OpenE2K/gcc
2
0
Fork 0
Code Issues Pull Requests Projects Releases Wiki Activity

Do not register a cast as an equivalence.

Browse Source 
Registering an equivalence between objects of the same size in a cast can
cause other relations to be incorrect.

	gcc/
	PR tree-optimization/101335
	* range-op.cc (operator_cast::lhs_op1_relation): Delete.

	gcc/testsuite/
	* gcc.dg/tree-ssa/pr101335.c: New.
This commit is contained in:
Andrew MacLeod 2021-07-12 11:38:17 -04:00
parent 9d4393af9d
commit a1539b797a
2 changed files with 17 additions and 25 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

25
gcc/range-op.cc
View File

@ -2159,10 +2159,6 @@ public:
const irange &lhs,
const irange &op2,
relation_kind rel = VREL_NONE) const;
virtual enum tree_code lhs_op1_relation (const irange &lhs,
const irange &op1,
const irange &op2) const;
private:
bool truncating_cast_p (const irange &inner, const irange &outer) const;
bool inside_domain_p (const wide_int &min, const wide_int &max,
@ -2171,27 +2167,6 @@ private:
const irange &outer) const;
} op_convert;
// Determine if there is a relationship between LHS and OP1.
enum tree_code
operator_cast::lhs_op1_relation (const irange &lhs,
const irange &op1,
const irange &op2 ATTRIBUTE_UNUSED) const
{
if (op1.undefined_p ())
return VREL_NONE;
// We can't make larger types equivalent to smaller types because we can
// miss sign extensions in a chain of casts.
// u32 = 0xfffff
// s32 = (s32) u32
// s64 = (s64) s32
// we cant simply "convert" s64 = (s64)u32 or we get positive 0xffff
// value instead of sign extended negative value.
if (TYPE_PRECISION (lhs.type ()) == TYPE_PRECISION (op1.type ()))
return EQ_EXPR;
return VREL_NONE;
}
// Return TRUE if casting from INNER to OUTER is a truncating cast.
inline bool

17
gcc/testsuite/gcc.dg/tree-ssa/pr101335.c Normal file
View File

@ -0,0 +1,17 @@
/* { dg-do run } */
/* { dg-options "-O2" } */
unsigned a = 0xFFFFFFFF;
int b;
int main()
{
int c = ~a;
unsigned d = c - 10;
if (d > c)
c = 20;
b = -(c | 0);
if (b > -8)
__builtin_abort ();
return 0;
}