* config/tc-alpha.c (O_lituse_jsrdirect): New.

[platform/upstream/binutils.git] / gas / doc / c-mips.texi

diff --git a/gas/doc/c-mips.texi b/gas/doc/c-mips.texi
index 6446c92..97469fe 100644 (file)
--- a/gas/doc/c-mips.texi
+++ b/gas/doc/c-mips.texi
@@ -26,6 +26,7 @@ Assembly Language Programming'' in the same work.
 * MIPS Object::        ECOFF object code
 * MIPS Stabs::         Directives for debugging information
 * MIPS ISA::           Directives to override the ISA level
+* MIPS symbol sizes::   Directives to override the size of symbols
 * MIPS autoextend::    Directives for extending MIPS 16 bit instructions
 * MIPS insn::          Directive to mark data as an instruction
 * MIPS option stack::  Directives to save and restore options
@@ -128,6 +129,10 @@ Insert nops to work around certain VR4120 errata.  This option is
 intended to be used on GCC-generated code: it is not designed to catch
 all problems in hand-written assembler code.
 
+@item -mfix-vr4130
+@itemx -no-mfix-vr4130
+Insert nops to work around the VR4130 @samp{mflo}/@samp{mfhi} errata.
+
 @item -m4010
 @itemx -no-m4010
 Generate code for the LSI @sc{r4010} chip.  This tells the assembler to
@@ -197,6 +202,13 @@ identical to @samp{-march=@var{cpu}}.
 Record which ABI the source code uses.  The recognized arguments
 are: @samp{32}, @samp{n32}, @samp{o64}, @samp{64} and @samp{eabi}.
 
+@item -msym32
+@itemx -mno-sym32
+@cindex -msym32
+@cindex -mno-sym32
+Equivalent to adding @code{.set sym32} or @code{.set nosym32} to
+the beginning of the assembler input.  @xref{MIPS symbol sizes}.
+
 @cindex @code{-nocpp} ignored (MIPS)
 @item -nocpp
 This option is ignored.  It is accepted for command-line compatibility with
@@ -297,6 +309,61 @@ not by traditional @sc{mips} debuggers (this enhancement is required to fully
 support C++ debugging).  These directives are primarily used by compilers, not
 assembly language programmers!
 
+@node MIPS symbol sizes
+@section Directives to override the size of symbols
+
+@cindex @code{.set sym32}
+@cindex @code{.set nosym32}
+The n64 ABI allows symbols to have any 64-bit value.  Although this
+provides a great deal of flexibility, it means that some macros have
+much longer expansions than their 32-bit counterparts.  For example,
+the non-PIC expansion of @samp{dla $4,sym} is usually:
+
+@smallexample
+lui     $4,%highest(sym)
+lui     $1,%hi(sym)
+daddiu  $4,$4,%higher(sym)
+daddiu  $1,$1,%lo(sym)
+dsll32  $4,$4,0
+daddu   $4,$4,$1
+@end smallexample
+
+whereas the 32-bit expansion is simply:
+
+@smallexample
+lui     $4,%hi(sym)
+daddiu  $4,$4,%lo(sym)
+@end smallexample
+
+n64 code is sometimes constructed in such a way that all symbolic
+constants are known to have 32-bit values, and in such cases, it's
+preferable to use the 32-bit expansion instead of the 64-bit
+expansion.
+
+You can use the @code{.set sym32} directive to tell the assembler
+that, from this point on, all expressions of the form
+@samp{@var{symbol}} or @samp{@var{symbol} + @var{offset}}
+have 32-bit values.  For example:
+
+@smallexample
+.set sym32
+dla     $4,sym
+lw      $4,sym+16
+sw      $4,sym+0x8000($4)
+@end smallexample
+
+will cause the assembler to treat @samp{sym}, @code{sym+16} and
+@code{sym+0x8000} as 32-bit values.  The handling of non-symbolic
+addresses is not affected.
+
+The directive @code{.set nosym32} ends a @code{.set sym32} block and
+reverts to the normal behavior.  It is also possible to change the
+symbol size using the command-line options @option{-msym32} and
+@option{-mno-sym32}.
+
+These options and directives are always accepted, but at present,
+they have no effect for anything other than n64.
+
 @node MIPS ISA
 @section Directives to override the ISA level