Implement simple register assignment for inline asms. This allows us to compile:

int %test(int %A, int %B) {
  %C = call int asm "xyz $0, $1, $2", "=r,r,r"(int %A, int %B)
  ret int %C
}

into:

 (0x8906130, LLVM BB @0x8902220):
        %r2 = OR4 %r3, %r3
        %r3 = OR4 %r4, %r4
        INLINEASM <es:xyz $0, $1, $2>, %r2<def>, %r2, %r3
        %r3 = OR4 %r2, %r2
        BLR

which asmprints as:

_test:
        or r2, r3, r3
        or r3, r4, r4
        xyz $0, $1, $2      ;; need to print the operands now :)
        or r3, r2, r2
        blr

llvm-svn: 25878