path: root/gas/doc/c-tilepro.texi

@c Copyright 2011
@c Free Software Foundation, Inc.
@c This is part of the GAS manual.
@c For copying conditions, see the file as.texinfo.
@ifset GENERIC
@page
@node TILEPro-Dependent
@chapter TILEPro Dependent Features
@end ifset
@ifclear GENERIC
@node Machine Dependencies
@chapter TILEPro Dependent Features
@end ifclear

@cindex TILEPro support
@menu
* TILEPro Options::		TILEPro Options
* TILEPro Syntax::		TILEPro Syntax
* TILEPro Directives::		TILEPro Directives
@end menu

@node TILEPro Options
@section Options

@code{@value{AS}} has no machine-dependent command-line options for
TILEPro.

@node TILEPro Syntax
@section Syntax
@cindex TILEPro syntax
@cindex syntax, TILEPro

Block comments are delimited by @samp{/*} and @samp{*/}.  End of line
comments may be introduced by @samp{#}.

Instructions consist of a leading opcode or macro name followed by
whitespace and an optional comma-separated list of operands:

@smallexample
@var{opcode} [@var{operand}, @dots{}]
@end smallexample

Instructions must be separated by a newline or semicolon.

There are two ways to write code: either write naked instructions,
which the assembler is free to combine into VLIW bundles, or specify
the VLIW bundles explicitly.

Bundles are specified using curly braces:

@smallexample
@{ @var{add} r3,r4,r5 ; @var{add} r7,r8,r9 ; @var{lw} r10,r11 @}
@end smallexample

A bundle can span multiple lines. If you want to put multiple
instructions on a line, whether in a bundle or not, you need to
separate them with semicolons as in this example.

A bundle may contain one or more instructions, up to the limit
specified by the ISA (currently three). If fewer instructions are
specified than the hardware supports in a bundle, the assembler
inserts @code{fnop} instructions automatically.

The assembler will prefer to preserve the ordering of instructions
within the bundle, putting the first instruction in a lower-numbered
pipeline than the next one, etc.  This fact, combined with the
optional use of explicit @code{fnop} or @code{nop} instructions,
allows precise control over which pipeline executes each instruction.

If the instructions cannot be bundled in the listed order, the
assembler will automatically try to find a valid pipeline
assignment. If there is no way to bundle the instructions together,
the assembler reports an error.

The assembler does not yet auto-bundle (automatically combine multiple
instructions into one bundle), but it reserves the right to do so in
the future.  If you want to force an instruction to run by itself, put
it in a bundle explicitly with curly braces and use @code{nop}
instructions (not @code{fnop}) to fill the remaining pipeline slots in
that bundle.

@menu
* TILEPro Opcodes::              Opcode Naming Conventions.
* TILEPro Registers::            Register Naming.
* TILEPro Modifiers::            Symbolic Operand Modifiers.
@end menu

@node TILEPro Opcodes
@subsection Opcode Names
@cindex TILEPro opcode names
@cindex opcode names, TILEPro

For a complete list of opcodes and descriptions of their semantics,
see @cite{TILE Processor User Architecture Manual}, available upon
request at www.tilera.com.

@node TILEPro Registers
@subsection Register Names
@cindex TILEPro register names
@cindex register names, TILEPro

General-purpose registers are represented by predefined symbols of the
form @samp{r@var{N}}, where @var{N} represents a number between
@code{0} and @code{63}.  However, the following registers have
canonical names that must be used instead:

@table @code
@item r54
sp

@item r55
lr

@item r56
sn

@item r57
idn0

@item r58
idn1

@item r59
udn0

@item r60
udn1

@item r61
udn2

@item r62
udn3

@item r63
zero

@end table

The assembler will emit a warning if a numeric name is used instead of
the canonical name.  The @code{.no_require_canonical_reg_names}
assembler pseudo-op turns off this
warning. @code{.require_canonical_reg_names} turns it back on.

