[llvm-commits] [llvm] r85558 - /llvm/trunk/lib/CodeGen/AsmPrinter/AsmPrinter.cpp

[Dan Gohman]

Author: djg
Date: Thu Oct 29 20:34:35 2009
New Revision: 85558

URL: http://llvm.org/viewvc/llvm-project?rev=85558&view=rev
Log:
Add some comments.

Modified:
    llvm/trunk/lib/CodeGen/AsmPrinter/AsmPrinter.cpp

Modified: llvm/trunk/lib/CodeGen/AsmPrinter/AsmPrinter.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/CodeGen/AsmPrinter/AsmPrinter.cpp?rev=85558&r1=85557&r2=85558&view=diff

==============================================================================
--- llvm/trunk/lib/CodeGen/AsmPrinter/AsmPrinter.cpp (original)
+++ llvm/trunk/lib/CodeGen/AsmPrinter/AsmPrinter.cpp Thu Oct 29 20:34:35 2009
@@ -1642,9 +1642,15 @@
 /// MachineBasicBlock, an alignment (if present) and a comment describing
 /// it if appropriate.
 void AsmPrinter::EmitBasicBlockStart(const MachineBasicBlock *MBB) const {
+  // Emit an alignment directive for this block, if needed.
   if (unsigned Align = MBB->getAlignment())
     EmitAlignment(Log2_32(Align));
 
+  // If the block has its address taken, emit a special label to satisfy
+  // references to the block. This is done so that we don't need to
+  // remember the number of this label, and so that we can make
+  // forward references to labels without knowing what their numbers
+  // will be.
   if (MBB->hasAddressTaken()) {
     GetBlockAddressSymbol(MBB->getBasicBlock()->getParent(),
                           MBB->getBasicBlock())->print(O, MAI);
@@ -1656,6 +1662,7 @@
     O << '\n';
   }
 
+  // Print the main label for the block.
   if (MBB->pred_empty() || MBB->isOnlyReachableByFallthrough()) {
     if (VerboseAsm)
       O << MAI->getCommentString() << " BB#" << MBB->getNumber() << ':';
@@ -1666,6 +1673,7 @@
       O << '\n';
   }
   
+  // Print some comments to accompany the label.
   if (VerboseAsm) {
     if (const BasicBlock *BB = MBB->getBasicBlock())
       if (BB->hasName()) {