linux-kernel - [bug report] perf jit: add source line info support

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Date:   Wed, 30 Nov 2016 21:48:22 +0300
From:   Dan Carpenter <dan.carpenter@...cle.com>
To:     eranian@...gle.com
Cc:     Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
        linux-kernel@...r.kernel.org
Subject: [bug report] perf jit: add source line info support

Hello Stephane Eranian,

The patch 598b7c6919c7: "perf jit: add source line info support" from
Nov 30, 2015, leads to the following static checker warning:

	./tools/perf/util/genelf_debug.c:211 emit_signed_LEB128()
	warn: potential left shift more than type allows '57'

./tools/perf/util/genelf_debug.c
   202  static void emit_signed_LEB128(struct buffer_ext *be, long data)
   203  {
   204          int more = 1;
   205          int negative = data < 0;
   206          int size = sizeof(long) * CHAR_BIT;
   207          while (more) {
   208                  ubyte cur = data & 0x7F;
   209                  data >>= 7;
   210                  if (negative)
   211                          data |= - (1 << (size - 7));
                                ^^^^^^^^^^^^^^^^^^^^^^^^^^^
This is a no-op on 64 bit systems.  I suspect it's not intentional?

   212                  if ((data == 0 && !(cur & 0x40)) ||
   213                      (data == -1l && (cur & 0x40)))
   214                          more = 0;
   215                  else
   216                          cur |= 0x80;
   217                  buffer_ext_add(be, &cur, 1);
   218          }
   219  }

regards,
dan carpenter