Hi!
The following patch implements the with_*_nonzero_bits* cleanups and
improvements I was talking about.
get_nonzero_bits is extended to also handle BIT_AND_EXPR (as a tree or
as SSA_NAME with BIT_AND_EXPR def_stmt), new function is added for the
bits known to be set (get_known_nonzero_bits) and the match.pd predicates
are renamed and adjusted, so that there is no confusion on which one to
use (one is named and documented to be internal), changed so that it can be
used only as a simple predicate, not match some operands, and that it doesn't
try to match twice for the GIMPLE case (where SSA_NAME with integral or pointer
type matches, but SSA_NAME with BIT_AND_EXPR def_stmt matched differently).
Furthermore, get_nonzero_bits just returns the all bits set (or
get_known_nonzero_bits no bits set) fallback if the argument isn't a
SSA_NAME (nor INTEGER_CST or whatever the functions handle explicitly).
Bootstrapped/regtested on x86_64-linux and i686-linux, ok for trunk?
2024-11-26 Jakub Jelinek <ja...@redhat.com>
PR tree-optimization/117420
* tree-ssanames.h (get_known_nonzero_bits): Declare.
* tree-ssanames.cc (get_nonzero_bits): New wrapper function. Move old
definition to ...
(get_nonzero_bits_1): ... here, add static. Change widest_int in
function comment to wide_int.
(get_known_nonzero_bits_1, get_known_nonzero_bits): New functions.
* match.pd (with_possible_nonzero_bits2): Rename to ...
(with_possible_nonzero_bits): ... this. Guard the bit_and case with
#if GENERIC. Change to a normal match predicate without parameters.
Rename the old with_possible_nonzero_bits match to ...
(with_possible_nonzero_bits_1): ... this.
(with_certain_nonzero_bits2): Remove.
(with_known_nonzero_bits_1, with_known_nonzero_bits): New match
predicates.
(X == C (or X & Z == Y | C) is impossible if ~nonzero(X) & C != 0):
Use with_known_nonzero_bits@0 instead of
(with_certain_nonzero_bits2 @1), use with_possible_nonzero_bits@0
instead of (with_possible_nonzero_bits2 @0) and
get_known_nonzero_bits (@1) instead of wi::to_wide (@1).
* gcc.dg/tree-ssa/pr117420.c: New test.
--- gcc/tree-ssanames.h.jj 2024-07-01 11:28:23.461228272 +0200
+++ gcc/tree-ssanames.h 2024-11-25 11:11:48.598982744 +0100
@@ -61,6 +61,7 @@ extern bool set_range_info (tree, const
extern void set_nonzero_bits (tree, const wide_int &);
extern void set_bitmask (tree, const wide_int &value, const wide_int &mask);
extern wide_int get_nonzero_bits (const_tree);
+extern wide_int get_known_nonzero_bits (const_tree);
extern bool ssa_name_has_boolean_range (tree);
extern void init_ssanames (struct function *, int);
extern void fini_ssanames (struct function *);
--- gcc/tree-ssanames.cc.jj 2024-11-23 13:00:31.536981942 +0100
+++ gcc/tree-ssanames.cc 2024-11-26 08:53:58.536649673 +0100
@@ -493,11 +493,11 @@ set_bitmask (tree name, const wide_int &
set_range_info (name, r);
}
-/* Return a widest_int with potentially non-zero bits in SSA_NAME
+/* Return a wide_int with potentially non-zero bits in SSA_NAME
NAME, the constant for INTEGER_CST, or -1 if unknown. */
-wide_int
-get_nonzero_bits (const_tree name)
+static wide_int
+get_nonzero_bits_1 (const_tree name)
{
if (TREE_CODE (name) == INTEGER_CST)
return wi::to_wide (name);
@@ -508,6 +508,9 @@ get_nonzero_bits (const_tree name)
/* Use element_precision instead of TYPE_PRECISION so complex and
vector types get a non-zero precision. */
unsigned int precision = element_precision (TREE_TYPE (name));
+ if (TREE_CODE (name) != SSA_NAME)
+ return wi::shwi (-1, precision);
+
if (POINTER_TYPE_P (TREE_TYPE (name)))
{
struct ptr_info_def *pi = SSA_NAME_PTR_INFO (name);
@@ -525,6 +528,81 @@ get_nonzero_bits (const_tree name)
return tmp.get_nonzero_bits ();
}
+/* Return a wide_int with potentially non-zero bits in SSA_NAME
+ NAME, the constant for INTEGER_CST, or -1 if unknown.
