Thank you for your time to investigate this. If you're really confident this is the right patch to apply, you can push it on mod as well as the other test which exhibits the bug on Windows x64.
Then, I'll retest on all platforms I have access to. If you still have doubt, let tcc official maintainers have an eye on it. Christian From: Tinycc-devel [mailto:tinycc-devel-bounces+eligis=orange...@nongnu.org] On Behalf Of Pursuer Sent: Wednesday, October 23, 2019 16:26 To: tinycc-devel Subject: *** SPAM *** Re: [Tinycc-devel] core dump because stack overwritten It seem to be a issue for all 64bit architectures. I advise to use PTR_SIZE == 8, like below. -------------------------- --- a/tccgen.c 2019-10-22 19:52:48.761977245 +0200 +++ b/tccgen.c 2019-10-23 11:18:14.871290060 +0200 @@ -2627,7 +2627,9 @@ static void gen_cvt_ftoi1(int t) gfunc_call(1); vpushi(0); vtop->r = REG_IRET; +#if PTR_SIZE == 8 /* REG_LRET only for VT_QLONG */ vtop->r2 = REG_LRET; +#endif } else { gen_cvt_ftoi(t); } -------------------------- Windows calling convention is different from System V, This may be the reason why test case happend to work on Windows. But this bug can be shown by another way. void test(unsigned long long a,unsigned long long c); int main(int argc,char *argv[]){ long long a; test((unsigned long long)a/1.0,(unsigned long long)a/1.0); return 0; } compile and then disassemble it. 22: f3 0f 7e 0d 00 00 00 movq 0x0(%rip),%xmm1 # 2a <main+0x2a> 29: 00 2a: f2 0f 5e c1 divsd %xmm1,%xmm0 2e: 66 49 0f 7e c2 movq %xmm0,%r10 33: 4c 89 d1 mov %r10,%rcx 36: e8 00 00 00 00 callq 3b <main+0x3b> 3b: 48 8b 4d f8 mov -0x8(%rbp),%rcx 3f: 49 89 ca mov %rcx,%r10 42: 48 89 45 f0 mov %rax,-0x10(%rbp) 46: 48 89 55 f8 mov %rdx,-0x8(%rbp) ### RDX should not be saved 4a: 4c 89 d1 mov %r10,%rcx 4d: e8 00 00 00 00 callq 52 <main+0x52> tcc should have saved only RAX(the return value of __fixunsdfdi). But in fact RDX is also saved. ------------------ Original ------------------ From: "Christian Jullien"<eli...@orange.fr>; Date: Wed, Oct 23, 2019 05:50 PM To: "tinycc-devel"<tinycc-devel@nongnu.org>;"jullien"<jull...@eligis.com>; Cc: "'Herman ten Brugge'"<hermantenbru...@home.nl>; Subject: Re: [Tinycc-devel] core dump because stack overwritten Again I've no idea of the best patch to apply, but two remarks: * First, 106_pthread.c fails on Windows because of: Test: 106_pthread... --- 106_pthread.expect 2019-10-22 20:47:55.982574300 +0200 +++ 106_pthread.output 2019-10-23 11:40:46.742218000 +0200 @@ -1 +1,2 @@ -ok +In file included from 106_pthread.c:2: +106_pthread.c:2: error: include file 'pthread.h' not found You should run this test only on Linux systems * Your new patch test TCC_TARGET_X86_64, how do you explain that with or without this patch your test case looks to work on Windows x64 and produces "42 42"? -----Original Message----- From: Tinycc-devel [mailto:tinycc-devel-bounces+eligis=orange...@nongnu.org] On Behalf Of Herman ten Brugge via Tinycc-devel Sent: Wednesday, October 23, 2019 11:23 To: jull...@eligis.com; tinycc-devel@nongnu.org Cc: Herman ten Brugge Subject: Re: [Tinycc-devel] core dump because stack overwritten How about this patch: -------------------------- --- a/tccgen.c 2019-10-22 19:52:48.761977245 +0200 +++ b/tccgen.c 2019-10-23 11:18:14.871290060 +0200 @@ -2627,7 +2627,9 @@ static void gen_cvt_ftoi1(int t) gfunc_call(1); vpushi(0); vtop->r = REG_IRET; +#if !defined(TCC_TARGET_X86_64) /* REG_LRET only for VT_QLONG */ vtop->r2 = REG_LRET; +#endif } else { gen_cvt_ftoi(t); } -------------------------- According to https://en.wikipedia.org/wiki/X86_calling_conventions the x86_64 only uses rax for 64 bits returns. Herman On 2019-10-23 07:20, Christian Jullien wrote: > I confirm your test case fails on Linux x64. It looks your patch pay attention to PTR_SIZE == 4 (i.e. it now enters if only with 32bit processor). > However, w.o. the patch I can't reproduce the core dump on aarch64 Linux nor with Windows x64 which are also a 64bit processors. They both correctly display "42 42" > No core dumps does not mean it works, memory may be corrupted somewhere else. > > Either your patch is only required for Linux x64 or there is something to investigate more carefully. > > I can only test on different platforms but I'm unable to give you further advices. > > M2c > > C. > > -----Original Message----- > From: Tinycc-devel [mailto:tinycc-devel-bounces+eligis=orange...@nongnu.org] On Behalf Of Herman ten Brugge via Tinycc-devel > Sent: Tuesday, October 22, 2019 22:15 > To: tinycc-devel@nongnu.org > Cc: Herman ten Brugge > Subject: [Tinycc-devel] core dump because stack overwritten > > I have a small testcase: > > -------------- > #include <stdio.h> > #include <stdlib.h> > #include <inttypes.h> > > int > main(void) > { > struct tst_struct { uint64_t cnt; } *tst = > (struct tst_struct *) malloc (sizeof (struct tst_struct)); > > tst->cnt = 42; > printf ("%" PRIu64 " %" PRIu64 "\n", tst->cnt, (uint64_t) (tst->cnt / > 1.0)); > return 0; > } > ---------------- > when I compile this with tcc and run it I get a core dump. The problem > is that the stack is overwritten. > I have a fix. > > ------------------------ > --- a/tccgen.c 2019-10-22 19:52:48.761977245 +0200 > +++ b/tccgen.c 2019-10-22 22:08:08.465825842 +0200 > @@ -1203,7 +1203,7 @@ ST_FUNC void save_reg_upstack(int r, int > } > #endif > /* special long long case */ > - if ((p->r2 & VT_VALMASK) < VT_CONST) { > + if (PTR_SIZE == 4 && (p->r2 & VT_VALMASK) < VT_CONST) { > sv.c.i += PTR_SIZE; > store(p->r2, &sv); > } > --------------------- > But am not sure if this is the correct fix. The code generator is quite > complex. > > Herman > > > _______________________________________________ > Tinycc-devel mailing list > Tinycc-devel@nongnu.org > https://lists.nongnu.org/mailman/listinfo/tinycc-devel > _______________________________________________ Tinycc-devel mailing list Tinycc-devel@nongnu.org https://lists.nongnu.org/mailman/listinfo/tinycc-devel _______________________________________________ Tinycc-devel mailing list Tinycc-devel@nongnu.org https://lists.nongnu.org/mailman/listinfo/tinycc-devel
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