My remark is from principle that "a function should tell what it does and does what it tells"
-----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 29, 2019 10:37 To: tinycc-devel@nongnu.org Cc: Herman ten Brugge Subject: Re: [Tinycc-devel] SSE calling convention bug Do you mean that I should call the testcase '109_calling.c' and add a comment in this file that this is for x86_64 sse calling? This is why I called the file '109_sse_calling.c'. The file name indicates that this is only solving a bug for x86_64. Herman On 2019-10-29 08:04, Christian Jullien wrote: > 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 _______________________________________________ Tinycc-devel mailing list Tinycc-devel@nongnu.org https://lists.nongnu.org/mailman/listinfo/tinycc-devel