+ In addition to what get_nonzero_bits_1 handles, this handles one
+ level of BIT_AND_EXPR, either as a def_stmt or tree directly. */
+
+wide_int
+get_nonzero_bits (const_tree name)
+{
+ if (TREE_CODE (name) == BIT_AND_EXPR)
+ return (get_nonzero_bits_1 (TREE_OPERAND (name, 0))
+ & get_nonzero_bits_1 (TREE_OPERAND (name, 1)));
+ if (TREE_CODE (name) == SSA_NAME)
+ {
+ gimple *g = SSA_NAME_DEF_STMT (name);
+ if (g
+ && is_gimple_assign (g)
+ && gimple_assign_rhs_code (g) == BIT_AND_EXPR)
+ return (get_nonzero_bits_1 (name)
+ & get_nonzero_bits_1 (gimple_assign_rhs1 (g))
+ & get_nonzero_bits_1 (gimple_assign_rhs2 (g)));
+ }
+ return get_nonzero_bits_1 (name);
+}
+
+/* Return a wide_int with known non-zero bits in SSA_NAME
+ NAME (bits whose values aren't known are also clear), the constant
+ for INTEGER_CST, or 0 if unknown. */
+
+static wide_int
+get_known_nonzero_bits_1 (const_tree name)
+{
+ if (TREE_CODE (name) == INTEGER_CST)
+ return wi::to_wide (name);
+
+ /* Use element_precision instead of TYPE_PRECISION so complex and
+ vector types get a non-zero precision. */
+ unsigned int precision = element_precision (TREE_TYPE (name));
+ if (TREE_CODE (name) != SSA_NAME || POINTER_TYPE_P (TREE_TYPE (name)))
+ return wi::shwi (0, precision);
+
+ if (!range_info_p (name) || !irange::supports_p (TREE_TYPE (name)))
+ return wi::shwi (0, precision);
+
+ int_range_max tmp;
+ range_info_get_range (name, tmp);
+ if (tmp.undefined_p ())
+ return wi::shwi (0, precision);
+ irange_bitmask bm = tmp.get_bitmask ();
+ return bm.value () & ~bm.mask ();
+}
+
+/* Return a wide_int with known non-zero bits in SSA_NAME
+ NAME, the constant for INTEGER_CST, or -1 if unknown.
+ In addition to what get_known_nonzero_bits_1 handles, this handles one
+ level of BIT_IOR_EXPR, either as a def_stmt or tree directly. */
+
+wide_int
+get_known_nonzero_bits (const_tree name)
+{
+ if (TREE_CODE (name) == BIT_IOR_EXPR)
+ return (get_known_nonzero_bits_1 (TREE_OPERAND (name, 0))
+ | get_known_nonzero_bits_1 (TREE_OPERAND (name, 1)));
+ if (TREE_CODE (name) == SSA_NAME)
+ {
+ gimple *g = SSA_NAME_DEF_STMT (name);
+ if (g
+ && is_gimple_assign (g)
+ && gimple_assign_rhs_code (g) == BIT_IOR_EXPR)
+ return (get_known_nonzero_bits_1 (name)
+ | get_known_nonzero_bits_1 (gimple_assign_rhs1 (g))
+ | get_known_nonzero_bits_1 (gimple_assign_rhs2 (g)));
+ }
+ return get_known_nonzero_bits_1 (name);
+}
+
/* Return TRUE is OP, an SSA_NAME has a range of values [0..1], false
otherwise.
