From c0490ac91502c3f9e791124c6f3a8ad17aab6a72 Mon Sep 17 00:00:00 2001
From: Jakob Stoklund Olesen <stoklund@2pi.dk>
Date: Thu, 24 Jun 2010 20:16:00 +0000
Subject: [PATCH] Teach AdjustCopiesBackFrom to also use CoalescerPair to
 identify compatible copies.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@106780 91177308-0d34-0410-b5e6-96231b3b80d8
---
 lib/CodeGen/SimpleRegisterCoalescing.cpp | 26 +++++++++++-------------
 lib/CodeGen/SimpleRegisterCoalescing.h   |  3 +--
 2 files changed, 13 insertions(+), 16 deletions(-)

diff --git a/lib/CodeGen/SimpleRegisterCoalescing.cpp b/lib/CodeGen/SimpleRegisterCoalescing.cpp
index 487306e57f4..62096714178 100644
--- a/lib/CodeGen/SimpleRegisterCoalescing.cpp
+++ b/lib/CodeGen/SimpleRegisterCoalescing.cpp
@@ -99,9 +99,12 @@ void SimpleRegisterCoalescing::getAnalysisUsage(AnalysisUsage &AU) const {
 ///
 /// This returns true if an interval was modified.
 ///
-bool SimpleRegisterCoalescing::AdjustCopiesBackFrom(LiveInterval &IntA,
-                                                    LiveInterval &IntB,
+bool SimpleRegisterCoalescing::AdjustCopiesBackFrom(const CoalescerPair &CP,
                                                     MachineInstr *CopyMI) {
+  LiveInterval &IntA =
+    li_->getInterval(CP.isFlipped() ? CP.getDstReg() : CP.getSrcReg());
+  LiveInterval &IntB =
+    li_->getInterval(CP.isFlipped() ? CP.getSrcReg() : CP.getDstReg());
   SlotIndex CopyIdx = li_->getInstructionIndex(CopyMI).getDefIndex();
 
   // BValNo is a value number in B that is defined by a copy from A.  'B3' in
@@ -145,26 +148,21 @@ bool SimpleRegisterCoalescing::AdjustCopiesBackFrom(LiveInterval &IntA,
 
   // If AValNo is defined as a copy from IntB, we can potentially process this.
   // Get the instruction that defines this value number.
-  unsigned SrcReg = li_->getVNInfoSourceReg(AValNo);
-  if (!SrcReg) return false;  // Not defined by a copy.
-
-  // If the value number is not defined by a copy instruction, ignore it.
-
-  // If the source register comes from an interval other than IntB, we can't
-  // handle this.
-  if (SrcReg != IntB.reg) return false;
+  if (!CP.isCoalescable(AValNo->getCopy()))
+    return false;
 
   // Get the LiveRange in IntB that this value number starts with.
   LiveInterval::iterator ValLR =
     IntB.FindLiveRangeContaining(AValNo->def.getPrevSlot());
-  assert(ValLR != IntB.end() && "Live range not found!");
+  if (ValLR == IntB.end())
+    return false;
 
   // Make sure that the end of the live range is inside the same block as
   // CopyMI.
   MachineInstr *ValLREndInst =
     li_->getInstructionFromIndex(ValLR->end.getPrevSlot());
-  if (!ValLREndInst ||
-      ValLREndInst->getParent() != CopyMI->getParent()) return false;
+  if (!ValLREndInst || ValLREndInst->getParent() != CopyMI->getParent())
+    return false;
 
   // Okay, we now know that ValLR ends in the same block that the CopyMI
   // live-range starts.  If there are no intervening live ranges between them in
@@ -1183,7 +1181,7 @@ bool SimpleRegisterCoalescing::JoinCopy(CopyRec &TheCopy, bool &Again) {
       LiveInterval *DefInt = &li_->getInterval(CP.getDstReg());
       if (CP.isFlipped())
         std::swap(UseInt, DefInt);
-      if (AdjustCopiesBackFrom(*UseInt, *DefInt, CopyMI) ||
+      if (AdjustCopiesBackFrom(CP, CopyMI) ||
           RemoveCopyByCommutingDef(*UseInt, *DefInt, CopyMI)) {
         JoinedCopies.insert(CopyMI);
         DEBUG(dbgs() << "\tTrivial!\n");
diff --git a/lib/CodeGen/SimpleRegisterCoalescing.h b/lib/CodeGen/SimpleRegisterCoalescing.h
index 8c5eebff15c..b65cbf1d144 100644
--- a/lib/CodeGen/SimpleRegisterCoalescing.h
+++ b/lib/CodeGen/SimpleRegisterCoalescing.h
@@ -119,8 +119,7 @@ namespace llvm {
     /// the source value number is defined by a copy from the destination reg
     /// see if we can merge these two destination reg valno# into a single
     /// value number, eliminating a copy.
-    bool AdjustCopiesBackFrom(LiveInterval &IntA, LiveInterval &IntB,
-                              MachineInstr *CopyMI);
+    bool AdjustCopiesBackFrom(const CoalescerPair &CP, MachineInstr *CopyMI);
 
     /// HasOtherReachingDefs - Return true if there are definitions of IntB
     /// other than BValNo val# that can reach uses of AValno val# of IntA.
-- 
2.34.1