compile-loc2c: Fix uninitialized variable error

Compiling with clang gives this warning/error:

  /home/emaisin/src/binutils-gdb/gdb/compile/compile-loc2c.c:731:6: error: variable 'uoffset' is uninitialized when used here [-Werror,-Wuninitialized]
              uoffset += dwarf2_per_cu_text_offset (per_cu);
              ^~~~~~~
  /home/emaisin/src/binutils-gdb/gdb/compile/compile-loc2c.c:669:23: note: initialize the variable 'uoffset' to silence this warning
        uint64_t uoffset, reg;
                        ^
                         = 0

I am really not sure if what this patch does is good, but it is my best
guess.  DW_OP_addr means that there's an constant address provided by
the DWARF bytecode that should be pushed on the stack.  That address is
considered skipped by the "op_ptr += addr_size", but it is never read.
uoffset is indeed read just after, without having been assigned first.

So I think the intent is to read the address, it was just omitted.

gdb/ChangeLog:

	* compile/compile-loc2c.c (do_compile_dwarf_expr_to_c): Read
	address when op is DW_OP_addr.

diff --git a/gdb/ChangeLog b/gdb/ChangeLog
index 86a41b6..8ccd7a4 100644 (file)
--- a/gdb/ChangeLog
+++ b/gdb/ChangeLog
@@ -1,3 +1,8 @@
+2017-07-09  Simon Marchi  <simon.marchi@ericsson.com>
+
+       * compile/compile-loc2c.c (do_compile_dwarf_expr_to_c): Read
+       address when op is DW_OP_addr.
+
 2017-07-09  Tom Tromey  <tom@tromey.com>
 
        * dwarf2loc.c (dwarf2_evaluate_loc_desc_full): Reverse size

diff --git a/gdb/compile/compile-loc2c.c b/gdb/compile/compile-loc2c.c
index a53214f..ead1003 100644 (file)
--- a/gdb/compile/compile-loc2c.c
+++ b/gdb/compile/compile-loc2c.c
@@ -722,6 +722,7 @@ do_compile_dwarf_expr_to_c (int indent, string_file &stream,
          break;
 
        case DW_OP_addr:
+         uoffset = extract_unsigned_integer (op_ptr, addr_size, byte_order);
          op_ptr += addr_size;
          /* Some versions of GCC emit DW_OP_addr before
             DW_OP_GNU_push_tls_address.  In this case the value is an