[llvm-commits] [llvm] r50004 - in /llvm/trunk: include/llvm/Instruction.h lib/VMCore/Instruction.cpp

[Chris Lattner]

Author: lattner
Date: Sun Apr 20 17:11:30 2008
New Revision: 50004

URL: http://llvm.org/viewvc/llvm-project?rev=50004&view=rev
Log:
add a handy helper method to instruction, useful for determining
whether it is used outside of some block.  This can be used to see
if there are any non-local references, for example.

Modified:
    llvm/trunk/include/llvm/Instruction.h
    llvm/trunk/lib/VMCore/Instruction.cpp

Modified: llvm/trunk/include/llvm/Instruction.h
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/include/llvm/Instruction.h?rev=50004&r1=50003&r2=50004&view=diff

==============================================================================
--- llvm/trunk/include/llvm/Instruction.h (original)
+++ llvm/trunk/include/llvm/Instruction.h Sun Apr 20 17:11:30 2008
@@ -72,6 +72,13 @@
   /// @brief Determine if one instruction is the same operation as another.
   bool isSameOperationAs(Instruction *I) const;
 
+  /// isUsedOutsideOfBlock - Return true if there are any uses of this
+  /// instruction in blocks other than the specified block.  Note that PHI nodes
+  /// are considered to evaluate their operands in the corresponding predecessor
+  /// block.
+  bool isUsedOutsideOfBlock(const BasicBlock *BB) const;
+  
+  
   /// use_back - Specialize the methods defined in Value, as we know that an
   /// instruction can only be used by other instructions.
   Instruction       *use_back()       { return cast<Instruction>(*use_begin());}

Modified: llvm/trunk/lib/VMCore/Instruction.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/VMCore/Instruction.cpp?rev=50004&r1=50003&r2=50004&view=diff

==============================================================================
--- llvm/trunk/lib/VMCore/Instruction.cpp (original)
+++ llvm/trunk/lib/VMCore/Instruction.cpp Sun Apr 20 17:11:30 2008
@@ -198,6 +198,29 @@
   return true;
 }
 
+/// isUsedOutsideOfBlock - Return true if there are any uses of I outside of the
+/// specified block.  Note that PHI nodes are considered to evaluate their
+/// operands in the corresponding predecessor block.
+bool Instruction::isUsedOutsideOfBlock(const BasicBlock *BB) const {
+  for (use_const_iterator UI = use_begin(), E = use_end(); UI != E; ++UI) {
+    // PHI nodes uses values in the corresponding predecessor block.  For other
+    // instructions, just check to see whether the parent of the use matches up.
+    const PHINode *PN = dyn_cast<PHINode>(*UI);
+    if (PN == 0) {
+      if (cast<Instruction>(*UI)->getParent() != BB)
+        return true;
+      continue;
+    }
+    
+    unsigned UseOperand = UI.getOperandNo();
+    if (PN->getIncomingBlock(UseOperand/2) != BB)
+      return true;
+  }
+  return false;    
+}
+
+
+
 /// mayWriteToMemory - Return true if this instruction may modify memory.
 ///
 bool Instruction::mayWriteToMemory() const {