Than you for your recent patch on mod. I just have a little remark about ' 109_sse_calling' file name. This new test is executed also on Windows and arm32/64 (which is fine). However, those backend don't use sse. IMHO, this test should not have sse in its name but a comment could explain that the test revealed a bug when see is used as with Linux.
Another solution is to add this new test in 22_floating_point + comment about sse -----Original Message----- From: Tinycc-devel [mailto:tinycc-devel-bounces+eligis=orange...@nongnu.org] On Behalf Of Michael Matz Sent: Monday, October 28, 2019 10:32 To: Herman ten Brugge via Tinycc-devel Cc: Herman ten Brugge Subject: *** SPAM *** Re: [Tinycc-devel] SSE calling convention bug Hi, On Sun, 27 Oct 2019, Herman ten Brugge via Tinycc-devel wrote: > Look like the code in x86_64-gen.c is wrong. It should read: > > if (sse_reg) { /* avoid redundant movaps %xmm0, %xmm0 > */ > /* movaps %xmm1, %xmmN */ > o(0x280f); > o(0xc1 + ((sse_reg+1) << 3)); > /* movaps %xmm0, %xmmN */ > o(0x280f); > o(0xc0 + (sse_reg << 3)); > } Yes. Ciao, Michael. > > The problem occurs when sse_reg == 1. Because then xmm1 is overwritten > before it is copied. > > Herman > > On 2019-10-27 07:32, Christian Jullien wrote: > > 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 > > _______________________________________________ Tinycc-devel mailing list Tinycc-devel@nongnu.org https://lists.nongnu.org/mailman/listinfo/tinycc-devel
