IBM PowerPC 750GX

User’s Manual
IBM PowerPC 750GX and 750GL RISC Microprocessor
Page 4 of 377
750gx_umTOC.fm.(1.2)
March 27, 2006
2. Programming Model .................................................................................................. 57
2.1 PowerPC 750GX Processor Register Set ....................................................................................... 57
2.1.1 Register Set ........................................................................................................................... 57
2.1.2 PowerPC 750GX-Specific Registers ...................................................................................... 64
2.1.2.1 Instruction Address Breakpoint Register (IABR) ............................................................ 64
2.1.2.2 Hardware-Implementation-Dependent Register 0 (HID0) .............................................. 65
2.1.2.3 Hardware-Implementation-Dependent Register 1 (HID1) .............................................. 70
2.1.2.4 Hardware-Implementation-Dependent Register 2 (HID2) .............................................. 71
2.1.2.5 Performance-Monitor Registers ...................................................................................... 72
2.1.3 Instruction Cache Throttling Control Register (ICTC) ............................................................ 77
2.1.4 Thermal-Management Registers (THRMn) ............................................................................ 78
2.1.4.1 Thermal-Management Registers 1–2 (THRM1–THRM2) ............................................... 78
2.1.4.2 Thermal-Management Register 3 (THRM3) ................................................................... 79
2.1.4.3 Thermal-Management Register 4 (THRM4) ................................................................... 80
2.1.5 L2 Cache Control Register (L2CR) ........................................................................................ 81
2.2 Operand Conventions ..................................................................................................................... 82
2.2.1 Data Organization in Memory and Data Transfers ................................................................ 82
2.2.2 Alignment and Misaligned Accesses ..................................................................................... 82
2.2.3 Floating-Point Operand and Execution Models—UISA ......................................................... 83
2.2.3.1 Denormalized Number Support ...................................................................................... 83
2.2.3.2 Non-IEEE Mode (Nondenormalized Mode) .................................................................... 83
2.2.3.3 Time-Critical Floating-Point Operation ........................................................................... 84
2.2.3.4 Floating-Point Storage Access Alignment ...................................................................... 84
2.2.3.5 Optional Floating-Point Graphics Instructions ................................................................ 84
2.3 Instruction Set Summary ................................................................................................................. 86
2.3.1 Classes of Instructions ........................................................................................................... 87
2.3.1.1 Definition of Boundedly Undefined ................................................................................. 87
2.3.1.2 Defined Instruction Class ................................................................................................ 87
2.3.1.3 Illegal Instruction Class ................................................................................................... 88
2.3.1.4 Reserved Instruction Class ............................................................................................. 89
2.3.2 Addressing Modes ................................................................................................................. 89
2.3.2.1 Memory Addressing ........................................................................................................ 89
2.3.2.2 Memory Operands .......................................................................................................... 89
2.3.2.3 Effective Address Calculation ......................................................................................... 90
2.3.2.4 Synchronization .............................................................................................................. 90
2.3.3 Instruction Set Overview ........................................................................................................ 91
2.3.4 PowerPC UISA Instructions ................................................................................................... 92
2.3.4.1 Integer Instructions ......................................................................................................... 92
2.3.4.2 Floating-Point Instructions .............................................................................................. 95
2.3.4.3 Load-and-Store Instructions ........................................................................................... 98
2.3.4.4 Branch and Flow-Control Instructions .......................................................................... 106
2.3.4.5 System Linkage Instruction—UISA .............................................................................. 108
2.3.4.6 Processor Control Instructions—UISA ......................................................................... 108
2.3.4.7 Memory Synchronization Instructions—UISA ............................................................... 113
2.3.5 PowerPC VEA Instructions .................................................................................................. 113
2.3.5.1 Processor Control Instructions—VEA ........................................................................... 113
2.3.5.2 Memory Synchronization Instructions—VEA ................................................................ 114
2.3.5.3 Memory Control Instructions—VEA .............................................................................. 115
2.3.5.4 Optional External Control Instructions .......................................................................... 117
2.3.6 PowerPC OEA Instructions .................................................................................................. 118