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combine.c (if_then_else_cond): Canonicalize BImode true to STORE_FLAG_VALUE.

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* combine.c (if_then_else_cond): Canonicalize BImode true to
        STORE_FLAG_VALUE.
        * explow.c (trunc_int_for_mode): Likewise.

From-SVN: r36507
This commit is contained in:
Richard Henderson 2000-09-18 11:30:24 -07:00 • committed by Richard Henderson
parent 5bd60ce6de
commit 1f3f36d154
3 changed files with 16 additions and 0 deletions
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4
gcc/ChangeLog
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@ -1,5 +1,9 @@
2000-09-18 Richard Henderson <rth@cygnus.com>
* combine.c (if_then_else_cond): Canonicalize BImode true to
STORE_FLAG_VALUE.
* explow.c (trunc_int_for_mode): Likewise.
* combine.c (combine_simplify_rtx): Use gen_unary to distribute
the NOT for De Morgan's rule.
* simplify-rtx.c (simplify_unary_operation): Simplify a BImode NOT

8
gcc/combine.c
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@ -7418,6 +7418,14 @@ if_then_else_cond (x, ptrue, pfalse)
|| ((cond0 = get_last_value (x)) != 0 && CONSTANT_P (cond0)))
;
/* If we're in BImode, canonicalize on 0 and STORE_FLAG_VALUE, as that
will be least confusing to the rest of the compiler. */
else if (mode == BImode)
{
*ptrue = GEN_INT (STORE_FLAG_VALUE), *pfalse = const0_rtx;
return x;
}
/* If X is known to be either 0 or -1, those are the true and
false values when testing X. */
else if (x == constm1_rtx || x == const0_rtx

4
gcc/explow.c
View file

@ -52,6 +52,10 @@ trunc_int_for_mode (c, mode)
{
int width = GET_MODE_BITSIZE (mode);
/* Canonicalize BImode to 0 and STORE_FLAG_VALUE. */
if (mode == BImode)
return c & 1 ? STORE_FLAG_VALUE : 0;
/* We clear out all bits that don't belong in MODE, unless they and our
sign bit are all one. So we get either a reasonable negative
value or a reasonable unsigned value. */