Hello,
just trying to shrink fold-const.c a bit more.
initializer_zerop is close to what I was looking for with zerop, but I
wasn't sure if it would be safe (it accepts some CONSTRUCTOR and
STRING_CST). At some point I tried using sign_bit_p, but using the return
of that function in the simplification confused the machinery too much. I
added an "overload" of element_precision like the one in element_mode, for
convenience.
Bootstrap+testsuite on ppc64le-redhat-linux.
2015-08-31 Marc Glisse <marc.gli...@inria.fr>
gcc/
* tree.h (zerop): New function.
* tree.c (zerop): Likewise.
(element_precision): Handle expressions.
* match.pd (define_predicates): Add zerop.
(x <= +Inf): Fix comment.
(abs (x) == 0, A & C == C, A & C != 0): Converted from ...
* fold-const.c (fold_binary_loc): ... here. Remove.
gcc/testsuite/
* gcc.dg/tree-ssa/cmp-1.c: New file.
--
Marc GlisseIndex: gcc/fold-const.c
===================================================================
--- gcc/fold-const.c (revision 227316)
+++ gcc/fold-const.c (working copy)
@@ -10761,25 +10761,20 @@ fold_binary_loc (location_t loc,
1)),
arg1, 0)
&& wi::extract_uhwi (TREE_OPERAND (arg0, 0), 0, 1) == 1)
{
return omit_two_operands_loc (loc, type,
code == NE_EXPR
? boolean_true_node : boolean_false_node,
TREE_OPERAND (arg0, 1), arg1);
}
- /* Convert ABS_EXPR<x> == 0 or ABS_EXPR<x> != 0 to x == 0 or x != 0. */
- if (TREE_CODE (arg0) == ABS_EXPR
- && (integer_zerop (arg1) || real_zerop (arg1)))
- return fold_build2_loc (loc, code, type, TREE_OPERAND (arg0, 0), arg1);
-
/* If this is an EQ or NE comparison with zero and ARG0 is
(1 << foo) & bar, convert it to (bar >> foo) & 1. Both require
two operations, but the latter can be done in one less insn
on machines that have only two-operand insns or on which a
constant cannot be the first operand. */
if (TREE_CODE (arg0) == BIT_AND_EXPR
&& integer_zerop (arg1))
{
tree arg00 = TREE_OPERAND (arg0, 0);
tree arg01 = TREE_OPERAND (arg0, 1);
@@ -10868,35 +10863,20 @@ fold_binary_loc (location_t loc,
((X >> C1) & C2) != 0 is rewritten as (X,false), and
((X >> C1) & C2) == 0 is rewritten as (X,true). */
else
return omit_one_operand_loc (loc, type,
code == EQ_EXPR ? integer_one_node
: integer_zero_node,
arg000);
}
}
- /* If we have (A & C) == C where C is a power of 2, convert this into
- (A & C) != 0. Similarly for NE_EXPR. */
- if (TREE_CODE (arg0) == BIT_AND_EXPR
- && integer_pow2p (TREE_OPERAND (arg0, 1))
- && operand_equal_p (TREE_OPERAND (arg0, 1), arg1, 0))
- return fold_build2_loc (loc, code == EQ_EXPR ? NE_EXPR : EQ_EXPR, type,
- arg0, fold_convert_loc (loc, TREE_TYPE (arg0),
- integer_zero_node));
-
- /* If we have (A & C) != 0 or (A & C) == 0 and C is the sign
- bit, then fold the expression into A < 0 or A >= 0. */
- tem = fold_single_bit_test_into_sign_test (loc, code, arg0, arg1, type);
- if (tem)
- return tem;
-
/* If we have (A & C) == D where D & ~C != 0, convert this into 0.
Similarly for NE_EXPR. */
if (TREE_CODE (arg0) == BIT_AND_EXPR
&& TREE_CODE (arg1) == INTEGER_CST
&& TREE_CODE (TREE_OPERAND (arg0, 1)) == INTEGER_CST)
{
tree notc = fold_build1_loc (loc, BIT_NOT_EXPR,
TREE_TYPE (TREE_OPERAND (arg0, 1)),
TREE_OPERAND (arg0, 1));
tree dandnotc
Index: gcc/match.pd
===================================================================
--- gcc/match.pd (revision 227316)
+++ gcc/match.pd (working copy)
@@ -21,20 +21,21 @@ for more details.
