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[PATCH 2/2] target/s390x: Fix determination of overflow condition code a
From: |
Thomas Huth |
Subject: |
[PATCH 2/2] target/s390x: Fix determination of overflow condition code after subtraction |
Date: |
Wed, 23 Mar 2022 17:26:21 +0100 |
Reported by Paul Eggert in
https://lists.gnu.org/archive/html/bug-gnulib/2021-09/msg00050.html
This program currently prints different results when run with TCG instead
of running on real s390x hardware:
#include <stdio.h>
int overflow_32 (int x, int y)
{
int sum;
return __builtin_sub_overflow (x, y, &sum);
}
int overflow_64 (long long x, long long y)
{
long sum;
return __builtin_sub_overflow (x, y, &sum);
}
int a1 = 0;
int b1 = -2147483648;
long long a2 = 0L;
long long b2 = -9223372036854775808L;
int main ()
{
{
int a = a1;
int b = b1;
printf ("a = 0x%x, b = 0x%x\n", a, b);
printf ("no_overflow = %d\n", ! overflow_32 (a, b));
}
{
long long a = a2;
long long b = b2;
printf ("a = 0x%llx, b = 0x%llx\n", a, b);
printf ("no_overflow = %d\n", ! overflow_64 (a, b));
}
}
Resolves: https://gitlab.com/qemu-project/qemu/-/issues/618
Suggested-by: Bruno Haible <bruno@clisp.org>
Signed-off-by: Thomas Huth <thuth@redhat.com>
---
target/s390x/tcg/cc_helper.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/target/s390x/tcg/cc_helper.c b/target/s390x/tcg/cc_helper.c
index e11cdb745d..b2e8d3d9f5 100644
--- a/target/s390x/tcg/cc_helper.c
+++ b/target/s390x/tcg/cc_helper.c
@@ -151,7 +151,7 @@ static uint32_t cc_calc_add_64(int64_t a1, int64_t a2,
int64_t ar)
static uint32_t cc_calc_sub_64(int64_t a1, int64_t a2, int64_t ar)
{
- if ((a1 > 0 && a2 < 0 && ar < 0) || (a1 < 0 && a2 > 0 && ar > 0)) {
+ if ((a1 >= 0 && a2 < 0 && ar < 0) || (a1 < 0 && a2 > 0 && ar > 0)) {
return 3; /* overflow */
} else {
if (ar < 0) {
@@ -211,7 +211,7 @@ static uint32_t cc_calc_add_32(int32_t a1, int32_t a2,
int32_t ar)
static uint32_t cc_calc_sub_32(int32_t a1, int32_t a2, int32_t ar)
{
- if ((a1 > 0 && a2 < 0 && ar < 0) || (a1 < 0 && a2 > 0 && ar > 0)) {
+ if ((a1 >= 0 && a2 < 0 && ar < 0) || (a1 < 0 && a2 > 0 && ar > 0)) {
return 3; /* overflow */
} else {
if (ar < 0) {
--
2.27.0
- [PATCH 1/2] target/s390x: Fix determination of overflow condition code after addition, (continued)
- [PATCH 1/2] target/s390x: Fix determination of overflow condition code after addition, Thomas Huth, 2022/03/23
- Re: [PATCH 1/2] target/s390x: Fix determination of overflow condition code after addition, David Hildenbrand, 2022/03/30
- Re: [PATCH 1/2] target/s390x: Fix determination of overflow condition code after addition, Thomas Huth, 2022/03/30
- Re: [PATCH 1/2] target/s390x: Fix determination of overflow condition code after addition, David Hildenbrand, 2022/03/30
- Re: [PATCH 1/2] target/s390x: Fix determination of overflow condition code after addition, Thomas Huth, 2022/03/30
- Re: [PATCH 1/2] target/s390x: Fix determination of overflow condition code after addition, David Hildenbrand, 2022/03/30
- Re: [PATCH 1/2] target/s390x: Fix determination of overflow condition code after addition, Thomas Huth, 2022/03/30
- Re: [PATCH 1/2] target/s390x: Fix determination of overflow condition code after addition, Thomas Huth, 2022/03/30
- Re: [PATCH 1/2] target/s390x: Fix determination of overflow condition code after addition, Richard Henderson, 2022/03/30
- Re: [PATCH 1/2] target/s390x: Fix determination of overflow condition code after addition, Thomas Huth, 2022/03/31
[PATCH 2/2] target/s390x: Fix determination of overflow condition code after subtraction,
Thomas Huth <=