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re PR middle-end/3074 (Statement with no effect not flagged with -Wall)

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PR middle-end/3074
	* fold-const.c (strip_compound_expr): Delete function.
	(count_cond): Delete function.
	(fold_binary_op_with_conditional_arg): Only perform transformations
	"a + (b?c:d) -> b ? a+c : a+d" and "(b?c:d) + a -> b ? c+a : d+a"
	when a is constant.  This greatly simplifies this routine.

	* tree.c (saved_expr_p): Delete function.
	* tree.h (saved_expr_p): Delete function prototype.

	* gcc.dg/pr3074-1.c: New test case.
	* gcc.dg/sequence-pt-1.c: Remove an XFAIL.

From-SVN: r82071
This commit is contained in:
Roger Sayle 2004-05-20 22:08:46 +00:00 committed by Roger Sayle
parent 3adf6cadbb
commit f4085d4c0b
7 changed files with 42 additions and 185 deletions
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12
gcc/ChangeLog
View File

@ -1,3 +1,15 @@
2004-05-20 Roger Sayle <roger@eyesopen.com>
PR middle-end/3074
* fold-const.c (strip_compound_expr): Delete function.
(count_cond): Delete function.
(fold_binary_op_with_conditional_arg): Only perform transformations
"a + (b?c:d) -> b ? a+c : a+d" and "(b?c:d) + a -> b ? c+a : d+a"
when a is constant. This greatly simplifies this routine.
* tree.c (saved_expr_p): Delete function.
* tree.h (saved_expr_p): Delete function prototype.
2004-05-20 Andrew Pinski <pinskia@physics.uc.edu>
* common.opt (ftree-loop-optimize): Remove.

