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gcc/0098-CHREC-multiplication-and-undefined-overflow.patch
huangzifeng 845ea89e1a Sync patches from branch openEuler-24.09
2024-11-21 11:35:14 +08:00

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From c4e4fef145c1e402f0558cc35f6c1ed0a08beffb Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?=E9=83=91=E6=99=A8=E5=8D=89?= <zhengchenhui1@huawei.com>
Date: Thu, 25 Jul 2024 20:16:52 +0800
Subject: [PATCH] CHREC multiplication and undefined overflow
This optimization is brought from https://gcc.gnu.org/pipermail/gcc-patches/2024-February/646531.html
When folding a multiply CHRECs are handled like {a, +, b} * c
is {a*c, +, b*c} but that isn't generally correct when overflow
invokes undefined behavior. The following uses unsigned arithmetic
unless either a is zero or a and b have the same sign.
I've used simple early outs for INTEGER_CSTs and otherwise use
a range-query since we lack a tree_expr_nonpositive_p and
get_range_pos_neg isn't a good fit.
---
gcc/common.opt | 4 ++
gcc/testsuite/gcc.dg/pr68317.c | 6 +-
gcc/testsuite/gcc.dg/torture/pr114074.c | 31 ++++++++++
gcc/tree-chrec.cc | 81 +++++++++++++++++++++----
gcc/tree-chrec.h | 2 +-
gcc/value-range.cc | 12 ++++
gcc/value-range.h | 2 +
7 files changed, 123 insertions(+), 15 deletions(-)
create mode 100644 gcc/testsuite/gcc.dg/torture/pr114074.c
diff --git a/gcc/common.opt b/gcc/common.opt
index b18f0b944..d3af3ba39 100644
--- a/gcc/common.opt
+++ b/gcc/common.opt
@@ -1771,6 +1771,10 @@ floop-interchange
Common Var(flag_loop_interchange) Optimization
Enable loop interchange on trees.
+fchrec-mul-fold-strict-overflow
+Common Var(flag_chrec_mul_fold_strict_overflow) Init(0)
+Enable strict overflow handling during constant folding of multiply CHRECs.
+
floop-block
Common Alias(floop-nest-optimize)
Enable loop nest transforms. Same as -floop-nest-optimize.
diff --git a/gcc/testsuite/gcc.dg/pr68317.c b/gcc/testsuite/gcc.dg/pr68317.c
index bd053a752..671a67d95 100644
--- a/gcc/testsuite/gcc.dg/pr68317.c
+++ b/gcc/testsuite/gcc.dg/pr68317.c
@@ -1,5 +1,5 @@
/* { dg-do compile } */
-/* { dg-options "-O2 -fdisable-tree-ethread" } */
+/* { dg-options "-O2 -fdisable-tree-ethread -fchrec-mul-fold-strict-overflow" } */
/* Note: Threader will collapse loop. */
@@ -12,8 +12,8 @@ foo ()
{
int32_t index = 0;
- for (index; index <= 10; index--) // expected warning here
+ for (index; index <= 10; index--) /* { dg-warning "iteration \[0-9\]+ invokes undefined behavior" } */
/* Result of the following multiply will overflow
when converted to signed int32_t. */
- bar ((0xcafe + index) * 0xdead); /* { dg-warning "iteration \[0-9\]+ invokes undefined behavior" } */
+ bar ((0xcafe + index) * 0xdead);
}
diff --git a/gcc/testsuite/gcc.dg/torture/pr114074.c b/gcc/testsuite/gcc.dg/torture/pr114074.c
