1 / 59

Chapter Six

Chapter Six. Sun SPARC Architecture. SPARC Registers. A SPARC processor includes two types of registers: general-purpose or “working ” data registers and control/status registers. IU’s general-purpose registers are called r registers

dagmar
Download Presentation

Chapter Six

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Chapter Six Sun SPARC Architecture

  2. SPARC Registers • A SPARC processor includes two types of registers: • general-purpose or “working” data registers and • control/status registers. • IU’s general-purpose registers are called r registers • FPU’s general-purpose registers are called f registers. • Coprocessor working registers are coprocessor-implementation dependent.

  3. SPARC Registers • IU control/status registers include: • Processor State Register (PSR) • Window Invalid Mask (WIM) • Trap Base Register (TBR) • Multiply/Divide Register (Y) • Program Counters (PC, nPC) • Implementation-dependent Ancillary State Registers (ASRs) • Implementation-dependent IU Deferred-Trap Queue

  4. SPARC Registers • FPU control/status registers include: • Floating-Point State Register (FSR) • Implementation-dependent Floating-Point Deferred-Trap Queue (FQ) • Coprocessor (CP) control/status registers, if present, may include: • Implementation-dependent Coprocessor State Register (CSR) • Implementation-dependent Coprocessor Deferred-Trap Queue (CQ)

  5. IU r Registers • An implementation of the IU may contain from 40 through 520 general-purpose32-bit r registers. • They are partitioned into 8 global registers, plus an implementation-dependent number of 16-register sets. • A register set is further partitioned into 8 in registers and 8 local registers.

  6. Overlapping of Windows • Thus any procedure can access only 32 registers (r0 – r31) • r0r7 : global registers that are accessible to all procedures • r8 r15 : (outs) contains parameters to be passed to the called procedure. • r16 r23 : (locals) contains local parameters of the procedure • r24 r31 : (ins) contain parameters passed by the procedure calling the current procedure

  7. Window Addressing

  8. Overlapping of Windows • Thus ‘outs’ of one window are ‘ins’ of the other window and this results in overlapping of windows as shown:

  9. Overlapping of Windows

  10. Overlapping of Windows • The register window of the currently running procedure, called active window is pointed by the current window pointer (CWP), a 5-bit counter field in the Processor State Register (PSR).

  11. Overlapping of Windows • The number of windows varies from 2 to 32. • Most SPARC architectures have 8 windows. • The last window overlaps with the first window, called as circular register windowing. • An example of 8-window implementation is as shown :

  12. Overlapping of Windows

  13. Overlapping of Windows • CWP is incremented by a RESTORE (or RETT) instruction and decremented by a SAVE instruction or a trap. • If the procedure using the window w0 executes a RESTORE(return), w1 will become the current window. • If the procedure using the window w0 executes a SAVE(call), a window_overflow trap occurs.

  14. IU Control/Status Registers

  15. SPARC Registers • IU control/status registers include: • Processor State Register (PSR) • Window Invalid Mask (WIM) • Trap Base Register (TBR) • Multiply/Divide Register (Y) • Program Counters (PC, nPC) • Implementation-dependent Ancillary State Registers (ASRs) • Implementation-dependent IU Deferred-Trap Queue

  16. Processor State Register(PSR) • 32-bit PSR contains various fields that control the processor and hold status information. • It can be modified by the SAVE, RESTORE, Ticc, and RETT instructions, and by all instructions that modify the condition codes. • The privileged RDPSR and WRPSR instructions read and write the PSR directly.

  17. Processor State Register(PSR) • impl: define a unique implementation or class of implementations of the architecture. • ver: to identify one or more particular implementations or is a readable and writable state field whose properties are implementation-dependent.

  18. Processor State Register(PSR) • icc: Integer Condition Codes • n: 1 = ALU result is negative, 0 = not negative • z: 1 = zero, 0 = nonzero. • v: 1 = overflow, 0 = no overflow. • c: 1 =carry, 0 = no carry.

  19. Processor State Register(PSR) • reserved: • Enable Coprocessor(EC): determines whether the implementation-dependent coprocessor is enabled. • Enable Floating Point(EF): determines whether the FPU is enabled • Processor Interrupt Level (PIL): identify the interrupt level above which the processor will accept an interrupt.

  20. Processor State Register(PSR) • Supervisor(S): determines whether the processor is in supervisor or user mode. 1 = supervisor mode, 0 = user mode. • Previous Supervisor(PS): contains the value of the S bit at the time of the most recent trap. • Enable Trap(ET): determines whether the FPU is enabled

  21. Processor State Register(PSR) • Current Window Pointer (CWP): a counter that identifies the current window

  22. SPARC Registers • IU control/status registers include: • Processor State Register (PSR) • Window Invalid Mask (WIM) • Trap Base Register (TBR) • Multiply/Divide Register (Y) • Program Counters (PC, nPC) • Implementation-dependent Ancillary State Registers (ASRs) • Implementation-dependent IU Deferred-Trap Queue

  23. Window Invalid Mask (WIM) • Window Invalid Mask register (WIM) is controlled by supervisor software and is used by hardware to determine whether a window overflow or underflow trap is to be generated • The structure of the WIM register is designed for 32-windows.

