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From: "Alex Bennée" <alex.bennee@linaro.org>
To: qemu-devel@nongnu.org
Cc: "Peter Maydell" <peter.maydell@linaro.org>,
	"Alex Bennée" <alex.bennee@linaro.org>,
	"Aurelien Jarno" <aurelien@aurel32.net>
Subject: [PATCH v1 5/7] fpu/softfloat: avoid undefined behaviour when normalising empty sigs
Date: Fri, 27 Mar 2020 09:49:43 +0000
Message-ID: <20200327094945.23768-6-alex.bennee@linaro.org> (raw)
In-Reply-To: <20200327094945.23768-1-alex.bennee@linaro.org>

The undefined behaviour checker pointed out that a shift of 64 would
lead to undefined behaviour.

Signed-off-by: Alex Bennée <alex.bennee@linaro.org>
---
 fpu/softfloat.c | 11 ++++++++---
 1 file changed, 8 insertions(+), 3 deletions(-)

diff --git a/fpu/softfloat.c b/fpu/softfloat.c
index 301ce3b537b..444d35920dd 100644
--- a/fpu/softfloat.c
+++ b/fpu/softfloat.c
@@ -3834,9 +3834,14 @@ void normalizeFloatx80Subnormal(uint64_t aSig, int32_t *zExpPtr,
 {
     int8_t shiftCount;
 
-    shiftCount = clz64(aSig);
-    *zSigPtr = aSig<<shiftCount;
-    *zExpPtr = 1 - shiftCount;
+    if (aSig) {
+        shiftCount = clz64(aSig);
+        *zSigPtr = aSig << shiftCount;
+        *zExpPtr = 1 - shiftCount;
+    } else {
+        *zSigPtr = 0;
+        *zExpPtr = 1 - 64;
+    }
 }
 
 /*----------------------------------------------------------------------------
-- 
2.20.1



  parent reply index

Thread overview: 24+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-03-27  9:49 [PATCH for 5.0 v1 0/7] A selection of sanitiser fixes Alex Bennée
2020-03-27  9:49 ` [PATCH v1 1/7] elf-ops: bail out if we have no function symbols Alex Bennée
2020-03-27 10:53   ` Philippe Mathieu-Daudé
2020-03-27 11:10     ` Philippe Mathieu-Daudé
2020-03-27 11:45   ` Peter Maydell
2020-03-27 22:09   ` Richard Henderson
2020-03-27  9:49 ` [PATCH v1 2/7] linux-user: protect fcntl64 with an #ifdef Alex Bennée
2020-03-27 10:40   ` Laurent Vivier
2020-03-27 22:10   ` Richard Henderson
2020-03-27  9:49 ` [PATCH v1 3/7] tests/tcg: remove extraneous pasting macros Alex Bennée
2020-03-27 10:54   ` Philippe Mathieu-Daudé
2020-03-27 22:11   ` Richard Henderson
2020-03-27  9:49 ` [PATCH v1 4/7] linux-user: more debug for init_guest_space Alex Bennée
2020-03-27 10:50   ` Laurent Vivier
2020-03-27  9:49 ` Alex Bennée [this message]
2020-03-27 10:09   ` [PATCH v1 5/7] fpu/softfloat: avoid undefined behaviour when normalising empty sigs Peter Maydell
2020-03-27 22:27     ` Richard Henderson
2020-03-27 22:33       ` Peter Maydell
2020-03-27 10:13   ` Aleksandar Markovic
2020-03-27 10:31     ` Alex Bennée
2020-03-27  9:49 ` [PATCH v1 6/7] target/xtensa: add FIXME for translation memory leak Alex Bennée
2020-03-27  9:49 ` [PATCH v1 7/7] gdbstub: fix compiler complaining Alex Bennée
2020-03-27 10:56   ` Philippe Mathieu-Daudé
2020-03-27 10:53 ` [PATCH for 5.0 v1 0/7] A selection of sanitiser fixes no-reply

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