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re PR tree-optimization/78496 (Missed opportunities for jump threading)

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PR tree-optimization/78496
	* tree-vrp.c (simplify_assert_expr_using_ranges): New function.
	(simplify_stmt_using_ranges): Call it.
	(vrp_dom_walker::before_dom_children): Extract equivalences
	from an ASSERT_EXPR with an equality comparison against a
	constant.

	PR tree-optimization/78496
	* gcc.dg/tree-ssa/ssa-thread-16.c: New test.
	* gcc.dg/tree-ssa/ssa-thread-17.c: New test.

From-SVN: r247721
This commit is contained in:
Jeff Law 2017-05-06 09:03:40 -06:00 committed by Jeff Law
parent 8ffa3150d3
commit 973dfbb4a6
5 changed files with 141 additions and 3 deletions
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9
gcc/ChangeLog
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@ -1,3 +1,12 @@
2017-05-06 Jeff Law <law@redhat.com>
PR tree-optimization/78496
* tree-vrp.c (simplify_assert_expr_using_ranges): New function.
(simplify_stmt_using_ranges): Call it.
(vrp_dom_walker::before_dom_children): Extract equivalences
from an ASSERT_EXPR with an equality comparison against a
constant.
2017-05-06 Richard Sandiford <richard.sandiford@linaro.org>
* lra-constraints.c (lra_copy_reg_equiv): New function.

6
gcc/testsuite/ChangeLog
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@ -1,3 +1,9 @@
2017-05-06 Jeff Law <law@redhat.com>
PR tree-optimization/78496
* gcc.dg/tree-ssa/ssa-thread-16.c: New test.
* gcc.dg/tree-ssa/ssa-thread-17.c: New test.
2017-05-06 Richard Sandiford <richard.sandiford@linaro.org>
* gcc.target/aarch64/spill_1.c: New test.

38
gcc/testsuite/gcc.dg/tree-ssa/ssa-thread-16.c Normal file
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@ -0,0 +1,38 @@
/* { dg-do compile } */
/* { dg-options "-O2 -fdump-tree-vrp1-details" } */
/* We should thread the if (exp == 2) conditional on the
the path from inside the if (x) THEN arm. It is the only
jump threading opportunity in this code. */
/* { dg-final { scan-tree-dump-times "Threaded" 1 "vrp1" } } */
extern void abort (void) __attribute__ ((__nothrow__, __leaf__))
__attribute__ ((__noreturn__));
int x;
int code;
void
do_jump (int exp)
{
switch (code)
{
case 4:
if ((exp) == 1)
goto normal;
if (x)
{
if (exp != 0)
abort ();
}
if ((exp) == 2)
goto normal;
case 3:
abort ();
}
normal:
;
}

36
gcc/testsuite/gcc.dg/tree-ssa/ssa-thread-17.c Normal file
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@ -0,0 +1,36 @@
/* { dg-do compile } */
/* { dg-options "-O2 -fdump-tree-vrp1-details" } */
/* We should simplify one ASSERT_EXPR from a relational
into an equality test. */
/* { dg-final { scan-tree-dump-times "Folded into:\[^\r\n\]*ASSERT_EXPR\*\[^\r\n\]* == 1" 1 "vrp1" } } */
/* And simplification of the ASSERT_EXPR leads to a jump threading opportunity. */
/* { dg-final { scan-tree-dump-times "Threaded" 1 "vrp1" } } */
extern void abort (void) __attribute__ ((__nothrow__, __leaf__))
__attribute__ ((__noreturn__));
union gimple_statement_d;
typedef union gimple_statement_d *gimple;
union gimple_statement_d
{
unsigned num_ops;
};
void
gimple_assign_set_rhs_with_ops_1 (int code, gimple stmt, unsigned new_rhs_ops)
{
stmt->num_ops = new_rhs_ops + 1;
if (stmt->num_ops <= 1)
abort ();
if (new_rhs_ops > 1)
if (stmt->num_ops <= 2)
abort ();
if (new_rhs_ops > 2)
abort ();
}

55
gcc/tree-vrp.c
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@ -9600,6 +9600,43 @@ range_fits_type_p (value_range *vr, unsigned dest_precision, signop dest_sgn)
return true;
}
/* Simplify STMT, an ASSERT_EXPR, using ranges. This is helpful because jump
threading looks at the ASSERT_EXPRs. Collapsing the condition of
an ASSERT_EXPR from a relational to an equality test is where most
of the benefit occurrs, so that's the only thing we currently do. */
static bool
simplify_assert_expr_using_ranges (gimple *stmt)
{
return false;
tree cond = TREE_OPERAND (gimple_assign_rhs1 (stmt), 1);
tree_code code = TREE_CODE (cond);
tree op0 = TREE_OPERAND (cond, 0);
/* The condition of the ASSERT_EXPR must be a simple relational
between an SSA_NAME (with a range) and a constant. */
if (TREE_CODE (op0) != SSA_NAME
|| !INTEGRAL_TYPE_P (TREE_TYPE (op0)))
return false;
tree op1 = TREE_OPERAND (cond, 1);
if (TREE_CODE (op1) != INTEGER_CST)
return false;
value_range *vr = get_value_range (op0);
if (!vr || vr->type != VR_RANGE)
return false;
tree res = test_for_singularity (code, op0, op1, vr);
if (res)
{
TREE_SET_CODE (cond, EQ_EXPR);
TREE_OPERAND (cond, 1) = res;
return true;
}
return false;
}
/* Simplify a conditional using a relational operator to an equality
test if the range information indicates only one value can satisfy
the original conditional. */
@ -10334,6 +10371,9 @@ simplify_stmt_using_ranges (gimple_stmt_iterator *gsi)
case MAX_EXPR:
return simplify_min_or_max_using_ranges (gsi, stmt);
case ASSERT_EXPR:
return simplify_assert_expr_using_ranges (stmt);
default:
break;
}
@ -10598,6 +10638,18 @@ vrp_dom_walker::before_dom_children (basic_block bb)
{
tree rhs1 = gimple_assign_rhs1 (stmt);
tree cond = TREE_OPERAND (rhs1, 1);
tree lhs = gimple_assign_lhs (stmt);
m_const_and_copies->record_const_or_copy (lhs, TREE_OPERAND (rhs1, 0));
if (TREE_CODE (cond) == EQ_EXPR)
{
tree cond_op0 = TREE_OPERAND (cond, 0);
tree cond_op1 = TREE_OPERAND (cond, 1);
if (TREE_CODE (cond_op0) == SSA_NAME)
m_const_and_copies->record_const_or_copy (cond_op0, cond_op1);
continue;
}
tree inverted = invert_truthvalue (cond);
vec<cond_equivalence> p;
p.create (3);
@ -10605,9 +10657,6 @@ vrp_dom_walker::before_dom_children (basic_block bb)
for (unsigned int i = 0; i < p.length (); i++)
m_avail_exprs_stack->record_cond (&p[i]);
tree lhs = gimple_assign_lhs (stmt);
m_const_and_copies->record_const_or_copy (lhs,
TREE_OPERAND (rhs1, 0));
p.release ();
continue;
}