gdb: fix selecting tail-call frames by name
I noticed that attempting to select a tail-call frame using 'frame
function NAME' wouldn't work:
(gdb) bt
#0 func_that_never_returns () at /tmp/build/gdb/testsuite/../../../src/gdb/testsuite/gdb.base/frame-selection.c:49
#1 0x0000000000401183 in func_that_tail_calls () at /tmp/build/gdb/testsuite/../../../src/gdb/testsuite/gdb.base/frame-selection.c:59
#2 0x00000000004011a5 in main () at /tmp/build/gdb/testsuite/../../../src/gdb/testsuite/gdb.base/frame-selection.c:70
(gdb) frame function func_that_tail_calls
No frame for function "func_that_tail_calls".
(gdb) up
#1 0x0000000000401183 in func_that_tail_calls () at /tmp/build/gdb/testsuite/../../../src/gdb/testsuite/gdb.base/frame-selection.c:59
59 func_that_never_returns ();
(gdb) disassemble
Dump of assembler code for function func_that_tail_calls:
0x000000000040117a <+0>: push %rbp
0x000000000040117b <+1>: mov %rsp,%rbp
0x000000000040117e <+4>: call 0x40116c <func_that_never_returns>
End of assembler dump.
(gdb)
The problem is that the 'function' mechanism uses get_frame_pc() and
then compares the address returned with the bounds of the function
we're looking for.
So in this case, the bounds of func_that_tail_calls are 0x40117a to
0x401183, with 0x401183 being the first address _after_ the function.
However, because func_that_tail_calls ends in a tail call, then the
get_frame_pc() is 0x401183, the first address after the function. As
a result, GDB fails to realise that frame #1 is inside the function
we're looking for, and the lookup fails.
The fix is to use get_frame_address_in_block, which will return an
adjusted address, in this case, 0x401182, which is within the function
bounds. Now the lookup works:
(gdb) frame function func_that_tail_calls
#1 0x0000000000401183 in func_that_tail_calls () at /tmp/build/gdb/testsuite/../../../src/gdb/testsuite/gdb.base/frame-selection.c:59
59 func_that_never_returns ();
(gdb)
I've extended the gdb.base/frame-selection.exp test to cover this
case.
3 files changed
