[LLVMbugs] [Bug 4475] New: clang: gdb warning for -g -O0: warning: Unmapped DWARF Register #61 encountered.

[bugzilla-daemon at cs.uiuc.edu]

http://llvm.org/bugs/show_bug.cgi?id=4475

           Summary: clang: gdb warning for -g -O0: warning: Unmapped DWARF
                    Register #61 encountered.
           Product: new-bugs
           Version: unspecified
          Platform: PC
        OS/Version: Linux
            Status: NEW
          Severity: normal
          Priority: P2
         Component: new bugs
        AssignedTo: unassignedbugs at nondot.org
        ReportedBy: edwintorok at gmail.com
                CC: llvmbugs at cs.uiuc.edu


When compiling code with -g -O0, and breakpointing in gdb I get warnings
every time the breakpoint is hit / every time I step in the code.
I can still print variables though, so this may be a benign warning for the -O0
case.

However if I compile with -O1 -g, I cannot print variables (see below), so this
may be a problem for the -O1 case (I assume the variable is assigned to a
register, but the DWARF information is missing this info?)

Here is what happens with -O0:
$ clang -g -O0 x.c -o a.out
$ gdb /a.out
GNU gdb 6.8-debian
Copyright (C) 2008 Free Software Foundation, Inc.
License GPLv3+: GNU GPL version 3 or later <http://gnu.org/licenses/gpl.html>
This is free software: you are free to change and redistribute it.
There is NO WARRANTY, to the extent permitted by law.  Type "show copying"
and "show warranty" for details.
This GDB was configured as "x86_64-linux-gnu"...

(gdb) b readString
Breakpoint 1 at 0x400582: file x.c, line 9.
(gdb) r
Starting program: /home/edwin/clam/git/builds/clang/a.out
Breakpoint 1, readString (p=warning: Unmapped DWARF Register #48 encountered.
warning: Unmapped DWARF Register #49 encountered.                            
warning: Unmapped DWARF Register #50 encountered.                            
warning: Unmapped DWARF Register #51 encountered.                            
warning: Unmapped DWARF Register #52 encountered.                            
warning: Unmapped DWARF Register #53 encountered.                            
warning: Unmapped DWARF Register #54 encountered.                            
warning: Unmapped DWARF Register #55 encountered.                            
0x7ffff16b9512 "k��\177", off=0x7ffff16b950c, len=10, ok=0x7ffff16b950b
"\001") at x.c:9
9           unsigned stringlen;
Current language:  auto; currently minimal
(gdb) n
warning: Unmapped DWARF Register #48 encountered.
warning: Unmapped DWARF Register #49 encountered.
warning: Unmapped DWARF Register #50 encountered.
warning: Unmapped DWARF Register #51 encountered.
warning: Unmapped DWARF Register #52 encountered.
warning: Unmapped DWARF Register #53 encountered.
warning: Unmapped DWARF Register #54 encountered.
warning: Unmapped DWARF Register #55 encountered.
10          char *str = (char*)readData(p, off, len, ok, &stringlen);
(gdb) n
warning: Unmapped DWARF Register #48 encountered.
warning: Unmapped DWARF Register #49 encountered.
warning: Unmapped DWARF Register #50 encountered.
warning: Unmapped DWARF Register #51 encountered.
warning: Unmapped DWARF Register #52 encountered.
warning: Unmapped DWARF Register #53 encountered.
warning: Unmapped DWARF Register #54 encountered.
warning: Unmapped DWARF Register #55 encountered.
warning: Unmapped DWARF Register #48 encountered.
warning: Unmapped DWARF Register #49 encountered.
warning: Unmapped DWARF Register #50 encountered.
warning: Unmapped DWARF Register #51 encountered.
warning: Unmapped DWARF Register #52 encountered.
warning: Unmapped DWARF Register #53 encountered.
warning: Unmapped DWARF Register #54 encountered.
warning: Unmapped DWARF Register #55 encountered.
warning: Unmapped DWARF Register #48 encountered.
warning: Unmapped DWARF Register #49 encountered.
warning: Unmapped DWARF Register #50 encountered.
warning: Unmapped DWARF Register #51 encountered.
warning: Unmapped DWARF Register #52 encountered.
warning: Unmapped DWARF Register #53 encountered.
warning: Unmapped DWARF Register #54 encountered.
warning: Unmapped DWARF Register #55 encountered.
11          if (*ok && stringlen && str[stringlen-1] != '\0') {
(gdb) p str
$1 = 0x2095010 ""


With -O1 -g:

$ gdb ./a.out
GNU gdb 6.8-debian
Copyright (C) 2008 Free Software Foundation, Inc.
License GPLv3+: GNU GPL version 3 or later <http://gnu.org/licenses/gpl.html>
This is free software: you are free to change and redistribute it.
There is NO WARRANTY, to the extent permitted by law.  Type "show copying"
and "show warranty" for details.
This GDB was configured as "x86_64-linux-gnu"...
(gdb) b readString
Breakpoint 1 at 0x400543: file x.c, line 10.
(gdb) r
Starting program: /home/edwin/clam/git/builds/clang/a.out

Breakpoint 1, readString () at x.c:10
10          char *str = (char*)readData(p, off, len, ok, &stringlen);
Current language:  auto; currently minimal
(gdb) n

warning: Unmapped DWARF Register #48 encountered.
warning: Unmapped DWARF Register #49 encountered.
warning: Unmapped DWARF Register #50 encountered.
warning: Unmapped DWARF Register #51 encountered.
warning: Unmapped DWARF Register #52 encountered.
warning: Unmapped DWARF Register #53 encountered.
warning: Unmapped DWARF Register #54 encountered.
warning: Unmapped DWARF Register #55 encountered.
warning: Unmapped DWARF Register #48 encountered.
warning: Unmapped DWARF Register #49 encountered.
warning: Unmapped DWARF Register #50 encountered.
warning: Unmapped DWARF Register #51 encountered.
warning: Unmapped DWARF Register #52 encountered.
warning: Unmapped DWARF Register #53 encountered.
warning: Unmapped DWARF Register #54 encountered.
warning: Unmapped DWARF Register #55 encountered.
warning: Unmapped DWARF Register #48 encountered.
warning: Unmapped DWARF Register #49 encountered.
warning: Unmapped DWARF Register #50 encountered.
warning: Unmapped DWARF Register #51 encountered.
warning: Unmapped DWARF Register #52 encountered.
warning: Unmapped DWARF Register #53 encountered.
warning: Unmapped DWARF Register #54 encountered.
warning: Unmapped DWARF Register #55 encountered.
11          if (*ok && stringlen && str[stringlen-1] != '\0') {
(gdb) p str
No symbol "str" in current context.


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