You should have received a copy of the GNU General Public License
along with GCC; see the file COPYING3. If not see
<http://www.gnu.org/licenses/>. */
/* Generic tree predicates we inherit. */
(define_predicates
integer_onep integer_zerop integer_all_onesp integer_minus_onep
integer_each_onep integer_truep integer_nonzerop
real_zerop real_onep real_minus_onep
+ zerop
CONSTANT_CLASS_P
tree_expr_nonnegative_p
integer_pow2p
HONOR_NANS)
/* Operator lists. */
(define_operator_list tcc_comparison
lt le eq ne ge gt unordered ordered unlt unle ungt unge uneq ltgt)
(define_operator_list inverted_tcc_comparison
ge gt ne eq lt le ordered unordered ge gt le lt ltgt uneq)
@@ -1570,21 +1571,21 @@ along with GCC; see the file COPYING3.
}
(switch
/* x > +Inf is always false, if with ignore sNANs. */
(if (code == GT_EXPR
&& ! HONOR_SNANS (@0))
{ constant_boolean_node (false, type); })
(if (code == LE_EXPR)
/* x <= +Inf is always true, if we don't case about NaNs. */
(if (! HONOR_NANS (@0))
{ constant_boolean_node (true, type); }
- /* x <= +Inf is the same as x == x, i.e. isfinite(x). */
+ /* x <= +Inf is the same as x == x, i.e. !isnan(x). */
(eq @0 @0)))
/* x == +Inf and x >= +Inf are always equal to x > DBL_MAX. */
(if (code == EQ_EXPR || code == GE_EXPR)
(with { real_maxval (&max, neg, TYPE_MODE (TREE_TYPE (@0))); }
(if (neg)
(lt @0 { build_real (TREE_TYPE (@0), max); })
(gt @0 { build_real (TREE_TYPE (@0), max); }))))
/* x < +Inf is always equal to x <= DBL_MAX. */
(if (code == LT_EXPR)
(with { real_maxval (&max, neg, TYPE_MODE (TREE_TYPE (@0))); }
@@ -1727,20 +1728,26 @@ along with GCC; see the file COPYING3.
(scmp @0 @1)))
(simplify
(cmp (negate @0) CONSTANT_CLASS_P@1)
(if (FLOAT_TYPE_P (TREE_TYPE (@0))
|| (ANY_INTEGRAL_TYPE_P (TREE_TYPE (@0))
&& TYPE_OVERFLOW_UNDEFINED (TREE_TYPE (@0))))
(with { tree tem = fold_unary (NEGATE_EXPR, TREE_TYPE (@0), @1); }
(if (tem && !TREE_OVERFLOW (tem))
(scmp @0 { tem; }))))))
+/* Convert ABS_EXPR<x> == 0 or ABS_EXPR<x> != 0 to x == 0 or x != 0. */
+(for op (eq ne)
+ (simplify
+ (op (abs @0) zerop@1)
+ (op @0 @1)))
+
/* From fold_sign_changed_comparison and fold_widened_comparison. */
(for cmp (simple_comparison)
(simplify
(cmp (convert@0 @00) (convert?@1 @10))
(if (TREE_CODE (TREE_TYPE (@0)) == INTEGER_TYPE
/* Disable this optimization if we're casting a function pointer
type on targets that require function pointer canonicalization. */
&& !(targetm.have_canonicalize_funcptr_for_compare ()
&& TREE_CODE (TREE_TYPE (@00)) == POINTER_TYPE
&& TREE_CODE (TREE_TYPE (TREE_TYPE (@00))) == FUNCTION_TYPE)
@@ -1833,20 +1840,42 @@ along with GCC; see the file COPYING3.
(simplify
(cmp (convert?@3 (bit_xor @0 INTEGER_CST@1)) INTEGER_CST@2)
(if (tree_nop_conversion_p (TREE_TYPE (@3), TREE_TYPE (@0)))
(cmp @0 (bit_xor @1 (convert @2)))))
(simplify
(cmp (convert? addr@0) integer_zerop)
(if (tree_single_nonzero_warnv_p (@0, NULL))
{ constant_boolean_node (cmp == NE_EXPR, type); })))
+/* If we have (A & C) == C where C is a power of 2, convert this into
+ (A & C) != 0. Similarly for NE_EXPR. */
+(for cmp (eq ne)
+ icmp (ne eq)
+ (simplify
+ (cmp (bit_and@2 @0 integer_pow2p@1) @1)
+ (icmp @2 { build_zero_cst (TREE_TYPE (@0)); })))
+
+/* If we have (A & C) != 0 where C is the sign bit of A, convert
+ this into A < 0. Similarly for (A & C) == 0 into A >= 0. */
+(for cmp (eq ne)
+ ncmp (ge lt)
+ (simplify
+ (cmp (bit_and (convert?@2 @0) integer_pow2p@1) integer_zerop)
+ (if (INTEGRAL_TYPE_P (TREE_TYPE (@0))
+ && (TYPE_PRECISION (TREE_TYPE (@0))
+ == GET_MODE_PRECISION (TYPE_MODE (TREE_TYPE (@0))))
+ && element_precision (@2) >= element_precision (@0)
+ && wi::only_sign_bit_p (@1, element_precision (@0)))
+ (with { tree stype = signed_type_for (TREE_TYPE (@0)); }
+ (ncmp (convert:stype @0) { build_zero_cst (stype); })))))
+
/* When the addresses are not directly of decls compare base and offset.
