From d79251d487b57ea0e3b10640747eed723a06365c Mon Sep 17 00:00:00 2001
From: lemon <lsof@mailbox.org>
Date: Sun, 23 Nov 2025 20:20:31 +0100
Subject: implement cvtfXu64 by lowering it in builder

this should probably be in a separate pass?
---
 ir/builder.c | 55 ++++++++++++++++++++++++++++++++++++++++++++++---------
 test/flt.c   |  4 ++--
 2 files changed, 48 insertions(+), 11 deletions(-)

diff --git a/ir/builder.c b/ir/builder.c
index b177a39..752c1bc 100644
--- a/ir/builder.c
+++ b/ir/builder.c
@@ -73,21 +73,24 @@ irbinop(struct function *fn, enum op op, enum irclass k, union ref l, union ref
       if (r.bits == l.bits && kisint(k))
          return ZEROREF;
       break;
-   case Olth:
-      break;
-   case Ogth:
-      break;
-   case Olte:
-      break;
-   case Ogte:
+   case Olth: case Ogth:
+   case Olte: case Ogte:
       break;
    case Oulth:
+      if (r.bits == ZEROREF.bits) /* x u< 0 ==> f */
+         return ZEROREF;
       break;
    case Ougth:
+      if (l.bits == ZEROREF.bits) /* 0 u> x ==> f */
+         return ZEROREF;
       break;
    case Oulte:
+      if (l.bits == ZEROREF.bits) /* 0 u<= x ==> f */
+         return ONE;
       break;
    case Ougte:
+      if (r.bits == ZEROREF.bits) /* x u>= 0 ==> f */
+         return ONE;
       break;
    default:
       assert(!"binop?");
@@ -95,6 +98,31 @@ irbinop(struct function *fn, enum op op, enum irclass k, union ref l, union ref
    return addinstr(fn, mkinstr(op, k, l, r));
 }
 
+/* implements f32/f64 -> u64 conversion */
+static union ref
+cvtfu64(struct function *fn, enum irclass from, union ref x)
+{
+   struct block *t, *f, *merge;
+   union ref tmp, phiarg[2];
+   /* if (x < 2p63) cvtfXs(x) else (cvtfXs(x - 2p63) | (1<<63)) */
+   union ref max = mkfltcon(from, 0x1.0p63);
+   enum op cvt = from == KF32 ? Ocvtf32s : Ocvtf64s;
+   putcondbranch(fn, irbinop(fn, Olth, from, x, max), t = newblk(fn), f = newblk(fn));
+
+   useblk(fn, t);
+   phiarg[0] = irunop(fn, cvt, KI64, x);
+   putbranch(fn, merge = newblk(fn));
+
+   useblk(fn, f);
+   tmp = irbinop(fn, Osub, from, x, max);
+   tmp = irunop(fn, cvt, KI64, tmp);
+   phiarg[1] = irbinop(fn, Oior, KI64, tmp, mkintcon(KI64, 1ull<<63));
+   putbranch(fn, merge);
+
+   useblk(fn, merge);
+   return addphi(fn, KI64, phiarg);
+}
+
 union ref
 irunop(struct function *fn, enum op op, enum irclass k, union ref a)
 {
@@ -112,8 +140,17 @@ irunop(struct function *fn, enum op op, enum irclass k, union ref a)
       if (ins && ins->op == Onot) /* ~(~x) ==> x */
          return ins->l;
       break;
-   case Ocvtf32s: case Ocvtf32u: case Ocvtf32f64: case Ocvtf64s:
-   case Ocvtf64u: case Ocvtf64f32: case Ocvts32f: case Ocvtu32f:
+   case Ocvtf32s: case Ocvtf32f64: case Ocvtf64s:
+      break;
+   case Ocvtf32u: case Ocvtf64u:
+      if (k == KI64) {
+         /* XXX some architectures like arm64 do have these instructions natively
+          * this should probably be handled in a separate "arithmetic-lowering" pass, earlier than isel
+          */
+         return cvtfu64(fn, op == Ocvtf32u ? KF32 : KF64, a);
+      }
+      break;
+   case Ocvtf64f32: case Ocvts32f: case Ocvtu32f:
    case Ocvts64f: case Ocvtu64f:
    case Oexts8: case Oextu8: case Oexts16: case Oextu16:
    case Oexts32: case Oextu32:
diff --git a/test/flt.c b/test/flt.c
index 7866c10..2ae773d 100644
--- a/test/flt.c
+++ b/test/flt.c
@@ -18,8 +18,8 @@ u32 f32_to_u32(f32 x) { return x; }
 s32 f64_to_s32(f64 x) { return x; }
 u32 f64_to_u32(f64 x) { return x; }
 s64 f32_to_s64(f32 x) { return x; }
-//u64 f32_to_u64(f32 x) { return x; }
+u64 f32_to_u64(f32 x) { return x; }
 s64 f64_to_s64(f64 x) { return x; }
-//u64 f64_to_u64(f64 x) { return x; }
+u64 f64_to_u64(f64 x) { return x; }
 f32 f64_to_f32(f64 x) { return x; }
 f64 f32_to_f64(f32 x) { return x; }
-- 
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