[X86] Deleting README-MMX.txt now that all tasks have been completed.

MMX buildvectors were improved at rL327247 - new MMX bugs should be raised on bugzilla

llvm-svn: 327300

llvm/lib/Target/X86/README-MMX.txt

@@ -1,42 +0,0 @@
-//===---------------------------------------------------------------------===//
-// Random ideas for the X86 backend: MMX-specific stuff.
-//===---------------------------------------------------------------------===//
-
-//===---------------------------------------------------------------------===//
-
-This:
-
-#include <mmintrin.h>
-
-__v2si qux(int A) {
-  return (__v2si){ 0, A };
-}
-
-is compiled into:
-
-_qux:
-        subl $28, %esp
-        movl 32(%esp), %eax
-        movd %eax, %mm0
-        movq %mm0, (%esp)
-        movl (%esp), %eax
-        movl %eax, 20(%esp)
-        movq %mm0, 8(%esp)
-        movl 12(%esp), %eax
-        movl %eax, 16(%esp)
-        movq 16(%esp), %mm0
-        addl $28, %esp
-        ret
-
-Yuck!
-
-GCC gives us:
-
-_qux:
-        subl    $12, %esp
-        movl    16(%esp), %eax
-        movl    20(%esp), %edx
-        movl    $0, (%eax)
-        movl    %edx, 4(%eax)
-        addl    $12, %esp
-        ret     $4