new file mode 100644
index 000000000..9a383d8fc
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/torture/pr114074.c
@@ -0,0 +1,31 @@
+/* { dg-do run } */
+<<<<<<< HEAD
+/* { dg-options "-fchrec-mul-fold-strict-overflow" } */
+=======
+/* { dg-options "-fchrec-mul-fold-strict-overflow"" } */
+>>>>>>> 47092575e7696f5a21cf75284fe3d4feb0c813ab
+int a, b, d;
+
+__attribute__((noipa)) void
+foo (void)
+{
+ ++d;
+}
+
+int
+main ()
+{
+ for (a = 0; a > -3; a -= 2)
+ {
+ int c = a;
+ b = __INT_MAX__ - 3000;
+ a = ~c * b;
+ foo ();
+ if (!a)
+ break;
+ a = c;
+ }
+ if (d != 2)
+ __builtin_abort ();
+ return 0;
+}
diff --git a/gcc/tree-chrec.cc b/gcc/tree-chrec.cc
index c44cea754..3323901bc 100644
--- a/gcc/tree-chrec.cc
+++ b/gcc/tree-chrec.cc
@@ -38,6 +38,8 @@ along with GCC; see the file COPYING3. If not see
#include "gimple.h"
#include "tree-ssa-loop.h"
#include "dumpfile.h"
+#include "value-range.h"
+#include "value-query.h"
#include "tree-scalar-evolution.h"
/* Extended folder for chrecs. */
@@ -404,6 +406,13 @@ chrec_fold_multiply (tree type,
|| automatically_generated_chrec_p (op1))
return chrec_fold_automatically_generated_operands (op0, op1);
+ if (flag_chrec_mul_fold_strict_overflow)
+ {
+ if (TREE_CODE (op0) != POLYNOMIAL_CHREC
+ && TREE_CODE (op1) == POLYNOMIAL_CHREC)
+ std::swap (op0, op1);
+ }
+
switch (TREE_CODE (op0))
{
case POLYNOMIAL_CHREC:
@@ -428,10 +437,53 @@ chrec_fold_multiply (tree type,
if (integer_zerop (op1))
return build_int_cst (type, 0);
- return build_polynomial_chrec
- (CHREC_VARIABLE (op0),
- chrec_fold_multiply (type, CHREC_LEFT (op0), op1),
- chrec_fold_multiply (type, CHREC_RIGHT (op0), op1));
+ if (flag_chrec_mul_fold_strict_overflow)
+ {
+ /* When overflow is undefined and CHREC_LEFT/RIGHT do not have the
+ same sign or CHREC_LEFT is zero then folding the multiply into
+ the addition does not have the same behavior on overflow. Use
+ unsigned arithmetic in that case. */
+ value_range rl, rr;
+ if (!ANY_INTEGRAL_TYPE_P (type)
+ || TYPE_OVERFLOW_WRAPS (type)
+ || integer_zerop (CHREC_LEFT (op0))
+ || (TREE_CODE (CHREC_LEFT (op0)) == INTEGER_CST
+ && TREE_CODE (CHREC_RIGHT (op0)) == INTEGER_CST
+ && (tree_int_cst_sgn (CHREC_LEFT (op0))
+ == tree_int_cst_sgn (CHREC_RIGHT (op0))))
+ || (get_range_query (cfun)->range_of_expr (rl, CHREC_LEFT (op0))
+ && !rl.undefined_p ()
+ && (rl.nonpositive_p () || rl.nonnegative_p ())
+ && get_range_query (cfun)->range_of_expr (rr,
+ CHREC_RIGHT (op0))
+ && !rr.undefined_p ()
+ && ((rl.nonpositive_p () && rr.nonpositive_p ())
+ || (rl.nonnegative_p () && rr.nonnegative_p ()))))
+ {
+ tree left = chrec_fold_multiply (type, CHREC_LEFT (op0), op1);
+ tree right = chrec_fold_multiply (type, CHREC_RIGHT (op0), op1);
+ return build_polynomial_chrec (CHREC_VARIABLE (op0), left, right);
+ }
+ else
+ {
+ tree utype = unsigned_type_for (type);
