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convert: Fix test for out of bounds shift count [PR113574] 

The following patch is miscompiled, because convert_to_integer_1 for
LSHIFT_EXPR tests if the INTEGER_CST shift count is too high, but
incorrectly compares it against TYPE_SIZE rather than TYPE_PRECISION.
The type in question is unsigned _BitInt(1), which has TYPE_PRECISION 1,
TYPE_SIZE 8, and the shift count is 2 in that case.

2024-01-25  Jakub Jelinek  <jakub@redhat.com>

	PR middle-end/113574
	* convert.cc (convert_to_integer_1) <case LSHIFT_EXPR>: Compare shift
	count against TYPE_PRECISION rather than TYPE_SIZE.

	* gcc.dg/torture/bitint-52.c: New test.
pull/79/merge
Jakub Jelinek 2024-01-25 13:15:23 +01:00
parent c3de14ba1b
commit fb1b7e2fec
2 changed files with 25 additions and 1 deletions
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3
gcc/convert.cc
View File

@ -762,7 +762,8 @@ convert_to_integer_1 (tree type, tree expr, bool dofold)
{
/* If shift count is less than the width of the truncated type,
really shift. */
if (tree_int_cst_lt (TREE_OPERAND (expr, 1), TYPE_SIZE (type)))
if (wi::to_widest (TREE_OPERAND (expr, 1))
< TYPE_PRECISION (type))
/* In this case, shifting is like multiplication. */
goto trunc1;
else

23
gcc/testsuite/gcc.dg/torture/bitint-52.c Normal file
View File

@ -0,0 +1,23 @@
/* PR middle-end/113574 */
/* { dg-do run { target bitint } } */
/* { dg-options "-std=c23 -pedantic-errors" } */
/* { dg-skip-if "" { ! run_expensive_tests } { "*" } { "-O0" "-O2" } } */
/* { dg-skip-if "" { ! run_expensive_tests } { "-flto" } { "" } } */
unsigned _BitInt(1) a;
unsigned _BitInt(8) b;
void
foo (unsigned _BitInt(16) x)
{
a += (x << 2) | b;
}
int
main ()
{
foo (0xfef1uwb);
if (a)
__builtin_abort ();
return 0;
}