[X86] Add isel pattern to match VZEXT_MOVL and a v2i64 scalar_to_vector bitcasted from x86mmx to MOVQ2DQ.

We already had the pattern for just the scalar to vector and bitcast,
but not the case where we wanted zeroes in the high half of the xmm.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@368972 91177308-0d34-0410-b5e6-96231b3b80d8

lib/Target/X86/X86InstrMMX.td

@@ -577,6 +577,10 @@ def : Pat<(x86mmx (MMX_X86movdq2q VR128:$src)),
 def : Pat<(x86mmx (MMX_X86movdq2q (v2i64 (nonvolatile_load addr:$src)))),
           (x86mmx (MMX_MOVQ64rm addr:$src))>;
 
+def : Pat<(v2i64 (X86vzmovl (scalar_to_vector
+                             (i64 (bitconvert (x86mmx VR64:$src)))))),
+          (MMX_MOVQ2DQrr VR64:$src)>;
+
 // Misc.
 let SchedRW = [SchedWriteShuffle.MMX] in {
 let Uses = [EDI], Predicates = [HasMMX, HasSSE1,Not64BitMode] in

test/CodeGen/X86/mmx-cvt.ll

@@ -346,8 +346,7 @@ define <4 x float> @cvt_v2i32_v2f32(<1 x i64>*) nounwind {
 ; X64:       # %bb.0:
 ; X64-NEXT:    movq (%rdi), %mm0
 ; X64-NEXT:    paddd %mm0, %mm0
-; X64-NEXT:    movq %mm0, %rax
-; X64-NEXT:    movq %rax, %xmm0
+; X64-NEXT:    movq2dq %mm0, %xmm0
 ; X64-NEXT:    cvtdq2ps %xmm0, %xmm0
 ; X64-NEXT:    retq
   %2 = bitcast <1 x i64>* %0 to x86_mmx*