Recent fixes and improvements in Berkeley f77

[Donn Seeley]

I gave up trying to stay current with bug reports a long time ago -- it
seems I have other things to do sometimes, like my job...  But I still
keep hacking at the f77 compiler.  Here is a chunk of my bug log which
describes some of the changes that have taken place since the last
posted bug reports, with comments added to make the remarks less cryptic:

------------------------------------------------------------------------
	fix for Peter Montgomery's bug with do 10 i = -i, i
		[if the loop variable appeared in the loop limit
		it had the value of the loop initializer instead
		of the original value]
	fix for Peter Montgomery's bug with -C and invalid subscripts
		[the compiler dumped core for bad constant subscripts]
	fix for Tom Quinn's trouble with -c vs. -o file
		[you now get an error message if you supply both flags]
	Mike Vevea's problem with undeclared variables
		[the constant folding code wanted to know their types;
		I ended up adding code to guess types when possible]
	Jerry Berkman's extensive grammar fixes
		[produce only one error message for gross errors in
		DO or EQUIVALENCE statements; close lots of loopholes
		with PARAMETER variables used as normal variables; stop
		generating parenthesis operators in constant expressions]
	A fix for Steve Caruso's PARAMETER errors
		[an error, not a warning, for setting PARAMETER variables
		to something other than a constant]
	Fixed Ravi Kulkarni's bug with optloop()
		[a memory management bug garbaged variables optimized
		out of loops]
	A fix for Peter Montgomery's error message bug
		[sometimes the file name printed as garbage]
	Fixed Steve Grandi's problem with putop() and conversions
		[f77 -i2 sometimes made bogus 'cvtll' instructions appear]
	Fixed Steve Grandi's problem with CSE and conversions
		[common subexpression elimination was not taking the type
		of expressions into account, hence some conversions with
		identical structure and different types were replaced]
	Added Jerry Berkman's fix to line buffer stderr
		[makes f77 run faster]
	Jerry Berkman's fix to prevent redimensioning of arrays
		[you can't inconsistently declare arrays any more]
	Fixes to pick up bad array declarations
		[allow only well-formed dimension bound expressions]
	fix to stop f77 from generating intermediate code after errors
		[prevent useless 'tag 5 in putx' messages]
	Fixed Tim Hopkins' bug with labeled PROGRAM statements (head & dcl)
		[who needs this?  fixed it anyway]
	Fixed Tim Hopkins' bug with PARAMETER variables in output lists
		[needed length info to do unformatted I/O properly]
	Fixed bug in fix to mkexpr() that caused IMPLICIT to affect intrinsics
		[ouch!  my fault -- it works better now (I promise!)]
	Changed stfcall() to remark on argument type clashes (Jerry Berkman)
		[statement function actuals are supposed to match the type
		of formals; convert and complain]
	Changed mkrealcon() and consconv() to shorten real constants (Jerry)
		[REAL constants were unexpectedly DOUBLE PRECISION]
	Fixed Steve Grandi's bug with character-to-integer conversions
		[it could convert variables but not expressions]
	Fixed Richard Wolff's bug with badly named common blocks
		[dereferenced a null pointer after detecting an error]
	Fixed bug that caused len() to be done inline only with -i2
	Fixed bug in expand() which stopped concatenations from being collapsed
		[normally associative concatenations are handled with only
		one subroutine call]
	Changed buffpower() to use putpower() instead of mkpower() for exp > 64
		[a more efficient way to handle ridiculous exponents]
	Gave in and added hack to mkexpr() to prevent 'ichar(c)-20' from
		bombing in consnegop -- i.e. no constant folding for TYUNKNOWN
		[constant folding is done before type classification,
		unfortunately; this shows why the type can't always be guessed]
	Richard Wolff's request for error messages for char to int conversions
	Fixed Tim Hopkins' memory management bug in startrw()
		[the compiler bombed for certain I/O statements because it
		freed some memory it still needed to use]
	SAVE statements (finally) save some labor
		[they used to be broken, were made to be useless, and now work]
	Added warnings for implicit conversions from character or address
		[a generalization of an earlier fix]
	Fixed Bjorn Bjornsson's bug with eqvcommon() breaking multi-level eqvs
		[equivalencing to something that was equivalenced to something
		which wasn't declared yet resulted in bad addresses for the
		objects -- the authors used minus where they meant plus]
	Made read-only the storage used for constants passed as function args
		[like VMS -- you can't change the value of 1 any more...
		this broke programs which read data into FORMAT statements
		(gack!) so we made an exception for them]
	Added Jerry Berkman's '-q' flag to make f77 shut up
		[he got tired of seeing 'foo: ... bar: ... etc.']
	Jerry's fixes to stop 'movf/movd' when optimization is off (new)
		[floating point move instructions cause reserved operand
		faults for non-normalized operands -- people who equivalenced
		REAL and INTEGER data got core dumps when not optimizing;
