diff options
Diffstat (limited to 'gas')
-rw-r--r-- | gas/doc/as.texinfo | 389 |
1 files changed, 243 insertions, 146 deletions
diff --git a/gas/doc/as.texinfo b/gas/doc/as.texinfo index 09f643e..9296706 100644 --- a/gas/doc/as.texinfo +++ b/gas/doc/as.texinfo @@ -21,11 +21,9 @@ @ifset H8/500 @set H8 @end ifset -@c start-sanitize-Hitachi-SH @ifset SH @set H8 @end ifset -@c end-sanitize-Hitachi-SH @c ------------ @ifset GENERIC @settitle Using @value{AS} @@ -39,7 +37,7 @@ @ifinfo @format START-INFO-DIR-ENTRY -* As: (as). The GNU assembler. +* As:: The GNU assembler. END-INFO-DIR-ENTRY @end format @end ifinfo @@ -320,9 +318,10 @@ the MIPS R2000/R3000 processors. @table @code @item -G @var{num} -This option sets the largest size of an object that can be referenced +This option sets the largest size of an object that will be referenced implicitly with the @code{gp} register. It is only accepted for targets -that use ECOFF format, such as a DECstation running Ultrix. +that use ECOFF format, such as a DECstation running Ultrix. The default +value is 8. @item -nocpp @itemx -EB, -EL @@ -380,18 +379,17 @@ machine architecture manual for this information. @ifclear GENERIC @ifset H8/300 For information on the H8/300 machine instruction set, see @cite{H8/300 -Series Programming Manual} (Hitachi ADE--602--025). +Series Programming Manual} (Hitachi ADE--602--025). For the H8/300H, +see @cite{H8/300H Series Programming Manual} (Hitachi). @end ifset @ifset H8/500 For information on the H8/500 machine instruction set, see @cite{H8/500 Series Programming Manual} (Hitachi M21T001). @end ifset -@c start-sanitize-Hitachi-SH @ifset SH For information on the Hitachi SH machine instruction set, see @cite{SH-Microcomputer User's Manual} (Hitachi Micro Systems, Inc.). @end ifset -@c end-sanitize-Hitachi-SH @ifset Z8000 For information on the Z8000 machine instruction set, see @cite{Z8000 CPU Technical Manual} @end ifset @@ -1014,11 +1012,9 @@ is considered a comment and is ignored. The line comment character is @ifset H8/500 @samp{!} for the H8/500 family; @end ifset -@c start-sanitize-Hitachi-SH @ifset SH @samp{!} for the Hitachi SH; @end ifset -@c end-sanitize-Hitachi-SH @ifset Z8000 @samp{!} for the Z8000; @end ifset @@ -1104,9 +1100,7 @@ are an exception: they don't end statements. @ifset H8 A @dfn{statement} ends at a newline character (@samp{\n}); or (for the H8/300) a dollar sign (@samp{$}); or (for the -@c start-sanitize-Hitachi-SH Hitachi-SH or the -@c end-sanitize-Hitachi-SH H8/500) a semicolon (@samp{;}). The newline or separator character is considered part of the preceding statement. Newlines and separators within character @@ -1329,9 +1323,7 @@ grave accent. A newline @end ifset @ifset H8 (or dollar sign @samp{$}, for the H8/300; or semicolon @samp{;} for the -@c start-sanitize-Hitachi-SH Hitachi SH or -@c end-sanitize-Hitachi-SH H8/500) @end ifset @end ifset @@ -1434,9 +1426,7 @@ to allow any of @samp{defghDEFGH}.) @end ignore On the