Volume 2, Part 2: IA-32 Application Support
2:597
For best performance, the following code sequence is recommended for transitioning
from Itanium to IA-32 instruction set:
{.mii
flushrs
// flush register stack
mov b7 = rTarget
// Setup IA-32 target address
nop.i
// nop.i or other instruction
;;
{.mib
nop.m
// nop.m or other instruction
nop.i
// nop.i or other instruction
br.ia.sptk b7
// branch to IA-32 target defined by
// lower 32-bits of branch register b7
;;
Key to performance is that the register stack flush (
flushrs
) and the
br.ia
instruction
are separated by a single cycle, and that the
br.ia
instruction is the first B-slot in the
bundle directly following the
flushrs
. The
nop
instruction slots in the code example
may be used for other instructions.
9.1.3
JMPE
JMPE is an IA-32 instruction that comes in a register indirect and absolute branch
flavors. The code segment descriptor base is held in the CSD application register
(ar.csd).
• JMPE reg16/32 computes the target of the Itanium instruction set as
IP = ([reg16/32] + CSD.base) & 0xfffffff0
• JMPE disp16/32 computes the target of the Itanium instruction set as
IP = (disp16/32 + CSD.base) & 0xfffffff0
Targets of the IA-32 JMPE instruction are forced to be 16-byte aligned, and are
constrained to the lower 4Gbytes of the 64-bit virtual address space. The JMPE
instruction leaves the IA-32 return address (address of the IA-32 instruction following
the JMPE itself) in IA_64 register GR1.
9.1.4
Procedure Calls between Intel
®
Itanium
®
and IA-32
Instruction Sets
If procedure call linkage is required between Itanium architecture-based and IA-32
subroutines, software needs to perform additional work as described in the next two
sections.
9.1.4.1
Itanium
®
Architecture-based Caller to IA-32 Callee
This section outlines what steps an Itanium architecture-based caller of an IA-32
procedure needs to perform. The ordering of the steps is approximate and need not be
executed exactly in the order presented.
1. Setup IA-32 execution environment, if not already done (see
for
details). Ensure that no NaTed registers are used to setup IA-32 environment nor
that they are passed as procedure call arguments to IA-32 code.
2. Marshall arguments from the register stack to memory stack according to IA-32
software conventions.
3. Set up exception handle unwind data structures according to OS convention.
Summary of Contents for ITANIUM ARCHITECTURE - SOFTWARE DEVELOPERS VOLUME 3 REV 2.3
Page 1: ......
Page 11: ...x Intel Itanium Architecture Software Developer s Manual Rev 2 3 ...
Page 13: ...1 2 Intel Itanium Architecture Software Developer s Manual Rev 2 3 ...
Page 33: ...1 22 Volume 1 Part 1 Introduction to the Intel Itanium Architecture ...
Page 57: ...1 46 Volume 1 Part 1 Execution Environment ...
Page 147: ...1 136 Intel Itanium Architecture Software Developer s Manual Rev 2 3 ...
Page 149: ...1 138 Volume 1 Part 2 About the Optimization Guide ...
Page 191: ...1 180 Volume 1 Part 2 Predication Control Flow and Instruction Stream ...
Page 230: ......
Page 248: ...236 Intel Itanium Architecture Software Developer s Manual Rev 2 3 ...
Page 250: ...2 2 Intel Itanium Architecture Software Developer s Manual Rev 2 3 ...
Page 264: ...2 16 Volume 2 Part 1 Intel Itanium System Environment ...
Page 380: ...2 132 Volume 2 Part 1 Interruptions ...
Page 398: ...2 150 Volume 2 Part 1 Register Stack Engine ...
Page 486: ...2 238 Volume 2 Part 1 IA 32 Interruption Vector Descriptions ...
Page 750: ...2 502 Intel Itanium Architecture Software Developer s Manual Rev 2 3 ...
Page 754: ...2 506 Volume 2 Part 2 About the System Programmer s Guide ...
Page 796: ...2 548 Volume 2 Part 2 Interruptions and Serialization ...
Page 808: ...2 560 Volume 2 Part 2 Context Management ...
Page 842: ...2 594 Volume 2 Part 2 Floating point System Software ...
Page 850: ...2 602 Volume 2 Part 2 IA 32 Application Support ...
Page 862: ...2 614 Volume 2 Part 2 External Interrupt Architecture ...
Page 870: ...2 622 Volume 2 Part 2 Performance Monitoring Support ...
Page 891: ......
Page 1099: ...3 200 Volume 3 Instruction Reference padd Interruptions Illegal Operation fault ...
Page 1295: ...3 396 Volume 3 Resource and Dependency Semantics ...
Page 1296: ......
Page 1302: ...402 Intel Itanium Architecture Software Developer s Manual Rev 2 3 ...
Page 1494: ...4 192 Volume 4 Base IA 32 Instruction Reference FWAIT Wait See entry for WAIT ...
Page 1647: ...Volume 4 Base IA 32 Instruction Reference 4 345 ROL ROR Rotate See entry for RCL RCR ROL ROR ...
Page 1884: ...4 582 Volume 4 IA 32 SSE Instruction Reference ...
Page 1885: ...Index Intel Itanium Architecture Software Developer s Manual Rev 2 3 Index ...
Page 1886: ...Index Intel Itanium Architecture Software Developer s Manual Rev 2 3 ...
Page 1898: ...INDEX Index 12 Index for Volumes 1 2 3 and 4 ...