From 53586d1f32dfe4f2e859178a3e43a6614520763f Mon Sep 17 00:00:00 2001
From: konsumlamm <44230978+konsumlamm@users.noreply.github.com>
Date: Sun, 6 Aug 2023 14:24:35 +0200
Subject: [PATCH] Fix some jsgen bugs (#22330)

Fix `succ`, `pred`
Fix `genRangeChck` for unsigned ints
Fix typo in `dec`
---
 compiler/jsgen.nim          | 53 +++++++++++++++++++++++++++++++------
 compiler/semmagic.nim       |  4 ---
 tests/int/tunsignedconv.nim | 36 ++++++++++++++++++-------
 3 files changed, 72 insertions(+), 21 deletions(-)

diff --git a/compiler/jsgen.nim b/compiler/jsgen.nim
index a5f4d29b27..f4d7d64563 100644
--- a/compiler/jsgen.nim
+++ b/compiler/jsgen.nim
@@ -676,8 +676,38 @@ proc arithAux(p: PProc, n: PNode, r: var TCompRes, op: TMagic) =
       applyFormat("modInt64($1, $2)", "$1 % $2")
     else:
       applyFormat("modInt($1, $2)", "Math.trunc($1 % $2)")
-  of mSucc: applyFormat("addInt($1, $2)", "($1 + $2)")
-  of mPred: applyFormat("subInt($1, $2)", "($1 - $2)")
+  of mSucc:
+    let typ = n[1].typ.skipTypes(abstractVarRange)
+    case typ.kind
+    of tyUInt..tyUInt32:
+      binaryUintExpr(p, n, r, "+")
+    of tyUInt64:
+      if optJsBigInt64 in p.config.globalOptions:
+        applyFormat("BigInt.asUintN(64, $1 + BigInt($2))")
+      else: binaryUintExpr(p, n, r, "+")
+    elif typ.kind == tyInt64 and optJsBigInt64 in p.config.globalOptions:
+      if optOverflowCheck notin p.options:
+        applyFormat("BigInt.asIntN(64, $1 + BigInt($2))")
+      else: binaryExpr(p, n, r, "addInt64", "addInt64($1, BigInt($2))")
+    else:
+      if optOverflowCheck notin p.options: applyFormat("$1 + $2")
+      else: binaryExpr(p, n, r, "addInt", "addInt($1, $2)")
+  of mPred:
+    let typ = n[1].typ.skipTypes(abstractVarRange)
+    case typ.kind
+    of tyUInt..tyUInt32:
+      binaryUintExpr(p, n, r, "-")
+    of tyUInt64:
+      if optJsBigInt64 in p.config.globalOptions:
+        applyFormat("BigInt.asUintN(64, $1 - BigInt($2))")
+      else: binaryUintExpr(p, n, r, "-")
+    elif typ.kind == tyInt64 and optJsBigInt64 in p.config.globalOptions:
+      if optOverflowCheck notin p.options:
+        applyFormat("BigInt.asIntN(64, $1 - BigInt($2))")
+      else: binaryExpr(p, n, r, "subInt64", "subInt64($1, BigInt($2))")
+    else:
+      if optOverflowCheck notin p.options: applyFormat("$1 - $2")
+      else: binaryExpr(p, n, r, "subInt", "subInt($1, $2)")
   of mAddF64: applyFormat("($1 + $2)", "($1 + $2)")
   of mSubF64: applyFormat("($1 - $2)", "($1 - $2)")
   of mMulF64: applyFormat("($1 * $2)", "($1 * $2)")
@@ -2346,7 +2376,7 @@ proc genMagic(p: PProc, n: PNode, r: var TCompRes) =
     of tyUInt64:
       if optJsBigInt64 in p.config.globalOptions:
         binaryExpr(p, n, r, "", "$1 = BigInt.asUintN(64, $3 - BigInt($2))", true)
-      else: binaryUintExpr(p, n, r, "+", true)
+      else: binaryUintExpr(p, n, r, "-", true)
     elif typ.kind == tyInt64 and optJsBigInt64 in p.config.globalOptions:
       if optOverflowCheck notin p.options:
         binaryExpr(p, n, r, "", "$1 = BigInt.asIntN(64, $3 - BigInt($2))", true)
@@ -2564,12 +2594,19 @@ proc genRangeChck(p: PProc, n: PNode, r: var TCompRes, magic: string) =
   gen(p, n[0], r)
   let src = skipTypes(n[0].typ, abstractVarRange)
   let dest = skipTypes(n.typ, abstractVarRange)
-  if src.kind in {tyInt64, tyUInt64} and dest.kind notin {tyInt64, tyUInt64} and optJsBigInt64 in p.config.globalOptions:
-    r.res = "Number($1)" % [r.res]
-  if optRangeCheck notin p.options or (dest.kind in {tyUInt..tyUInt64} and
-      checkUnsignedConversions notin p.config.legacyFeatures):
-    discard "XXX maybe emit masking instructions here"
+  if optRangeCheck notin p.options:
+    return
+  elif dest.kind in {tyUInt..tyUInt64} and checkUnsignedConversions notin p.config.legacyFeatures:
+    if src.kind in {tyInt64, tyUInt64} and optJsBigInt64 in p.config.globalOptions:
+      r.res = "BigInt.asUintN($1, $2)" % [$(dest.size * 8), r.res]
+    else:
+      r.res = "BigInt.asUintN($1, BigInt($2))" % [$(dest.size * 8), r.res]
+    if not (dest.kind == tyUInt64 and optJsBigInt64 in p.config.globalOptions):
+      r.res = "Number($1)" % [r.res]
   else:
+    if src.kind in {tyInt64, tyUInt64} and dest.kind notin {tyInt64, tyUInt64} and optJsBigInt64 in p.config.globalOptions:
+      # we do a range check anyway, so it's ok if the number gets rounded
+      r.res = "Number($1)" % [r.res]
     gen(p, n[1], a)
     gen(p, n[2], b)
     useMagic(p, "chckRange")
diff --git a/compiler/semmagic.nim b/compiler/semmagic.nim
index 97a3207744..4fba4eaf92 100644
--- a/compiler/semmagic.nim
+++ b/compiler/semmagic.nim
@@ -656,10 +656,6 @@ proc magicsAfterOverloadResolution(c: PContext, n: PNode,
     if not checkIsolate(n[1]):
       localError(c.config, n.info, "expression cannot be isolated: " & $n[1])
     result = n
-  of mPred:
-    if n[1].typ.skipTypes(abstractInst).kind in {tyUInt..tyUInt64}:
-      n[0].sym.magic = mSubU
-    result = n
   of mPrivateAccess:
     result = semPrivateAccess(c, n)
   of mArrToSeq:
diff --git a/tests/int/tunsignedconv.nim b/tests/int/tunsignedconv.nim
index c32f85b4dc..6c73521d38 100644
--- a/tests/int/tunsignedconv.nim
+++ b/tests/int/tunsignedconv.nim
@@ -1,15 +1,19 @@
+discard """
+  targets: "c cpp js"
+"""
+
 # Tests unsigned literals and implicit conversion between uints and ints
 
