Hi. On GNU/Linux x86, tcc built 24/10/2019, same test case produces 5.00 too.
ian. Le 27/10/2019 à 07:32, Christian Jullien a écrit : > Trying your sample with mod on Windows -m64/-m32 I get: > > c: >tcc -m32 foo.c && foo > 5.000000 > > c:>tcc -m64 foo.c && foo > 5.000000 > > It only return 3.0000 on Linux x64 (I've not tested your code on Linux x86). > > C. > > > -----Original Message----- > From: Tinycc-devel [mailto:tinycc-devel-bounces+eligis=orange...@nongnu.org] > On Behalf Of Shachaf Ben-Kiki > Sent: Saturday, October 26, 2019 12:59 > To: tinycc-devel@nongnu.org > Subject: [Tinycc-devel] SSE calling convention bug > > Hello, > > I ran into a bug in the SSE function call code in x86_64-gen.c. It's > in the following lines, in gfunc_call: > > if (sse_reg) { /* avoid redundant movaps %xmm0, %xmm0 */ > /* movaps %xmm0, %xmmN */ > o(0x280f); > o(0xc0 + (sse_reg << 3)); > /* movaps %xmm1, %xmmN */ > o(0x280f); > o(0xc1 + ((sse_reg+1) << 3)); > } > > When sse_reg is %xmm1, this generates > > 0f 28 c8 movaps %xmm0,%xmm1 > 0f 28 d1 movaps %xmm1,%xmm2 > > Such that the first mov overwrites xmm1 before the second mov uses it. > Since the registers are used in reverse order and only one or two at a > time, I think swapping the order of the movs should be sufficient to > fix it. > > Here's a test case: > > #include <stdio.h> > > struct Point { > float x; > float y; > }; > > struct Rect { > struct Point top_left; > struct Point size; > }; > > float foo(struct Point p, struct Rect r) { > return r.size.x; > } > > int main(int argc, char **argv) { > struct Point p = {1, 2}; > struct Rect r = {{3, 4}, {5, 6}}; > printf("%f\n", foo(p, r)); > return 0; > } > > This program should print 5, but it prints 3 in tcc. > > Is this the right place to post this? I can post it elsewhere, or send > a patch (it took a while to track this down but I think the fix should > be easy). > > Thanks, > Shachaf > > _______________________________________________ > 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 -- -- i...@sibian.fr -- Développeur compulsif
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