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* [Bug target/46975] New: Replace 32 bit instructions with 16 bit instructions in thumb2 @ 2010-12-16 0:39 carrot at google dot com 2010-12-16 15:25 ` [Bug target/46975] " rguenth at gcc dot gnu.org ` (3 more replies) 0 siblings, 4 replies; 5+ messages in thread From: carrot at google dot com @ 2010-12-16 0:39 UTC (permalink / raw) To: gcc-bugs http://gcc.gnu.org/bugzilla/show_bug.cgi?id=46975 Summary: Replace 32 bit instructions with 16 bit instructions in thumb2 Product: gcc Version: 4.6.0 Status: UNCONFIRMED Severity: normal Priority: P3 Component: target AssignedTo: unassigned@gcc.gnu.org ReportedBy: carrot@google.com Compile the following c code with options -march=armv7-a -mthumb -Os int gzeof (int s) { return s == 1; } GCC 4.6 generates: 00000000 <gzeof>: 0: f1a0 0301 sub.w r3, r0, #1 // A 4: 4258 negs r0, r3 6: eb40 0003 adc.w r0, r0, r3 // B a: 4770 bx lr Notice that instructions A and B are 32 bits, we can change them to subs and adcs so both will be 16 bits. The code sequence is generated by the following peephole2 8731 ;; Attempt to improve the sequence generated by the compare_scc splitters 8732 ;; not to use conditional execution. 8733 (define_peephole2 8734 [(set (reg:CC CC_REGNUM) 8735 (compare:CC (match_operand:SI 1 "register_operand" "") 8736 (match_operand:SI 2 "arm_rhs_operand" ""))) 8737 (cond_exec (ne (reg:CC CC_REGNUM) (const_int 0)) 8738 (set (match_operand:SI 0 "register_operand" "") (const_int 0))) 8739 (cond_exec (eq (reg:CC CC_REGNUM) (const_int 0)) 8740 (set (match_dup 0) (const_int 1))) 8741 (match_scratch:SI 3 "r")] 8742 "TARGET_32BIT" 8743 [(set (match_dup 3) (minus:SI (match_dup 1) (match_dup 2))) 8744 (parallel 8745 [(set (reg:CC CC_REGNUM) 8746 (compare:CC (const_int 0) (match_dup 3))) 8747 (set (match_dup 0) (minus:SI (const_int 0) (match_dup 3)))]) 8748 (set (match_dup 0) 8749 (plus:SI (plus:SI (match_dup 0) (match_dup 3)) 8750 (geu:SI (reg:CC CC_REGNUM) (const_int 0))))]) 8751 We should change the new instructions to use subs and adcs. ^ permalink raw reply [flat|nested] 5+ messages in thread
* [Bug target/46975] Replace 32 bit instructions with 16 bit instructions in thumb2 2010-12-16 0:39 [Bug target/46975] New: Replace 32 bit instructions with 16 bit instructions in thumb2 carrot at google dot com @ 2010-12-16 15:25 ` rguenth at gcc dot gnu.org 2011-04-04 21:22 ` ramana at gcc dot gnu.org ` (2 subsequent siblings) 3 siblings, 0 replies; 5+ messages in thread From: rguenth at gcc dot gnu.org @ 2010-12-16 15:25 UTC (permalink / raw) To: gcc-bugs http://gcc.gnu.org/bugzilla/show_bug.cgi?id=46975 Richard Guenther <rguenth at gcc dot gnu.org> changed: What |Removed |Added ---------------------------------------------------------------------------- Severity|normal |enhancement ^ permalink raw reply [flat|nested] 5+ messages in thread
