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cse.c (fold_rtx): Update comments for (const (minus (label) (label))) case.

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* cse.c (fold_rtx): Update comments for (const (minus (label) (label)))
        case.
        (cse_insn): Avoid creating a bogus REG_EQUAL note for
        (const (minus (label) (label)))
        (record_jump_cond): Fix mismatched paren in comment.
Fixes powerpc label-label problem.
Bootstraps on the x86.

Co-Authored-By: Jeffrey A Law <law@cygnus.com>

From-SVN: r25527
This commit is contained in:
Franz Sirl 1999-03-02 00:45:45 +00:00 committed by Jeff Law
parent 560a78fc8a
commit ac7ef8d56b
2 changed files with 26 additions and 4 deletions
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9
gcc/ChangeLog
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@ -1,3 +1,12 @@
Tue Mar 2 01:40:01 1999 Franz Sirl <Franz.Sirl-kernel@lauterbach.com>
Jeffrey A Law (law@cygnus.com)
* cse.c (fold_rtx): Update comments for (const (minus (label) (label)))
case.
(cse_insn): Avoid creating a bogus REG_EQUAL note for
(const (minus (label) (label)))
(record_jump_cond): Fix mismatched paren in comment.
Tue Mar 2 01:07:12 1999 Dan Nicolaescu <dann@godzilla.ics.uci.edu>
* final.c (end_final): There are 11 words in the "main header"

21
gcc/cse.c
View File

@ -5292,7 +5292,11 @@ fold_rtx (x, insn)
/* Indicate this is a constant. This isn't a
valid form of CONST, but it will only be used
to fold the next insns and then discarded, so
it should be safe. */
it should be safe.
Note this expression must be explicitly discarded,
by cse_insn, else it may end up in a REG_EQUAL note
and "escape" to cause problems elsewhere. */
return gen_rtx_CONST (GET_MODE (new), new);
}
}
@ -6037,7 +6041,7 @@ record_jump_cond (code, mode, op0, op1, reversed_nonequality)
/* If OP0 and OP1 are known equal, and either is a paradoxical SUBREG,
we know that they are also equal in the smaller mode (this is also
true for all smaller modes whether or not there is a SUBREG, but
is not worth testing for with no SUBREG. */
is not worth testing for with no SUBREG). */
/* Note that GET_MODE (op0) may not equal MODE. */
if (code == EQ && GET_CODE (op0) == SUBREG
@ -7170,9 +7174,18 @@ cse_insn (insn, libcall_insn)
equivalent constant, we want to add a REG_NOTE. We don't want
to write a REG_EQUAL note for a constant pseudo since verifying that
that pseudo hasn't been eliminated is a pain. Such a note also
won't help anything. */
won't help anything.
Avoid a REG_EQUAL note for (CONST (MINUS (LABEL_REF) (LABEL_REF)))
which can be created for a reference to a compile time computable
entry in a jump table. */
if (n_sets == 1 && src_const && GET_CODE (dest) == REG
&& GET_CODE (src_const) != REG)
&& GET_CODE (src_const) != REG
&& ! (GET_CODE (src_const) == CONST
&& GET_CODE (XEXP (src_const, 0)) == MINUS
&& GET_CODE (XEXP (XEXP (src_const, 0), 0)) == LABEL_REF
&& GET_CODE (XEXP (XEXP (src_const, 0), 1)) == LABEL_REF))
{
tem = find_reg_note (insn, REG_EQUAL, NULL_RTX);