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SPARC Assembly Language Reference Manual

2.3.7 Special Symbols - Registers

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

Table 2–2

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

 

Coprocessor registers 

%c0 … %c31

 

Coprocessor status register 

%csr

 

Coprocessor queue 

%cq

 

Program status register 

%psr

 

Trap vector base address register 

%tbr

 

Window invalid mask 

%wim

 

Y register 

%y

 

Unary operators 

%lo

Extracts least significant 10 bits 

 

%hi

Extracts most significant 22 bits 

 

%r_disp32

Used only in Sun compiler-generated code. 

 

%r_plt32

Used only in Sun 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