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compiler limitations
--------------------
These are not implemented:
a. bit fields
kludgily implemented (everything padded to char, int or long; can store
values wider than the specified field width)
g. signed char type, other ANSI extensions
compiler bugs
-------------
6. weird but doable casts are not always done for initializers
15. calls to a (casted) absolute address produce an immediate prefix. as386
doesn't mind this but complains about the absolute address. as09 complains
about the prefix but can handle the absolute address
23. char *f(); &f() is accepted as f() but produces botched nodetype
(calc char **).
31. null byte in string initialiser should be ignored if it doesn't fit
Non-null bytes which don't fit should be ignored with a warning
32. static char c = "xyz"; is allowed, and bad FCB is generated
37. init of union will store multiple comma-separated entries
38. arrays sizes larger than the amount of memory are accepted
40. structure and union definitions are confused with each other. So
struct foo may be used in a declaration like "union foo bar;"
42. pointer arithmetic is performed on pointers to undefined structures
(of unknown size). Size is taken as 0 although alignmask is set early
59. preprocessor stuff (# lines or macro names) between the identifier for
a label and the colon for the label messes up the label
60. some things involving switches are now broken for 6809 due to lack of
frame pointer
61. assembler may get lost on lines of length exactly (?) 256
65. expressions in emum lists or not properly checked for overflow. They
should fit in ints. The ordinal number is allowed to overflow
66. sizeof has type int instead of size_t
68. "return expr;" in a function returning a void is reported as a compiler
bug not as a semantic error
69. an argument declared as float is (correctly) promoted to double, but
not demoted to float when it is used
71. identifiers longer than 64 are botched (scanning of the identifier is
stopped but the remaining characters in the identifier are left to
mess up the input stream
72. check for too many macro parameters is not working
74. union { char a, b; } foo; gives the wrong offset for b. Unions work OK
if the declaration lists have length 1
75. stack gets cleaned up too early in bee = foo ? bar : baz() where baz()
returns a struct although there is kludge to make plain bee = baz() work
76. have reintroduced reduced-type bugs, so sizeof(1 ? 1 : 2) is 1
78. fix to require comma in arg list may be half-baked
79. compiler starts trying to load the void expression (i ? (void)0 : (void)0)
80. (unsigned char *) - (char *) causes error and message is obscure
81. 'defined' is a reserved word
82. conditionals with voids don't work
83. float = 1e100 gets overflow exception
84. #endif seems to be seen in
#if 1
foo #endif bar
85. line numbers from cpp are not quite right.
bugs that may be fixed
----------------------
41. typedef's are not scoped properly
nonstandard things that are not done quite right
------------------------------------------------
3. arguments declared as register are not being dumped by #asm, register
vars anyway not being passed to #asm
26. should clear label ptrs when starting #asm
things that have to be be done better
-------------------------------------
11. push order reversed in genloads.c (temp) - might try to get DP order right
12. need to clean up handling of sc specs (maybe rename flags to sc)
And local statics and externs
24. gvarsc is not returned properly for struct/union since the members
affect gvarsc (incorrectly). There should be a flag set when
inside a struct/union definition to disable sc specs. This could
replace the tests in abdeclarator and declselt
Best may be to carry the sc along with the type a bit more (in a
global symbol structure). Also, the symbol should record sc in a better
way than now
25. need to check stack sometimes. Xenix cc does it when allocating >= 100
bytes locals and this is essential in Xenix as the stack is grown
dynamically
68. overflow checking for constants
things that could be done better
--------------------------------
4. install new 6809 code for branch patching (after redundancy checks)
5. can improve code for compare with global adr in non-posindependent case
6. char *s; long *pl;
code for *s += *pl is poor, for *s += (int) *pl is good
7. most mov's from to ax would be faster and smaller done by xchg's
7a. check ptr add/sub operations earlier
8. tests for against 1 and -1 can sometimes be done with dec's and inc's
9. __opreg is used unnec when the ptr is already in it
9a. double indirect ptrs should maybe be made direct rather than singly
indirect by makelessindirect
10. in cmpsmallconst(), the comparison constant should be incorporated in
the offset if the indcount is 0 and lea() called. It is harmless to
use the lea() trick for non-small constants
20. when saved registers are popped in assign() they may overwrite the
expression value, anywhere else? May be fixed now
27. better if loadexpression returned the register used
28. better if source.c did not #include storage.h - it only references
DEFINITION, in some blank-skipping code which could be moved to
scan.c or preproc.c. preproc.c, scan.c and type.c also #include
storage.h, just to get at the DEFINITION and KEYWORD definitions
29. need nodetype() to know about all optimisations in advance, including
int % small power of 2 (including 0, 1). Need to delete all type
assignments in final code gen, specially the one that convert short
to int
30. overflow checking at runtime
31. Use more than the first char from multiple character constants
56. --i++ is not detected as an error in the parser
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