[SystemZ] Add CodeGen support for v2f64

This adds ABI and CodeGen support for the v2f64 type, which is natively
supported by z13 instructions.

Based on a patch by Richard Sandiford.

llvm-svn: 236522
diff --git a/llvm/test/CodeGen/SystemZ/vec-log-01.ll b/llvm/test/CodeGen/SystemZ/vec-log-01.ll
new file mode 100644
index 0000000..f9b7402
--- /dev/null
+++ b/llvm/test/CodeGen/SystemZ/vec-log-01.ll
@@ -0,0 +1,15 @@
+; Test v2f64 logarithm.
+;
+; RUN: llc < %s -mtriple=s390x-linux-gnu -mcpu=z13 | FileCheck %s
+
+declare <2 x double> @llvm.log.v2f64(<2 x double>)
+
+define <2 x double> @f1(<2 x double> %val) {
+; CHECK-LABEL: f1:
+; CHECK: brasl %r14, log@PLT
+; CHECK: brasl %r14, log@PLT
+; CHECK: vmrhg %v24,
+; CHECK: br %r14
+  %ret = call <2 x double> @llvm.log.v2f64(<2 x double> %val)
+  ret <2 x double> %ret
+}