+Tue Jan 4 02:22:27 2000 Jeffrey A Law (law@cygnus.com)
+
+ Mon Oct 18 18:50:51 1999 Andreas Schwab <schwab@suse.de>
+ * config/m68k/m68k.h (INITIAL_FRAME_POINTER_OFFSET): Add one word
+ if the pic register is used.
+
+ Sat Sep 25 13:11:07 1999 Jeffrey A Law (law@cygnus.com)
+ * cse.c: Update comments.
+ (cse_insn): When converting a conditional/computed jump into
+ an unconditional jump, always make sure a BARRIER immediately
+ follows the converted jump. Do not delete unreachable code.
+ (cse_basic_block): Do not delete unreachable code.
+ * toplev.c (rest_of_compilation): Move call to
+ delete_trivially_dead_insns after the conditional call to
+ jump_optimize.
+
+
Wed Dec 29 22:47:43 1999 Jeffrey A Law (law@cygnus.com)
1999-12-12 Stephen L Moshier <moshier@mediaone.net>
/* Common subexpression elimination for GNU compiler.
- Copyright (C) 1987, 88, 89, 92-7, 1998, 1999 Free Software Foundation, Inc.
+ Copyright (C) 1987, 88, 89, 92-99, 2000 Free Software Foundation, Inc.
This file is part of GNU CC.
expressions encountered with the cheapest equivalent expression.
It is too complicated to keep track of the different possibilities
- when control paths merge; so, at each label, we forget all that is
- known and start fresh. This can be described as processing each
- basic block separately. Note, however, that these are not quite
- the same as the basic blocks found by a later pass and used for
- data flow analysis and register packing. We do not need to start fresh
- after a conditional jump instruction if there is no label there.
+ when control paths merge in this code; so, at each label, we forget all
+ that is known and start fresh. This can be described as processing each
+ extended basic block separately. We have a separate pass to perform
+ global CSE.
+
+ Note CSE can turn a conditional or computed jump into a nop or
+ an unconditional jump. When this occurs we arrange to run the jump
+ optimizer after CSE to delete the unreachable code.
We use two data structures to record the equivalent expressions:
a hash table for most expressions, and several vectors together
rtx new = emit_jump_insn_before (gen_jump (XEXP (src, 0)), insn);
JUMP_LABEL (new) = XEXP (src, 0);
LABEL_NUSES (XEXP (src, 0))++;
- delete_insn (insn);
insn = new;
}
else
Until the right place is found, might as well do this here. */
INSN_CODE (insn) = -1;
- /* Now that we've converted this jump to an unconditional jump,
- there is dead code after it. Delete the dead code until we
- reach a BARRIER, the end of the function, or a label. Do
- not delete NOTEs except for NOTE_INSN_DELETED since later
- phases assume these notes are retained. */
-
- p = insn;
-
- while (NEXT_INSN (p) != 0
- && GET_CODE (NEXT_INSN (p)) != BARRIER
- && GET_CODE (NEXT_INSN (p)) != CODE_LABEL)
- {
- /* Note, we must update P with the return value from
- delete_insn, otherwise we could get an infinite loop
- if NEXT_INSN (p) had INSN_DELETED_P set. */
- if (GET_CODE (NEXT_INSN (p)) != NOTE
- || NOTE_LINE_NUMBER (NEXT_INSN (p)) == NOTE_INSN_DELETED)
- p = PREV_INSN (delete_insn (NEXT_INSN (p)));
- else
- p = NEXT_INSN (p);
- }
-
- /* If we don't have a BARRIER immediately after INSN, put one there.
- Much code assumes that there are no NOTEs between a JUMP_INSN and
- BARRIER. */
-
- if (NEXT_INSN (insn) == 0
- || GET_CODE (NEXT_INSN (insn)) != BARRIER)
- emit_barrier_before (NEXT_INSN (insn));
-
- /* We might have two BARRIERs separated by notes. Delete the second
- one if so. */
-
- if (p != insn && NEXT_INSN (p) != 0
- && GET_CODE (NEXT_INSN (p)) == BARRIER)
- delete_insn (NEXT_INSN (p));
+ /* Now emit a BARRIER after the unconditional jump. Do not bother
+ deleting any unreachable code, let jump/flow do that. */
+ if (NEXT_INSN (insn) != 0
+ && GET_CODE (NEXT_INSN (insn)) != BARRIER)
+ emit_barrier_after (insn);
cse_jumps_altered = 1;
sets[i].rtl = 0;
insn = NEXT_INSN (to);
- if (LABEL_NUSES (to) == 0)
- insn = delete_insn (to);
-
/* If TO was the last insn in the function, we are done. */
if (insn == 0)
return 0;
/* Top level of GNU C compiler
- Copyright (C) 1987, 88, 89, 92-98, 1999 Free Software Foundation, Inc.
+ Copyright (C) 1987, 88, 89, 92-99, 2000 Free Software Foundation, Inc.
This file is part of GNU CC.
TIMEVAR (cse_time, tem = cse_main (insns, max_reg_num (),
0, rtl_dump_file));
- TIMEVAR (cse_time, delete_trivially_dead_insns (insns, max_reg_num ()));
-
if (tem || optimize > 1)
TIMEVAR (jump_time, jump_optimize (insns, !JUMP_CROSS_JUMP,
!JUMP_NOOP_MOVES,
!JUMP_AFTER_REGSCAN));
+ /* Run this after jump optmizations remove all the unreachable code
+ so that unreachable code will not keep values live. */
+ TIMEVAR (cse_time, delete_trivially_dead_insns (insns, max_reg_num ()));
+
/* Dump rtl code after cse, if we are doing that. */
if (cse_dump)
projects / thirdparty / gcc.git / commitdiff