* [Bug target/46975] Replace 32 bit instructions with 16 bit instructions in thumb2 2010-12-16 0:39 [Bug target/46975] New: Replace 32 bit instructions with 16 bit instructions in thumb2 carrot at google dot com 2010-12-16 15:25 ` [Bug target/46975] " rguenth at gcc dot gnu.org @ 2011-04-04 21:22 ` ramana at gcc dot gnu.org 2011-04-28 16:45 ` rguenth at gcc dot gnu.org 2023-05-15 5:19 ` pinskia at gcc dot gnu.org 3 siblings, 0 replies; 5+ messages in thread From: ramana at gcc dot gnu.org @ 2011-04-04 21:22 UTC (permalink / raw) To: gcc-bugs http://gcc.gnu.org/bugzilla/show_bug.cgi?id=46975 Ramana Radhakrishnan <ramana at gcc dot gnu.org> changed: What |Removed |Added ---------------------------------------------------------------------------- Keywords| |missed-optimization Status|UNCONFIRMED |NEW Last reconfirmed| |2011.04.04 21:22:11 CC| |ramana at gcc dot gnu.org Target Milestone|--- |4.7.0 Ever Confirmed|0 |1 ^ permalink raw reply [flat|nested] 5+ messages in thread
* [Bug target/46975] Replace 32 bit instructions with 16 bit instructions in thumb2 2010-12-16 0:39 [Bug target/46975] New: Replace 32 bit instructions with 16 bit instructions in thumb2 carrot at google dot com 2010-12-16 15:25 ` [Bug target/46975] " rguenth at gcc dot gnu.org 2011-04-04 21:22 ` ramana at gcc dot gnu.org @ 2011-04-28 16:45 ` rguenth at gcc dot gnu.org 2023-05-15 5:19 ` pinskia at gcc dot gnu.org 3 siblings, 0 replies; 5+ messages in thread From: rguenth at gcc dot gnu.org @ 2011-04-28 16:45 UTC (permalink / raw) To: gcc-bugs http://gcc.gnu.org/bugzilla/show_bug.cgi?id=46975 Richard Guenther <rguenth at gcc dot gnu.org> changed: What |Removed |Added ---------------------------------------------------------------------------- Target Milestone|4.7.0 |--- ^ permalink raw reply [flat|nested] 5+ messages in thread
* [Bug target/46975] Replace 32 bit instructions with 16 bit instructions in thumb2 2010-12-16 0:39 [Bug target/46975] New: Replace 32 bit instructions with 16 bit instructions in thumb2 carrot at google dot com ` (2 preceding siblings ...) 2011-04-28 16:45 ` rguenth at gcc dot gnu.org @ 2023-05-15 5:19 ` pinskia at gcc dot gnu.org 3 siblings, 0 replies; 5+ messages in thread From: pinskia at gcc dot gnu.org @ 2023-05-15 5:19 UTC (permalink / raw) To: gcc-bugs https://gcc.gnu.org/bugzilla/show_bug.cgi?id=46975 Andrew Pinski <pinskia at gcc dot gnu.org> changed: What |Removed |Added ---------------------------------------------------------------------------- Status|NEW |RESOLVED Target Milestone|--- |4.7.0 Resolution|--- |FIXED --- Comment #1 from Andrew Pinski <pinskia at gcc dot gnu.org> --- The fix was committed as r0-109399-g527e82c2679a4b but since the commit log didn't have the bug # in it, it didn't reach here. The bug # is in the changelog though. ^ permalink raw reply [flat|nested] 5+ messages in thread
end of thread, other threads:[~2023-05-15 5:19 UTC | newest] Thread overview: 5+ messages (download: mbox.gz / follow: Atom feed) -- links below jump to the message on this page -- 2010-12-16 0:39 [Bug target/46975] New: Replace 32 bit instructions with 16 bit instructions in thumb2 carrot at google dot com 2010-12-16 15:25 ` [Bug target/46975] " rguenth at gcc dot gnu.org 2011-04-04 21:22 ` ramana at gcc dot gnu.org 2011-04-28 16:45 ` rguenth at gcc dot gnu.org 2023-05-15 5:19 ` pinskia at gcc dot gnu.org
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