@node TILEPro Modifiers
@subsection Symbolic Operand Modifiers
@cindex TILEPro modifiers
@cindex symbol modifiers, TILEPro

The assembler supports several modifiers when using symbol addresses
in TILEPro instruction operands.  The general syntax is the following:

@smallexample
modifier(symbol)
@end smallexample

The following modifiers are supported:

@table @code

@item lo16

This modifier is used to load the low 16 bits of the symbol's address,
sign-extended to a 32-bit value (sign-extension allows it to be
range-checked against signed 16 bit immediate operands without
complaint).

@item hi16

This modifier is used to load the high 16 bits of the symbol's
address, also sign-extended to a 32-bit value.

@item ha16

@code{ha16(N)} is identical to @code{hi16(N)}, except if
@code{lo16(N)} is negative it adds one to the @code{hi16(N)}
value. This way @code{lo16} and @code{ha16} can be added to create any
32-bit value using @code{auli}.  For example, here is how you move an
arbitrary 32-bit address into r3:

@smallexample
moveli r3, lo16(sym)
auli r3, r3, ha16(sym)
@end smallexample

@item got

This modifier is used to load the offset of the GOT entry
corresponding to the symbol.

@item got_lo16

This modifier is used to load the sign-extended low 16 bits of the
offset of the GOT entry corresponding to the symbol.

@item got_hi16

This modifier is used to load the sign-extended high 16 bits of the
offset of the GOT entry corresponding to the symbol.

@item got_ha16

This modifier is like @code{got_hi16}, but it adds one if
@code{got_lo16} of the input value is negative.

@item plt

This modifier is used for function symbols.  It causes a
@emph{procedure linkage table}, an array of code stubs, to be created
at the time the shared object is created or linked against, together
with a global offset table entry.  The value is a pc-relative offset
to the corresponding stub code in the procedure linkage table.  This
arrangement causes the run-time symbol resolver to be called to look
up and set the value of the symbol the first time the function is
called (at latest; depending environment variables).  It is only safe
to leave the symbol unresolved this way if all references are function
calls.

@item tls_gd

This modifier is used to load the offset of the GOT entry of the
symbol's TLS descriptor, to be used for general-dynamic TLS accesses.

@item tls_gd_lo16

This modifier is used to load the sign-extended low 16 bits of the
offset of the GOT entry of the symbol's TLS descriptor, to be used for
general dynamic TLS accesses.

@item tls_gd_hi16

This modifier is used to load the sign-extended high 16 bits of the
offset of the GOT entry of the symbol's TLS descriptor, to be used for
general dynamic TLS accesses.

@item tls_gd_ha16

This modifier is like @code{tls_gd_hi16}, but it adds one to the value
if @code{tls_gd_lo16} of the input value is negative.

@item tls_ie

This modifier is used to load the offset of the GOT entry containing
the offset of the symbol's address from the TCB, to be used for
initial-exec TLS accesses.

@item tls_ie_lo16

This modifier is used to load the low 16 bits of the offset of the GOT
entry containing the offset of the symbol's address from the TCB, to
be used for initial-exec TLS accesses.

@item tls_ie_hi16

This modifier is used to load the high 16 bits of the offset of the
GOT entry containing the offset of the symbol's address from the TCB,
to be used for initial-exec TLS accesses.

@item tls_ie_ha16

This modifier is like @code{tls_ie_hi16}, but it adds one to the value
if @code{tls_ie_lo16} of the input value is negative.

@end table

@node TILEPro Directives
@section TILEPro Directives
@cindex machine directives, TILEPro
@cindex TILEPro machine directives

@table @code

@cindex @code{.align} directive, TILEPro
@item .align @var{expression} [, @var{expression}]
This is the generic @var{.align} directive.  The first argument is the
requested alignment in bytes.

@cindex @code{.allow_suspicious_bundles} directive, TILEPro
@item .allow_suspicious_bundles
Turns on error checking for combinations of instructions in a bundle
that probably indicate a programming error.  This is on by default.

@item .no_allow_suspicious_bundles
Turns off error checking for combinations of instructions in a bundle
that probably indicate a programming error.

@cindex @code{.require_canonical_reg_names} directive, TILEPro
@item .require_canonical_reg_names
Require that canonical register names be used, and emit a warning if
the numeric names are used.  This is on by default.

@item .no_require_canonical_reg_names
Permit the use of numeric names for registers that have canonical
names.

@end table