[patch] Fix BZ15121 -- x/a broken for addresses in shared libraries

[Paul Pluzhnikov <ppluzhnikov@gmail.com>]

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Greetings,

Attached patch fixes BZ #15121 -- x/a broken for addresses in shared libraries.
Not adding a new test since this is already covered by gdb.base/long_long.exp

Tested on Linux/x86_64, no new failures.

Thanks,

ChangeLog:

2015-09-06  Paul Pluzhnikov  <ppluzhnikov@google.com>

        [BZ #15121]
        * gdb/value.c (unpack_pointer): Don't sign-extend.

testsuite/ChangeLog:

2015-09-06  Paul Pluzhnikov  <ppluzhnikov@google.com>

        * gdb.base/long_long.exp: Adjust.

-- 
Paul Pluzhnikov

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diff --git a/gdb/testsuite/gdb.base/long_long.exp b/gdb/testsuite/gdb.base/long_long.exp
index 5eea391..f4f3961 100644
--- a/gdb/testsuite/gdb.base/long_long.exp
+++ b/gdb/testsuite/gdb.base/long_long.exp
@@ -255,7 +255,7 @@ gdb_test "x/2bd b" "1.*-89"
 gdb_test "x/2bu b" "1.*167"
 gdb_test "x/2bo b" "01.*0247"
 gdb_test "x/2bt b" "00000001.*10100111"
-gdb_test_ptr "x/2ba b" "" "" "0x1.*0xffffffa7" "0x1.*0xffffffffffffffa7"
+gdb_test_ptr "x/2ba b" "" "" "0x1.*0xa7" "0x1.*0xa7"
 gdb_test "x/2bc b" "1 '.001'.*-89 '.\[0-9\]*'"
 gdb_test "x/2bf b" "1.*-89"
 
@@ -264,7 +264,7 @@ gdb_test "x/2hd h" "291.*-22738"
 gdb_test "x/2hu h" "291.*42798"
 gdb_test "x/2ho h" "0443.*0123456"
 gdb_test "x/2ht h" "0000000100100011.*1010011100101110"
-gdb_test_ptr "x/2ha h" "" ""  "0x123.*0xffffa72e" "0x123.*0xffffffffffffa72e"
+gdb_test_ptr "x/2ha h" "" ""  "0x123.*0xa72e" "0x123.*0xa72e"
 gdb_test "x/2hc h" "35 '.'.*46 '.'"
 gdb_test "x/2hf h" "291.*-22738"
 
@@ -273,7 +273,7 @@ gdb_test "x/2wd w" "19088743.*-1490098887"
 gdb_test "x/2wu w" "19088743.*2804868409"
 gdb_test "x/2wo w" "0110642547.*024713562471"
 gdb_test "x/2wt w" "00000001001000110100010101100111.*10100111001011101110010100111001"
-gdb_test_ptr "x/2wa w" "" ""  "0x1234567.*0xa72ee539" "0x1234567.*0xffffffffa72ee539"
+gdb_test_ptr "x/2wa w" "" ""  "0x1234567.*0xa72ee539" "0x1234567.*0xa72ee539"
 gdb_test "x/2wc w" "103 'g'.*57 '9'"
 gdb_test "x/2wf w" "2.99881655e-0?38.*-2.42716126e-0?15"
 
diff --git a/gdb/value.c b/gdb/value.c
index 91bf49e..0624b90 100644
--- a/gdb/value.c
+++ b/gdb/value.c
@@ -2927,7 +2927,13 @@ unpack_pointer (struct type *type, const gdb_byte *valaddr)
 {
   /* Assume a CORE_ADDR can fit in a LONGEST (for now).  Not sure
      whether we want this to be true eventually.  */
-  return unpack_long (type, valaddr);
+  LONGEST ret = unpack_long (type, valaddr);
+  int len = TYPE_LENGTH (type);
+  if (sizeof (CORE_ADDR) > len && ret < 0) {
+    /* Don't sign-extend 32-bit pointer.  BZ 15121.  */
+    return ret & ((1UL << (8 * len)) - 1);
+  }
+  return ret;
 }
 
 \f