Don't elide all inlined frames

This patch essentially causes GDB to treat inlined frames like "normal"
frames from the user's perspective.  This means, for example, that when a
user sets a breakpoint in an inlined function, GDB will now actually stop
"in" that function.

Using the test case from breakpoints/17534,

3	static inline void NVIC_EnableIRQ(int IRQn)
4	{
5	  volatile int y;
6	  y = IRQn;
7	}
8
9	__attribute__( ( always_inline ) ) static inline void __WFI(void)
10	{
11	    __asm volatile ("nop");
12	}
13
14	int main(void) {
15
16	    x= 42;
17
18	    if (x)
19	      NVIC_EnableIRQ(16);
20	    else
21	      NVIC_EnableIRQ(18);
(gdb) b NVIC_EnableIRQ
Breakpoint 1 at 0x4003e4: NVIC_EnableIRQ. (2 locations)
(gdb) r
Starting program: 17534

Breakpoint 1, main () at 17534.c:19
19	      NVIC_EnableIRQ(16);

Because skip_inline_frames currently skips every inlined frame, GDB "stops"
in the caller.  This patch adds a new parameter to skip_inline_frames
that allows us to pass in a bpstat stop chain.  The breakpoint locations
on the stop chain can be used to determine if we've stopped inside an inline
function (due to a user breakpoint).  If we have, we do not elide the frame.

With this patch, GDB now reports that the inferior has stopped inside the
inlined function:

(gdb) r
Starting program: 17534

Breakpoint 1, NVIC_EnableIRQ (IRQn=16) at 17534.c:6
6	  y = IRQn;

Many thanks to Jan and Pedro for guidance on this.

gdb/ChangeLog:

	* breakpoint.c (build_bpstat_chain): New function, moved from
	bpstat_stop_status.
	(bpstat_stop_status): Add optional parameter, `stop_chain'.
	If no stop chain is passed, call build_bpstat_chain to build it.
	* breakpoint.h (build_bpstat_chain): Declare.
	(bpstat_stop_status): Move documentation here from breakpoint.c.
	* infrun.c (handle_signal_stop): Before eliding inlined frames,
	build the stop chain and pass it to skip_inline_frames.
	Pass this stop chain to bpstat_stop_status.
	* inline-frame.c: Include breakpoint.h.
	(stopped_by_user_bp_inline_frame): New function.
	(skip_inline_frames): Add parameter `stop_chain'.
	Move documention to inline-frame.h.
	If non-NULL, use stopped_by_user_bp_inline_frame to determine
	whether the frame should be elided.
	* inline-frame.h (skip_inline_frames): Add parameter `stop_chain'.
	Add moved documentation and update for new parameter.

gdb/testsuite/ChangeLog:

	* gdb.ada/bp_inlined_func.exp: Update inlined frame locations
	in expected breakpoint stop locations.
	* gdb.dwarf2/implptr.exp (implptr_test_baz): Use up/down to
	move to proper scope to test variable values.
	* gdb.opt/inline-break.c (inline_func1, not_inline_func1)
	(inline_func2, not_inline_func2, inline_func3, not_inline_func3):
	New functions.
	(main): Call not_inline_func3.
	* gdb.opt/inline-break.exp: Start inferior and set breakpoints at
	inline_func1, inline_func2, and inline_func3.  Test that when each
	breakpoint is hit, GDB properly reports both the stop location
	and the backtrace. Repeat tests for temporary breakpoints.

1 files changed, 20 insertions, 0 deletions

diff --git a/gdb/ChangeLog b/gdb/ChangeLog
index 264875d..263ce81 100644
--- a/gdb/ChangeLog
+++ b/gdb/ChangeLog
@@ -1,3 +1,23 @@
+2018-05-17  Keith Seitz  <keiths@redhat.com>
+
+	* breakpoint.c (build_bpstat_chain): New function, moved from
+	bpstat_stop_status.
+	(bpstat_stop_status): Add optional parameter, `stop_chain'.
+	If no stop chain is passed, call build_bpstat_chain to build it.
+	* breakpoint.h (build_bpstat_chain): Declare.
+	(bpstat_stop_status): Move documentation here from breakpoint.c.
+	* infrun.c (handle_signal_stop): Before eliding inlined frames,
+	build the stop chain and pass it to skip_inline_frames.
+	Pass this stop chain to bpstat_stop_status.
+	* inline-frame.c: Include breakpoint.h.
+	(stopped_by_user_bp_inline_frame): New function.
+	(skip_inline_frames): Add parameter `stop_chain'.
+	Move documention to inline-frame.h.
+	If non-NULL, use stopped_by_user_bp_inline_frame to determine
+	whether the frame should be elided.
+	* inline-frame.h (skip_inline_frames): Add parameter `stop_chain'.
+	Add moved documentation and update for new parameter.
+
 2018-05-17  Simon Marchi  <simon.marchi@ericsson.com>
 
 	PR cli/14975