Hello,
trying to move a first pattern from fold_comparison.
I first tried without single_use. It brought the number of 'free' in
g++.dg/tree-ssa/pr61034.C down to 11, changed gcc.dg/sms-6.c to only 2 SMS
(I don't think the generated code was worse, maybe even better, but I
don't know ppc asm), broke Wstrict-overflow-18.c (the optimization moved
from VRP to CCP if I remember correctly), and caused IVOPTS to make a mess
in guality/pr54693-2.c (much longer code, and many <optimized> debug
variables). If someone wants to drop the single_use, they can work on that
after this patch is in.
The conditions do not exactly match the ones in fold-const.c, but I guess
they are close. The warning in the constant case was missing in
fold_comparison, but present in VRP, so I had to add it not to regress.
I don't think we were warning much from match.pd. I can't say that I am a
big fan of those strict overflow warnings, but I expect people would
complain if we just dropped the existing ones when moving the transforms
to match.pd?
I wanted to restrict the equality case to TYPE_OVERFLOW_WRAPS ||
TYPE_OVERFLOW_UNDEFINED, but that broke 20041114-1.c at -O1 (no strict
overflow), so I went with some kind of complement we use elsewhere. Now
that I am writing this, I don't remember why I didn't just add
-fstrict-overflow to the testcase, or xfail it at -O1. The saturating case
could be handled as long as the constant is not an extremum, but I don't
think we really handle saturating integers anyway.
I split the equality case, because it was already getting ugly.
Bootstrap+regtest on powerpc64le-unknown-linux-gnu.
2016-04-25 Marc Glisse <marc.gli...@inria.fr>
gcc/
* fold-const.h: Include flag-types.h.
(fold_overflow_warning): Declare.
* fold-const.c (fold_overflow_warning): Make non-static.
(fold_comparison): Move the transformation of X +- C1 CMP C2
into X CMP C2 -+ C1 ...
* match.pd: ... here.
* tree-ssa-forwprop.c (execute): Protect fold_stmt with
fold_defer_overflow_warnings.
gcc/testsuite/
* gcc.dg/tree-ssa/20040305-1.c: Adjust.
--
Marc GlisseIndex: trunk4/gcc/fold-const.c
===================================================================
--- trunk4/gcc/fold-const.c (revision 235384)
+++ trunk4/gcc/fold-const.c (working copy)
@@ -290,21 +290,21 @@ fold_undefer_and_ignore_overflow_warning
bool
fold_deferring_overflow_warnings_p (void)
{
return fold_deferring_overflow_warnings > 0;
}
/* This is called when we fold something based on the fact that signed
overflow is undefined. */
-static void
+void
fold_overflow_warning (const char* gmsgid, enum warn_strict_overflow_code wc)
{
if (fold_deferring_overflow_warnings > 0)
{
if (fold_deferred_overflow_warning == NULL
|| wc < fold_deferred_overflow_code)
{
fold_deferred_overflow_warning = gmsgid;
fold_deferred_overflow_code = wc;
}
@@ -8366,89 +8366,20 @@ fold_comparison (location_t loc, enum tr
{
const bool equality_code = (code == EQ_EXPR || code == NE_EXPR);
tree arg0, arg1, tem;
arg0 = op0;
arg1 = op1;
STRIP_SIGN_NOPS (arg0);
STRIP_SIGN_NOPS (arg1);
- /* Transform comparisons of the form X +- C1 CMP C2 to X CMP C2 -+ C1. */
- if ((TREE_CODE (arg0) == PLUS_EXPR || TREE_CODE (arg0) == MINUS_EXPR)
- && (equality_code
- || (ANY_INTEGRAL_TYPE_P (TREE_TYPE (arg0))
- && TYPE_OVERFLOW_UNDEFINED (TREE_TYPE (arg0))))
- && TREE_CODE (TREE_OPERAND (arg0, 1)) == INTEGER_CST
- && !TREE_OVERFLOW (TREE_OPERAND (arg0, 1))
- && TREE_CODE (arg1) == INTEGER_CST
- && !TREE_OVERFLOW (arg1))
- {
- const enum tree_code
- reverse_op = TREE_CODE (arg0) == PLUS_EXPR ? MINUS_EXPR : PLUS_EXPR;
- tree const1 = TREE_OPERAND (arg0, 1);
- tree const2 = fold_convert_loc (loc, TREE_TYPE (const1), arg1);
- tree variable = TREE_OPERAND (arg0, 0);
- tree new_const = int_const_binop (reverse_op, const2, const1);
-
- /* If the constant operation overflowed this can be
- simplified as a comparison against INT_MAX/INT_MIN. */
- if (TREE_OVERFLOW (new_const)
- && !TYPE_OVERFLOW_WRAPS (TREE_TYPE (arg0)))
- {
- int const1_sgn = tree_int_cst_sgn (const1);
- enum tree_code code2 = code;
-
- /* Get the sign of the constant on the lhs if the
- operation were VARIABLE + CONST1. */
- if (TREE_CODE (arg0) == MINUS_EXPR)
- const1_sgn = -const1_sgn;
-
- /* The sign of the constant determines if we overflowed
- INT_MAX (const1_sgn == -1) or INT_MIN (const1_sgn == 1).
