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SPARC Assembly Language Reference Manual

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Updated: October 2017
 
 

1.3 Assembler Lexical Features

This section describes the lexical features of the assembler syntax.

1.3.1 Case Distinction in Assembler

Uppercase and lowercase letters are distinct everywhere except in the names of special symbols. Special symbol names have no case distinction.

1.3.2 Comments in Assembler

A comment is preceded by an exclamation mark character (!); the exclamation mark character and all following characters up to the end of the line are ignored. C language-style comments (``/*…*/'') are also permitted and may span multiple lines.

1.3.3 Labels in Assembler

A label is either a symbol or a single decimal digit n (0...99). A label is immediately followed by a colon ( : ).

Numeric labels may be defined repeatedly in an assembly file; symbolic labels may be defined only once.

A numeric label n is referenced after its definition (backward reference) as nb, and before its definition (forward reference) as nf.

1.3.4 Numbers in Assembler

Decimal, hexadecimal, and octal numeric constants are recognized and are written as in the C language. However, integer suffixes (such as L) are not recognized.

For floating-point pseudo-operations, floating-point constants are written with 0r or 0R (where r or R means REAL) followed by a string acceptable to atof(3); that is, an optional sign followed by a non-empty string of digits with optional decimal point and optional exponent.

The special names 0rnan and 0rinf represent the special floating-point values Not-A-Number (NaN) and INFinity. Negative Not-A-Number and Negative INFinity are specified as 0r-nan and 0r-inf.


Note - The names of these floating-point constants begin with the digit zero, not the letter "O".

1.3.5 Strings in Assembler

A string is a sequence of characters quoted with either double-quote mark (") or single-quote mark (') characters. The sequence must not include a newline character. When used in an expression, the numeric value of a string is the numeric value of the ASCII representation of its first character.

The suggested style is to use single quote mark characters for the ASCII value of a single character, and double quote mark characters for quoted-string operands such as used by pseudo-ops. An example of assembly code in the suggested style is:

add %g1,'a'-'A',%g1 ! g1 + ('a' - 'A') --> g1 

The escape codes described in Figure 1, Table 1, Escape Codes Recognized in Strings, derived from ANSI C, are recognized in strings.

Table 1  Escape Codes Recognized in Strings
Escape Code
Description
\a
Alert
\b
Backspace
\f
Form feed
\n
Newline (line feed)
\r
Carriage return
\t
Horizontal tab
\v
Vertical tab
\nnn
Octal value nnn
\xnn...
Hexadecimal value nn...

1.3.6 Symbol Names in Assembler

The syntax for a symbol name is:

{ letter | _ | $ | . }   { letter | _ | $ | . | digit }* 

In the above syntax:

  • Uppercase and lowercase letters are distinct; the underscore ( _ ), dollar sign ($), and dot ( . ) are treated as alphabetic characters.

  • Symbol names that begin with a dot ( . ) are assumed to be local symbols. To simplify debugging, avoid using this type of symbol name in hand-coded assembly language routines.

  • The symbol dot ( . ) is predefined and always refers to the address of the beginning of the current assembly language statement.

  • External variable names beginning with the underscore character are reserved by the ANSI C Standard. Do not begin these names with the underscore; otherwise, the program will not conform to ANSI C and unpredictable behavior may result.

1.3.7 Special Symbols - Registers

Special symbol names begin with a percentage sign (%) to avoid conflict with user symbols. Figure 2, Table 2, Special Symbol Names lists these special symbol names.

Table 2  Special Symbol Names
Symbol Object
Name
Comment
General-purpose registers
%r0 … %r31
General-purpose global registers
%g0 … %g7
Same as %r0 … %r7
General-purpose out registers
%o0 … %o7
Same as %r8 … %r15
General-purpose local registers
%l0 … %l7
Same as %r16 … %r23
General-purpose in registers
%i0 … %i7
Same as %r24 … %r31
Stack-pointer register
%sp
(%sp = %o6 = %r14)
Frame-pointer register
%fp
(%fp = %i6 = %r30)
Floating-point registers
%f0 … %f31
Floating-point status register
%fsr
Front of floating-point queue
%fq
Program status register
%psr
Trap vector base address register
%tbr
Window invalid mask
%wim
Y register
%y
Unary operator
%lo
Extracts least significant 10 bits
Unary operator
%hi
Extracts most significant 22 bits
Unary operator
%r_disp32
Used only in Oracle Solaris Studio compiler-generated code.
Unary operator
%r_plt32
Used only in Oracle Solaris Studio compiler-generated code.
Ancillary state registers
%asr1 … %asr31

There is no case distinction in special symbols. For example, %PSR is equivalent to %psr.

