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From: "rearnsha at gcc dot gnu dot org" <gcc-bugzilla@gcc.gnu.org> To: gcc-bugs@gcc.gnu.org Subject: [Bug rtl-optimization/15342] [arm-linux] internal compiler error: in verify_local_live_at_start Date: Fri, 29 Oct 2004 16:44:00 -0000 [thread overview] Message-ID: <20041029164410.20070.qmail@sourceware.org> (raw) In-Reply-To: <20040508184142.15342.pb@gcc.gnu.org> ------- Additional Comments From rearnsha at gcc dot gnu dot org 2004-10-29 16:43 ------- I think the key to what has failed here is that the reg-rename pass has missed the equivalence between start->index and a member of the copied structure. In pseudo code, the output from the previous pass has the following instructions r2 := [ip+8]/4 cc := cmp r2, #0 ne(cc): r0, r1, r2 := [r0]/12 ne(cc): [ip]/12 := r0, r1, r2 // Note [ip+8]/4 set to new r2 ... cc := cmp r2, #1 // ...so no need to reload it here gt(cc): r3 := #0 gt(cc): [ip+8]/4 := r3 return Note that r2 is updated by the first conditional instruction (a conditional ldm on ARM). The conditional move code on ARM uses hard registers, but CSE has clearly noticed this equivalence at some point and merged the two uses to avoid a redundant re-load of start->index. Unfortunately, rename_registers has missed this and split the two uses up again. This creates a use of r2 when it isn't correctly initialized. r1 := [ip+8]/4 cc := cmp r1, #0 ne(cc): r0, r1, r2 := [r0]/12 ne(cc): [ip]/12 := r0, r1, r2 cc := cmp r2, #1 // r2 incorrect if previous insn not exec gt(cc): r3 := #0 gt(cc): [ip+8]/4 := r3 return -- What |Removed |Added ---------------------------------------------------------------------------- Component|target |rtl-optimization http://gcc.gnu.org/bugzilla/show_bug.cgi?id=15342
next prev parent reply other threads:[~2004-10-29 16:44 UTC|newest] Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top 2004-05-08 18:41 [Bug target/15342] New: " pb at gcc dot gnu dot org 2004-05-08 18:42 ` [Bug target/15342] " pb at gcc dot gnu dot org 2004-05-08 21:51 ` belyshev at lubercy dot com 2004-05-09 13:59 ` belyshev at lubercy dot com 2004-05-09 15:25 ` pinskia at gcc dot gnu dot org 2004-10-29 16:44 ` rearnsha at gcc dot gnu dot org [this message] 2004-11-04 14:08 ` [Bug rtl-optimization/15342] " cvs-commit at gcc dot gnu dot org 2005-01-23 23:47 ` pinskia at gcc dot gnu dot org 2005-01-23 23:48 ` pinskia at gcc dot gnu dot org 2005-09-01 13:09 ` cvs-commit at gcc dot gnu dot org 2005-09-01 13:14 ` rearnsha at gcc dot gnu dot org 2005-09-01 13:15 ` pinskia at gcc dot gnu dot org
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