+ tree uop1 = chrec_convert_rhs (utype, op1);
+ tree uleft0 = chrec_convert_rhs (utype, CHREC_LEFT (op0));
+ tree uright0 = chrec_convert_rhs (utype, CHREC_RIGHT (op0));
+ tree left = chrec_fold_multiply (utype, uleft0, uop1);
+ tree right = chrec_fold_multiply (utype, uright0, uop1);
+ tree tem = build_polynomial_chrec (CHREC_VARIABLE (op0),
+ left, right);
+ return chrec_convert_rhs (type, tem);
+ }
+ }
+ else
+ {
+ return build_polynomial_chrec
+ (CHREC_VARIABLE (op0),
+ chrec_fold_multiply (type, CHREC_LEFT (op0), op1),
+ chrec_fold_multiply (type, CHREC_RIGHT (op0), op1));
+ }
}
CASE_CONVERT:
@@ -449,13 +501,20 @@ chrec_fold_multiply (tree type,
switch (TREE_CODE (op1))
{
case POLYNOMIAL_CHREC:
- gcc_checking_assert
- (!chrec_contains_symbols_defined_in_loop (op1,
- CHREC_VARIABLE (op1)));
- return build_polynomial_chrec
- (CHREC_VARIABLE (op1),
- chrec_fold_multiply (type, CHREC_LEFT (op1), op0),
- chrec_fold_multiply (type, CHREC_RIGHT (op1), op0));
+ if (flag_chrec_mul_fold_strict_overflow)
+ {
+ gcc_unreachable ();
+ }
+ else
+ {
+ gcc_checking_assert
+ (!chrec_contains_symbols_defined_in_loop (op1,
+ CHREC_VARIABLE (op1)));
+ return build_polynomial_chrec
+ (CHREC_VARIABLE (op1),
+ chrec_fold_multiply (type, CHREC_LEFT (op1), op0),
+ chrec_fold_multiply (type, CHREC_RIGHT (op1), op0));
+ }
CASE_CONVERT:
if (tree_contains_chrecs (op1, NULL))
diff --git a/gcc/tree-chrec.h b/gcc/tree-chrec.h
index fcf41710d..cdc97d5d9 100644
--- a/gcc/tree-chrec.h
+++ b/gcc/tree-chrec.h
@@ -63,7 +63,7 @@ extern tree chrec_fold_plus (tree, tree, tree);
extern tree chrec_fold_minus (tree, tree, tree);
extern tree chrec_fold_multiply (tree, tree, tree);
extern tree chrec_convert (tree, tree, gimple *, bool = true, tree = NULL);
-extern tree chrec_convert_rhs (tree, tree, gimple *);
+extern tree chrec_convert_rhs (tree, tree, gimple * = NULL);
extern tree chrec_convert_aggressive (tree, tree, bool *);
/* Operations. */
diff --git a/gcc/value-range.cc b/gcc/value-range.cc
index 000bbcf89..a1dc10a24 100644
--- a/gcc/value-range.cc
+++ b/gcc/value-range.cc
@@ -656,6 +656,18 @@ irange::contains_p (tree cst) const
return false;
}
+bool
+irange::nonnegative_p () const
+{
+ return wi::ge_p (lower_bound (), 0, TYPE_SIGN (type ()));
+}
+
+bool
+irange::nonpositive_p () const
+{
+ return wi::le_p (upper_bound (), 0, TYPE_SIGN (type ()));
+}
+
/* Normalize addresses into constants. */
diff --git a/gcc/value-range.h b/gcc/value-range.h
index d4cba22d5..2dc0907de 100644
--- a/gcc/value-range.h
+++ b/gcc/value-range.h
@@ -69,6 +69,8 @@ public:
bool varying_p () const;
bool singleton_p (tree *result = NULL) const;
bool contains_p (tree) const;
+ bool nonnegative_p () const;
+ bool nonpositive_p () const;
// In-place operators.
void union_ (const irange &);
--
2.33.0
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