isa_abi_headache
上传用户:qaz666999
上传日期:2022-08-06
资源大小:2570k
文件大小:5k
- Copyright 2000 Free Software Foundation, Inc.
- This file is part of the GNU MP Library.
- The GNU MP Library is free software; you can redistribute it and/or modify
- it under the terms of the GNU Lesser General Public License as published by
- the Free Software Foundation; either version 3 of the License, or (at your
- option) any later version.
- The GNU MP Library is distributed in the hope that it will be useful, but
- WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
- or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public
- License for more details.
- You should have received a copy of the GNU Lesser General Public License
- along with the GNU MP Library. If not, see http://www.gnu.org/licenses/.
- Terms Used In This Document:
- ISA = Instruction Set Architecture. The instructions the current
- processor provides.
- ABI = Application Binary Interface. Specifies calling convention,
- type sizes, etc.
- AR64 = Arithmetic operations are 64-bit using 64-bit instructions
- (E.g., addition, subtraction, load, store, of 64-bit integer types
- are done with single instructions, not 32 bits at a time.)
- Environment = The operating system and compiler.
- GMP is a very complex package to build since its speed is very
- sensitive to the ISA and ABI. For example, if the ISA provides 64-bit
- instructions, it is crucial that GMP is configured to use them.
- Most environments that run on a 64-bit ISA provide more than one ABI.
- Typically one of the supported ABI's is a backward compatible 32-bit
- ABI, and one ABI provides 64-bit addressing and `long' (sometimes
- known as LP64). But a few environments (IRIX, HP-UX) provide
- intermediate ABI's using 32-bit addressing but allow efficient 64-bit
- operations through a `long long' type. For the latter to be useful to
- GMP, the ABI must allow operations using the native 64-bit
- instructions provided by the ISA, and allow passing of 64-bit
- quantities atomically.
- The ABI is typically chosen by means of command line options to the
- compiler tools (gcc, cc, c89, nm, ar, ld, as). Different environments
- use different defaults, but as of this writing (May 2000) the
- dominating default is to the plain 32-bit ABI in its most arcane form.
- The GMP 3.0.x approach was to compile using the ABI that gives the
- best performance. That places the burden on users to pass special
- options to the compiler when they compile their GMP applications.
- That approach has its advantages and disadvantages. The main
- advantage is that users don't unknowingly get bad GMP performance.
- The main disadvantage is that users' compiles (actually links) will
- fail unless they pass special compiler options.
- ** SPARC
- System vendors often confuse ABI, ISA, and implementation. The worst
- case is Solaris, were the unbundled compiler confuses ISA and ABI, and
- the options have very confusing names.
- option interpretation
- ====== ==============
- cc -xarch=v8plus ISA=sparcv9, ABI=V8plus (PTR=32, see below)
- gcc -mv8plus ISA=sparcv9, ABI=V8plus (see below)
- cc -xarch=v9 ISA=sparcv9, ABI=V9 (implying AR=64, PTR=64)
- It's hard to believe, but the option v8plus really means ISA=V9!
- Solaris releases prior to version 7 running on a V9 CPU fails to
- save/restore the upper 32 bits of the `i' and `l' registers. The
- `v8plus' option generates code that use as many V9 features as
- possible under such circumstances.
- ** MIPS
- The IRIX 6 compilers gets things right. They have a clear
- understanding of the differences between ABI and ISA. The option
- names are descriptive.
- option interpretation
- ====== ==============
- cc -n32 ABI=n32 (implying AR=64, PTR=32)
- gcc -mabi=n32 ABI=n32 (implying AR=64, PTR=32)
- cc -64 ABI=64 (implying AR=64, PTR=64)
- gcc -mabi=64 ABI=64 (implying AR=64, PTR=64)
- cc -mips3 ISA=mips3
- gcc -mips3 ISA=mips3
- cc -mips4 ISA=mips4
- gcc -mips4 ISA=mips4
- ** HP-PA
- HP-UX is somewhat weird, but not as broken as Solaris.
- option interpretation
- ====== ==============
- cc +DA2.0 ABI=32bit (implying AR=64, PTR=32)
- cc +DD64 ABI=64bit (implying AR=64, PTR=64)
- Code performing 64-bit arithmetic in the HP-UX 32-bit is not
- compatible with the 64-bit ABI; the former has a calling convention
- that passes/returns 64-bit integer quantities as two 32-bit chunks.
- ** PowerPC
- While the PowerPC ABI's are capable of supporting 64-bit
- registers/operations, the compilers under AIX are similar to Solaris'
- cc in that they don't currently provide any 32-bit addressing with
- 64-bit arithmetic.
- option interpretation
- ====== ==============
- cc -q64 ABI=64bit (implying AR=64, PTR=64)
- gcc -maix64 -mpowerpc64 ABI=64bit (implying AR=64, PTR=64)