             let ident, isConst = def.Value
             if not ident.DoNotInline && not ident.ToBeInlined && not ident.VarDecl.Value.isEverWrittenAfterDecl then
                 match localReferences.TryGetValue(def.Key), allReferences.TryGetValue(def.Key) with
-                | (_, 1), (_, 1) when isConst -> ident.ToBeInlined <- true
-                | (_, 0), (_, 0) -> ident.ToBeInlined <- true
+                | (_, 1), (_, 1) when isConst ->
+                    debug $"inlining variable '{Printer.debugIdent ident}' because it's safe to inline and used only once"
+                    ident.ToBeInlined <- true
+                | (_, 0), (_, 0) ->
+                    debug $"inlining variable '{Printer.debugIdent ident}' because it's safe to inline and unused"
+                    ident.ToBeInlined <- true
                 | _ -> ()
 
     let isTrivialExpr = function
@@ -114,11 +118,13 @@ module private VariableInlining =
                         // Top-level values are special, in particular in HLSL. Keep them for now.
                         if not isTopLevel then
                             // Never-written locals without init should be unused: inline (remove) them.
+                            debug $"inlining (removing) unassigned local '{Printer.debugDecl def}'"
                             def.name.ToBeInlined <- true
                     | Some init ->
                         if canBeInlined init then
                             // Never-written locals and globals are inlined when their value is "simple enough".
                             // This can increase non-compressed size but decreases compressed size.
+                            debug $"inlining variable '{Printer.debugDecl def}' because it's never written and has a 'simple' definition"
                             def.name.ToBeInlined <- true
         | _ -> ()
 
@@ -322,6 +328,7 @@ module private FunctionInlining =
         if not funcInfo.funcType.fName.DoNotInline && verifyArgsUses funcInfo.func callSites then
             // Mark both the call site (so that simplifyExpr can remove it) and the function (to remember to remove it).
             // We cannot simply rely on unused functions removal, because it might be disabled through its own flag.
+            debug $"inlining function '{funcInfo.funcType}' into {callSites.Length} call sites"
             for callSite in callSites do
                 callSite.ident.ToBeInlined <- true
             funcInfo.funcType.fName.ToBeInlined <- true

src/api.fs

@@ -21,6 +21,7 @@ let private readFile file =
     stream.ReadToEnd()
 
 let minify (files: (string*string)[]) =
+    let names = files |> Array.map (fun (n,_) -> n) |> String.Concat in debug $"----- minifying {names}"
     vprintf "Input file size is: %d\n" (files |> Array.sumBy (fun (_, s) -> s.Length))
     let shaders = files |> Array.map (fun (f, c) -> Parse.runParser f c)
     vprintf "File parsed. "; printSize shaders

src/options.fs

@@ -2,6 +2,7 @@
 
 open System.IO
 open Argu
+open System
 
 let version = "1.3.6" // Shader Minifier version
 let debugMode = false
@@ -23,6 +24,7 @@ type FieldSet =
 type CliArguments =
     | [<CustomCommandLine("-o")>] OutputName of string
     | [<CustomCommandLine("-v")>] Verbose
+    | [<CustomCommandLine("--debug")>] Debug
     | [<CustomCommandLine("--hlsl")>] Hlsl
     | [<CustomCommandLine("--format")>] FormatArg of OutputFormat
     | [<CustomCommandLine("--field-names")>] FieldNames of FieldSet
@@ -45,6 +47,7 @@ type CliArguments =
             match s with
             | OutputName _ -> "Set the output filename (default is shader_code.h)"
             | Verbose -> "Verbose, display additional information"
+            | Debug -> "Debug, display more additional information"
             | Hlsl -> "Use HLSL (default is GLSL)"
             | FormatArg _ -> "Choose to format the output (use 'text' if you want just the shader)"
             | FieldNames _ -> "Choose the field names for vectors: 'rgba', 'xyzw', or 'stpq'"
@@ -66,6 +69,7 @@ type Options() =
     member val outputName = "shader_code.h" with get, set
     member val outputFormat = CVariables with get, set
     member val verbose = false with get, set
+    member val debug = false with get, set
     member val smoothstepTrick = false with get, set
     member val canonicalFieldNames = "xyzw" with get, set
     member val preserveExternals = false with get, set
@@ -88,6 +92,9 @@ module Globals =
     // like printfn when verbose option is set
     let vprintf fmt = fprintf (if options.verbose then stdout else TextWriter.Null) fmt
 