  24. SPARC Registers • IU control/status registers include: • Processor State Register (PSR) • Window Invalid Mask (WIM) • Trap Base Register (TBR) • Multiply/Divide Register (Y) • Program Counters (PC, nPC) • Implementation-dependent Ancillary State Registers (ASRs) • Implementation-dependent IU Deferred-Trap Queue

  25. Trap Base Register (TBR) • This register determine the address to which control is transferred in case of trap. • TBA(Trap Base Address):It contains the most-significant 20 bits of the trap table address • tt(trap type): This 8-bit field is written by the hardware when a trap occurs and provides an offset into the trap table • zero: zeros

  26. SPARC Registers • IU control/status registers include: • Processor State Register (PSR) • Window Invalid Mask (WIM) • Trap Base Register (TBR) • Multiply/Divide Register (Y) • Program Counters (PC, nPC) • Implementation-dependent Ancillary State Registers (ASRs) • Implementation-dependent IU Deferred-Trap Queue

  27. Multiply/Divide Register (Y) • It contains the most significant word of the double precision product of integer multiplication. • It also hold the most significant word of the double precision dividend of the integer divide

  28. SPARC Registers • IU control/status registers include: • Processor State Register (PSR) • Window Invalid Mask (WIM) • Trap Base Register (TBR) • Multiply/Divide Register (Y) • Program Counters (PC, nPC) • Implementation-dependent Ancillary State Registers (ASRs) • Implementation-dependent IU Deferred-Trap Queue

  29. Program Counters (PC, nPC) • PC(Program Counter): contains the address of the instruction currently being executed by IU • nPC (Next Program Counter): holds the address of the next instruction to be executed

  30. SPARC Registers • IU control/status registers include: • Processor State Register (PSR) • Window Invalid Mask (WIM) • Trap Base Register (TBR) • Multiply/Divide Register (Y) • Program Counters (PC, nPC) • Implementation-dependent Ancillary State Registers (ASRs) • Implementation-dependent IU Deferred-Trap Queue

  31. Ancillary State Registers (ASRs) • ASR’s numbered 1-15 are reserved • ASR’s numbered 16-31 are available for implementation-dependent uses such as timers, counters, diagnostic registers, self-test registers and trap-control registers.

  32. SPARC Registers • IU control/status registers include: • Processor State Register (PSR) • Window Invalid Mask (WIM) • Trap Base Register (TBR) • Multiply/Divide Register (Y) • Program Counters (PC, nPC) • Implementation-dependent Ancillary State Registers (ASRs) • Implementation-dependent IU Deferred-Trap Queue

  33. IU Deferred-Trap Queue • It contains sufficient state to implement resumable deferred traps caused by the IU

  34. FPU’s f registers. • FPU contains 32 32-bit floating-point f registers numbered from f[0] to f[31]. • At a given time an instruction has access to any of the 32 f registers.

  35. FPU’s f registers. • A single f register can hold one single-precision operand. • A double-precision operand requires an aligned pair of f registers. • A quad-precision operand requires an aligned quadruple of f registers.

  36. FPU Control/Status Registers

  37. Floating-Point State Register (FSR) • RD (Rounding Direction): select the rounding direction for floating-point results

  38. Floating-Point State Register (FSR) • u (Unused): reserved • TEM(Trap Enable Masks) : enable bits for five floating-point exceptions • NVM(Non Valid Mask): An operand is improper for the operation to be performed. For e.g.0÷0, ∞-∞ are invalid. (1 = invalid operand, 0 = valid operand.) • OFM(Overflow Trap Mask):1 = overflow, 0 = no overflow.

  39. Floating-Point State Register (FSR) • TEM : • UFM(Overflow Trap Mask):1 = underflow, 0 = no underflow.(magnitude is smaller) • DZM(Division by Zero Trap): X÷0.Note that 0÷0 is not considered here. 1 = division-by-zero, 0 = no division-by-zero. • NXM(Not Exact Trap Mask) The rounded result differs from the infinitely precise correct result. 1 = inexact result, 0 = exact result.

  40. Floating-Point State Register (FSR) • NS(Not Standard): When set to 1, causes FPU to produce results that may not correspond to ANSI/IEEE Standard 754-1985. • res: reserved bits • ver: indicates version

  41. Floating-Point State Register (FSR) • ftt(floating point trap type):identify floating-point exception trap types

  42. Floating-Point State Register (FSR) • qne(queue not empty): indicates whether the optional floating-point deferred-trap queue (FQ) is empty. If qne = 0, the queue is empty; if qne = 1, the queue is not empty. • u: unused • fcc:

  43. Floating-Point State Register (FSR) • fcc: • contain the FPU condition codes. • are updated by floating-point compare instructions • f rs1 and f rs2 correspond to values in the f registers specified by an instruction’s rs1 and rs2 fields.

  44. Floating-Point State Register (FSR) • aexc: • Accumulate floating-point exceptions while fp_exception traps are disabled using the TEM field.

  45. Floating-Point State Register (FSR) • cexc: • indicate that one or more IEEE_754 floating-point exceptions were generated by the most recently executed FPop instruction. • The absence of an exception causes corresponding bit to be cleared.

  46. Floating-Point Deferred-TrapQueue (FQ) • FQ, if present in an implementation, contains sufficient state information to implement resumable, deferred floating point traps.

  47. CP Registers • All of the coprocessor data and control/status registers are optional and implementation-dependent. • Coprocessor registers are accessed via load/store coprocessor and CPop1/CPop2 format instructions. • The architecture also provides instruction support for reading and writing a Coprocessor State Register (CSR) and a coprocessor deferred-trap queue (CQ).

  48. SPARC Instruction Format • Instructions are encoded in three major 32-bit formats. • They are • CALL • Branch Instructions • Operate instructions(register-to-register)

  49. SPARC Instruction Format

  50. SPARC Instruction Format • The instruction fields are interpreted as follows: • op and op2:These 2- and 3-bit fields encode the 3 major formats and the format 2 instructions according to

More Related