remove dead code elimination option (#7669)

compiler/ast.nim

@@ -262,7 +262,8 @@ type
                       # variable is a thread variable
     sfCompileTime,    # proc can be evaluated at compile time
     sfConstructor,    # proc is a C++ constructor
-    sfDeadCodeElim,   # dead code elimination for the module is turned on
+    sfDispatcher,     # copied method symbol is the dispatcher
+                      # deprecated and unused, except for the con
     sfBorrow,         # proc is borrowed
     sfInfixCall,      # symbol needs infix call syntax in target language;
                       # for interfacing with C++, JS
@@ -275,10 +276,9 @@ type
   TSymFlags* = set[TSymFlag]
 
 const
-  sfDispatcher* = sfDeadCodeElim # copied method symbol is the dispatcher
   sfNoInit* = sfMainModule       # don't generate code to init the variable
 
-  sfImmediate* = sfDeadCodeElim
+  sfImmediate* = sfDispatcher
     # macro or template is immediately expanded
     # without considering any possible overloads
   sfAllUntyped* = sfVolatile # macro or template is immediately expanded \

compiler/ccgexprs.nim

@@ -2264,7 +2264,7 @@ proc expr(p: BProc, n: PNode, d: var TLoc) =
   of nkEmpty: discard
   of nkWhileStmt: genWhileStmt(p, n)
   of nkVarSection, nkLetSection: genVarStmt(p, n)
-  of nkConstSection: genConstStmt(p, n)
+  of nkConstSection: discard  # consts generated lazily on use
   of nkForStmt: internalError(n.info, "for statement not eliminated")
   of nkCaseStmt: genCase(p, n, d)
   of nkReturnStmt: genReturnStmt(p, n)
@@ -2315,8 +2315,7 @@ proc expr(p: BProc, n: PNode, d: var TLoc) =
       # are not transformed correctly. We work around this issue (#411) here
       # by ensuring it's no inner proc (owner is a module):
       if prc.skipGenericOwner.kind == skModule and sfCompileTime notin prc.flags:
-        if (not emitLazily(prc)) or
-            ({sfExportc, sfCompilerProc} * prc.flags == {sfExportc}) or
+        if ({sfExportc, sfCompilerProc} * prc.flags == {sfExportc}) or
             (sfExportc in prc.flags and lfExportLib in prc.loc.flags) or
             (prc.kind == skMethod):
           # we have not only the header:

compiler/ccgstmts.nim

@@ -280,20 +280,6 @@ proc genVarStmt(p: BProc, n: PNode) =
     else:
       genVarTuple(p, it)
 
-proc genConstStmt(p: BProc, n: PNode) =
-  for it in n.sons:
-    if it.kind == nkCommentStmt: continue
-    if it.kind != nkConstDef: internalError(n.info, "genConstStmt")
-
-    let sym = it.sons[0].sym
-    if sym.typ.containsCompileTimeOnly or
-        sym.typ.kind notin ConstantDataTypes or
-        sym.ast.len == 0 or
-        emitLazily(sym):
-      continue
-
-    requestConstImpl(p, sym)
-
 proc genIf(p: BProc, n: PNode, d: var TLoc) =
   #
   #  { if (!expr1) goto L1;
@@ -587,7 +573,7 @@ proc genRaiseStmt(p: BProc, t: PNode) =
     genLineDir(p, t)
     if isImportedException(typ):
       lineF(p, cpsStmts, "throw $1;$n", [e])
-    else:      
+    else:
       lineCg(p, cpsStmts, "#raiseException((#Exception*)$1, $2);$n",
           [e, makeCString(typ.sym.name.s)])
   else:
@@ -836,7 +822,7 @@ proc genTryCpp(p: BProc, t: PNode, d: var TLoc) =
     else:
       for j in 0..t[i].len-2:
         if t[i][j].isInfixAs():
-          let exvar = t[i][j][2] # ex1 in `except ExceptType as ex1:` 
+          let exvar = t[i][j][2] # ex1 in `except ExceptType as ex1:`
           fillLoc(exvar.sym.loc, locTemp, exvar, mangleLocalName(p, exvar.sym), OnUnknown)
           startBlock(p, "catch ($1& $2) {$n", getTypeDesc(p.module, t[i][j][1].typ), rdLoc(exvar.sym.loc))
         else:

compiler/ccgutils.nim

@@ -211,8 +211,4 @@ proc mangle*(name: string): string =
   if requiresUnderscore:
     result.add "_"
 
-proc emitLazily*(s: PSym): bool {.inline.} =
-  result = optDeadCodeElim in gGlobalOptions or
-           sfDeadCodeElim in getModule(s).flags
-
 initTypeTables()

compiler/cgen.nim

@@ -1309,10 +1309,6 @@ proc newModule(g: BModuleList; module: PSym): BModule =
   growCache g.modules, module.position
   g.modules[module.position] = result
 
