numbering values in live ranges for physical registers.
The alpha backend currently generates code that looks like this:
vreg = preg
...
preg = vreg
use preg
...
preg = vreg
use preg
etc. Because vreg contains the value of preg coming in, each of the
copies back into preg contain that initial value as well.
In the case of the Alpha, this allows this testcase:
void "foo"(int %blah) {
store int 5, int *%MyVar
store int 12, int* %MyVar2
ret void
}
to compile to:
foo:
ldgp $29, 0($27)
ldiq $0,5
stl $0,MyVar
ldiq $0,12
stl $0,MyVar2
ret $31,($26),1
instead of:
foo:
ldgp $29, 0($27)
bis $29,$29,$0
ldiq $1,5
bis $0,$0,$29
stl $1,MyVar
ldiq $1,12
bis $0,$0,$29
stl $1,MyVar2
ret $31,($26),1
This does not seem to have any noticable effect on X86 code.
This fixes PR535.
llvm-svn: 20536
