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author | Franz Sirl <Franz.Sirl-kernel@lauterbach.com> | 1999-02-27 16:55:27 -0700 |
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committer | Jeff Law <law@gcc.gnu.org> | 1999-02-27 16:55:27 -0700 |
commit | baa8d3ab9eba4468e4c0256bca03ab649c5f63db (patch) | |
tree | 9d1d5cca9f31c55fab9cb7665938ed7b05830e15 | |
parent | 77c1d679bb968d85062b0f2d743feb9db308c617 (diff) | |
download | gcc-baa8d3ab9eba4468e4c0256bca03ab649c5f63db.tar.gz |
cse.c (fold_rtx): Update comments for (const (minus (label) (label))) case.
�
* 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.
From-SVN: r25490
-rw-r--r-- | gcc/cse.c | 21 |
1 files changed, 17 insertions, 4 deletions
diff --git a/gcc/cse.c b/gcc/cse.c index 3b543f4ba69..cfcc4fac8ef 100644 --- a/gcc/cse.c +++ b/gcc/cse.c @@ -5167,7 +5167,11 @@ 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); } } @@ -5913,7 +5917,7 @@ 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 @@ -7046,9 +7050,18 @@ 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); |