The suggested style is to use lowercase letters.

The lack of case distinction allows for the use of non-recursive preprocessor substitutions, for example:

#define psr %PSR

The special symbols %hi and %lo are true unary operators which can be used in any expression and, as other unary operators, have higher precedence than binary operations. For example:

%hi a+b  =  (%hi a)+b
%lo a+b  =  (%lo a)+b

To avoid ambiguity, enclose operands of the %hi or %lo operators in parentheses. For example:

%hi(a) + b

1.3.8 Attributes in Assembler

Attributes, in the form #attribute, can be used to modify certain pseudo-operations and instructions. Pseudo-ops .global, .section, .register, and .type accept specific attributes that correspond to linker attribute flags, as shown in Figure 13, Table 13, Pseudo-op Linker Attributes.

Several instructions, such as membar and prefetch, also accept attributes. See the instruction descriptions in the Oracle SPARC Architecture Specifications for details on the attributes a given instruction supports.

1.3.9 Operators and Expressions in Assembler

The operators described in Figure 3, Table 3, Operators Recognized in Constant Expressions are recognized in constant expressions.

Table 3  Operators Recognized in Constant Expressions
Binary
Operators
Unary
Operators
+
Integer addition
+
(No effect)
Integer subtraction
2's Complement
*
Integer multiplication
~
1's Complement
/
Integer division
%lo(address)
Extract least significant 10 bits as computed by: (address & 0x3ff)
%
Modulo
%hi(address)
Extract most significant 22 bits as computed by: (address >>10)
^
Exclusive OR
%r_disp32
%r_disp64
Used in Oracle Solaris Studio compiler-generated code only to instruct the assembler to generate specific relocation information for the given expression.
<<
Left shift
%r_plt32
%r_plt64
Used in Oracle Solaris Studio compiler-generated code only to instruct the assembler to generate specific relocation information for the given expression.
>>
Right shift
&
Bitwise AND
|
Bitwise OR

Since these operators have the same precedence as in the C language, put expressions in parentheses to avoid ambiguity.

To avoid confusion with register names or with the %hi, %lo, %r_disp32/64, or %r_plt32/64 operators, the modulo operator % must not be immediately followed by a letter or digit. The modulo operator is typically followed by a space or left parenthesis character.

1.3.10 SPARC V9 Operators and Expressions

The following V9 64-bit operators and expressions in Figure 4, Table 4, V9 64-bit Operators and Expressions ease the task of converting from V8/V8plus assembly code to V9 assembly code.

Table 4  V9 64-bit Operators and Expressions
Unary
Calculation
Operators
%hh
(address) >> 42
Extract bits 42-63 of a 64-bit word
%hm
((address) >> 32) & 0x3ff
Extract bits 32-41 of a 64-bit word
%lm
(((address) >> 10) & 0x3fffff)
Extract bits 10-31 of a 64-bit word

For example:

sethi %hh (address), %l1
or %l1, %hm (address), %l1
sethi %lm (address), %12
or %12, %lo (address), %12
sllx %l1, 32, %l1
or %l1, %12, %l1

The V9 high 32-bit operators and expressions are identified in Figure 5, Table 5, V9 32-bit Operators and Expressions.

Table 5  V9 32-bit Operators and Expressions
Unary
Calculation
Operators
%hix
((((address) ^ 0xffffffffffffffff >> 10) &0x4fffff)
Invert every bit and extract bits 10-31
%lox
((address) & 0x3ff | 0x1c00
Extract bits 0-9 and sign extend that to 13 bits

For example:

%sethi %hix (address), %l1
or %l1, %lox (address), %l1

The V9 low 44-bit operators and expressions are identified in Figure 6, Table 6, Low 44-Bit Operators and Expressions.

Table 6  Low 44-Bit Operators and Expressions
Unary
Calculation
Operators
%h44
((address) >> 22)
Extract bits 22-43 of a 64-bit word
%m44
((address) >> 12) & 0x3ff
Extract bits 12-21 of a 64-bit word
%l44
(address) & 0xfff
Extract bits 0-11 of a 64-bit word

For example:

%sethi %h44 (address), %l1
or %l1, %m44 (address), %l1
sllx %l1, 12, %l1
or %l1, %

l44 (address), %l1