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User’s Manual
IBM PowerPC 750GX and 750GL RISC Microprocessor
Programming Model
Page 86 of 377
gx_02.fm.(1.2)
March 27, 2006
2.3 Instruction Set Summary
This section describes instructions and addressing modes defined for the 750GX. These instructions are
divided into the following functional categories:
Note: This grouping of instructions does not necessarily indicate the execution unit that processes a particu-
lar instruction or group of instructions. That information, which is useful for scheduling instructions most effec-
tively, is provided in Chapter 6, Instruction Timing, on page 209.
Integer instructions operate on word operands. Floating-point instructions operate on single-precision and
double-precision floating-point operands. The PowerPC Architecture uses instructions that are 4 bytes long
and word-aligned. It provides for byte, half-word, and word operand loads and stores between memory and a
set of 32 General Purpose Registers (GPRs). It provides for word and double-word operand loads and stores
between memory and a set of 32 Floating Point Registers (FPRs).
Arithmetic and logical instructions do not read or modify memory. To use the contents of a memory location in
a computation and then modify the same or another memory location, the memory contents must be loaded
into a register, modified, and then written to the target location using load-and-store instructions.
The description of each instruction beginning on page 92 includes the mnemonic and a formatted list of oper-
ands. To simplify assembly language programming, a set of simplified mnemonics and symbols is provided
for some of the frequently-used instructions; see Appendix F, “Simplified Mnemonics,” in the PowerPC Micro-
processor Family: The Programming Environments Manual for a complete list of simplified mnemonics. Note
Integer These include arithmetic and logical instructions. For more information, see
Section 2.3.4.1 on page 92.
Floating-point These include floating-point arithmetic instructions (single-precision and double-
precision), as well as instructions that affect the Floating-Point Status and Control
Register (FPSCR). For more information, see Section 2.3.4.2 on page 95.
Load and store These include integer and floating-point (including quantized) load-and-store
instructions. For more information, see Section 2.3.4.3 on page 98.
Flow control These include branching instructions, Condition Register logical instructions, trap
instructions, and other instructions that affect the instruction flow. For more infor-
mation, see Section 2.3.4.4 on page 106.
Processor control These instructions are used for synchronizing memory accesses and managing
caches, translation lookaside buffers (TLBs), and Segment Registers. For more
information, see Section 2.3.4.6 on page 108, Section 2.3.5.1 on page 113, and
Section 2.3.6.2 on page 118.
Memory synchronization These instructions are used for memory synchronizing. For more information, see
Section 2.3.4.7 on page 113 and Section 2.3.5.2 on page 114.
Memory control These instructions provide control of caches, TLBs, and Segment Registers. For
more information, see Section 2.3.5.3 on page 115 and Section 2.3.6.3 on
page 119.
External control These include instructions for use with special input/output devices. For more infor-
mation, see Section 2.3.5.4 on page 117.