From a280a700fb016178776cb599d8cf918185df8697 Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?C=C3=A9dric=20Le=20Goater?= Date: Tue, 23 May 2023 12:34:33 +0200 Subject: [PATCH 11/22] target/s390x: Fix determination of overflow condition code after subtraction MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit RH-Author: Cédric Le Goater RH-MergeRequest: 279: Backport latest s390x-related fixes from upstream QEMU for qemu-kvm in RHEL 8.9 RH-Bugzilla: 2169308 2209605 RH-Acked-by: Thomas Huth RH-Acked-by: David Hildenbrand RH-Acked-by: Cornelia Huck RH-Commit: [10/21] 14792faddfca784503f89c292ebaba5be8d3fc96 Bugzilla: https://bugzilla.redhat.com/2169308 commit fc6e0d0f2db5126592bb4066d484fcdfc14ccf36 Author: Bruno Haible Date: Wed Mar 23 17:26:21 2022 +0100 target/s390x: Fix determination of overflow condition code after subtraction 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 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)); } } Signed-off-by: Bruno Haible Resolves: https://gitlab.com/qemu-project/qemu/-/issues/618 Message-Id: <20220323162621.139313-3-thuth@redhat.com> Signed-off-by: Thomas Huth Signed-off-by: Cédric Le Goater --- 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) { -- 2.37.3