Codegen long >> 2 to this:
foo:
mov %EAX, DWORD PTR [%ESP + 4]
mov %EDX, DWORD PTR [%ESP + 8]
shrd %EAX, %EDX, 2
sar %EDX, 2
ret
instead of this:
test1:
mov %ECX, DWORD PTR [%ESP + 4]
shr %ECX, 2
mov %EDX, DWORD PTR [%ESP + 8]
mov %EAX, %EDX
shl %EAX, 30
or %EAX, %ECX
sar %EDX, 2
ret
and long << 2 to this:
foo:
mov %EAX, DWORD PTR [%ESP + 4]
mov %ECX, DWORD PTR [%ESP + 8]
*** mov %EDX, %EAX
shrd %EDX, %ECX, 30
shl %EAX, 2
ret
instead of this:
foo:
mov %EAX, DWORD PTR [%ESP + 4]
mov %ECX, %EAX
shr %ECX, 30
mov %EDX, DWORD PTR [%ESP + 8]
shl %EDX, 2
or %EDX, %ECX
shl %EAX, 2
ret
The extra copy (marked ***) can be eliminated when I teach the code generator
that shrd32rri8 is really commutative.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@19681 91177308-0d34-0410-b5e6-96231b3b80d8
1 file changed