Re: Watchpoint-related changes in go32-nat.c and friends

[DJ Delorie <dj@delorie.com>]

I applied the djgpp-specific patches, but had to manually patch some
due to whitespace differences.  Please get the latest version before
you send any more patches so that the whitespace will match.

I didn't apply the infrun.c patch; I know it's djgpp-specific but I
wanted someone to say "yup, it's OK to put that kind of djgpp-specific
stuff there" and it's only printfs so I figured it could wait for a
decision.

> The following changes make watchpoints work much better in the DJGPP
> port of GDB.  In particular, I can now watch double values.  These
> patches also prevent crashes when single-stepping over INT nn
> instructions.
> 
> 1999-08-16  Eli Zaretskii  <eliz@is.elta.co.il>
> 
> 	* go32-nat.c (go32_wait): If we are in a single-step mode, and the
> 	next instruction is INT nn or INTO, use a temporary breakpoint to
> 	simulate single-step mode, and reset the trace flag.
> 
> 1999-08-14  Eli Zaretskii  <eliz@is.elta.co.il>
> 
> 	* go32-nat.c (wp_op): New typedef.
> 	(SHOW_DR): Print the length of watched region as well.
> 	(go32_insert_aligned_watchpoint): Remove unused argument PID.  All
> 	callers and the prototype changed.
> 	(go32_handle_nonaligned_watchpoint): Renamed from
> 	go32_insert_nonaligned_watchpoint.  Now handles all operations on
> 	non-aligned watchpoints: insertion, deletion, and counting.  If
> 	called with wp_count as the first argument, return the count of
> 	debug registers needed to watch the region.  Don't break out of
> 	the loop before all the addresses in the region are processed.
> 	(go32_remove_watchpoint): Call go32_remove_aligned_watchpoint to
> 	do the actual work.
> 	(go32_remove_aligned_watchpoint): New function, modeled after
> 	go32_insert_aligned_watchpoint.  Removes watchpoints that watch
> 	regions of arbitrary length by calling
> 	go32_handle_nonaligned_watchpoint as needed.
> 	(go32_region_ok_for_watchpoint): New function, called from
> 	can_use_hardware_watchpoint via the new macro
> 	TARGET_REGION_OK_FOR_HW_WATCHPOINT.
> 
> 	* config/i386/nm-go32.h (TARGET_REGION_OK_FOR_HW_WATCHPOINT):
> 	Define to call go32_region_ok_for_watchpoint.
> 	(DECR_PC_AFTER_HW_BREAK): Define back to zero (previous redefinition
> 	to 1 was due to a bug in go32-nat.c).
> 
> 1999-08-07  Eli Zaretskii  <eliz@is.elta.co.il>
> 
> 	* go32-nat.c (cleanup_dregs): New function.
> 	(go32_mourn_inferior): Call it.
> 	(IS_REG_FREE, LOCAL_ENABLE_REG, GLOBAL_ENABLE_REG, DISABLE_REG,
> 	SET_BREAK, SET_WATCH, IS_WATCH, WATCH_HIT): Protect arguments with
> 	parentheses.
> 	(SET_BREAK): Increment the debug register's reference count.
> 	(DR_DEF): New macro, returns the access and length bits of the
> 	breakpoint.
> 	(SHOW_DR): Print the reference count of each register.  Disable or
> 	enable print-out depending on an environment variable GDB_SHOW_DR.
> 	(go32_insert_aligned_watchpoint): Look for an occupied debug
> 	register with the same address and access/length bits, and reuse
> 	it by incrementing reference the count, before occupying another
> 	register.  Return zero upon success.
> 	(go32_insert_nonaligned_watchpoint): Pass the read/write bits to
> 	go32_remove_watchpoint.
> 	(go32_remove_watchpoint): Accept an additional parameter: the
> 	read/write bits of the watchpoint to remove, and only remove a
> 	watchpoint if it's occupied and its address and read/write bits
> 	match.  Only disable the register if its reference count is zero;
> 	otherwise just decrease the reference count.
> 	(go32_remove_hw_breakpoint): Only decrease reference count and
> 	disable the debug register if it is occupied and its access bits
> 	match those of an instruction breakpoint.
> 	(go32_insert_hw_breakpoint): Before occupying another debug
> 	register, look for an already occupied register that defines an
> 	instruction breakpoint with the same address.  If found, increment
> 	its reference count.  Call SHOW_DR even if failed to insert a
> 	breakpoint.
> 
> 	* config/i386/nm-go32.h (target_remove_watchpoint): Accept the
> 	TYPE argument as well.
> 
> 1999-08-06  Eli Zaretskii  <eliz@is.elta.co.il>
> 
> 	* infrun.c (proceed) [__DJGPP__]: If some hardware breakpoints
> 	couldn't be inserted, print a message that they may have set too
> 	many of them.
> 	(normal_stop) [__DJGPP__]: Likewise.
> 	Reset breakpoints_failed, they might do something that will cause
> 	insert_breakpoints() succeed next time.