- Canonicalize to the INT_MIN overflow by swapping the comparison
- if necessary. */
- if (const1_sgn == -1)
- code2 = swap_tree_comparison (code);
-
- /* We now can look at the canonicalized case
- VARIABLE + 1 CODE2 INT_MIN
- and decide on the result. */
- switch (code2)
- {
- case EQ_EXPR:
- case LT_EXPR:
- case LE_EXPR:
- return
- omit_one_operand_loc (loc, type, boolean_false_node, variable);
-
- case NE_EXPR:
- case GE_EXPR:
- case GT_EXPR:
- return
- omit_one_operand_loc (loc, type, boolean_true_node, variable);
-
- default:
- gcc_unreachable ();
- }
- }
- else
- {
- if (!equality_code)
- fold_overflow_warning ("assuming signed overflow does not occur "
- "when changing X +- C1 cmp C2 to "
- "X cmp C2 -+ C1",
- WARN_STRICT_OVERFLOW_COMPARISON);
- return fold_build2_loc (loc, code, type, variable, new_const);
- }
- }
-
/* For comparisons of pointers we can decompose it to a compile time
comparison of the base objects and the offsets into the object.
This requires at least one operand being an ADDR_EXPR or a
POINTER_PLUS_EXPR to do more than the operand_equal_p test below. */
if (POINTER_TYPE_P (TREE_TYPE (arg0))
&& (TREE_CODE (arg0) == ADDR_EXPR
|| TREE_CODE (arg1) == ADDR_EXPR
|| TREE_CODE (arg0) == POINTER_PLUS_EXPR
|| TREE_CODE (arg1) == POINTER_PLUS_EXPR))
{
Index: trunk4/gcc/fold-const.h
===================================================================
--- trunk4/gcc/fold-const.h (revision 235384)
+++ trunk4/gcc/fold-const.h (working copy)
@@ -13,20 +13,22 @@ WARRANTY; without even the implied warra
FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
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/>. */
#ifndef GCC_FOLD_CONST_H
#define GCC_FOLD_CONST_H
+#include <flag-types.h>
+
/* Non-zero if we are folding constants inside an initializer; zero
otherwise. */
extern int folding_initializer;
/* Convert between trees and native memory representation. */
extern int native_encode_expr (const_tree, unsigned char *, int, int off = -1);
extern tree native_interpret_expr (tree, const unsigned char *, int);
/* Fold constants as much as possible in an expression.
Returns the simplified expression.
@@ -79,20 +81,21 @@ extern bool fold_convertible_p (const_tr
fold_convert_loc (UNKNOWN_LOCATION, T1, T2)
extern tree fold_convert_loc (location_t, tree, tree);
extern tree fold_single_bit_test (location_t, enum tree_code, tree, tree,
tree);
extern tree fold_ignored_result (tree);
extern tree fold_abs_const (tree, tree);
extern tree fold_indirect_ref_1 (location_t, tree, tree);
extern void fold_defer_overflow_warnings (void);
extern void fold_undefer_overflow_warnings (bool, const gimple *, int);
extern void fold_undefer_and_ignore_overflow_warnings (void);
extern bool fold_deferring_overflow_warnings_p (void);
+extern void fold_overflow_warning (const char*, enum
warn_strict_overflow_code);
extern int operand_equal_p (const_tree, const_tree, unsigned int);
extern int multiple_of_p (tree, const_tree, const_tree);
#define omit_one_operand(T1,T2,T3)\
omit_one_operand_loc (UNKNOWN_LOCATION, T1, T2, T3)
extern tree omit_one_operand_loc (location_t, tree, tree, tree);
#define omit_two_operands(T1,T2,T3,T4)\
omit_two_operands_loc (UNKNOWN_LOCATION, T1, T2, T3, T4)
extern tree omit_two_operands_loc (location_t, tree, tree, tree, tree);
#define invert_truthvalue(T)\
invert_truthvalue_loc (UNKNOWN_LOCATION, T)
Index: trunk4/gcc/match.pd
===================================================================
--- trunk4/gcc/match.pd (revision 235384)
+++ trunk4/gcc/match.pd (working copy)
@@ -3071,10 +3071,54 @@ DEFINE_INT_AND_FLOAT_ROUND_FN (RINT)
(simplify
/* signbit(x) -> 0 if x is nonnegative. */
(SIGNBIT tree_expr_nonnegative_p@0)
{ integer_zero_node; })
(simplify
