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6656dd1a78
int %test_cpuid(int %op) {
%B = alloca int
%C = alloca int
%D = alloca int
%A = call int asm "cpuid", "=eax,==ebx,==ecx,==edx,eax"(int* %B, int* %C, int* %D, int %op)
%Bv = load int* %B
%Cv = load int* %C
%Dv = load int* %D
%x = add int %A, %Bv
%y = add int %x, %Cv
%z = add int %y, %Dv
ret int %z
}
to this:
_test_cpuid:
sub %ESP, 16
mov DWORD PTR [%ESP], %EBX
mov %EAX, DWORD PTR [%ESP + 20]
cpuid
mov DWORD PTR [%ESP + 8], %ECX
mov DWORD PTR [%ESP + 12], %EBX
mov DWORD PTR [%ESP + 4], %EDX
mov %ECX, DWORD PTR [%ESP + 12]
add %EAX, %ECX
mov %ECX, DWORD PTR [%ESP + 8]
add %EAX, %ECX
mov %ECX, DWORD PTR [%ESP + 4]
add %EAX, %ECX
mov %EBX, DWORD PTR [%ESP]
add %ESP, 16
ret
... note the proper register allocation. :)
it is unclear to me why the loads aren't folded into the adds.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@25827 91177308-0d34-0410-b5e6-96231b3b80d8
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