[llvm-commits] [llvm] r171597 - in /llvm/trunk: include/llvm/CodeGen/MachineRegisterInfo.h lib/CodeGen/MachineRegisterInfo.cpp

[Jakob Stoklund Olesen]

Author: stoklund
Date: Fri Jan  4 22:38:12 2013
New Revision: 171597

URL: http://llvm.org/viewvc/llvm-project?rev=171597&view=rev
Log:
Add MachineRegisterInfo::moveOperands().

This function works like memmove() for MachineOperands, except it also
updates any use-def chains containing the moved operands.

The use-def chains are updated without affecting the order of operands
in the list. That isn't possible when using the
removeRegOperandFromUseList() and addRegOperandToUseList() functions.

Callers to follow soon.

Modified:
    llvm/trunk/include/llvm/CodeGen/MachineRegisterInfo.h
    llvm/trunk/lib/CodeGen/MachineRegisterInfo.cpp

Modified: llvm/trunk/include/llvm/CodeGen/MachineRegisterInfo.h
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/include/llvm/CodeGen/MachineRegisterInfo.h?rev=171597&r1=171596&r2=171597&view=diff
==============================================================================
--- llvm/trunk/include/llvm/CodeGen/MachineRegisterInfo.h (original)
+++ llvm/trunk/include/llvm/CodeGen/MachineRegisterInfo.h Fri Jan  4 22:38:12 2013
@@ -156,6 +156,9 @@
   // Strictly for use by MachineInstr.cpp.
   void removeRegOperandFromUseList(MachineOperand *MO);
 
+  // Strictly for use by MachineInstr.cpp.
+  void moveOperands(MachineOperand *Dst, MachineOperand *Src, unsigned NumOps);
+
   /// reg_begin/reg_end - Provide iteration support to walk over all definitions
   /// and uses of a register within the MachineFunction that corresponds to this
   /// MachineRegisterInfo object.

Modified: llvm/trunk/lib/CodeGen/MachineRegisterInfo.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/CodeGen/MachineRegisterInfo.cpp?rev=171597&r1=171596&r2=171597&view=diff
==============================================================================
--- llvm/trunk/lib/CodeGen/MachineRegisterInfo.cpp (original)
+++ llvm/trunk/lib/CodeGen/MachineRegisterInfo.cpp Fri Jan  4 22:38:12 2013
@@ -180,6 +180,55 @@
   MO->Contents.Reg.Next = 0;
 }
 
+/// Move NumOps operands from Src to Dst, updating use-def lists as needed.
+///
+/// The Dst range is assumed to be uninitialized memory. (Or it may contain
+/// operands that won't be destroyed, which is OK because the MO destructor is
+/// trivial anyway).
+///
+/// The Src and Dst ranges may overlap.
+void MachineRegisterInfo::moveOperands(MachineOperand *Dst,
+                                       MachineOperand *Src,
+                                       unsigned NumOps) {
+  assert(Src != Dst && NumOps && "Noop moveOperands");
+
+  // Copy backwards if Dst is within the Src range.
+  int Stride = 1;
+  if (Dst >= Src && Dst < Src + NumOps) {
+    Stride = -1;
+    Dst += NumOps - 1;
+    Src += NumOps - 1;
+  }
+
+  // Copy one operand at a time.
+  do {
+    new (Dst) MachineOperand(*Src);
+
+    // Dst takes Src's place in the use-def chain.
+    if (Src->isReg()) {
+      MachineOperand *&Head = getRegUseDefListHead(Src->getReg());
+      MachineOperand *Prev = Src->Contents.Reg.Prev;
+      MachineOperand *Next = Src->Contents.Reg.Next;
+      assert(Head && "List empty, but operand is chained");
+      assert(Prev && "Operand was not on use-def list");
+
+      // Prev links are circular, next link is NULL instead of looping back to
+      // Head.
+      if (Src == Head)
+        Head = Dst;
+      else
+        Prev->Contents.Reg.Next = Dst;
+
+      // Update Prev pointer. This also works when Src was pointing to itself
+      // in a 1-element list. In that case Head == Dst.
+      (Next ? Next : Head)->Contents.Reg.Prev = Dst;
+    }
+
+    Dst += Stride;
+    Src += Stride;
+  } while (--NumOps);
+}
+
 /// replaceRegWith - Replace all instances of FromReg with ToReg in the
 /// machine function.  This is like llvm-level X->replaceAllUsesWith(Y),
 /// except that it also changes any definitions of the register as well.