/* signbit(x) -> x<0 if x doesn't have signed zeros. */
(SIGNBIT @0)
(if (!HONOR_SIGNED_ZEROS (@0))
(convert (lt @0 { build_real (TREE_TYPE (@0), dconst0); }))))
+
+/* Transform comparisons of the form X +- C1 CMP C2 to X CMP C2 -+ C1. */
+(for cmp (eq ne)
+ (for op (plus minus)
+ rop (minus plus)
+ (simplify
+ (cmp (op@3 @0 INTEGER_CST@1) INTEGER_CST@2)
+ (if (!TREE_OVERFLOW (@1) && !TREE_OVERFLOW (@2)
+ && !TYPE_OVERFLOW_SANITIZED (TREE_TYPE (@0))
+ && !TYPE_OVERFLOW_TRAPS (TREE_TYPE (@0))
+ && !TYPE_SATURATING (TREE_TYPE (@0)))
+ (with { tree res = int_const_binop (rop, @2, @1); }
+ (if (TREE_OVERFLOW (res))
+ { constant_boolean_node (cmp == NE_EXPR, type); }
+ (if (single_use (@3))
+ (cmp @0 { res; }))))))))
+(for cmp (lt le gt ge)
+ (for op (plus minus)
+ rop (minus plus)
+ (simplify
+ (cmp (op@3 @0 INTEGER_CST@1) INTEGER_CST@2)
+ (if (!TREE_OVERFLOW (@1) && !TREE_OVERFLOW (@2)
+ && TYPE_OVERFLOW_UNDEFINED (TREE_TYPE (@0)))
+ (with { tree res = int_const_binop (rop, @2, @1); }
+ (if (TREE_OVERFLOW (res))
+ {
+ fold_overflow_warning (("assuming signed overflow does not occur "
+ "when simplifying conditional to constant"),
+ WARN_STRICT_OVERFLOW_CONDITIONAL);
+ bool less = cmp == LE_EXPR || cmp == LT_EXPR;
+ /* wi::ges_p (@2, 0) should be sufficient for a signed type. */
+ bool ovf_high = wi::lt_p (@1, 0, TYPE_SIGN (TREE_TYPE (@1)))
+ != (op == MINUS_EXPR);
+ constant_boolean_node (less == ovf_high, type);
+ }
+ (if (single_use (@3))
+ (with
+ {
+ fold_overflow_warning (("assuming signed overflow does not occur "
+ "when changing X +- C1 cmp C2 to "
+ "X cmp C2 -+ C1"),
+ WARN_STRICT_OVERFLOW_COMPARISON);
+ }
+ (cmp @0 { res; })))))))))
Index: trunk4/gcc/testsuite/gcc.dg/tree-ssa/20040305-1.c
===================================================================
--- trunk4/gcc/testsuite/gcc.dg/tree-ssa/20040305-1.c (revision 235384)
+++ trunk4/gcc/testsuite/gcc.dg/tree-ssa/20040305-1.c (working copy)
@@ -16,15 +16,15 @@ void foo(int edx, int eax)
}
if (eax == 100)
{
if (-- edx == 0)
afred[0] = 2;
}
}
/* Verify that we did a forward propagation. */
-/* { dg-final { scan-tree-dump-times "Replaced" 1 "forwprop1"} } */
+/* { dg-final { scan-tree-dump-times "gimple_simplified" 1 "forwprop1"} } */
/* After cddce we should have two IF statements remaining as the other
two tests can be threaded. */
/* { dg-final { scan-tree-dump-times "if " 2 "cddce2"} } */
Index: trunk4/gcc/tree-ssa-forwprop.c
===================================================================
--- trunk4/gcc/tree-ssa-forwprop.c (revision 235384)
+++ trunk4/gcc/tree-ssa-forwprop.c (working copy)
@@ -2299,37 +2299,41 @@ pass_forwprop::execute (function *fun)
{
gimple *stmt = gsi_stmt (gsi);
gimple *orig_stmt = stmt;
bool changed = false;
bool was_noreturn = (is_gimple_call (stmt)
&& gimple_call_noreturn_p (stmt));
/* Mark stmt as potentially needing revisiting. */
gimple_set_plf (stmt, GF_PLF_1, false);
+ fold_defer_overflow_warnings ();
if (fold_stmt (&gsi, fwprop_ssa_val))
{
changed = true;
stmt = gsi_stmt (gsi);
if (maybe_clean_or_replace_eh_stmt (orig_stmt, stmt))
bitmap_set_bit (to_purge, bb->index);
if (!was_noreturn
&& is_gimple_call (stmt) && gimple_call_noreturn_p (stmt))
to_fixup.safe_push (stmt);
/* Cleanup the CFG if we simplified a condition to
true or false. */
if (gcond *cond = dyn_cast <gcond *> (stmt))
if (gimple_cond_true_p (cond)
|| gimple_cond_false_p (cond))
cfg_changed = true;
update_stmt (stmt);
+ fold_undefer_overflow_warnings (!gimple_no_warning_p (stmt),
stmt, 0);
}
+ else
+ fold_undefer_overflow_warnings (false, NULL, 0);
switch (gimple_code (stmt))
{
case GIMPLE_ASSIGN:
{
tree rhs1 = gimple_assign_rhs1 (stmt);
enum tree_code code = gimple_assign_rhs_code (stmt);
if (code == COND_EXPR
|| code == VEC_COND_EXPR)