This implements some remaining parts of fold_comparison address
comparisons but still no complete part of it. Still it is good
enough to make fold_stmt not regress when not dispatching to fold_binary.
*/
(for cmp (simple_comparison)
(simplify
(cmp (convert1?@2 addr@0) (convert2? addr@1))
(with
{
HOST_WIDE_INT off0, off1;
Index: gcc/testsuite/gcc.dg/tree-ssa/cmp-1.c
===================================================================
--- gcc/testsuite/gcc.dg/tree-ssa/cmp-1.c (revision 0)
+++ gcc/testsuite/gcc.dg/tree-ssa/cmp-1.c (working copy)
@@ -0,0 +1,19 @@
+/* { dg-do compile } */
+/* { dg-options "-O -fdump-tree-gimple -fdump-tree-optimized" } */
+
+int f(int a){
+ int b = -__INT_MAX__-1;
+ a &= b;
+ return a == b;
+}
+int g(int x){
+ x = x < 0 ? -x : x;
+ return x == 0;
+}
+
+/* This should work even if int is not 32 bits, it is just not meaningful in
+ that case. */
+/* { dg-final { scan-tree-dump-not "-2147483648" "optimized"} } */
+/* { dg-final { scan-tree-dump " < 0" "optimized"} } */
+/* { dg-final { scan-tree-dump "ABS_EXPR" "gimple"} } */
+/* { dg-final { scan-tree-dump-not "ABS_EXPR" "optimized"} } */
Index: gcc/tree.c
===================================================================
--- gcc/tree.c (revision 227316)
+++ gcc/tree.c (working copy)
@@ -2208,20 +2208,31 @@ grow_tree_vec_stat (tree v, int len MEM_
record_node_allocation_statistics (TREE_VEC, length - oldlength);
v = (tree) ggc_realloc (v, length PASS_MEM_STAT);
TREE_VEC_LENGTH (v) = len;
return v;
}
+/* Return 1 if EXPR is the constant zero, whether it is integral, float or
+ fixed, and scalar, complex or vector. */
+
+int
+zerop (const_tree expr)
+{
+ return (integer_zerop (expr)
+ || real_zerop (expr)
+ || fixed_zerop (expr));
+}
+
/* Return 1 if EXPR is the integer constant zero or a complex constant
of zero. */
int
integer_zerop (const_tree expr)
{
STRIP_NOPS (expr);
switch (TREE_CODE (expr))
{
@@ -7505,20 +7516,22 @@ valid_constant_size_p (const_tree size)
return false;
return true;
}
/* Return the precision of the type, or for a complex or vector type the
precision of the type of its elements. */
unsigned int
element_precision (const_tree type)
{
+ if (!TYPE_P (type))
+ type = TREE_TYPE (type);
enum tree_code code = TREE_CODE (type);
if (code == COMPLEX_TYPE || code == VECTOR_TYPE)
type = TREE_TYPE (type);
return TYPE_PRECISION (type);
}
/* Return true if CODE represents an associative tree code. Otherwise
return false. */
bool
Index: gcc/tree.h
===================================================================
--- gcc/tree.h (revision 227316)
+++ gcc/tree.h (working copy)
@@ -4102,20 +4102,24 @@ extern bool initializer_zerop (const_tre
/* Given a vector VEC, return its first element if all elements are
the same. Otherwise return NULL_TREE. */
extern tree uniform_vector_p (const_tree);
/* Given a CONSTRUCTOR CTOR, return the element values as a vector. */
extern vec<tree, va_gc> *ctor_to_vec (tree);
+/* zerop (tree x) is nonzero if X is a constant of value 0. */
+
+extern int zerop (const_tree);
+
/* integer_zerop (tree x) is nonzero if X is an integer constant of value 0.
*/
extern int integer_zerop (const_tree);
/* integer_onep (tree x) is nonzero if X is an integer constant of value 1. */
extern int integer_onep (const_tree);
/* integer_onep (tree x) is nonzero if X is an integer constant of value 1, or
a vector or complex where each part is 1. */
