From cf405ba7a6e9448b753d9b72940059530c70ea90 Mon Sep 17 00:00:00 2001
From: Devang Patel <dpatel@apple.com>
Date: Thu, 8 Dec 2011 21:33:23 +0000
Subject: [PATCH] Filter "sink to" candidate blocks sooner. This avoids
 unnecessary computation to determine whether the block dominates all uses or
 not.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@146184 91177308-0d34-0410-b5e6-96231b3b80d8
---
 lib/CodeGen/MachineSink.cpp | 24 +++++++++++++-----------
 1 file changed, 13 insertions(+), 11 deletions(-)

diff --git a/lib/CodeGen/MachineSink.cpp b/lib/CodeGen/MachineSink.cpp
index 8a342377890..0d14b63b632 100644
--- a/lib/CodeGen/MachineSink.cpp
+++ b/lib/CodeGen/MachineSink.cpp
@@ -499,10 +499,21 @@ bool MachineSinking::SinkInstruction(MachineInstr *MI, bool &SawStore) {
       // we should sink to.
       for (MachineBasicBlock::succ_iterator SI = ParentBlock->succ_begin(),
            E = ParentBlock->succ_end(); SI != E; ++SI) {
+	MachineBasicBlock *SuccBlock = *SI;
+	// It is not possible to sink an instruction into its own block.  This can
+	// happen with loops.
+	if (ParentBlock == SuccBlock)
+	  continue;
+
+	// It's not safe to sink instructions to EH landing pad. Control flow into
+	// landing pad is implicitly defined.
+	if (SuccBlock->isLandingPad())
+	  continue;
+
         bool LocalUse = false;
-        if (AllUsesDominatedByBlock(Reg, *SI, ParentBlock,
+        if (AllUsesDominatedByBlock(Reg, SuccBlock, ParentBlock,
                                     BreakPHIEdge, LocalUse)) {
-          SuccToSinkTo = *SI;
+          SuccToSinkTo = SuccBlock;
           break;
         }
         if (LocalUse)
@@ -520,15 +531,6 @@ bool MachineSinking::SinkInstruction(MachineInstr *MI, bool &SawStore) {
   if (SuccToSinkTo == 0)
     return false;
 
-  // It's not safe to sink instructions to EH landing pad. Control flow into
-  // landing pad is implicitly defined.
-  if (SuccToSinkTo->isLandingPad())
-    return false;
-
-  // It is not possible to sink an instruction into its own block.  This can
-  // happen with loops.
-  if (MI->getParent() == SuccToSinkTo)
-    return false;
 
   // If the instruction to move defines a dead physical register which is live
   // when leaving the basic block, don't move it because it could turn into a