From c5d837d2cd9a57e453da9eaab0e41e0c185e084e Mon Sep 17 00:00:00 2001
From: lemon <lsof@mailbox.org>
Date: Thu, 4 Aug 2022 10:07:13 +0200
Subject: fold & more

---
 bootstrap/types.c | 122 ++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 122 insertions(+)

(limited to 'bootstrap/types.c')

diff --git a/bootstrap/types.c b/bootstrap/types.c
index 8e735d0..401f9e6 100644
--- a/bootstrap/types.c
+++ b/bootstrap/types.c
@@ -206,3 +206,125 @@ visittypes(void (*visitor)(const struct type *, void *), void *arg) {
       for (struct typesnode *n = types.buckets[i]; n; n = n->next)
          visitor(&n->ty, arg);
 }
+
+const struct type *
+constify(const struct type *ty) {
+   struct type ty2 = *ty;
+   if (ty->konst)
+      return ty;
+   if (ty2.t != TYfn)
+      ty2.konst = 1;
+   return interntype(ty2);
+}
+
+const struct type *
+unconstify(const struct type *ty) {
+   struct type ty2 = *ty;
+   if (!ty->konst)
+      return ty;
+   ty2.konst = 0;
+   return interntype(ty2);
+}
+
+const struct type *
+constifychild(const struct type *ty) {
+   struct type ty2 = *ty;
+   const struct type *child = constify(ty->child);
+   if (child == ty->child)
+      return ty;
+   ty2.child = child;
+   return interntype(ty2);
+}
+
+static const struct type *
+arraydecay(const struct type *ty) {
+   struct type ty2 = *ty;
+
+   if (ty->t != TYarr)
+      return ty;
+   
+   ty2.t = TYptr;
+   return interntype(ty2);
+}
+
+int
+numtype2rank(const struct type *a) {
+   if (a->t == TYint) {
+      if (a->size < g_targ.intsize || a == ty_int)
+         return 0;
+      if (a == ty_uint) return 1;
+      if (a == ty_i32) return 2;
+      if (a == ty_u32) return 3;
+      if (a == ty_i64) return 4;
+      if (a == ty_u64) return 5;
+   }
+   if (a == ty_f32) return 6;
+   if (a == ty_f64) return 7;
+   return -1;
+}
+
+const struct type *
+rank2numtype(int r) {
+   static const struct type **types[] = {
+      &ty_int, &ty_uint, &ty_i32, &ty_u32,
+      &ty_i64, &ty_u64, &ty_f32, &ty_f64,
+   };
+   assert(r >= 0 && r < ARRAY_LENGTH(types));
+   return *types[r];
+}
+
+bool
+isnumtype(const struct type *a) {
+   return a->t == TYint || a->t == TYfloat;
+}
+
+// peer type resolution
+const struct type *
+typeof2(const struct type *a, const struct type *b) {
+   if (isnumtype(a) && isnumtype(b)) {
+      int ra = numtype2rank(a), rb = numtype2rank(b);
+      return rank2numtype(MAX(ra, rb));
+   }
+   if (a == b)
+      return a;
+   if (unconstify(a) == b)
+      return a;
+   if (a == unconstify(b))
+      return b;
+   if (a->t == TYarr && b->t == TYarr)
+      a = arraydecay(a);
+   if (a->t == TYptr && b->t == TYarr)
+      b = arraydecay(b);
+   if (a->t == TYarr && b->t == TYptr)
+      a = arraydecay(a);
+   if (a->t == TYptr && b->t == TYptr) {
+      bool akonst = a->child->konst,
+           bkonst = b->child->konst;
+      const struct type *uac = unconstify(a->child),
+                        *ubc = unconstify(b->child);
+      if (uac == ubc)
+         return akonst ? a : b;
+      if (uac == ty_void) {
+         if (bkonst && !akonst)
+            return constifychild(a);
+         return a;
+      }
+      if (ubc == ty_void) {
+         if (akonst && !bkonst)
+            return constifychild(b);
+         return b;
+      }
+      if (uac == ty_u8) {
+         if (bkonst && !akonst)
+            return constifychild(a);
+         return a;
+      }
+      if (ubc == ty_u8) {
+         if (akonst && !bkonst)
+            return constifychild(b);
+         return b;
+      }
+
+   }
+   return NULL;
+}
-- 
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