-var h8:uint8 = 128
-var h16:uint16 = 32768
-var h32:uint32 = 2147483648'u32
-var h64:uint64 = 9223372036854775808'u64
-var foobar:uint64 = 9223372036854775813'u64 # Issue 728
+var h8: uint8 = 128
+var h16: uint16 = 32768
+var h32: uint32 = 2147483648'u32
+var h64: uint64 = 9223372036854775808'u64
+var foobar: uint64 = 9223372036854775813'u64 # Issue 728
 
-var v8:uint8 = 10
-var v16:uint16 = 10
-var v32:uint32 = 10
-var v64:uint64 = 10
+var v8: uint8 = 10
+var v16: uint16 = 10
+var v32: uint32 = 10
+var v64: uint64 = 10
 
 # u8 + literal produces u8:
 var a8: uint8 = v8 + 10
@@ -95,3 +99,17 @@ template main() =
 
 static: main()
 main()
+
+block:
+  let a = uint64.high
+  let b = uint32.high
+
+  doAssert a.uint64 == a
+  doAssert a.uint32 == uint32.high
+  doAssert a.uint16 == uint16.high
+  doAssert a.uint8 == uint8.high
+
+  doAssert b.uint64 == b
+  doAssert b.uint32 == b
+  doAssert b.uint16 == uint16.high
+  doAssert b.uint8 == uint8.high