-  if (optDeadCodeElim in gGlobalOptions):
-    if (sfDeadCodeElim in module.flags):
-      internalError("added pending module twice: " & toFilename(FileIndex module.position))
-
 template injectG(config) {.dirty.} =
   if graph.backend == nil:
     graph.backend = newModuleList(config)

compiler/commands.nim

@@ -268,7 +268,6 @@ proc testCompileOption*(switch: string, info: TLineInfo): bool =
   of "movechecks": result = contains(gOptions, optMoveCheck)
   of "linedir": result = contains(gOptions, optLineDir)
   of "assertions", "a": result = contains(gOptions, optAssert)
-  of "deadcodeelim": result = contains(gGlobalOptions, optDeadCodeElim)
   of "run", "r": result = contains(gGlobalOptions, optRun)
   of "symbolfiles": result = gSymbolFiles != disabledSf
   of "genscript": result = contains(gGlobalOptions, optGenScript)
@@ -509,7 +508,7 @@ proc processSwitch(switch, arg: string, pass: TCmdLinePass, info: TLineInfo;
   of "movechecks": processOnOffSwitch({optMoveCheck}, arg, pass, info)
   of "linedir": processOnOffSwitch({optLineDir}, arg, pass, info)
   of "assertions", "a": processOnOffSwitch({optAssert}, arg, pass, info)
-  of "deadcodeelim": processOnOffSwitchG({optDeadCodeElim}, arg, pass, info)
+  of "deadcodeelim": discard # deprecated, dead code elim always on
   of "threads":
     processOnOffSwitchG({optThreads}, arg, pass, info)
     #if optThreads in gGlobalOptions: incl(gNotes, warnGcUnsafe)

compiler/options.nim

@@ -41,7 +41,8 @@ type                          # please make sure we have under 32 options
 
   TOptions* = set[TOption]
   TGlobalOption* = enum       # **keep binary compatible**
-    gloptNone, optForceFullMake, optDeadCodeElim,
+    gloptNone, optForceFullMake,
+    optDeadCodeElimUnused,    # deprecated, always on
     optListCmd, optCompileOnly, optNoLinking,
     optCDebug,                # turn on debugging information
     optGenDynLib,             # generate a dynamic library

compiler/pragmas.nim

@@ -44,7 +44,9 @@ const
     wWarnings, wHints,
     wLinedir, wStacktrace, wLinetrace, wOptimization, wHint, wWarning, wError,
     wFatal, wDefine, wUndef, wCompile, wLink, wLinksys, wPure, wPush, wPop,
-    wBreakpoint, wWatchPoint, wPassl, wPassc, wDeadCodeElim, wDeprecated,
+    wBreakpoint, wWatchPoint, wPassl, wPassc,
+    wDeadCodeElimUnused,  # deprecated, always on
+    wDeprecated,
     wFloatchecks, wInfChecks, wNanChecks, wPragma, wEmit, wUnroll,
     wLinearScanEnd, wPatterns, wEffects, wNoForward, wReorder, wComputedGoto,
     wInjectStmt, wDeprecated, wExperimental, wThis}
@@ -215,10 +217,6 @@ proc onOff(c: PContext, n: PNode, op: TOptions) =
   if isTurnedOn(c, n): gOptions = gOptions + op
   else: gOptions = gOptions - op
 
-proc pragmaDeadCodeElim(c: PContext, n: PNode) =
-  if isTurnedOn(c, n): incl(c.module.flags, sfDeadCodeElim)
-  else: excl(c.module.flags, sfDeadCodeElim)
-
 proc pragmaNoForward(c: PContext, n: PNode; flag=sfNoForward) =
   if isTurnedOn(c, n): incl(c.module.flags, flag)
   else: excl(c.module.flags, flag)
@@ -764,7 +762,7 @@ proc singlePragma(c: PContext, sym: PSym, n: PNode, i: var int,
       of wThreadVar:
         noVal(it)
         incl(sym.flags, sfThread)
-      of wDeadCodeElim: pragmaDeadCodeElim(c, it)
+      of wDeadCodeElimUnused: discard  # deprecated, dead code elim always on
       of wNoForward: pragmaNoForward(c, it)
       of wReorder: pragmaNoForward(c, it, sfReorder)
       of wMagic: processMagic(c, it, sym)
@@ -960,10 +958,6 @@ proc singlePragma(c: PContext, sym: PSym, n: PNode, i: var int,
         if sym.kind != skType or sym.typ == nil: invalidPragma(it)
         else:
           incl(sym.typ.flags, tfPartial)
-          # .partial types can only work with dead code elimination
-          # to prevent the codegen from doing anything before we compiled
-          # the whole program:
-          incl gGlobalOptions, optDeadCodeElim
       of wInject, wGensym:
         # We check for errors, but do nothing with these pragmas otherwise
         # as they are handled directly in 'evalTemplate'.

compiler/wordrecg.nim

@@ -55,7 +55,8 @@ type
     wFloatchecks, wNanChecks, wInfChecks, wMoveChecks,
     wAssertions, wPatterns, wWarnings,
     wHints, wOptimization, wRaises, wWrites, wReads, wSize, wEffects, wTags,
-    wDeadCodeElim, wSafecode, wPackage, wNoForward, wReorder, wNoRewrite,
+    wDeadCodeElimUnused,  # deprecated, dead code elim always happens
+    wSafecode, wPackage, wNoForward, wReorder, wNoRewrite,
     wPragma,
     wCompileTime, wNoInit,
     wPassc, wPassl, wBorrow, wDiscardable,
@@ -143,7 +144,8 @@ const
 
     "assertions", "patterns", "warnings", "hints",
     "optimization", "raises", "writes", "reads", "size", "effects", "tags",
-    "deadcodeelim", "safecode", "package", "noforward", "reorder", "norewrite",
+    "deadcodeelim",  # deprecated, dead code elim always happens
+    "safecode", "package", "noforward", "reorder", "norewrite",
     "pragma",
     "compiletime", "noinit",
     "passc", "passl", "borrow", "discardable", "fieldchecks",