vm: convert slurp and staticRead to vmops (#947)

## Summary

Convert `slurp` and `staticRead` in the `system` module from magics to
VM callback operations.

## Details

Removal of the magic requires creating a conditional compilation step,
here `nimskullReworkStaticExec` conditional symbol was resued (see:
`condsym`). Two definitions of `slurp` and `staticRead` now exist, one
with the magic and one without. Without this, bootstrapping would no
longer work.

Also marked `slurp` as deprecated, `staticRead` is a far better name.
The reason for the deprecation is that `slurp` is just not as clear as
`staticRead`.

Removed `mSlurp` magic enum, and the `opcSlurp` VM opcode.

compiler/ast/ast_query.nim

@@ -617,8 +617,7 @@ proc isSinkType*(t: PType): bool {.inline.} =
   t.kind == tySink
 
 const magicsThatCanRaise* = {
-  mNone, mSlurp, mParseExprToAst, mParseStmtToAst, mEcho,
-  mChckRange }
+  mNone, mParseExprToAst, mParseStmtToAst, mEcho, mChckRange }
 
 proc canRaiseConservative*(fn: PNode): bool =
   if fn.kind == nkSym and fn.sym.magic notin magicsThatCanRaise:

compiler/ast/ast_types.nim

@@ -742,7 +742,7 @@ type
     mDefined, mDeclared, mDeclaredInScope, mCompiles, mArrGet, mArrPut, mAsgn,
     mLow, mHigh, mSizeOf, mAlignOf, mOffsetOf, mTypeTrait,
     mIs, mOf, mAddr, mType, mTypeOf,
-    mPlugin, mEcho, mShallowCopy, mSlurp,
+    mPlugin, mEcho, mShallowCopy,
     mStatic,
     mParseExprToAst, mParseStmtToAst, mExpandToAst, mQuoteAst,
     mInc, mDec, mOrd,

compiler/backend/ccgexprs.nim

@@ -1839,7 +1839,7 @@ proc genMagicExpr(p: BProc, e: CgNode, d: var TLoc, op: TMagic) =
   of mDefault: genDefault(p, e, d)
   of mEcho: genEcho(p, e[1].skipConv)
   of mArrToSeq: genArrToSeq(p, e, d)
-  of mNLen..mNError, mSlurp..mQuoteAst:
+  of mNLen..mNError, mStatic..mQuoteAst:
     localReport(p.config, e.info, reportSym(
       rsemConstExpressionExpected, e[0].sym))
 

compiler/backend/jsgen.nim

@@ -2009,7 +2009,7 @@ proc genMagic(p: PProc, n: CgNode, r: var TCompRes) =
   of mDefault: genDefault(p, n, r)
   of mWasMoved: genReset(p, n)
   of mEcho: genEcho(p, n, r)
-  of mNLen..mNError, mSlurp:
+  of mNLen..mNError:
     localReport(p.config, n.info, reportSym(
       rsemConstExpressionExpected, n[0].sym))
 

compiler/vm/vm.nim

@@ -2026,6 +2026,7 @@ proc rawExecute(c: var TCtx, pc: var int): YieldReason =
                  heap: addr c.heap,
                  graph: c.graph,
                  config: c.config,
+                 currentModule: c.module,
                  cache: c.cache,
                  idgen: c.idgen))
       of ckDefault:
@@ -2625,12 +2626,6 @@ proc rawExecute(c: var TCtx, pc: var int): YieldReason =
         raiseVmError(VmEvent(
           kind: vmEvtNodeNotASymbol, ast: regs[rb].nimNode))
 
-    of opcSlurp:
-      decodeB(akString)
-      checkHandle(regs[rb])
-      regs[ra].strVal = opSlurp($regs[rb].strVal, c.debug[pc],
-                                     c.module, c.config)
-
     of opcParseExprToAst, opcParseStmtToAst:
       decodeBC(rkNimNode)
 

compiler/vm/vm_enums.nim

@@ -117,7 +117,6 @@ type
     opcNccValue, opcNccInc, opcNcsAdd, opcNcsIncl, opcNcsLen, opcNcsAt,
     opcNctPut, opcNctLen, opcNctGet, opcNctHasNext, opcNctNext, opcNodeId,
 