		now we use integer moves instead]
	flag to c2 makes it act like f2
		[f2 was almost identical to c2, except it possessed a hack to
		change floating moves to integer moves, and was missing most of
		the bug fixes to c2; I merged the code back together]
	Fixed bug in buffmnmx() introduced by cat/assign fixes
		[problems arising from the changes to make concatenations go
		directly into the lhs of an assignment instead of a temporary]
	Bumped version number in version.h (Jerry Berkman)
	Bug in equop() in c21.c allows c2 to throw away entry masks as well
		as common code (Richard Wolff)
		[blech!  this affected functions with ENTRY points and very
		similar bodies under two entries]
	Fixes to entrystab() and enddcl() to make dbx recognize common vars
		[dbx was confused by too many symbol table entries for
		functions -- COMMON variables looked like they were in
		some nonexistent hence inaccessible function]
	Jerry Berkman's changes to precompile format statments
		[30% faster formatted I/O!  Thanks, Jerry]
	Fixed f77 to use '/bin/cat' instead of just 'cat' (drivedefs.h, f77.c)
		[I ran f77 in a directory with a file named 'cat' one day]
	Changed the assignment/concatenation code again -- we do NOT copy the
		concatenation into a temporary; this fixes problems with
		nonconstant lhs lengths. (optim.c, put.c, putpcc.c)
		[I backed out the earlier change because I found that it made
		'c1 = c2 // c1' do an absurd thing, but this broke assignments
		with variable length lhs's...  the standard says that 'c1 =
		c2 // c1' is illegal anyway, so I put the earlier hack back in]
	Hacked Peter Montgomery's bug in register allocation where the wrong
		common variable in register is thought to have gone stale
		[prevented array elements in COMMON from being put in register
		due to difficulty in distinguishing instances of them]
	Added fix to let 'call f((1))' pass a temporary instead of a constant
		[helps out folks who modify constant arguments to functions]
	Put profiling routine arg in data space instead of constant space (JB)
		[another thing that broke when constants were made read-only]
	Arranged to make intrinsic functions have storage type STGINTR
		[optimizations for intrinsic functions were failing because
		the compiler was labelling them incorrectly internally]
	Fixed bug that did register rewriting on loop tests twice (and wrong!)
		[if a variable was in register in an outer loop and not an
		inner one, the loop test was wrong]
	Fixed bug that caused register updating and assignment to conflict
		['a = f(a)' didn't work if 'a' was in register -- the register
		was updated for side effects AFTER the assignment was performed]
	Fixed safedim() so it complains about array references in dimension
		bound expressions (for Greg Woods)
		[if an array argument was dimensioned with an element from
		another array argument before the latter array was adjusted
		for 1-based addressing, we got it wrong; now I understand the
		wisdom of the standards committee in restricting dimension
		bound expressions...]
	Invented 'pcc.h', changed all pass 2 references to use its definitions
		[f77, C and pascal now get their intermediate code definitions
		from a commmon include file; there used to be 4 different
		places where opcodes were defined]
	Bob Corbett's ugly hack to prevent conflicts between register asst
		and subroutine call side effects in inner loops
		[the compiler now produces slower but correct code for loops
		as a result of our discovering ghastly design problems in the
		register allocator...  anyone wanna write a register allocator?]
	Added hack to make implicit character->integer conversions copy more
		than 1 byte of the string (for Helge Skrivervik)
		[this still gets a warning]
	Fixed bugs with short logicals in the i/o library
		[the I/O library didn't realize logicals were short when
		compiled with -i2, and cheerfully clobbered objects which
		were unfortunate enough to be next to them]
	Fixed bugs with short integers and ASSIGN (error instead of warning)
		['ASSIGN 10 TO I' is now an error if I is short]
	Made integer constants have the same default type as integers
		[produces better code for integers when -i2 is used and
		shuts up the compiler code that checks for type mismatches in
		(e.g.) statement functions]
	Fixed bug which caused all ASSIGNS to get 'implicit conversion' warns
		[dumb, dumb, dumb -- ASSIGN used to be an implicit conversion
		from type 'address' to type 'integer'; now it is an intrinsic
		conversion and doesn't get a complaint.  my fault again]
------------------------------------------------------------------------

Machine-dependent inline functions still exist only in a prototype
compiler; they probably won't become official unless I can find someone
willing to make the effort to improve the assembler math library.  Too
bad -- program speed goes up a lot if trivial functions like nint() are
no longer done with subroutines...

I hope this list will tide you over until 4.3 BSD comes out,

Donn Seeley    University of Utah CS Dept    donn at utah-cs.arpa
40 46' 6"N 111 50' 34"W    (801) 581-5668    decvax!utah-cs!donn