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simplify the inline assembly

master
Andrew Kelley 2020-03-06 20:02:08 -05:00
parent 49817c6add
commit e0d5f94a70
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GPG Key ID: 7C5F548F728501A9
1 changed files with 15 additions and 32 deletions
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47
lib/std/zig/system/x86.zig
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@ -519,38 +519,21 @@ fn cpuid(leaf_id: u32, subid: u32) CpuidLeaf {
// Inline assembly in zig only supports one output,
// so we pass a pointer to the struct.
var cpuid_leaf = CpuidLeaf{ .eax = 0, .ebx = 0, .ecx = 0, .edx = 0 };
var leaf_ptr = &cpuid_leaf;
switch (Target.current.cpu.arch) {
.i386 => {
_ = asm volatile (
\\ cpuid
\\ movl %%eax, (%%edi)
\\ movl %%ebx, 4(%%edi)
\\ movl %%ecx, 8(%%edi)
\\ movl %%edx, 12(%%edi)
:
: [leaf_id] "{eax}" (leaf_id),
[subid] "{ecx}" (subid),
[leaf_ptr] "{edi}" (leaf_ptr)
: "eax", "ebx", "ecx", "edx"
);
},
.x86_64 => {
_ = asm volatile (
\\ cpuid
\\ movl %%eax, (%%rdi)
\\ movl %%ebx, 4(%%rdi)
\\ movl %%ecx, 8(%%rdi)
\\ movl %%edx, 12(%%rdi)
:
: [leaf_id] "{eax}" (leaf_id),
[subid] "{ecx}" (subid),
[leaf_ptr] "{rdi}" (leaf_ptr)
: "eax", "ebx", "ecx", "edx"
);
},
else => unreachable,
}
const leaf_ptr = &cpuid_leaf;
// valid for both x86 and x86_64
asm volatile (
\\ cpuid
\\ movl %%eax, (%[leaf_ptr])
\\ movl %%ebx, 4(%[leaf_ptr])
\\ movl %%ecx, 8(%[leaf_ptr])
\\ movl %%edx, 12(%[leaf_ptr])
:
: [leaf_id] "{eax}" (leaf_id),
[subid] "{ecx}" (subid),
[leaf_ptr] "r" (leaf_ptr)
: "eax", "ebx", "ecx", "edx"
);
return cpuid_leaf;
}