-    opcSlurp,
     opcParseExprToAst,
     opcParseStmtToAst,
     opcNGetLineInfo, opcNSetLineInfo,

compiler/vm/vmdef.nim

@@ -399,6 +399,7 @@ type
     # compiler interfacing:
     graph*: ModuleGraph
     config*: ConfigRef
+    currentModule*: PSym ## module currently being compiled
     cache*: IdentCache
     idgen*: IdGenerator
 

compiler/vm/vmgen.nim

@@ -1907,7 +1907,6 @@ proc genMagic(c: var TCtx; n: CgNode; dest: var TDest; m: TMagic) =
     c.gABx(n, opcNSetType, tmp, c.genTypeInfo(n[1].typ))
     c.gABC(n, opcTypeTrait, dest, tmp)
     c.freeTemp(tmp)
-  of mSlurp: genUnaryABC(c, n, dest, opcSlurp)
   of mNLen: genUnaryABI(c, n, dest, opcLenSeq, nimNodeFlag)
   of mGetImpl: genUnaryABC(c, n, dest, opcGetImpl)
   of mGetImplTransf: genUnaryABC(c, n, dest, opcGetImplTransf)

compiler/vm/vmops.nim

@@ -391,6 +391,14 @@ iterator compileTimeOps*(): Override =
 
   override "stdlib.os.getCurrentCompilerExe", proc (a: VmArgs) {.nimcall.} =
     setResult(a, getAppFilename())
+
+  # xxx: not really a compile-time query, but runs at compiletime and unlike
+  #      osOps it directly impacts compilation
+  for op in ["stdlib.system.slurp", "stdlib.system.staticRead"]:
+    override op, proc (a: VmArgs) {.nimcall.} =
+      let output = opSlurp(getString(a, 0), a.currentLineInfo, a.currentModule,
+                           a.config)
+      writeResult(output)
 
 iterator gorgeOps*(): Override =
   ## Special operations for executing external programs at compile time.

lib/system.nim

@@ -2570,23 +2570,21 @@ proc `[]=`*[Idx, T](a: var array[Idx, T]; i: BackwardsIndex; x: T) {.inline.} =
 proc `[]=`*(s: var string; i: BackwardsIndex; x: char) {.inline.} =
   s[s.len - int(i)] = x
 
-proc slurp*(filename: string): string {.magic: "Slurp".}
-  ## This is an alias for `staticRead <#staticRead,string>`_.
-  ## to be deprecated, use `staticRead`
+when defined(nimskullReworkStaticExec):
+  proc slurp*(filename: string): string {.compileTime,
+    deprecated: "use staticRead".} = discard
+    ## This is an alias for `staticRead <#staticRead,string>`_.
 
-proc staticRead*(filename: string): string {.magic: "Slurp".}
-  ## Compile-time `readFile <io.html#readFile,string>`_ proc for easy
-  ## `resource`:idx: embedding:
-  ##
-  ## The maximum file size limit that `staticRead` and `slurp` can read is
-  ## near or equal to the *free* memory of the device you are using to compile.
-  ##
-  ## .. code-block:: Nim
-  ##     const myResource = staticRead"mydatafile.bin"
-  ##
-  ## `slurp <#slurp,string>`_ is an alias for `staticRead`.
+  proc staticRead*(filename: string): string {.compileTime.} = discard
+    ## Compile-time `readFile <io.html#readFile,string>`_ proc for easy
+    ## `resource`:idx: embedding:
+    ##
+    ## The maximum file size limit that `staticRead` and `slurp` can read is
+    ## near or equal to the *free* memory of the device you are using to compile.
+    ##
+    ## .. code-block:: Nim
+    ##     const myResource = staticRead"mydatafile.bin"
 
-when defined(nimskullReworkStaticExec):
   proc gorge*(command: string, input = "", cache = ""): string {.
     compileTime, deprecated: "use staticExec".} = discard
     ## This is an alias for `staticExec <#staticExec,string,string,string>`_.
@@ -2620,6 +2618,12 @@ when defined(nimskullReworkStaticExec):
     ## 
     ## Deprecate/Replace with variant that returns the exit code and output
 else:
+  proc slurp*(filename: string): string {.magic: "Slurp".} = discard
+    ## kept for bootstrapping
+
+  proc staticRead*(filename: string): string {.magic: "Slurp".} = discard
+    ## kept for bootstrapping
+
   proc gorge*(command: string, input = "", cache = ""): string {.
     magic: "StaticExec".} = discard
     ## kept for bootstrapping

tests/vm/tslurp.nim

@@ -1,4 +1,4 @@
-import os
+import std/os
 
 template getScriptDir(): string =
   parentDir(instantiationInfo(-1, true).filename)