[PowerPC][AIX] Adds support for writing the .data section in assembly files

Summary:
Adds support for generating the .data section in assembly files for global variables with a non-zero initialization. The support for writing the .data section in XCOFF object files will be added in a follow-on patch. Any relocations are not included in this patch.

Reviewers: hubert.reinterpretcast, sfertile, jasonliu, daltenty, Xiangling_L

Reviewed by: hubert.reinterpretcast

Subscribers: nemanjai, hiraditya, kbarton, MaskRay, jsji, wuzish, shchenz, DiggerLin, llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D66154

llvm-svn: 369869
diff --git a/llvm/lib/MC/MCAsmStreamer.cpp b/llvm/lib/MC/MCAsmStreamer.cpp
index e20ba2f..e37bc4a 100644
--- a/llvm/lib/MC/MCAsmStreamer.cpp
+++ b/llvm/lib/MC/MCAsmStreamer.cpp
@@ -1119,6 +1119,16 @@
 void MCAsmStreamer::EmitValueToAlignment(unsigned ByteAlignment, int64_t Value,
                                          unsigned ValueSize,
                                          unsigned MaxBytesToEmit) {
+  if (MAI->useDotAlignForAlignment()) {
+    if (!isPowerOf2_32(ByteAlignment))
+      report_fatal_error("Only power-of-two alignments are supported "
+                         "with .align.");
+    OS << "\t.align\t";
+    OS << Log2_32(ByteAlignment);
+    EmitEOL();
+    return;
+  }
+
   // Some assemblers don't support non-power of two alignments, so we always
   // emit alignments as a power of two if possible.
   if (isPowerOf2_32(ByteAlignment)) {