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From: "olegendo at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org> To: gcc-bugs@gcc.gnu.org Subject: [Bug target/54272] [SH] Add support for addv / subv instructions Date: Thu, 16 Aug 2012 20:35:00 -0000 [thread overview] Message-ID: <bug-54272-4-WprEP57DHM@http.gcc.gnu.org/bugzilla/> (raw) In-Reply-To: <bug-54272-4@http.gcc.gnu.org/bugzilla/> http://gcc.gnu.org/bugzilla/show_bug.cgi?id=54272 Oleg Endo <olegendo at gcc dot gnu.org> changed: What |Removed |Added ---------------------------------------------------------------------------- Status|UNCONFIRMED |ASSIGNED Last reconfirmed| |2012-08-16 Ever Confirmed|0 |1 --- Comment #5 from Oleg Endo <olegendo at gcc dot gnu.org> 2012-08-16 20:34:53 UTC --- Regarding saturating arithmetic, I took the function FIXED_SSADD from libgcc/fixed-bit.c and substituted FIXED_C_TYPE with int. int test_01 (int a, int b) { int c; int x, y, z; x = a; y = b; z = x + y; if ((((x ^ y) >> 31) & 1) == 0) { if (((z ^ x) >> 31) & 1) { z = 1; z = z << 31; if (x >= 0) z--; } } c = z; return c; } compiled with -O2 -m4 -ml: div0s r4,r5 mov r4,r0 bt/s .L4 add r5,r0 div0s r0,r4 bt/s .L6 cmp/pz r4 .L4: rts nop .align 1 .L6: mov.l .L7,r0 movt r1 rts sub r1,r0 .L8: .align 2 .L7: .long -2147483648 In this case combine can successfully match the div0s sign comparison patterns that I added in PR 52933. However, after matching those, it does not try to combine the patterns any further (probably because of the conditional branches). I guess this would be a job for an optimization at the GIMPLE level.
next prev parent reply other threads:[~2012-08-16 20:35 UTC|newest] Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top 2012-08-15 16:03 [Bug target/54272] New: " olegendo at gcc dot gnu.org 2012-08-15 16:17 ` [Bug target/54272] " olegendo at gcc dot gnu.org 2012-08-16 11:24 ` kkojima at gcc dot gnu.org 2012-08-16 12:43 ` olegendo at gcc dot gnu.org 2012-08-16 13:00 ` kkojima at gcc dot gnu.org 2012-08-16 20:35 ` olegendo at gcc dot gnu.org [this message] 2013-09-19 11:07 ` olegendo at gcc dot gnu.org 2014-07-24 19:23 ` olegendo at gcc dot gnu.org 2014-11-16 2:26 ` olegendo at gcc dot gnu.org
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