This removes the odd check of size_type_node when handling left-shifts
as multiplications of 1 << N and instead uses the type as specified.
It also moves left-shift handling next to multiplications where it
semantically belongs.
Boostrap and regtest pending on x86_64-unknown-linux-gnu.
OK? (I failed to short-cut the wide_int_to_tree for a
poly_int_cst_p bottom)
Thanks,
Richard.
2022-01-24 Richard Biener <rguent...@suse.de>
* fold-const.cc (multiple_of_p): Re-write and move LSHIFT_EXPR
handling.
---
gcc/fold-const.cc | 33 ++++++++++++++++-----------------
1 file changed, 16 insertions(+), 17 deletions(-)
diff --git a/gcc/fold-const.cc b/gcc/fold-const.cc
index b155611578d..a0a4913c45e 100644
--- a/gcc/fold-const.cc
+++ b/gcc/fold-const.cc
@@ -14068,7 +14068,7 @@ int
multiple_of_p (tree type, const_tree top, const_tree bottom)
{
gimple *stmt;
- tree t1, op1, op2;
+ tree op1, op2;
if (operand_equal_p (top, bottom, 0))
return 1;
@@ -14114,6 +14114,21 @@ multiple_of_p (tree type, const_tree top, const_tree
bottom)
return (multiple_of_p (type, TREE_OPERAND (top, 1), bottom)
|| multiple_of_p (type, TREE_OPERAND (top, 0), bottom));
+ case LSHIFT_EXPR:
+ /* Handle X << CST as X * (1 << CST) and only process the constant. */
+ if (TREE_CODE (TREE_OPERAND (top, 1)) == INTEGER_CST)
+ {
+ op1 = TREE_OPERAND (top, 1);
+ if (wi::gtu_p (TYPE_PRECISION (type), wi::to_wide (op1)))
+ {
+ wide_int mul_op
+ = wi::one (TYPE_PRECISION (type)) << wi::to_wide (op1);
+ return multiple_of_p (type,
+ wide_int_to_tree (type, mul_op), bottom);
+ }
+ }
+ return 0;
+
case MINUS_EXPR:
/* It is impossible to prove if op0 - op1 is multiple of bottom
precisely, so be conservative here checking if both op0 and op1
@@ -14133,22 +14148,6 @@ multiple_of_p (tree type, const_tree top, const_tree
bottom)
return (multiple_of_p (type, op1, bottom)
&& multiple_of_p (type, TREE_OPERAND (top, 0), bottom));
- case LSHIFT_EXPR:
- if (TREE_CODE (TREE_OPERAND (top, 1)) == INTEGER_CST)
- {
- op1 = TREE_OPERAND (top, 1);
- /* const_binop may not detect overflow correctly,
- so check for it explicitly here. */
- if (wi::gtu_p (TYPE_PRECISION (TREE_TYPE (size_one_node)),
- wi::to_wide (op1))
- && (t1 = fold_convert (type,
- const_binop (LSHIFT_EXPR, size_one_node,
- op1))) != 0
- && !TREE_OVERFLOW (t1))
- return multiple_of_p (type, t1, bottom);
- }
- return 0;
-
CASE_CONVERT:
/* Can't handle conversions from non-integral or wider integral type. */
if ((TREE_CODE (TREE_TYPE (TREE_OPERAND (top, 0))) != INTEGER_TYPE)
--
2.31.1