H8/300, H8/500, -@c start-sanitize-Hitachi-SH Hitachi SH, -@c end-sanitize-Hitachi-SH and AMD 29K architectures, the letter must be one of the letters @samp{DFPRSX} (in upper or lower case). @@ -1562,9 +1552,7 @@ the task of adjusting mentions of object-file addresses so they refer to the proper run-time addresses. @ifset H8 For the H8/300 and H8/500, -@c start-sanitize-Hitachi-SH and for the Hitachi SH, -@c end-sanitize-Hitachi-SH @code{@value{AS}} pads sections if needed to ensure they end on a word (sixteen bit) boundary. @end ifset @@ -1874,9 +1862,7 @@ of @code{@value{AS}}.) @ifset H8 On the H8/300 and H8/500 platforms, each subsection is zero-padded to a word boundary (two bytes). -@c start-sanitize-Hitachi-SH The same is true on the Hitachi SH. -@c end-sanitize-Hitachi-SH @end ifset @ifset I960 @c FIXME section padding (alignment)? @@ -2018,9 +2004,7 @@ body of a symbol name, though not at its beginning. @ifset SPECIAL-SYMS @ifset H8 Symbol names begin with a letter or with one of @samp{._}. On the -@c start-sanitize-Hitachi-SH Hitachi SH or the -@c end-sanitize-Hitachi-SH H8/500, you can also use @code{$} in symbol names. That character may be followed by any string of digits, letters, dollar signs (save on the H8/300), and underscores. @@ -3007,10 +2991,9 @@ the program. @ifclear GENERIC @ifset H8 -On the H8/300 and H8/500, @code{.int} emits 16-bit integers. -@c start-sanitize-Hitachi-SH -On the Hitachi SH, however, @code{.int} emits 32-bit integers. -@c end-sanitize-Hitachi-SH +On the H8/500 and most forms of the H8/300, @code{.int} emits 16-bit +integers. On the H8/300H and the Hitachi SH, however, @code{.int} emits +32-bit integers. @end ifset @end ifclear @@ -3636,11 +3619,9 @@ subject, see the hardware manufacturer's manual. @ifset H8/500 * H8/500-Dependent:: Hitachi H8/500 Dependent Features @end ifset -@c start-sanitize-Hitachi-SH @ifset SH * SH-Dependent:: Hitachi SH Dependent Features @end ifset -@c end-sanitize-Hitachi-SH @ifset I960 * i960-Dependent:: Intel 80960 Dependent Features @end ifset @@ -4182,10 +4163,7 @@ family. @menu * H8/300-Dependent:: Hitachi H8/300 Dependent Features * H8/500-Dependent:: Hitachi H8/500 Dependent Features -@c start-sanitize-Hitachi-SH - * SH-Dependent:: Hitachi SH Dependent Features -@c end-sanitize-Hitachi-SH @end menu @down @end ifclear @@ -4240,7 +4218,7 @@ Therefore @emph{you may not use @samp{$} in symbol names} on the H8/300. @subsection Register Names @cindex H8/300 registers -@cindex registers, H8/300 +@cindex register names, H8/300 You can use predefined symbols of the form @samp{r@var{n}h} and @samp{r@var{n}l} to refer to the H8/300 registers as sixteen 8-bit general-purpose registers. @var{n} is a digit from @samp{0} to @@ -4251,10 +4229,14 @@ You can also use the eight predefined symbols @samp{r@var{n}} to refer to the H8/300 registers as 16-bit registers (you must use this form for addressing). +On the H8/300H, you can also use the eight predefined symbols +@samp{er@var{n}} (@samp{er0} @dots{} @samp{er7}) to refer to the 32-bit +general purpose registers. + The two control registers are called @code{pc} (program counter; a -16-bit register) and @code{ccr} (condition code register; an 8-bit -register). @code{r7} is used as the stack pointer, and can also be -called @code{sp}. +16-bit register, except on the H8/300H where it is 24 bits) and +@code{ccr} (condition code register; an 8-bit register). @code{r7} is +used as the stack pointer, and can also be called @code{sp}. @node H8/300-Addressing @subsection Addressing Modes @@ -4271,9 +4253,9 @@ Register indirect @item @@(@var{d}, r@var{n}) @itemx @@(@var{d}:16, r@var{n}) -Register indirect: 16-bit displacement @var{d} from register @var{n}. -(You may specify the @samp{:16} for clarity if you wish, but it is not -required and has no effect.) +@itemx @@(@var{d}:24, r@var{n}) +Register indirect: 16-bit or 24-bit displacement @var{d} from register +@var{n}. (24-bit displacements are only meaningful on the H8/300H.) @item @@r@var{n}+ Register indirect with post-increment @@ -4284,16 +4266,18 @@ Register indirect with pre-decrement @item @code{@@}@var{aa} @itemx @code{@@}@var{aa}:8 @itemx @code{@@}@var{aa}:16 -Absolute address @code{aa}. You may specify the @samp{:8} or @samp{:16} -for clarity, if you wish; but @code{@value{AS}} neither requires this nor -uses it---the address size required is taken from context. +@itemx @code{@@}@var{aa}:24 +Absolute address @code{aa}. (The address size @samp{:24} only makes +sense on the H8/300H.) @item #@var{xx} @itemx #@var{xx}:8 @itemx #@var{xx}:16 -Immediate data @var{xx}. You may specify the @samp{:8} or @samp{:16} -for clarity, if you wish; but @code{@value{AS}} neither requires this nor -uses it---the data size required is taken from context. +@itemx #@var{xx}:32 +Immediate data @var{xx}. You may specify the @samp{:8}, @samp{:16}, or +@samp{:32} for clarity, if you wish; but @code{@value{AS}} neither +requires this nor uses it---the data size required is taken from +context. @item @code{@@}@code{@@}@var{aa} @itemx @code{@@}@code{@@}@var{aa}:8 @@ -4306,8 +4290,11 @@ wish; but @code{@value{AS}} neither requires this nor uses it. @cindex floating point, H8/300 (@sc{ieee}) @cindex H8/300 floating point (@sc{ieee}) -The H8/300 family uses @sc{ieee} floating-point numbers. +The H8/300 family has no hardware floating point, but the @code{.float} +directive generates @sc{ieee} floating-point numbers for compatibility +with other development tools. +@page @node H8/300 Directives @section H8/300 Machine Directives @@ -4315,8 +4302,18 @@ The H8/300 family uses @sc{ieee} floating-point numbers. @cindex machine directives, H8/300 (none) @cindex @code{word} directive, H8/300 @cindex @code{int} directive, H8/300 -@code{@value{AS}} has no machine-dependent directives for the H8/300. -However, on this platform the @samp{.int} and @samp{.word} directives +@code{@value{AS}} has only one machine-dependent directive for the +H8/300: + +@table @code +@item .h300h +@cindex H8/300H, assembling for +Recognize and emit additional instructions for the H8/300H variant, and +also make @code{.int} emit 32-bit numbers rather than the usual (16-bit) +for the H8/300 family. +@end table + +On the H8/300 family (including the H8/300H) @samp{.word} directives generate 16-bit numbers. @node H8/300 Opcodes @@ -4327,115 +4324,175 @@ generate 16-bit numbers. @cindex mnemonics, H8/300 @cindex instruction summary, H8/300 For detailed information on the H8/300 machine instruction set, see -@cite{H8/300 Series Programming Manual} (Hitachi ADE--602--025). +@cite{H8/300 Series Programming Manual} (Hitachi ADE--602--025). For +information specific to the H8/300H, see @cite{H8/300H Series +Programming Manual} (Hitachi). @code{@value{AS}} implements all the standard H8/300 opcodes. No additional pseudo-instructions are needed on this family. -The following table summarizes the opcodes and their arguments: -@c kluge due to lack of group outside example -@page +The following table summarizes the H8/300 opcodes, and their arguments. +Entries marked @samp{*} are opcodes used only on the H8/300H. + @smallexample -@c In texinfo 2.102, @group makes this doublepsace!! -@c @group +@c Using @group seems to use the normal baselineskip, not the smallexample +@c baselineskip; looks approx doublespaced. @i{Legend:} Rs @r{source register} Rd @r{destination register} + abs @r{absolute address} imm @r{immediate data} - x:3 @r{a bit (as a number between 0 and 7)} - d:8 @r{eight bit displacement from @code{pc}} - d:16 @r{sixteen bit displacement from @code{Rs}} - -add.b Rs,Rd biand #x:3,Rd -add.b #imm:8,Rd biand #x:3,@@Rd -add.w Rs,Rd biand #x:3,@@aa:8 -adds #1,Rd bild #x:3,Rd -adds #2,Rd bild #x:3,@@Rd -addx #imm:8,Rd bild #x:3,@@aa:8 -addx Rs,Rd bior #x:3,Rd -and #imm:8,Rd bior #x:3,@@Rd -and Rs,Rd bior #x:3,@@aa:8 -andc #imm:8,ccr bist #x:3,Rd -band #x:3,Rd bist #x:3,@@Rd -band #x:3,@@Rd bist #x:3,@@aa:8 -bra d:8 bixor #x:3,Rd -bt d:8 bixor #x:3,@@Rd -brn d:8 bixor #x:3,@@aa:8 -bf d:8 bld #x:3,Rd -bhi d:8 bld #x:3,@@Rd -bls d:8 bld #x:3,@@aa:8 -bcc d:8 bnot #x:3,Rd -bhs d:8 bnot #x:3,@@Rd -bcs d:8 bnot #x:3,@@aa:8 -blo d:8 bnot Rs,Rd -bne d:8 bnot Rs,@@Rd -beq d:8 bnot Rs,@@aa:8 -bvc d:8 bor #x:3,Rd -bvs d:8 bor #x:3,@@Rd -bpl d:8 bor #x:3,@@aa:8 -bmi d:8 bset #x:3,@@Rd -bge d:8 bset #x:3,@@aa:8 -blt d:8 bset Rs,Rd -bgt d:8 bset Rs,@@Rd -ble d:8 bset Rs,@@aa:8 -bclr #x:3,Rd bsr d:8 -bclr #x:3,@@Rd bst #x:3,Rd -bclr #x:3,@@aa:8 bst #x:3,@@Rd -bclr Rs,Rd bst #x:3,@@aa:8 -bclr Rs,@@Rd btst #x:3,Rd -@c @end group + disp:N @r{N-bit displacement from a register} + pcrel:N @r{N-bit displacement relative to program counter} + + add.b #imm,rd * andc #imm,ccr + add.b rs,rd band #imm,rd + add.w rs,rd band #imm,@@rd +* add.w #imm,rd band #imm,@@abs:8 +* add.l rs,rd bra pcrel:8 +* add.l #imm,rd * bra pcrel:16 + adds #imm,rd bt pcrel:8 + addx #imm,rd * bt pcrel:16 + addx rs,rd brn pcrel:8 + and.b #imm,rd * brn pcrel:16 + and.b rs,rd bf pcrel:8 +* and.w rs,rd * bf pcrel:16 +* and.w #imm,rd bhi pcrel:8 +* and.l #imm,rd * bhi pcrel:16 +* and.l rs,rd bls pcrel:8 +@page +* bls pcrel:16 bld #imm,rd + bcc pcrel:8 bld #imm,@@rd +* bcc pcrel:16 bld #imm,@@abs:8 + bhs pcrel:8 bnot #imm,rd +* bhs pcrel:16 bnot #imm,@@rd + bcs pcrel:8 bnot #imm,@@abs:8 +* bcs pcrel:16 bnot rs,rd + blo pcrel:8 bnot rs,@@rd +* blo pcrel:16 bnot rs,@@abs:8 + bne pcrel:8 bor #imm,rd +* bne pcrel:16 bor #imm,@@rd + beq pcrel:8 bor #imm,@@abs:8 +* beq pcrel:16 bset #imm,rd + bvc pcrel:8 bset #imm,@@rd +* bvc pcrel:16 bset #imm,@@abs:8 + bvs pcrel:8 bset rs,rd +* bvs pcrel:16 bset rs,@@rd + bpl pcrel:8 bset rs,@@abs:8 +* bpl pcrel:16 bsr pcrel:8 + bmi pcrel:8 bsr pcrel:16 +* bmi pcrel:16 bst #imm,rd + bge pcrel:8 bst #imm,@@rd +* bge pcrel:16 bst #imm,@@abs:8 + blt pcrel:8 btst #imm,rd +* blt pcrel:16 btst #imm,@@rd + bgt pcrel:8 btst #imm,@@abs:8 +* bgt pcrel:16 btst rs,rd + ble pcrel:8 btst rs,@@rd +* ble pcrel:16 btst rs,@@abs:8 + bclr #imm,rd bxor #imm,rd + bclr #imm,@@rd bxor #imm,@@rd + bclr #imm,@@abs:8 bxor #imm,@@abs:8 + bclr rs,rd cmp.b #imm,rd + bclr rs,@@rd cmp.b rs,rd + bclr rs,@@abs:8 cmp.w rs,rd + biand #imm,rd cmp.w rs,rd + biand #imm,@@rd * cmp.w #imm,rd + biand #imm,@@abs:8 * cmp.l #imm,rd + bild #imm,rd * cmp.l rs,rd + bild #imm,@@rd daa rs + bild #imm,@@abs:8 das rs + bior #imm,rd dec.b rs + bior #imm,@@rd * dec.w #imm,rd + bior #imm,@@abs:8 * dec.l #imm,rd + bist #imm,rd divxu.b rs,rd + bist #imm,@@rd * divxu.w rs,rd + bist #imm,@@abs:8 * divxs.b rs,rd + bixor #imm,rd * divxs.w rs,rd + bixor #imm,@@rd eepmov + bixor #imm,@@abs:8 * eepmovw +@page +* exts.w rd mov.w rs,@@abs:16 +* exts.l rd * mov.l #imm,rd +* extu.w rd * mov.l rs,rd +* extu.l rd * mov.l @@rs,rd + inc rs * mov.l @@(disp:16,rs),rd +* inc.w #imm,rd * mov.l @@(disp:24,rs),rd +* inc.l #imm,rd * mov.l @@rs+,rd + jmp @@rs * mov.l @@abs:16,rd + jmp abs * mov.l @@abs:24,rd + jmp @@@@abs:8 * mov.l rs,@@rd + jsr @@rs * mov.l rs,@@(disp:16,rd) + jsr abs * mov.l rs,@@(disp:24,rd) + jsr @@@@abs:8 * mov.l rs,@@-rd + ldc #imm,ccr * mov.l rs,@@abs:16 + ldc rs,ccr * mov.l rs,@@abs:24 +* ldc @@abs:16,ccr movfpe @@abs:16,rd +* ldc @@abs:24,ccr movtpe rs,@@abs:16 +* ldc @@(disp:16,rs),ccr mulxu.b rs,rd +* ldc @@(disp:24,rs),ccr * mulxu.w rs,rd +* ldc @@rs+,ccr * mulxs.b rs,rd +* ldc @@rs,ccr * mulxs.w rs,rd +* mov.b @@(disp:24,rs),rd neg.b rs +* mov.b rs,@@(disp:24,rd) * neg.w rs + mov.b @@abs:16,rd * neg.l rs + mov.b rs,rd nop + mov.b @@abs:8,rd not.b rs + mov.b rs,@@abs:8 * not.w rs + mov.b rs,rd * not.l rs + mov.b #imm,rd or.b #imm,rd + mov.b @@rs,rd or.b rs,rd + mov.b @@(disp:16,rs),rd * or.w #imm,rd + mov.b @@rs+,rd * or.w rs,rd + mov.b @@abs:8,rd * or.l #imm,rd + mov.b rs,@@rd * or.l rs,rd + mov.b rs,@@(disp:16,rd) orc #imm,ccr + mov.b rs,@@-rd pop.w rs + mov.b rs,@@abs:8 * pop.l rs + mov.w rs,@@rd push.w rs +* mov.w @@(disp:24,rs),rd * push.l rs +* mov.w rs,@@(disp:24,rd) rotl.b rs +* mov.w @@abs:24,rd * rotl.w rs +* mov.w rs,@@abs:24 * rotl.l rs + mov.w rs,rd rotr.b rs + mov.w #imm,rd * rotr.w rs + mov.w @@rs,rd * rotr.l rs + mov.w @@(disp:16,rs),rd rotxl.b rs + mov.w @@rs+,rd * rotxl.w rs + mov.w @@abs:16,rd * rotxl.l rs + mov.w rs,@@(disp:16,rd) rotxr.b rs + mov.w rs,@@-rd * rotxr.w rs @page -@c @group -btst #x:3,@@Rd mov.w @@(d:16, Rs),Rd -btst #x:3,@@aa:8 mov.w @@Rs+,Rd -btst Rs,Rd mov.w @@aa:16,Rd -btst Rs,@@Rd mov.w Rs,@@Rd -btst Rs,@@aa:8 mov.w Rs,@@(d:16, Rd) -bxor #x:3,Rd mov.w Rs,@@-Rd -bxor #x:3,@@Rd mov.w Rs,@@aa:16 -bxor #x:3,@@aa:8 movfpe @@aa:16,Rd -cmp.b #imm:8,Rd movtpe Rs,@@aa:16 -cmp.b Rs,Rd mulxu Rs,Rd -cmp.w Rs,Rd neg Rs -daa Rs nop -das Rs not Rs -dec Rs or #imm:8,Rd -divxu Rs,Rd or Rs,Rd -eepmov orc #imm:8,ccr -inc Rs pop Rs -jmp @@Rs push Rs -jmp @@aa:16 rotl Rs -jmp @@@@aa rotr Rs -jsr @@Rs rotxl Rs -jsr @@aa:16 rotxr Rs -jsr @@@@aa:8 rte -ldc #imm:8,ccr rts -ldc Rs,ccr shal Rs -mov.b Rs,Rd shar Rs -mov.b #imm:8,Rd shll Rs -mov.b @@Rs,Rd shlr Rs -mov.b @@(d:16, Rs),Rd sleep -mov.b @@Rs+,Rd stc ccr,Rd -mov.b @@aa:16,Rd sub.b Rs,Rd -mov.b @@aa:8,Rd sub.w Rs,Rd -mov.b Rs,@@Rd subs #1,Rd -mov.b Rs,@@(d:16, Rd) subs #2,Rd -mov.b Rs,@@-Rd subx #imm:8,Rd -mov.b Rs,@@aa:16 subx Rs,Rd -mov.b Rs,@@aa:8 xor #imm:8,Rd -mov.w Rs,Rd xor Rs,Rd -mov.w #imm:16,Rd xorc #imm:8,ccr -mov.w @@Rs,Rd -@c @end group +* rotxr.l rs * stc ccr,@@(disp:24,rd) + bpt * stc ccr,@@-rd + rte * stc ccr,@@abs:16 + rts * stc ccr,@@abs:24 + shal.b rs sub.b rs,rd +* shal.w rs sub.w rs,rd +* shal.l rs * sub.w #imm,rd + shar.b rs * sub.l rs,rd +* shar.w rs * sub.l #imm,rd +* shar.l rs subs #imm,rd + shll.b rs subx #imm,rd +* shll.w rs subx rs,rd +* shll.l rs * trapa #imm + shlr.b rs xor #imm,rd +* shlr.w rs xor rs,rd +* shlr.l rs * xor.w #imm,rd + sleep * xor.w rs,rd + stc ccr,rd * xor.l #imm,rd +* stc ccr,@@rs * xor.l rs,rd +* stc ccr,@@(disp:16,rd) xorc #imm,ccr @end smallexample @cindex size suffixes, H8/300 @cindex H8/300 size suffixes Four H8/300 instructions (@code{add}, @code{cmp}, @code{mov}, -@code{sub}) are defined with variants using the suffixes @samp{.b} and -@samp{.w} to specify the size of a memory operand. @code{@value{AS}} -supports these suffixes, but does not require them; since one of the -operands is always a register, @code{@value{AS}} can deduce the correct size. +@code{sub}) are defined with variants using the suffixes @samp{.b}, +@samp{.w}, and @samp{.l} to specify the size of a memory operand. +@code{@value{AS}} supports these suffixes, but does not require them; +since one of the operands is always a register, @code{@value{AS}} can +deduce the correct size. For example, since @code{r0} refers to a 16-bit register, @example @@ -4444,8 +4501,8 @@ mov r0,@@foo mov.w r0,@@foo @end example -If you use the size suffixes, @code{@value{AS}} will issue a warning if -there's a mismatch between the suffix and the register size. +If you use the size suffixes, @code{@value{AS}} issues a warning when +the suffix