+    let forceDebug = Environment.GetEnvironmentVariable("MINIFIER_DEBUG", EnvironmentVariableTarget.Process ||| EnvironmentVariableTarget.User) <> null
+    let debug str = fprintfn (if options.debug || forceDebug then stdout else IO.TextWriter.Null) "%s" str
+
 open Globals
 
 let helpTextMessage = sprintf "Shader Minifier %s - https://github.com/laurentlb/Shader_Minifier" version
@@ -111,6 +118,7 @@ let private initPrivate argv needFiles =
         options.outputName <- args.GetResult(OutputName, defaultValue = "shader_code.h")
         options.outputFormat <- args.GetResult(FormatArg, defaultValue = CVariables)
         options.verbose <- args.Contains(Verbose)
+        options.debug <- args.Contains(Debug)
         options.smoothstepTrick <- args.Contains(Smoothstep)
         options.canonicalFieldNames <- (sprintf "%A" (args.GetResult(FieldNames, defaultValue = XYZW))).ToLower()
         options.preserveExternals <- args.Contains(PreserveExternals) || args.Contains(PreserveAllGlobals)

src/printer.fs

@@ -319,3 +319,16 @@ let print tl = printIndented tl |> stripIndentation
 let writeSymbols shader = (new PrinterImpl()).WriteSymbols shader
 let exprToS x = (new PrinterImpl()).ExprToS 0 x |> stripIndentation
 let typeToS ty = (new PrinterImpl()).TypeToS ty |> stripIndentation
+
+let debugDecl (t: DeclElt) =
+    let size = if t.size = None then "" else $"[{t.size}]"
+    let init = match t.init with
+                | Some e -> $" = {exprToS e}"
+                | None -> ""
+    let sem = if t.semantics.IsEmpty then "" else $": {t.semantics}" in
+    $"{t.name.OldName}{size}{init}{sem}"
+
+let debugIdent (ident: Ident) =
+    match ident.Declaration with
+    | Declaration.Variable rv -> debugDecl rv.decl
+    | _ -> ident.OldName.ToString()

src/rewriter.fs

@@ -348,7 +348,7 @@ module private RewriterImpl =
 
     // Squeeze top-level declarations, e.g. uniforms
     let rec squeezeTLDeclarations = function
-        | []-> []
+        | [] -> []
         | TLDecl(ty1, li1) :: TLDecl(ty2, li2) :: l when ty1 = ty2 ->
             squeezeTLDeclarations (TLDecl(ty1, li1 @ li2) :: l)
         | e::l -> e :: squeezeTLDeclarations l
@@ -549,7 +549,9 @@ module private RewriterImpl =
                 |> List.map (fun c -> c.prototype)
                 |> List.contains funcInfo.funcType.prototype) // when in doubt wrt overload resolution, keep the function.
             canBeRenamed && not isCalled && not funcInfo.funcType.isExternal
-        let unused = set [for funcInfo in funcInfos do if isUnused funcInfo then yield funcInfo.func]
+        let unused = [for funcInfo in funcInfos do if isUnused funcInfo then yield funcInfo]
+        if not unused.IsEmpty then debug($"removing unused functions: " + String.Join(", ", unused |> List.map (fun fi -> fi.funcType)))
+        let unused = unused |> List.map (fun fi -> fi.func) |> set
         let mutable edited = false
         let code = code |> List.filter (function
             | Function _ as t -> if Set.contains t unused then edited <- true; false else true
@@ -615,6 +617,7 @@ module private ArgumentInlining =
                         let argExprs = callSites |> List.map (fun c -> c.argExprs |> List.item argIndex) |> List.distinct
                         match argExprs with
                         | [argExpr] when isInlinableExpr argExpr -> // The argExpr must always be the same at all call sites.
+                            debug $"inlining expression '{Printer.exprToS argExpr}' into argument '{Printer.debugDecl varDecl.decl}' of '{funcInfo.funcType}'"
                             argInlinings <- {func=funcInfo.func; argIndex=argIndex; varDecl=varDecl; argExpr=argExpr} :: argInlinings
                         | _ -> ()
                     | _ -> ()
@@ -677,7 +680,10 @@ let rec private iterateSimplifyAndInline li =
 
     let li = if options.noInlining then li else ArgumentInlining.apply didInline li
 
-    if didInline.Value then iterateSimplifyAndInline li else li
+    if didInline.Value
+    then debug $"inlining happened: running analysis again..."
+         iterateSimplifyAndInline li
+    else li
 
 let simplify li =
     li