kbaladurin added inline comments.
Herald added a reviewer: espindola.
================
Comment at:
packages/Python/lldbsuite/test/arm/breakpoint-thumb-codesection/TestBreakpointThumbCodesection.py:29
+
+ self.runCmd("run")
+
----------------
labath wrote:
> Do you think there's any added value in making sure that the breakpoint is
> *hit* (instead of just making sure that it's resolved to the right file
> address). If it's the latter we could make this a non-execution test and have
> it run everywhere (e.g., via lldb-test breakpoint) instead of just on arm
> hardware.
I think we need to make sure that breakpoint is *hit* and program can
successfully continue execution after it, because it is resolved to right
address in both cases:
lldb without this patch:
```
$ llvm-arm/bin/lldb thumb-bp
(lldb) target create "thumb-bp"
Current executable set to 'thumb-bp' (arm).
(lldb) b bp.c:3
Breakpoint 1: where = thumb-bp`f + 6 at bp.c:3, address = 0x000103f6
(lldb) r
Process 22192 launched: '/home/kbaladurin/thumb-bp' (arm)
Process 22192 stopped
* thread #1: tid = 22192, 0x000103d0 thumb-bp`__libc_csu_init + 32, name =
'thumb-bp', stop reason = signal SIGSEGV: invalid address (fault address: 0x0)
frame #0: 0x000103d0 thumb-bp`__libc_csu_init + 32
thumb-bp`__libc_csu_init:
-> 0x103d0 <+32>: ldr r3, [r5], #4
0x103d4 <+36>: mov r2, r9
0x103d6 <+38>: mov r1, r8
0x103d8 <+40>: mov r0, r7
(lldb) disas -n f
thumb-bp`f:
0x103f0 <+0>: strmi r11, [r1], -r2, lsl #1
0x103f4 <+4>: stmdals r1, {r0, r12, pc}
0x103f8 <+8>: .long 0x91003001 ; unknown opcode
0x103fc <+12>: ldrbmi r11, [r0, -r2]!
```
lldb with this patch:
```
$ llvm-arm-patch/bin/lldb thumb-bp
(lldb) target create "thumb-bp"
Current executable set to 'thumb-bp' (arm).
(lldb) b bp.c:3
Breakpoint 1: where = thumb-bp`f + 6 at bp.c:3, address = 0x000103f6
(lldb) r
Process 22282 launched: '/home/kbaladurin/thumb-bp' (arm)
Process 22282 stopped
* thread #1: tid = 22282, 0x000103f6 thumb-bp`f(a=10) + 6 at bp.c:3, name =
'thumb-bp', stop reason = breakpoint 1.1
frame #0: 0x000103f6 thumb-bp`f(a=10) + 6 at bp.c:3
1 __attribute__((section("__codesection")))
2 int f(int a) {
-> 3 return a + 1; // Set break point at this line.
4 }
5
6 int main() {
7 return f(10);
(lldb) disas
thumb-bp`f:
0x103f0 <+0>: sub sp, #0x8
0x103f2 <+2>: mov r1, r0
0x103f4 <+4>: str r0, [sp, #0x4]
-> 0x103f6 <+6>: ldr r0, [sp, #0x4]
0x103f8 <+8>: adds r0, #0x1
0x103fa <+10>: str r1, [sp]
0x103fc <+12>: add sp, #0x8
0x103fe <+14>: bx lr
```
In both cases resolved address is 0x103f6 that is right according to the debug
information:
```
Line Number Statements:
[0x00000025] Extended opcode 2: set Address to 0x103f0
[0x0000002c] Special opcode 6: advance Address by 0 to 0x103f0 and Line by 1
to 2
[0x0000002d] Set column to 10
[0x0000002f] Set prologue_end to true
[0x00000030] Special opcode 90: advance Address by 6 to 0x103f6 and Line by
1 to 3
```
But lldb uses arm breakpoint in the first case and thumb one in the second.
https://reviews.llvm.org/D44998
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