From: Dmitry Bely <dmitry.bely@gmail.com>
To: caml-list@inria.fr
Subject: [Caml-list] Compiler bug?
Date: Mon, 6 Aug 2012 14:04:27 +0400 [thread overview]
Message-ID: <CAMT7qiTJD4hFd4Jr0tKCzhmR=ngN0yV9Pw6CCgEfRPP6a6DYvg@mail.gmail.com> (raw)
Trying to catch some very rare floating-point related bug I've
realized that I probably don't understand some basic things about
OCaml execution model. Let's consider the simplest function:
let add1 x = x +. 1.
For x86 it is compiled as
.CODE
ALIGN 4
PUBLIC _camlTest__add1_1008
_camlTest__add1_1008:
sub esp, 8
L100:
mov ebx, eax
L101: mov eax, _caml_young_ptr
sub eax, 12
mov _caml_young_ptr, eax
cmp eax, _caml_young_limit
jb L102
lea eax, [eax+4]
mov DWORD PTR [eax-4],2301
fld1
fadd REAL8 PTR [ebx]
fstp REAL8 PTR [eax]
add esp, 8
ret
L102: call _caml_call_gc
L103: jmp L101
X parameter is passed as a pointer to float value ([eax] which is
immediately saved to [ebx]). But If GC happens (L102), float value can
be moved around the OCaml heap and [ebx] become invalid, right? So the
generated code is just wrong. Am I missing something?
- Dmitry Bely
next reply other threads:[~2012-08-06 10:04 UTC|newest]
Thread overview: 30+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-08-06 10:04 Dmitry Bely [this message]
2012-08-06 10:11 ` Alain Frisch
2012-08-06 10:20 ` Dmitry Bely
2012-08-06 10:34 ` Alain Frisch
2012-08-06 11:03 ` Dmitry Bely
2012-08-06 11:32 ` Alain Frisch
2012-08-06 12:16 ` Dmitry Bely
2012-08-07 1:35 ` Cedric Cellier
2012-08-08 16:03 ` Dmitry Bely
2012-08-08 18:03 ` Alain Frisch
2012-08-08 18:22 ` Jesper Louis Andersen
2012-08-08 18:40 ` Dmitry Bely
2012-08-08 19:29 ` Fabrice Le Fessant
2012-08-08 23:34 ` Anil Madhavapeddy
2012-08-09 0:53 ` Francois Berenger
-- strict thread matches above, loose matches on Subject: below --
2006-05-17 23:14 compiler bug? Dan Koppel
2006-05-17 23:33 ` [Caml-list] " John Carr
2006-05-18 17:15 ` Xavier Leroy
2006-05-18 17:34 ` Jacques Carette
2006-05-18 17:46 ` Xavier Leroy
2006-05-18 19:31 ` Jacques Carette
2006-05-18 20:07 ` David Brown
2006-05-18 20:15 ` Jacques Carette
2006-05-18 20:20 ` Alain Frisch
2006-05-18 18:19 ` skaller
2006-05-18 18:53 ` Jacques Carette
2006-05-19 1:47 ` skaller
2006-05-19 2:17 ` Brian Hurt
2006-05-19 3:11 ` skaller
2006-05-19 16:48 ` Jacques Carette
2006-05-19 19:10 ` skaller
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