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* [Bug tree-optimization/42646] Jump threading breaks canonical loop forms [not found] <bug-42646-4@http.gcc.gnu.org/bugzilla/> @ 2021-08-05 21:36 ` pinskia at gcc dot gnu.org 0 siblings, 0 replies; 5+ messages in thread From: pinskia at gcc dot gnu.org @ 2021-08-05 21:36 UTC (permalink / raw) To: gcc-bugs https://gcc.gnu.org/bugzilla/show_bug.cgi?id=42646 Andrew Pinski <pinskia at gcc dot gnu.org> changed: What |Removed |Added ---------------------------------------------------------------------------- Keywords| |missed-optimization --- Comment #5 from Andrew Pinski <pinskia at gcc dot gnu.org> --- This seems to finally have been fixed on the trunk. ^ permalink raw reply [flat|nested] 5+ messages in thread
* [Bug tree-optimization/42646] New: Jump threading breaks canonical loop forms @ 2010-01-07 14:27 joefoxreal at gmail dot com 2010-01-07 14:29 ` [Bug tree-optimization/42646] " joefoxreal at gmail dot com ` (3 more replies) 0 siblings, 4 replies; 5+ messages in thread From: joefoxreal at gmail dot com @ 2010-01-07 14:27 UTC (permalink / raw) To: gcc-bugs pass_dominator tries to thread jumps.But sometimes this will cause that the loop's exit bb does not dominator its latch bb again. ------------------------------------- void foo (int x) { int i; for (i=0; i < 10 ; i++) if (x) { if (i == 0) fun_1 (); else fun_2 (); } } --------------------------------------- $ gcc -O3 -S foo.c $ cat foo.s .file "foo.c" .text .p2align 4,,15 .globl foo .type foo, @function foo: pushl %ebp movl %esp, %ebp pushl %ebx movl $1, %ebx subl $4, %esp movl 8(%ebp), %eax testl %eax, %eax jne .L3 addl $4, %esp popl %ebx popl %ebp ret .p2align 4,,7 .p2align 3 .L7: call fun_1 .L5: addl $1, %ebx .L3: cmpl $1, %ebx je .L7 call fun_2 cmpl $9, %ebx jle .L5 addl $4, %esp popl %ebx popl %ebp ret .size foo, .-foo .ident "GCC: (GNU) 4.5.0 20100107 (experimental)" .section .note.GNU-stack,"",@progbits ------------------------------------------- $ gcc -O3 -fno-tree-dominator-opts -S foo.c $ cat foo.s .file "foo.c" .text .p2align 4,,15 .globl foo .type foo, @function foo: pushl %ebp movl %esp, %ebp subl $8, %esp movl 8(%ebp), %eax testl %eax, %eax je .L1 call fun_1 call fun_2 .p2align 4,,5 call fun_2 .p2align 4,,5 call fun_2 .p2align 4,,5 call fun_2 .p2align 4,,5 call fun_2 .p2align 4,,5 call fun_2 .p2align 4,,5 call fun_2 .p2align 4,,5 call fun_2 leave jmp fun_2 .p2align 4,,7 .p2align 3 .L1: leave ret .size foo, .-foo .ident "GCC: (GNU) 4.5.0 20100107 (experimental)" .section .note.GNU-stack,"",@progbits ------------------------------------------- $ gcc -v Using built-in specs. COLLECT_GCC=gcc COLLECT_LTO_WRAPPER=/home/eric/install/trunk/libexec/gcc/i686-pc-linux-gnu/4.5.0/lto-wrapper Target: i686-pc-linux-gnu Configured with: ../trunk/configure --prefix=/home/eric/install/trunk --with-gmp=/home/eric/install/generic --with-mpfr=/home/eric/install/generic --with-mpc=/home/eric/install/generic/ --enable-languages=c Thread model: posix gcc version 4.5.0 20100107 (experimental) (GCC) -- Summary: Jump threading breaks canonical loop forms Product: gcc Version: tree-ssa Status: UNCONFIRMED Severity: normal Priority: P3 Component: tree-optimization AssignedTo: unassigned at gcc dot gnu dot org ReportedBy: joefoxreal at gmail dot com GCC target triplet: i686-pc-linux-gnu http://gcc.gnu.org/bugzilla/show_bug.cgi?id=42646 ^ permalink raw reply [flat|nested] 5+ messages in thread
