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UserspaceEmulator: Remove an unnecessary step in some instructions

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We don't need to move the result of shifts around like this, we can
just use inline assembly outputs to make it end up in the right place.
This commit is contained in:
Andreas Kling
2020-07-13 13:11:06 +02:00
parent 80d3306840
commit a9f92e5d75
1 changed files with 45 additions and 33 deletions
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78
DevTools/UserspaceEmulator/SoftCPU.cpp
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@@ -472,20 +472,24 @@ static T op_shr(SoftCPU& cpu, T data, u8 steps)
u32 result = 0;
u32 new_flags = 0;
if constexpr (sizeof(T) == 4)
asm volatile("shrl %%cl, %%eax\n" ::"a"(data), "c"(steps));
else if constexpr (sizeof(T) == 2)
asm volatile("shrw %%cl, %%ax\n" ::"a"(data), "c"(steps));
else if constexpr (sizeof(T) == 1)
asm volatile("shrb %%cl, %%al\n" ::"a"(data), "c"(steps));
if constexpr (sizeof(T) == 4) {
asm volatile("shrl %%cl, %%eax\n"
: "=a"(result)
: "a"(data), "c"(steps));
} else if constexpr (sizeof(T) == 2) {
asm volatile("shrw %%cl, %%ax\n"
: "=a"(result)
: "a"(data), "c"(steps));
} else if constexpr (sizeof(T) == 1) {
asm volatile("shrb %%cl, %%al\n"
: "=a"(result)
: "a"(data), "c"(steps));
}
asm volatile(
"mov %%eax, %%ebx\n"
: "=b"(result));
asm volatile(
"pushf\n"
"pop %%eax"
: "=a"(new_flags));
"pop %%ebx"
: "=b"(new_flags));
cpu.set_flags_oszapc(new_flags);
return result;
@@ -500,20 +504,24 @@ static T op_shl(SoftCPU& cpu, T data, u8 steps)
u32 result = 0;
u32 new_flags = 0;
if constexpr (sizeof(T) == 4)
asm volatile("shll %%cl, %%eax\n" ::"a"(data), "c"(steps));
else if constexpr (sizeof(T) == 2)
asm volatile("shlw %%cl, %%ax\n" ::"a"(data), "c"(steps));
else if constexpr (sizeof(T) == 1)
asm volatile("shlb %%cl, %%al\n" ::"a"(data), "c"(steps));
if constexpr (sizeof(T) == 4) {
asm volatile("shll %%cl, %%eax\n"
: "=a"(result)
: "a"(data), "c"(steps));
} else if constexpr (sizeof(T) == 2) {
asm volatile("shlw %%cl, %%ax\n"
: "=a"(result)
: "a"(data), "c"(steps));
} else if constexpr (sizeof(T) == 1) {
asm volatile("shlb %%cl, %%al\n"
: "=a"(result)
: "a"(data), "c"(steps));
}
asm volatile(
"mov %%eax, %%ebx\n"
: "=b"(result));
asm volatile(
"pushf\n"
"pop %%eax"
: "=a"(new_flags));
"pop %%ebx"
: "=b"(new_flags));
cpu.set_flags_oszapc(new_flags);
return result;
@@ -1355,20 +1363,24 @@ static T op_sar(SoftCPU& cpu, T data, u8 steps)
u32 result = 0;
u32 new_flags = 0;
if constexpr (sizeof(T) == 4)
asm volatile("sarl %%cl, %%eax\n" ::"a"(data), "c"(steps));
else if constexpr (sizeof(T) == 2)
asm volatile("sarw %%cl, %%ax\n" ::"a"(data), "c"(steps));
else if constexpr (sizeof(T) == 1)
asm volatile("sarb %%cl, %%al\n" ::"a"(data), "c"(steps));
if constexpr (sizeof(T) == 4) {
asm volatile("sarl %%cl, %%eax\n"
: "=a"(result)
: "a"(data), "c"(steps));
} else if constexpr (sizeof(T) == 2) {
asm volatile("sarw %%cl, %%ax\n"
: "=a"(result)
: "a"(data), "c"(steps));
} else if constexpr (sizeof(T) == 1) {
asm volatile("sarb %%cl, %%al\n"
: "=a"(result)
: "a"(data), "c"(steps));
}
asm volatile(
"mov %%eax, %%ebx\n"
: "=b"(result));
asm volatile(
"pushf\n"
"pop %%eax"
: "=a"(new_flags));
"pop %%ebx"
: "=b"(new_flags));
cpu.set_flags_oszapc(new_flags);
return result;