183
gcc/fold-const.c
View File

@ -98,10 +98,8 @@ static tree fold_truthop (enum tree_code, tree, tree, tree);
static tree optimize_minmax_comparison (tree);
static tree extract_muldiv (tree, tree, enum tree_code, tree);
static tree extract_muldiv_1 (tree, tree, enum tree_code, tree);
static tree strip_compound_expr (tree, tree);
static int multiple_of_p (tree, tree, tree);
static tree constant_boolean_node (int, tree);
static int count_cond (tree, int);
static tree fold_binary_op_with_conditional_arg (enum tree_code, tree, tree,
tree, int);
static bool fold_real_zero_addition_p (tree, tree, int);
@ -4738,40 +4736,6 @@ extract_muldiv_1 (tree t, tree c, enum tree_code code, tree wide_type)
return 0;
}
/* If T contains a COMPOUND_EXPR which was inserted merely to evaluate
S, a SAVE_EXPR, return the expression actually being evaluated. Note
that we may sometimes modify the tree. */
static tree
strip_compound_expr (tree t, tree s)
{
enum tree_code code = TREE_CODE (t);
/* See if this is the COMPOUND_EXPR we want to eliminate. */
if (code == COMPOUND_EXPR && TREE_CODE (TREE_OPERAND (t, 0)) == CONVERT_EXPR
&& TREE_OPERAND (TREE_OPERAND (t, 0), 0) == s)
return TREE_OPERAND (t, 1);
/* See if this is a COND_EXPR or a simple arithmetic operator. We
don't bother handling any other types. */
else if (code == COND_EXPR)
{
TREE_OPERAND (t, 0) = strip_compound_expr (TREE_OPERAND (t, 0), s);
TREE_OPERAND (t, 1) = strip_compound_expr (TREE_OPERAND (t, 1), s);
TREE_OPERAND (t, 2) = strip_compound_expr (TREE_OPERAND (t, 2), s);
}
else if (TREE_CODE_CLASS (code) == '1')
TREE_OPERAND (t, 0) = strip_compound_expr (TREE_OPERAND (t, 0), s);
else if (TREE_CODE_CLASS (code) == '<'
|| TREE_CODE_CLASS (code) == '2')
{
TREE_OPERAND (t, 0) = strip_compound_expr (TREE_OPERAND (t, 0), s);
TREE_OPERAND (t, 1) = strip_compound_expr (TREE_OPERAND (t, 1), s);
}
return t;
}
/* Return a node which has the indicated constant VALUE (either 0 or
1), and is of the indicated TYPE. */
@ -4792,25 +4756,6 @@ constant_boolean_node (int value, tree type)
}
}
/* Utility function for the following routine, to see how complex a nesting of
COND_EXPRs can be. EXPR is the expression and LIMIT is a count beyond which
we don't care (to avoid spending too much time on complex expressions.). */
static int
count_cond (tree expr, int lim)
{
int ctrue, cfalse;
if (TREE_CODE (expr) != COND_EXPR)
return 0;
else if (lim <= 0)
return 0;
ctrue = count_cond (TREE_OPERAND (expr, 1), lim - 1);
cfalse = count_cond (TREE_OPERAND (expr, 2), lim - 1 - ctrue);
return MIN (lim, 1 + ctrue + cfalse);
}
/* Transform `a + (b ? x : y)' into `b ? (a + x) : (a + y)'.
Transform, `a + (x < y)' into `(x < y) ? (a + 1) : (a + 0)'. Here
CODE corresponds to the `+', COND to the `(b ? x : y)' or `(x < y)'
@ -4827,53 +4772,13 @@ fold_binary_op_with_conditional_arg (enum tree_code code, tree type,
tree test, true_value, false_value;
tree lhs = NULL_TREE;
tree rhs = NULL_TREE;
/* In the end, we'll produce a COND_EXPR. Both arms of the
conditional expression will be binary operations. The left-hand
side of the expression to be executed if the condition is true
will be pointed to by TRUE_LHS. Similarly, the right-hand side
of the expression to be executed if the condition is true will be
pointed to by TRUE_RHS. FALSE_LHS and FALSE_RHS are analogous --
but apply to the expression to be executed if the conditional is
false. */
tree *true_lhs;
tree *true_rhs;
tree *false_lhs;
tree *false_rhs;
/* These are the codes to use for the left-hand side and right-hand
side of the COND_EXPR. Normally, they are the same as CODE. */
enum tree_code lhs_code = code;
enum tree_code rhs_code = code;
/* And these are the types of the expressions. */
tree lhs_type = type;
tree rhs_type = type;
int save = 0;
if (TREE_CODE (cond) != COND_EXPR
&& TREE_CODE_CLASS (code) == '<')
/* This transformation is only worthwhile if we don't have to wrap
arg in a SAVE_EXPR, and the operation can be simplified on atleast
one of the branches once its pushed inside the COND_EXPR. */
if (!TREE_CONSTANT (arg))
return NULL_TREE;
if (TREE_CODE (arg) == COND_EXPR
&& count_cond (cond, 25) + count_cond (arg, 25) > 25)
return NULL_TREE;
if (TREE_SIDE_EFFECTS (arg)
&& (lang_hooks.decls.global_bindings_p () != 0
|| CONTAINS_PLACEHOLDER_P (arg)))
return NULL_TREE;
if (cond_first_p)
{
true_rhs = false_rhs = &arg;
true_lhs = &true_value;
false_lhs = &false_value;
}
else
{
true_lhs = false_lhs = &arg;
true_rhs = &true_value;
false_rhs = &false_value;
}
if (TREE_CODE (cond) == COND_EXPR)
{
test = TREE_OPERAND (cond, 0);
@ -4881,28 +4786,11 @@ fold_binary_op_with_conditional_arg (enum tree_code code, tree type,
false_value = TREE_OPERAND (cond, 2);
/* If this operand throws an expression, then it does not make
sense to try to perform a logical or arithmetic operation
involving it. Instead of building `a + throw 3' for example,
we simply build `a, throw 3'. */
involving it. */
if (VOID_TYPE_P (TREE_TYPE (true_value)))
{
if (! cond_first_p)
{
lhs_code = COMPOUND_EXPR;
lhs_type = void_type_node;
}
else
lhs = true_value;
}
lhs = true_value;
if (VOID_TYPE_P (TREE_TYPE (false_value)))
{
if (! cond_first_p)
{
rhs_code = COMPOUND_EXPR;
rhs_type = void_type_node;
}
else
rhs = false_value;
}
rhs = false_value;
}
else
{
@ -4912,60 +4800,15 @@ fold_binary_op_with_conditional_arg (enum tree_code code, tree type,
false_value = fold_convert (testtype, integer_zero_node);
}
/* If ARG is complex we want to make sure we only evaluate it once. Though
this is only required if it is volatile, it might be more efficient even
if it is not. However, if we succeed in folding one part to a constant,
we do not need to make this SAVE_EXPR. Since we do this optimization
primarily to see if we do end up with constant and this SAVE_EXPR
interferes with later optimizations, suppressing it when we can is
important.
If we are not in a function, we can't make a SAVE_EXPR, so don't try to
do so. Don't try to see if the result is a constant if an arm is a
COND_EXPR since we get exponential behavior in that case. */
if (saved_expr_p (arg))
save = 1;
else if (lhs == 0 && rhs == 0
&& !TREE_CONSTANT (arg)
&& lang_hooks.decls.global_bindings_p () == 0
&& ((TREE_CODE (arg) != VAR_DECL && TREE_CODE (arg) != PARM_DECL)
|| TREE_SIDE_EFFECTS (arg)))
{
if (TREE_CODE (true_value) != COND_EXPR)
lhs = fold (build (lhs_code, lhs_type, *true_lhs, *true_rhs));
if (TREE_CODE (false_value) != COND_EXPR)
rhs = fold (build (rhs_code, rhs_type, *false_lhs, *false_rhs));
if ((lhs == 0 || ! TREE_CONSTANT (lhs))
&& (rhs == 0 || !TREE_CONSTANT (rhs)))
{
arg = save_expr (arg);
lhs = rhs = 0;
save = saved_expr_p (arg);
}
}
if (lhs == 0)
lhs = fold (build (lhs_code, lhs_type, *true_lhs, *true_rhs));
lhs = fold (cond_first_p ? build2 (code, type, true_value, arg)
: build2 (code, type, arg, true_value));
if (rhs == 0)
rhs = fold (build (rhs_code, rhs_type, *false_lhs, *false_rhs));
rhs = fold (cond_first_p ? build2 (code, type, false_value, arg)
: build2 (code, type, arg, false_value));
test = fold (build (COND_EXPR, type, test, lhs, rhs));
/* If ARG involves a SAVE_EXPR, we need to ensure it is evaluated
ahead of the COND_EXPR we made. Otherwise we would have it only
evaluated in one branch, with the other branch using the result
but missing the evaluation code. Beware that the save_expr call
above might not return a SAVE_EXPR, so testing the TREE_CODE
of ARG is not enough to decide here. */
if (save)
return build (COMPOUND_EXPR, type,
fold_convert (void_type_node, arg),
strip_compound_expr (test, arg));
else
return fold_convert (type, test);
test = fold (build3 (COND_EXPR, type, test, lhs, rhs));
return fold_convert (type, test);
}

