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From: Eduardo Habkost <ehabkost@redhat.com>
To: Peter Maydell <peter.maydell@linaro.org>
Cc: qemu-devel@nongnu.org, "Paolo Bonzini" <pbonzini@redhat.com>,
	"Andreas Färber" <afaerber@suse.de>,
	"Richard Henderson" <rth@twiddle.net>
Subject: [Qemu-devel] [PULL 1/2] target-i386: Don't left shift negative constant
Date: Wed, 28 Oct 2015 12:15:08 -0200	[thread overview]
Message-ID: <1446041709-26510-2-git-send-email-ehabkost@redhat.com> (raw)
In-Reply-To: <1446041709-26510-1-git-send-email-ehabkost@redhat.com>

Left shift of negative values is undefined behavior. Detected by clang:
  qemu/target-i386/translate.c:2423:26: runtime error:
    left shift of negative value -8

This changes the code to reverse the sign after the left shift.

Signed-off-by: Eduardo Habkost <ehabkost@redhat.com>
---
 target-i386/translate.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/target-i386/translate.c b/target-i386/translate.c
index 764b1e4..862f8e0 100644
--- a/target-i386/translate.c
+++ b/target-i386/translate.c
@@ -2432,7 +2432,7 @@ static void gen_pusha(DisasContext *s)
 {
     int i;
     gen_op_movl_A0_reg(R_ESP);
-    gen_op_addl_A0_im(-8 << s->dflag);
+    gen_op_addl_A0_im(-(8 << s->dflag));
     if (!s->ss32)
         tcg_gen_ext16u_tl(cpu_A0, cpu_A0);
     tcg_gen_mov_tl(cpu_T[1], cpu_A0);
-- 
2.1.0

  reply	other threads:[~2015-10-28 14:15 UTC|newest]

Thread overview: 4+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2015-10-28 14:15 [Qemu-devel] [PULL 0/2] target-i386: Finally enable "check" mode by default Eduardo Habkost
2015-10-28 14:15 ` Eduardo Habkost [this message]
2015-10-28 14:15 ` [Qemu-devel] [PULL 2/2] target-i386: Enable " Eduardo Habkost
2015-10-28 15:52 ` [Qemu-devel] [PULL 0/2] target-i386: Finally enable " Peter Maydell

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