https://gcc.gnu.org/bugzilla/show_bug.cgi?id=81065
Richard Biener <rguenth at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Status|NEW |ASSIGNED
Assignee|unassigned at gcc dot gnu.org |rguenth at gcc dot
gnu.org
--- Comment #2 from Richard Biener <rguenth at gcc dot gnu.org> ---
Oh, and I think it's fine to always distribute
CST * (x * CST1 + CST2)
in case x * CST1 and CST2 have the same sign.
So the previous fix was incomplete and we now hit
/* If we were able to eliminate our operation from the first side,
apply our operation to the second side and reform the PLUS. */
if (t1 != 0 && (TREE_CODE (t1) != code || code == MULT_EXPR))
return fold_build2 (tcode, ctype, fold_convert (ctype, t1), op1);
where the code immediately following it is correct:
/* The last case is if we are a multiply. In that case, we can
apply the distributive law to commute the multiply and addition
if the multiplication of the constants doesn't overflow
and overflow is defined. With undefined overflow
op0 * c might overflow, while (op0 + orig_op1) * c doesn't. */
if (code == MULT_EXPR && TYPE_OVERFLOW_WRAPS (ctype))
return fold_build2 (tcode, ctype,
fold_build2 (code, ctype,
fold_convert (ctype, op0),
fold_convert (ctype, c)),
op1);
Mine. Testing
Index: gcc/fold-const.c
===================================================================
--- gcc/fold-const.c (revision 249112)
+++ gcc/fold-const.c (working copy)
@@ -6243,7 +6243,7 @@ extract_muldiv_1 (tree t, tree c, enum t
/* If we were able to eliminate our operation from the first side,
apply our operation to the second side and reform the PLUS. */
- if (t1 != 0 && (TREE_CODE (t1) != code || code == MULT_EXPR))
+ if (t1 != 0 && TREE_CODE (t1) != code)
return fold_build2 (tcode, ctype, fold_convert (ctype, t1), op1);
/* The last case is if we are a multiply. In that case, we can
