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Diffstat (limited to 'gas/doc/c-mips.texi')
| -rw-r--r-- | gas/doc/c-mips.texi | 18 |
1 files changed, 11 insertions, 7 deletions
diff --git a/gas/doc/c-mips.texi b/gas/doc/c-mips.texi index 87d5d2f..a114fee 100644 --- a/gas/doc/c-mips.texi +++ b/gas/doc/c-mips.texi @@ -75,13 +75,17 @@ instruction sets during the assembly; see @ref{MIPS ISA, Directives to override the ISA level}. @item -mgp32 -Assume that 32-bit general purpose registers are available. This -affects synthetic instructions such as @code{move}, which will assemble -to a 32-bit or a 64-bit instruction depending on this flag. On some -MIPS variants there is a 32-bit mode flag; when this flag is set, -64-bit instructions generate a trap. Also, some 32-bit OSes only save -the 32-bit registers on a context switch, so it is essential never to -use the 64-bit registers. +@itemx -mfp32 +Some macros have different expansions for 32-bit and 64-bit registers. +The register sizes are normally inferred from the ISA and ABI, but these +flags force a certain group of registers to be treated as 32 bits wide at +all times. @samp{-mgp32} controls the size of general-purpose registers +and @samp{-mfp32} controls the size of floating-point registers. + +On some MIPS variants there is a 32-bit mode flag; when this flag is +set, 64-bit instructions generate a trap. Also, some 32-bit OSes only +save the 32-bit registers on a context switch, so it is essential never +to use the 64-bit registers. @item -mgp64 Assume that 64-bit general purpose registers are available. This is |