It's not clear whether we should use pxor or xorps / xorpd to clear XMM
registers. The choice may depend on subtarget information. We should do some
more experiments on different x86 machines.
+
+//===---------------------------------------------------------------------===//
+
+Evaluate what the best way to codegen sdiv X, (2^C) is. For X/8, we currently
+get this:
+
+int %test1(int %X) {
+ %Y = div int %X, 8
+ ret int %Y
+}
+
+_test1:
+ movl 4(%esp), %eax
+ movl %eax, %ecx
+ sarl $31, %ecx
+ shrl $29, %ecx
+ addl %ecx, %eax
+ sarl $3, %eax
+ ret
+
+GCC knows several different ways to codegen it, one of which is this:
+
+_test1:
+ movl 4(%esp), %eax
+ cmpl $-1, %eax
+ leal 7(%eax), %ecx
+ cmovle %ecx, %eax
+ sarl $3, %eax
+ ret
+
+which is probably slower, but it's interesting at least :)
+