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* [gcc r14-8423] convert: Fix test for out of bounds shift count [PR113574]
@ 2024-01-25 12:16 Jakub Jelinek
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From: Jakub Jelinek @ 2024-01-25 12:16 UTC (permalink / raw)
To: gcc-cvs
https://gcc.gnu.org/g:fb1b7e2fec951ba0bf4f68fac6a16929f4f63910
commit r14-8423-gfb1b7e2fec951ba0bf4f68fac6a16929f4f63910
Author: Jakub Jelinek <jakub@redhat.com>
Date: Thu Jan 25 13:15:23 2024 +0100
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.
Diff:
---
gcc/convert.cc | 3 ++-
gcc/testsuite/gcc.dg/torture/bitint-52.c | 23 +++++++++++++++++++++++
2 files changed, 25 insertions(+), 1 deletion(-)
diff --git a/gcc/convert.cc b/gcc/convert.cc
index 179f5e69008..5ad24ad2c08 100644
--- a/gcc/convert.cc
+++ b/gcc/convert.cc
@@ -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
diff --git a/gcc/testsuite/gcc.dg/torture/bitint-52.c b/gcc/testsuite/gcc.dg/torture/bitint-52.c
new file mode 100644
index 00000000000..d2896da2f9a
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/torture/bitint-52.c
@@ -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;
+}
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