[unix-history] / usr / src / contrib / gas-1.38 / NOTES

gdb debugging of assembly sources:
	write a function linestab() that generates a .stabd symbol
		independently of the input
	write a function filestab() to generate a .stabs symbol
	we need to take especial care with #line directives
		since we want to handle locore, and locore is passed thru cpp
		this could be tough
	outline of a solution:
		cpp sends us lines of the form
			# logical-line "logical-file" trash
		these lines are interpreted ahead of the gas preprocess pass
		in the starting state, the logical filename is the same
			as the real filename (in case there're no #lines)
		the initial logical line number is 1
		every time we're ready to process a new instruction line,
			if the source file has changed,
				emit a .stabs for the logical file
			emit a .stabd for the logical line
			bump the logical line number
				can gas eat multiple actual lines in one insn?

i386 nits:
	jmp *$foo produces a short relative branch
	string quotes in comments
		Bill says gas eats text across newlines to find matches
		works fine for me
		I think it's most likely due to cpp
	make / no longer be a comment char
		it's now like the VAX: # is the only comment char
	incorrectly assembles lcall, int3, into, bsr/f instructions
	constant expressions fail if more than a few terms
		gives (low+2)*3+4*5 as an example
		works fine for me
	cpp seems to think $ is a valid literal
		use -$ in /usr/bin/cpp
Commit	Line	Data
98a8897d C	1	gdb debugging of assembly sources:
	2	write a function linestab() that generates a .stabd symbol
	3	independently of the input
	4	write a function filestab() to generate a .stabs symbol
	5	we need to take especial care with #line directives
	6	since we want to handle locore, and locore is passed thru cpp
	7	this could be tough
	8	outline of a solution:
	9	cpp sends us lines of the form
	10	# logical-line "logical-file" trash
	11	these lines are interpreted ahead of the gas preprocess pass
	12	in the starting state, the logical filename is the same
	13	as the real filename (in case there're no #lines)
	14	the initial logical line number is 1
	15	every time we're ready to process a new instruction line,
	16	if the source file has changed,
	17	emit a .stabs for the logical file
	18	emit a .stabd for the logical line
	19	bump the logical line number
	20	can gas eat multiple actual lines in one insn?
	21
	22	i386 nits:
	23	jmp *$foo produces a short relative branch
	24	string quotes in comments
	25	Bill says gas eats text across newlines to find matches
	26	works fine for me
	27	I think it's most likely due to cpp
	28	make / no longer be a comment char
	29	it's now like the VAX: # is the only comment char
	30	incorrectly assembles lcall, int3, into, bsr/f instructions
	31	constant expressions fail if more than a few terms
	32	gives (low+2)3+45 as an example
	33	works fine for me
	34	cpp seems to think $ is a valid literal
	35	use -$ in /usr/bin/cpp