From 0319f265eddd17c32cb037b71489d9882a6eb00d Mon Sep 17 00:00:00 2001
From: Jakub Jelinek <jakub@redhat.com>
Date: Fri, 15 Mar 2024 10:10:57 +0100
Subject: [PATCH] expand: EXTEND_BITINT CALL_EXPR results [PR114332]
The x86-64 and aarch64 psABIs (and the unwritten ia64 psABI part) say that
the padding bits of _BitInt are undefined, while the expansion internally
typically assumes that non-mode precision integers are sign/zero extended
and extends after operations. We handle that mismatch with EXTEND_BITINT
done when reading from untrusted sources like function arguments, reading
_BitInt from memory etc. but otherwise keep relying on stuff being extended
internally (say in pseudos).
The return value of a function is an ABI boundary though too and we need
to extend that too.
2024-03-15 Jakub Jelinek <jakub@redhat.com>
PR middle-end/114332
* expr.cc (expand_expr_real_1): EXTEND_BITINT also CALL_EXPR results.
---
gcc/expr.cc | 3 ++-
gcc/testsuite/gcc.dg/torture/bitint-64.c | 22 ++++++++++++++++++++++
2 files changed, 24 insertions(+), 1 deletion(-)
create mode 100644 gcc/testsuite/gcc.dg/torture/bitint-64.c
diff --git a/gcc/expr.cc b/gcc/expr.cc
index f7d74525c15b..2918c4697354 100644
--- a/gcc/expr.cc
+++ b/gcc/expr.cc
@@ -12350,7 +12350,8 @@ expand_expr_real_1 (tree exp, rtx target, machine_mode tmode,
return expand_builtin (exp, target, subtarget, tmode, ignore);
}
}
- return expand_call (exp, target, ignore);
+ temp = expand_call (exp, target, ignore);
+ return EXTEND_BITINT (temp);
case VIEW_CONVERT_EXPR:
op0 = NULL_RTX;
diff --git a/gcc/testsuite/gcc.dg/torture/bitint-64.c b/gcc/testsuite/gcc.dg/torture/bitint-64.c
new file mode 100644
index 000000000000..8f0f21cbee29
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/torture/bitint-64.c
@@ -0,0 +1,22 @@
+/* PR middle-end/114332 */
+/* { dg-do run { target bitint } } */
+/* { dg-options "-std=c23 -fwrapv" } */
+/* { dg-skip-if "" { ! run_expensive_tests } { "*" } { "-O0" "-O2" } } */
+/* { dg-skip-if "" { ! run_expensive_tests } { "-flto" } { "" } } */
+
+enum E { E22 = 22 } e = E22;
+
+_BitInt (5)
+foo (void)
+{
+ _Atomic _BitInt (5) b = 0;
+ b += e;
+ return b;
+}
+
+int
+main ()
+{
+ if (foo () != -10)
+ __builtin_abort ();
+}
--
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