From 7575014858314c87ab7ce9f1754dd48f2e8c3a00 Mon Sep 17 00:00:00 2001
From: metagn <metagngn@gmail.com>
Date: Mon, 11 Nov 2024 09:17:44 +0300
Subject: [PATCH] cbuilder: adapt `switch` generation with `if` fallbacks

---
 compiler/ccgstmts.nim | 66 ++++++++++++++++++++++++++++---------------
 1 file changed, 44 insertions(+), 22 deletions(-)

diff --git a/compiler/ccgstmts.nim b/compiler/ccgstmts.nim
index bc05b7905852..5512ed01c8f1 100644
--- a/compiler/ccgstmts.nim
+++ b/compiler/ccgstmts.nim
@@ -884,18 +884,23 @@ proc genRaiseStmt(p: BProc, t: PNode) =
     p.s(cpsStmts).addCallStmt(cgsymValue(p.module, "reraiseException"))
   raiseInstr(p, p.s(cpsStmts))
 
-template genCaseGenericBranch(p: BProc, b: PNode, e: TLoc,
-                          rangeFormat, eqFormat: FormatStr, labl: TLabel) =
+template genCaseGenericBranch(p: BProc, b: PNode, e: TLoc, labl: TLabel,
+                          rangeFormat, eqFormat: untyped) =
   var x, y: TLoc
   for i in 0..<b.len - 1:
+    let rlabel {.inject.} = labl
     if b[i].kind == nkRange:
       x = initLocExpr(p, b[i][0])
       y = initLocExpr(p, b[i][1])
-      lineCg(p, cpsStmts, rangeFormat,
-           [rdCharLoc(e), rdCharLoc(x), rdCharLoc(y), labl])
+      let ra {.inject.} = rdCharLoc(e)
+      let rb {.inject.} = rdCharLoc(x)
+      let rc {.inject.} = rdCharLoc(y)
+      rangeFormat
     else:
       x = initLocExpr(p, b[i])
-      lineCg(p, cpsStmts, eqFormat, [rdCharLoc(e), rdCharLoc(x), labl])
+      let ra {.inject.} = rdCharLoc(e)
+      let rb {.inject.} = rdCharLoc(x)
+      eqFormat
 
 proc genCaseSecondPass(p: BProc, t: PNode, d: var TLoc,
                        labId, until: int): TLabel =
@@ -912,9 +917,8 @@ proc genCaseSecondPass(p: BProc, t: PNode, d: var TLoc,
   result = lend
 
 template genIfForCaseUntil(p: BProc, t: PNode, d: var TLoc,
-                       rangeFormat, eqFormat: FormatStr,
-                       until: int, a: TLoc): TLabel =
-  # XXX doesn't work with cbuilder
+                       until: int, a: TLoc,
+                       rangeFormat, eqFormat: untyped): TLabel =
   # generate a C-if statement for a Nim case statement
   var res: TLabel
   var labId = p.labels
@@ -922,7 +926,7 @@ template genIfForCaseUntil(p: BProc, t: PNode, d: var TLoc,
     inc(p.labels)
     let lab = "LA" & $p.labels & "_"
     if t[i].kind == nkOfBranch: # else statement
-      genCaseGenericBranch(p, t[i], a, rangeFormat, eqFormat, lab)
+      genCaseGenericBranch(p, t[i], a, lab, rangeFormat, eqFormat)
     else:
       p.s(cpsStmts).addGoto(lab)
   if until < t.len-1:
@@ -936,10 +940,9 @@ template genIfForCaseUntil(p: BProc, t: PNode, d: var TLoc,
   res
 
 template genCaseGeneric(p: BProc, t: PNode, d: var TLoc,
-                    rangeFormat, eqFormat: FormatStr) =
-  # XXX doesn't work with cbuilder
+                    rangeFormat, eqFormat: untyped) =
   var a: TLoc = initLocExpr(p, t[0])
-  var lend = genIfForCaseUntil(p, t, d, rangeFormat, eqFormat, t.len-1, a)
+  var lend = genIfForCaseUntil(p, t, d, t.len-1, a, rangeFormat, eqFormat)
   fixLabel(p, lend)
 
 proc genCaseStringBranch(p: BProc, b: PNode, e: TLoc, labl: TLabel,
@@ -1003,10 +1006,15 @@ proc genStringCase(p: BProc, t: PNode, stringKind: TTypeKind, d: var TLoc) =
     var lend = genCaseSecondPass(p, t, d, labId, t.len-1)
     fixLabel(p, lend)
   else:
-    if stringKind == tyCstring:
-      genCaseGeneric(p, t, d, "", "if (#eqCstrings($1, $2)) goto $3;$n")
-    else:
-      genCaseGeneric(p, t, d, "", "if (#eqStrings($1, $2)) goto $3;$n")
+    let eqFn = cgsymValue(p.module,
+      if stringKind == tyCstring: "eqCstrings"
+      else: "eqStrings")
+    genCaseGeneric(p, t, d):
+      discard
+    do:
+      p.s(cpsStmts).addSingleIfStmt(
+          cCall(eqFn, ra, rb)):
+        p.s(cpsStmts).addGoto(rlabel)
 
 proc branchHasTooBigRange(b: PNode): bool =
   result = false
@@ -1054,10 +1062,17 @@ proc genOrdinalCase(p: BProc, n: PNode, d: var TLoc) =
 
   # generate if part (might be empty):
   var a: TLoc = initLocExpr(p, n[0])
-  var lend = if splitPoint > 0: genIfForCaseUntil(p, n, d,
-                    rangeFormat = "if ($1 >= $2 && $1 <= $3) goto $4;$n",
-                    eqFormat = "if ($1 == $2) goto $3;$n",
-                    splitPoint, a) else: ""
+  var lend: TLabel = ""
+  if splitPoint > 0:
+    lend = genIfForCaseUntil(p, n, d, splitPoint, a):
+      p.s(cpsStmts).addSingleIfStmt(cOp(And,
+          cOp(GreaterEqual, ra, rb),
+          cOp(LessEqual, ra, rc))):
+        p.s(cpsStmts).addGoto(rlabel)
+    do:
+      p.s(cpsStmts).addSingleIfStmt(
+          removeSinglePar(cOp(Equal, ra, rb))):
+        p.s(cpsStmts).addGoto(rlabel)
 
   # generate switch part (might be empty):
   if splitPoint+1 < n.len:
@@ -1098,8 +1113,15 @@ proc genCase(p: BProc, t: PNode, d: var TLoc) =
   of tyCstring:
     genStringCase(p, t, tyCstring, d)
   of tyFloat..tyFloat128:
-    genCaseGeneric(p, t, d, "if ($1 >= $2 && $1 <= $3) goto $4;$n",
-                            "if ($1 == $2) goto $3;$n")
+    genCaseGeneric(p, t, d):
+      p.s(cpsStmts).addSingleIfStmt(cOp(And,
+          cOp(GreaterEqual, ra, rb),
+          cOp(LessEqual, ra, rc))):
+        p.s(cpsStmts).addGoto(rlabel)
+    do:
+      p.s(cpsStmts).addSingleIfStmt(
+          removeSinglePar(cOp(Equal, ra, rb))):
+        p.s(cpsStmts).addGoto(rlabel)
   else:
     if t[0].kind == nkSym and sfGoto in t[0].sym.flags:
       genGotoForCase(p, t)