commit 362f034c1b91d52ea2cf971314ed4e0c24348bff

Merge: 260b9b4 f5d424a

Author: Mike Pall <mike>

Date:   Sun May 20 12:28:10 2018 +0200

    Merge branch 'master' into v2.1

From f5d424afe8b9395f0df05aba905e0e1f6a2262b8 Mon Sep 17 00:00:00 2001

From: Mike Pall <mike>

Date: Sun, 20 May 2018 12:25:36 +0200

Subject: [PATCH 39/72] FFI: Make FP to U64 conversions match JIT backend

 behavior.

---

 src/lj_obj.h | 18 +++++++++++++-----

 1 file changed, 13 insertions(+), 5 deletions(-)

diff --git a/src/lj_obj.h b/src/lj_obj.h

index e70b003..2ee526c 100644

--- a/src/lj_obj.h

+++ b/src/lj_obj.h

@@ -816,14 +816,22 @@ static LJ_AINLINE int32_t lj_num2bit(lua_Number n)

 #define lj_num2int(n)   ((int32_t)(n))

+/*

+** This must match the JIT backend behavior. In particular for archs

+** that don't have a common hardware instruction for this conversion.

+** Note that signed FP to unsigned int conversions have an undefined

+** result and should never be relied upon in portable FFI code.

+** See also: C99 or C11 standard, 6.3.1.4, footnote of (1).

+*/

 static LJ_AINLINE uint64_t lj_num2u64(lua_Number n)

 {

-#ifdef _MSC_VER

-  if (n >= 9223372036854775808.0)  /* They think it's a feature. */

-    return (uint64_t)(int64_t)(n - 18446744073709551616.0);

-  else

+#if LJ_TARGET_X86ORX64 || LJ_TARGET_MIPS

+  int64_t i = (int64_t)n;

+  if (i < 0) i = (int64_t)(n - 18446744073709551616.0);

+  return (uint64_t)i;

+#else

+  return (uint64_t)n;

 #endif

-    return (uint64_t)n;

 }

 static LJ_AINLINE int32_t numberVint(cTValue *o)

-- 

2.20.1