* [Bug tree-optimization/42646] Jump threading breaks canonical loop forms 2010-01-07 14:27 [Bug tree-optimization/42646] New: " joefoxreal at gmail dot com @ 2010-01-07 14:29 ` joefoxreal at gmail dot com 2010-01-08 1:40 ` joefoxreal at gmail dot com ` (2 subsequent siblings) 3 siblings, 0 replies; 5+ messages in thread From: joefoxreal at gmail dot com @ 2010-01-07 14:29 UTC (permalink / raw) To: gcc-bugs ------- Comment #1 from joefoxreal at gmail dot com 2010-01-07 14:29 ------- Created an attachment (id=19498) --> (http://gcc.gnu.org/bugzilla/attachment.cgi?id=19498&action=view) cfg of the function foo -- http://gcc.gnu.org/bugzilla/show_bug.cgi?id=42646 ^ permalink raw reply [flat|nested] 5+ messages in thread
* [Bug tree-optimization/42646] Jump threading breaks canonical loop forms 2010-01-07 14:27 [Bug tree-optimization/42646] New: " joefoxreal at gmail dot com 2010-01-07 14:29 ` [Bug tree-optimization/42646] " joefoxreal at gmail dot com @ 2010-01-08 1:40 ` joefoxreal at gmail dot com 2010-01-08 1:42 ` joefoxreal at gmail dot com 2010-01-08 11:53 ` rguenth at gcc dot gnu dot org 3 siblings, 0 replies; 5+ messages in thread From: joefoxreal at gmail dot com @ 2010-01-08 1:40 UTC (permalink / raw) To: gcc-bugs ------- Comment #2 from joefoxreal at gmail dot com 2010-01-08 01:40 ------- Created an attachment (id=19504) --> (http://gcc.gnu.org/bugzilla/attachment.cgi?id=19504&action=view) the cfg of foo.c.079t.copyrename3 -- http://gcc.gnu.org/bugzilla/show_bug.cgi?id=42646 ^ permalink raw reply [flat|nested] 5+ messages in thread
* [Bug tree-optimization/42646] Jump threading breaks canonical loop forms 2010-01-07 14:27 [Bug tree-optimization/42646] New: " joefoxreal at gmail dot com 2010-01-07 14:29 ` [Bug tree-optimization/42646] " joefoxreal at gmail dot com 2010-01-08 1:40 ` joefoxreal at gmail dot com @ 2010-01-08 1:42 ` joefoxreal at gmail dot com 2010-01-08 11:53 ` rguenth at gcc dot gnu dot org 3 siblings, 0 replies; 5+ messages in thread From: joefoxreal at gmail dot com @ 2010-01-08 1:42 UTC (permalink / raw) To: gcc-bugs ------- Comment #3 from joefoxreal at gmail dot com 2010-01-08 01:41 ------- Created an attachment (id=19505) --> (http://gcc.gnu.org/bugzilla/attachment.cgi?id=19505&action=view) the cfg of foo.c.080t.dom1 -- http://gcc.gnu.org/bugzilla/show_bug.cgi?id=42646 ^ permalink raw reply [flat|nested] 5+ messages in thread
* [Bug tree-optimization/42646] Jump threading breaks canonical loop forms 2010-01-07 14:27 [Bug tree-optimization/42646] New: " joefoxreal at gmail dot com ` (2 preceding siblings ...) 2010-01-08 1:42 ` joefoxreal at gmail dot com @ 2010-01-08 11:53 ` rguenth at gcc dot gnu dot org 3 siblings, 0 replies; 5+ messages in thread From: rguenth at gcc dot gnu dot org @ 2010-01-08 11:53 UTC (permalink / raw) To: gcc-bugs ------- Comment #4 from rguenth at gcc dot gnu dot org 2010-01-08 11:52 ------- It just means that we shouldn't thread to the header but always to the latch block. Note that this restriction should probably be restricted to the threading before loop optimizations. Or the 1st jump threading should simply avoid to thread over backedges (equivalent to removing the 1st DOM pass - though there is interesting fallout regarding jump-threading / loop header copying pass ordering). -- http://gcc.gnu.org/bugzilla/show_bug.cgi?id=42646 ^ permalink raw reply [flat|nested] 5+ messages in thread
end of thread, other threads:[~2021-08-05 21:36 UTC | newest] Thread overview: 5+ messages (download: mbox.gz / follow: Atom feed) -- links below jump to the message on this page -- [not found] <bug-42646-4@http.gcc.gnu.org/bugzilla/> 2021-08-05 21:36 ` [Bug tree-optimization/42646] Jump threading breaks canonical loop forms pinskia at gcc dot gnu.org 2010-01-07 14:27 [Bug tree-optimization/42646] New: " joefoxreal at gmail dot com 2010-01-07 14:29 ` [Bug tree-optimization/42646] " joefoxreal at gmail dot com 2010-01-08 1:40 ` joefoxreal at gmail dot com 2010-01-08 1:42 ` joefoxreal at gmail dot com 2010-01-08 11:53 ` rguenth at gcc dot gnu dot org
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