SPARC 大会问题
我想在我的 C 程序中编写一个非常简单的内联汇编例程，它什么也不做 否则，将本地寄存器 %l0 - %l7 设置为不同的值。我尝试了以下简单的方法：
asm volatile (
".text\n\t"
"mov 0, %%l0 \n\t"
"mov 1, %%l1 \n\t"
"mov 2, %%l2 \n\t"
"mov 3, %%l3 \n\t"
"mov 4, %%l4 \n\t"
"mov 5, %%l5 \n\t"
"mov 6, %%l6 \n\t"
"mov 7, %%l7 \n\t"
);
不幸的是，汇编器告诉：每条指令的操作数都是非法的。有人能好心地告诉我如何正确地将立即值传递给 SPARC 汇编器吗？
非常感谢！
编辑：谢谢克里斯，我做了你建议的更改，但 Sparc 编译器仍然告诉一些有关非法操作数的信息......
I wanna write a very simple inline assembly routine in my C program which does nothing
else then setting the local registers %l0 - %l7 to different values. I tried the following straightforward approach:
asm volatile (
".text\n\t"
"mov 0, %%l0 \n\t"
"mov 1, %%l1 \n\t"
"mov 2, %%l2 \n\t"
"mov 3, %%l3 \n\t"
"mov 4, %%l4 \n\t"
"mov 5, %%l5 \n\t"
"mov 6, %%l6 \n\t"
"mov 7, %%l7 \n\t"
);
unfortuantely, the assembler tells: illegal operand for each instruction. Could somebody please be so nice to point me out how I can properly pass immediate values to the SPARC assembler?
Thanks so much!
EDIT: Thanks Chris, I made the changes you suggested but the Sparc compiler still tells some something about illegal operands...
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SPARC 本身不发出“立即移动”指令；有
或可以像或 %g0, 123, %l0一样使用（或者用零寄存器来表示一个不超过 11 位的常量，< code>%g0，导致将所述常量移动到目标寄存器中），或可用于设置 a 的高 21 位的sethi指令登记。为了适应任何（32位）常量，您必须首先对高位执行sethi来合成一个两步set后面跟着一个or以及较低的那些。SPARC 汇编程序通常知道一个
set ..., %tgtregister快捷方式来创建此序列，和/或消除一条指令（如果常量适合该指令）。另请注意，在 64 位/sparcv9 中，
set指令最终可能会计算出最多五个指令的序列，将事物移位/或在一起。SPARC doesn't mave "immediate move" instructions as such; there's either
orwhich can be used likeor %g0, 123, %l0(or'ing a no-more-than 11-bit constant with the zero register,%g0, resulting in moving said constant into the target register), or thesethiinstruction that can be used to set the upper 21 bits of a register. In order to accommodate any (32bit) constant, you therefore have to synthesise a two-stepsetby doing asethifirst for the upper bits followed by anorwith the lower ones.SPARC assemblers usually know a
set ..., %tgtregistershortcut to create this sequence, and/or eliminate one instruction should the constant be fit for that.Also note that in 64bit / sparcv9, the
setinstruction may ultimately evaluate to a sequence of up to five instructions, shifting/or'ing things together.您需要像
mov 0, %%l0-- 源然后目标这样的行，并且常量只是常量，没有“#”字符。编辑
如果您的 asm 指令中没有任何约束（只是一个字符串），则 gcc 不会处理该字符串的 % 转义符。因此，在这种情况下，您只需在寄存器名称前添加一个
%字符即可。但是，如果您添加任何约束（甚至只是在字符串后添加::- 一个空约束集），它会查找 %-转义符，因此您需要%%用于寄存器名称。因此，要么在
)之前添加::，要么取消重复的%字符。You want lines like
mov 0, %%l0-- source then destination, and constants are just constants, no '#' character.edit
If you have no constraints in your asm directive (just a string), then gcc doesn't process the string for %-escapes. So in that case you need just single
%characters before the register name. But if you add any constraints (or even just::after the string -- an empty constraint set), it will look for %-escapes, so you need%%for register names.So either add a
::just before the)or un-duplicate the%characters.