procyberian/gcc
1
0
Fork 0
Code Issues Pull requests Projects Releases Packages Wiki Activity Actions

Adjust LSHIFT_EXPR handling of multiple_of_p

Browse source 
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.

2022-01-24  Richard Biener  <rguenther@suse.de>

	* fold-const.cc (multiple_of_p): Re-write and move LSHIFT_EXPR
	handling.
This commit is contained in:
Richard Biener 2022-01-24 15:26:46 +01:00
parent 38948b77db
commit 24c72fb0ee
1 changed files with 16 additions and 17 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

33
gcc/fold-const.cc
View file

@ -14079,7 +14079,7 @@ 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;
@ -14125,6 +14125,21 @@ 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::to_widest (op1) < TYPE_PRECISION (type))
{
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
@ -14144,22 +14159,6 @@ 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)