8.1.2.3 Register Names
General-purpose registers are represented by predefined symbols of the form GR
nnn (for global registers) or LR
nnn (for local registers), where nnn represents a number between 0 and 127, written with no leading zeros. The leading letters may be in either upper or lower case; for example, gr13 and LR7 are both valid register names.
You may also refer to general-purpose registers by specifying the register number as the result of an expression (prefixed with %% to flag the expression as a register number):
%%expression
—where expression must be an absolute expression evaluating to a number between 0 and 255. The range [0, 127] refers to global registers, and the range [128, 255] to local registers.
In addition, as understands the following protected special-purpose register names for the AMD 29K family:
vab chd pc0
ops chc pc1
cps rbp pc2
cfg tmc mmu
cha tmr lru
These unprotected special-purpose register names are also recognized:
ipc alu fpe
ipa bp inte
ipb fc fps
q cr exop