Simplify operand padding by keying off tabs in the asm stream.  If
padding is disabled, tabs get replaced by spaces except in the case of
the first operand, where the tab is output to line up the operands after
the mnemonics.

Add some better comments and eliminate redundant code.

Fix some testcases to not assume tabs.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@77740 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/CodeGen/AsmPrinter/AsmPrinter.cpp b/lib/CodeGen/AsmPrinter/AsmPrinter.cpp
index 077d72e..e19631f 100644
--- a/lib/CodeGen/AsmPrinter/AsmPrinter.cpp
+++ b/lib/CodeGen/AsmPrinter/AsmPrinter.cpp
@@ -847,8 +847,28 @@
   }
   O << '\n';
 }
-
     
+/// PadToColumn - This gets called every time a tab is emitted.  If
+/// column padding is turned on, we replace the tab with the
+/// appropriate amount of padding.  If not, we replace the tab with a
+/// space, except for the first operand so that initial operands are
+/// always lined up by tabs.
+void AsmPrinter::PadToColumn(unsigned Operand) const {
+  if (TAI->getOperandColumn(Operand) > 0) {
+    O.PadToColumn(TAI->getOperandColumn(Operand), 1);
+  }
+  else {
+    if (Operand == 1) {
+      // Emit the tab after the mnemonic.
+      O << '\t';
+    }
+    else {
+      // Replace the tab with a space.
+      O << ' ';
+    }
+  }
+}
+
 /// EmitZeros - Emit a block of zeros.
 ///
 void AsmPrinter::EmitZeros(uint64_t NumZeros, unsigned AddrSpace) const {