and the register size do not match. @end ifset @ifset H8/500 @@ -4713,7 +4770,6 @@ mov[:g] sz ea,rd @end smallexample @end ifset -@c start-sanitize-Hitachi-SH @ifset SH @page @node SH-Dependent @@ -4971,7 +5027,6 @@ stc SR,Rn @end ifset @end ifset -@c end-sanitize-Hitachi-SH @ifset I960 @ifset GENERIC @page @@ -6543,7 +6598,49 @@ The MIPS @value{AS} supports the MIPS R2000 and R3000 processors. It ignores the @kbd{-nocpp}, @kbd{-EL}, and @kbd{-EB} options. -@i{FIXME: What other information do we need to note here?} +Not all traditional MIPS macro instructions are currently supported. +Specifically, @code{li.d} and @code{li.s} are not currently supported. + +When using @code{@value{GCC}} with MIPS @value{AS}, @code{@value{GCC}} +must be configured using the -with-gnu-as switch (this is the case for +Cygnus distributions) or @code{@value{GCC}} must be invoked with the +-mgas option. + +Assembling for a MIPS ECOFF target supports some additional sections +besides the usual @code{.text}, @code{.data} and @code{.bss}. The +additional sections are @code{.rdata}, used for readonly data, +@code{.sdata}, used for small data, and @code{.sbss}, used for small +common objects. + +When assembling for ECOFF, the assembler will automatically use the $gp +($28) register when forming the address of a small object. Any object +in the .sdata or .sbss sections is considered to be small. For external +objects or objects in the @code{.bss} section, the -G switch may be used +to control the size of objects for which the $gp register will be used; +the default value is 8, meaning that a reference to any object eight +bytes or smaller will use $gp. Passing -G 0 to @value{AS} will prevent +it from using the $gp register. The size of an object in the +@code{.bss} section is set by the @code{.comm} or @code{.lcomm} +pseudo-op that defines it. The size of an external object may be set +using the @code{.extern} pseudo-op. For example, @samp{.extern sym,4} +declares that the object at @code{sym} is 4 bytes in length, whie +leaving @code{sym} otherwise undefined. + +Using small ECOFF objects requires linker support, and assumes that the +$gp register has been correctly initialized (normally done automatically +by the startup code). MIPS ECOFF assembly code must avoid modifying the +$gp register. + +MIPS ECOFF @value{AS} supports several pseudo-ops used for generating +debugging information which are not support by traditional MIPS +assemblers. These are @code{.def}, @code{.endef}, @code{.dim}, +@code{.file}, @code{.scl}, @code{.size}, @code{.tag}, @code{.type}, +@code{.val}, @code{.stabd}, @code{.stabn}, and @code{.stabs}. The +debugging information generated by the three @code{.stab} pseudo-ops can +only be read by GDB, not by traditional MIPS debuggers (this enhancement +is required to fully support C++ debugging). These psuedo-ops are +primarily used by compilers, not assembly language programmers, and are +described elsewhere in the manual. @end ifset |