--- gcc/match.pd.jj 2024-11-22 19:50:15.389344167 +0100
+++ gcc/match.pd 2024-11-25 13:08:06.430386845 +0100
@@ -2869,32 +2869,45 @@ DEFINE_INT_AND_FLOAT_ROUND_FN (RINT)
{ constant_boolean_node (cmp == LT_EXPR, type); })))))
/* Arguments on which one can call get_nonzero_bits to get the bits
- possibly set. */
-(match with_possible_nonzero_bits
+ possibly set. with_possible_nonzero_bits_1 is an internal version,
+ use with_possible_nonzero_bits. */
+(match with_possible_nonzero_bits_1
INTEGER_CST@0)
-(match with_possible_nonzero_bits
+(match with_possible_nonzero_bits_1
POLY_INT_CST@0)
-(match with_possible_nonzero_bits
+(match with_possible_nonzero_bits_1
SSA_NAME@0
(if (INTEGRAL_TYPE_P (TREE_TYPE (@0)) || POINTER_TYPE_P (TREE_TYPE (@0)))))
/* Slightly extended version, do not make it recursive to keep it cheap. */
-(match (with_possible_nonzero_bits2 @0)
- with_possible_nonzero_bits@0)
-(match (with_possible_nonzero_bits2 @0)
- (bit_and:c with_possible_nonzero_bits@0 @2))
+(match with_possible_nonzero_bits
+ with_possible_nonzero_bits_1@0)
+#if GENERIC
+(match with_possible_nonzero_bits
+ (bit_and:c with_possible_nonzero_bits_1@0 @1))
+#endif
-/* Same for bits that are known to be set, but we do not have
- an equivalent to get_nonzero_bits yet. */
-(match (with_certain_nonzero_bits2 @0)
+/* Arguments on which one can call get_known_nonzero_bits to get the
+ bits known to be set. with_known_nonzero_bits_1 is an internal version,
+ use with_known_nonzero_bits. */
+(match with_known_nonzero_bits_1
INTEGER_CST@0)
-(match (with_certain_nonzero_bits2 @0)
- (bit_ior @1 INTEGER_CST@0))
+(match with_known_nonzero_bits_1
+ SSA_NAME@0
+ (if (INTEGRAL_TYPE_P (TREE_TYPE (@0)))))
+/* Slightly extended version, do not make it recursive to keep it cheap. */
+(match with_known_nonzero_bits
+ with_known_nonzero_bits_1@0)
+#if GENERIC
+(match with_known_nonzero_bits
+ (bit_ior:c with_known_nonzero_bits_1@0 @1))
+#endif
/* X == C (or X & Z == Y | C) is impossible if ~nonzero(X) & C != 0. */
(for cmp (eq ne)
(simplify
- (cmp:c (with_possible_nonzero_bits2 @0) (with_certain_nonzero_bits2 @1))
- (if (wi::bit_and_not (wi::to_wide (@1), get_nonzero_bits (@0)) != 0)
+ (cmp:c with_possible_nonzero_bits@0 with_known_nonzero_bits@1)
+ (if (wi::bit_and_not (get_known_nonzero_bits (@1),
+ get_nonzero_bits (@0)) != 0)
{ constant_boolean_node (cmp == NE_EXPR, type); })))
/* ((X inner_op C0) outer_op C1)
--- gcc/testsuite/gcc.dg/tree-ssa/pr117420.c.jj 2024-11-25 12:52:41.090468349
+0100
+++ gcc/testsuite/gcc.dg/tree-ssa/pr117420.c 2024-11-25 12:53:40.308631183
+0100
@@ -0,0 +1,16 @@
+/* PR tree-optimization/117420 */
+/* { dg-do compile } */
+/* { dg-options "-O2 -fno-tree-ccp -fdump-tree-optimized" } */
+/* { dg-final { scan-tree-dump "return 0;" "optimized" } } */
+
+int
+foo (unsigned long x, unsigned long y)
+{
+ x |= 0x11000L;
+ x &= ~0xfffL;
+ x += 42L;
+ y &= ~0x10ffL;
+ y |= 0x100L;
+ y += 21L;
+ return x == y;
+}
Jakub
