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From: "Philippe Mathieu-Daudé" <f4bug@amsat.org>
To: qemu-devel@nongnu.org
Cc: "Thomas Huth" <thuth@redhat.com>,
	"David Hildenbrand" <david@redhat.com>,
	"Cornelia Huck" <cohuck@redhat.com>,
	"Richard Henderson" <richard.henderson@linaro.org>,
	"Philippe Mathieu-Daudé" <f4bug@amsat.org>,
	"Richard W . M . Jones" <rjones@redhat.com>,
	qemu-s390x@nongnu.org, "Miroslav Rezanina" <mrezanin@redhat.com>
Subject: [PATCH] tcg/s390: Fix compare instruction from extended-immediate facility
Date: Thu,  4 Feb 2021 19:29:02 +0100	[thread overview]
Message-ID: <20210204182902.1742826-1-f4bug@amsat.org> (raw)

The code is currently comparing c2 to the type promotion of
uint32_t and int32_t. That is, the conversion rules are as:

  (common_type) c2 == (common_type) (uint32_t)
                        (is_unsigned
                        ? (uint32_t)c2
                        : (uint32_t)(int32_t)c2)

In the signed case we lose the desired sign extensions because
of the argument promotion rules of the ternary operator.

Solve the problem by doing the round-trip parsing through the
intermediate type and back to the desired common type (all at
one expression).

Fixes: a534bb15f30 ("tcg/s390: Use constant pool for cmpi")
Reported-by: Miroslav Rezanina <mrezanin@redhat.com>
Reported-by: Richard W.M. Jones <rjones@redhat.com>
Suggested-by: David Hildenbrand <david@redhat.com>
Suggested-by: Eric Blake <eblake@redhat.com>
Signed-off-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
---
 tcg/s390/tcg-target.c.inc | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/tcg/s390/tcg-target.c.inc b/tcg/s390/tcg-target.c.inc
index b67470137c4..695d7ee6523 100644
--- a/tcg/s390/tcg-target.c.inc
+++ b/tcg/s390/tcg-target.c.inc
@@ -1067,7 +1067,7 @@ static int tgen_cmp(TCGContext *s, TCGType type, TCGCond c, TCGReg r1,
                 op = (is_unsigned ? RIL_CLFI : RIL_CFI);
                 tcg_out_insn_RIL(s, op, r1, c2);
                 goto exit;
-            } else if (c2 == (is_unsigned ? (uint32_t)c2 : (int32_t)c2)) {
+            } else if (c2 == (is_unsigned ? (TCGArg)(uint32_t)c2 : (TCGArg)(int32_t)c2)) {
                 op = (is_unsigned ? RIL_CLGFI : RIL_CGFI);
                 tcg_out_insn_RIL(s, op, r1, c2);
                 goto exit;
-- 
2.26.2



             reply	other threads:[~2021-02-04 19:01 UTC|newest]

Thread overview: 4+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-02-04 18:29 Philippe Mathieu-Daudé [this message]
2021-02-04 18:54 ` [PATCH] tcg/s390: Fix compare instruction from extended-immediate facility Richard Henderson
2021-02-04 19:25 ` David Hildenbrand
2021-02-04 22:06 ` Richard W.M. Jones

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