gcc的spec中arch什么的指定

最新推荐文章于 2022-07-31 16:15:49 发布

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最新推荐文章于 2022-07-31 16:15:49 发布 · 1.1k 阅读

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#gcc #android #编译器 #thread #struct #float

本文探讨了GCC编译器中`-march`和`-mtune`选项的使用，通过GDB调试展示了它们在gcc源码中的处理过程。示例显示了如何设置这些参数来针对特定的CPU架构（如armv4t和arm920t）。同时提到了`-mfloat-abi`选项，并提及在Android环境下如何修改specs文件以适应不同平台的需求。

gcc/gcc.c中的set_collect_gcc_options这里面有COLLECT_GCC_OPTIONS='-march=armv4t' '-mtune=arm920t

(gdb) p switches[0]
$15 = {part1 = 0x80792b1 "march=armv4t", args = 0x0, live_cond = 1,
validated = 1 '/001', ordering = 0 '/000'}
(gdb) p switches[1]
$16 = {part1 = 0x80792c1 "mtune=arm920t", args = 0x0, live_cond = 0,
validated = 1 '/001', ordering = 0 '/000'}
(gdb) p switches[2]
$17 = {part1 = 0x80792d1 "mfloat-abi=soft", args = 0x0, live_cond = 0,
validated = 1 '/001', ordering = 0 '/000'}
(gdb) p switches[3]
$18 = {part1 = 0x0, args = 0xf7fb3420, live_cond = 1768697683,
validated = 98 'b', ordering = 47 '/'}
(gdb) p n_switches
$19 = 3

switches的赋值在do_self_spec和process_command

多次调用do_self_spec

Breakpoint 1, do_self_spec (
    spec=0xffffd150 "%{!march=*:%{!mcpu=*:-mcpu=arm920t}}")
    at ../../gcc-4.4.5/gcc/gcc.c:4614
4614    do_spec_2 (spec);

Breakpoint 1, do_self_spec (
    spec=0xffffd150 "%{!march=*:%{!mcpu=*:-march=armv4t}}")
    at ../../gcc-4.4.5/gcc/gcc.c:4614
4614    do_spec_2