[llvm-objdump] Align instructions to a tab stop in disassembly output

This relands D60376/rL358405, with the difference: sed 'y/\t/ /' -> tr '\t' ' '
BSD sed doesn't support escape characters for the 'y' command.
I didn't use it in rL358405 because it was not listed at
https://llvm.org/docs/GettingStarted.html#software but it
should be available.

Original description:

In GNU objdump, -w/--wide aligns instructions in the disassembly output.
This patch does the same to llvm-objdump. However, we always use the
wide format (-w/--wide is ignored), because the narrow format
(instructions are misaligned) is probably not very useful.

In llvm-readobj, we made a similar decision: always use the wide format,
accept but ignore -W/--wide.

To save some columns, we change the tab before hex bytes (controlled by
--[no-]show-raw-insn) to a space.

llvm-svn: 358474

1 files changed, 18 insertions, 5 deletions

diff --git a/llvm/tools/llvm-objdump/llvm-objdump.cpp b/llvm/tools/llvm-objdump/llvm-objdump.cpp
index 2606d9b..9568d34 100644
--- a/llvm/tools/llvm-objdump/llvm-objdump.cpp
+++ b/llvm/tools/llvm-objdump/llvm-objdump.cpp
@@ -595,12 +595,25 @@ public:
                          std::vector<RelocationRef> *Rels = nullptr) {
     if (SP && (PrintSource || PrintLines))
       SP->printSourceLine(OS, Address);
-    if (!NoLeadingAddr)
-      OS << format("%8" PRIx64 ":", Address.Address);
-    if (!NoShowRawInsn) {
-      OS << "\t";
-      dumpBytes(Bytes, OS);
+
+    {
+      formatted_raw_ostream FOS(OS);
+      if (!NoLeadingAddr)
+        FOS << format("%8" PRIx64 ":", Address.Address);
+      if (!NoShowRawInsn) {
+        FOS << ' ';
+        dumpBytes(Bytes, FOS);
+      }
+      FOS.flush();
+      // The output of printInst starts with a tab. Print some spaces so that
+      // the tab has 1 column and advances to the target tab stop.
+      unsigned TabStop = NoShowRawInsn ? 16 : 40;
+      unsigned Column = FOS.getColumn();
+      FOS.indent(Column < TabStop - 1 ? TabStop - 1 - Column : 7 - Column % 8);
+
+      // The dtor calls flush() to ensure the indent comes before printInst().
     }
+
     if (MI)
       IP.printInst(MI, OS, "", STI);
     else