Implement initial memory alignment awareness for SSE instructions. Vector loads

and stores that have a specified alignment of less than 16 bytes now use
instructions that support misaligned memory references.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@40015 91177308-0d34-0410-b5e6-96231b3b80d8

test/CodeGen/X86/sse-align-6.ll

@@ -0,0 +1,8 @@
+; RUN: llvm-as < %s | llc -march=x86-64 | grep movdqu | wc -l | grep 1
+
+define <2 x i64> @bar(<2 x i64>* %p, <2 x i64> %x)
+{
+  %t = load <2 x i64>* %p, align 8
+  %z = mul <2 x i64> %t, %x
+  ret <2 x i64> %z
+}