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tree-optimization/110243 - IVOPTs introducing undefined overflow

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The following addresses IVOPTs rewriting expressions in its
strip_offset without caring for definedness of overflow.  Rather
than the earlier attempt of just using the proper
split_constant_offset from data-ref analysis the following adjusts
IVOPTs helper trying to minimize changes from this fix, possibly
easing backports.

	PR tree-optimization/110243
	PR tree-optimization/111336
	* tree-ssa-loop-ivopts.cc (strip_offset_1): Rewrite
	operations with undefined behavior on overflow to
	unsigned arithmetic.

	* gcc.dg/torture/pr110243.c: New testcase.
	* gcc.dg/torture/pr111336.c: Likewise.
This commit is contained in:
Richard Biener
2023-10-20 14:08:46 +02:00
parent d70575f542
commit 44e7e4498c
3 changed files with 75 additions and 3 deletions
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22
gcc/testsuite/gcc.dg/torture/pr110243.c Normal file
View File

@@ -0,0 +1,22 @@
/* { dg-do run } */
/* { dg-require-effective-target lp64 } */
#define X 1100000000
unsigned char a;
long b = X;
int c[9][1];
unsigned d;
static long *e = &b, *f = &b;
int g() {
if (a && a <= '9')
return '0';
if (a)
return 10;
return -1;
}
int main() {
d = 0;
for (; (int)*f -(X-1) + d < 9; d++)
c[g() + (int)*f + ((int)*e - X) -(X-1) + d]
[0] = 0;
}

25
gcc/testsuite/gcc.dg/torture/pr111336.c Normal file
View File

@@ -0,0 +1,25 @@
/* { dg-do run } */
/* { dg-require-effective-target lp64 } */
extern void abort (void);
int a, b;
long c = 3521733542;
int d[2];
int e(int f, int g) {
if (f == 0)
return 0;
if (f > 200)
return 0;
if (g)
return 5 * f;
return 0;
}
int main()
{
int h = 0;
for (; e((int)c + 773233762, c + 60) + 773163185 + h < 2; h++)
d[h] = b;
if (a != 0)
abort ();
return 0;
}

31
gcc/tree-ssa-loop-ivopts.cc
View File

@@ -2829,12 +2829,29 @@ strip_offset_1 (tree expr, bool inside_addr, bool top_compref,
else if (integer_zerop (op0))
{
if (code == MINUS_EXPR)
expr = fold_build1 (NEGATE_EXPR, type, op1);
{
if (TYPE_OVERFLOW_UNDEFINED (type))
{
type = unsigned_type_for (type);
op1 = fold_convert (type, op1);
}
expr = fold_build1 (NEGATE_EXPR, type, op1);
}
else
expr = op1;
}
else
expr = fold_build2 (code, type, op0, op1);
{
if (TYPE_OVERFLOW_UNDEFINED (type))
{
type = unsigned_type_for (type);
if (code == POINTER_PLUS_EXPR)
code = PLUS_EXPR;
op0 = fold_convert (type, op0);
op1 = fold_convert (type, op1);
}
expr = fold_build2 (code, type, op0, op1);
}
return fold_convert (orig_type, expr);
@@ -2852,7 +2869,15 @@ strip_offset_1 (tree expr, bool inside_addr, bool top_compref,
if (integer_zerop (op0))
expr = op0;
else
expr = fold_build2 (MULT_EXPR, type, op0, op1);
{
if (TYPE_OVERFLOW_UNDEFINED (type))
{
type = unsigned_type_for (type);
op0 = fold_convert (type, op0);
op1 = fold_convert (type, op1);
}
expr = fold_build2 (MULT_EXPR, type, op0, op1);
}
return fold_convert (orig_type, expr);