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From: "amylaar at gcc dot gnu dot org" <gcc-bugzilla@gcc.gnu.org> To: gcc-bugs@gcc.gnu.org Subject: [Bug target/18032] [4.0.0] SH: wrong code for EH Date: Mon, 18 Oct 2004 15:49:00 -0000 [thread overview] Message-ID: <20041018154915.6726.qmail@sourceware.org> (raw) In-Reply-To: <20041016082157.18032.kkojima@gcc.gnu.org> ------- Additional Comments From amylaar at gcc dot gnu dot org 2004-10-18 15:49 ------- We don't emit call frame information for the epilogue. If we did, than any basic blocks that happen to come after the epilogue due to block reordering would end up with incorrect cfi information, since we don't have any machinery for writing compensating cfi when we skip over an epilogue. Thus, the only way we have to make this work with the current infrastructure is to avoid scheduling the epilogue with previous basic blocks when exception handling is enabled (this also affects debugging information, but I'd say we shouldn't pessimize -O2 code to get better debugging information). There is already code in sh.c:sh_expand_epilogue to emit a blockage instruction before the stack adjustments. However, if a frame pointer is needed, the initial adjustment of the frame pointer isn't adjusted, since this doesn't matter for interrupts: if (frame_pointer_needed) { output_stack_adjust (frame_size, frame_pointer_rtx, e, &live_regs_mask); /* We must avoid moving the stack pointer adjustment past code which reads from the local frame, else an interrupt could occur after the SP adjustment and clobber data in the local frame. */ emit_insn (gen_blockage ()); emit_insn (GEN_MOV (stack_pointer_rtx, frame_pointer_rtx)); } So, if flag_exceptions is set, we should emit this blockage before the frame pointer adjustment. -- What |Removed |Added ---------------------------------------------------------------------------- CC| |amylaar at gcc dot gnu dot | |org http://gcc.gnu.org/bugzilla/show_bug.cgi?id=18032
next prev parent reply other threads:[~2004-10-18 15:49 UTC|newest] Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top 2004-10-16 8:22 [Bug target/18032] New: " kkojima at gcc dot gnu dot org 2004-10-16 8:26 ` [Bug target/18032] " kkojima at gcc dot gnu dot org 2004-10-16 13:58 ` pinskia at gcc dot gnu dot org 2004-10-18 15:49 ` amylaar at gcc dot gnu dot org [this message] 2004-10-18 22:43 ` kkojima at gcc dot gnu dot org 2004-10-20 13:57 ` cvs-commit at gcc dot gnu dot org 2004-10-20 17:39 ` pinskia at gcc dot gnu dot org
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