6
gcc/testsuite/ChangeLog
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@ -1,3 +1,9 @@
2004-05-20 Roger Sayle <roger@eyesopen.com>
PR middle-end/3074
* gcc.dg/pr3074-1.c: New test case.
* gcc.dg/sequence-pt-1.c: Remove an XFAIL.
2004-05-20 Falk Hueffner <falk@debian.org>
PR other/15526

10
gcc/testsuite/gcc.dg/pr3074-1.c Normal file
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@ -0,0 +1,10 @@
/* PR middle-end/3074 */
/* { dg-do compile } */
/* { dg-options "-Wall" } */
void foo()
{
int a;
5 * (a == 1) | (a == 2); /* { dg-warning "no effect" "no effect" } */
}

2
gcc/testsuite/gcc.dg/sequence-pt-1.c
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@ -56,7 +56,7 @@ foo (int a, int b, int n, int p, int *ptr, struct s *sptr,
ap[a+=1] += a++; /* { dg-warning "undefined" "sequence point warning" } */
a = a++, b = a; /* { dg-warning "undefined" "sequence point warning" } */
b = a, a = a++; /* { dg-warning "undefined" "sequence point warning" } */
a = (b++ ? n : a) + b; /* { dg-warning "undefined" "sequence point warning" { xfail *-*-* } } */
a = (b++ ? n : a) + b; /* { dg-warning "undefined" "sequence point warning" } */
b ? a = a++ : a; /* { dg-warning "undefined" "sequence point warning" } */
b && (a = a++); /* { dg-warning "undefined" "sequence point warning" } */
(a = a++) && b; /* { dg-warning "undefined" "sequence point warning" } */

9
gcc/tree.c
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@ -1432,15 +1432,6 @@ skip_simple_arithmetic (tree expr)
return inner;
}
/* Return TRUE if EXPR is a SAVE_EXPR or wraps simple arithmetic around a
SAVE_EXPR. Return FALSE otherwise. */
bool
saved_expr_p (tree expr)
{
return TREE_CODE (skip_simple_arithmetic (expr)) == SAVE_EXPR;
}
/* Arrange for an expression to be expanded multiple independent
times. This is useful for cleanup actions, as the backend can
expand them multiple times in different places. */

5
gcc/tree.h
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@ -3177,11 +3177,6 @@ extern tree save_expr (tree);
extern tree skip_simple_arithmetic (tree);
/* Return TRUE if EXPR is a SAVE_EXPR or wraps simple arithmetic around a
SAVE_EXPR. Return FALSE otherwise. */
extern bool saved_expr_p (tree);
/* Returns the index of the first non-tree operand for CODE, or the number
of operands if all are trees. */