From 67352b3ce7110541475ed7fb335ee95954f0523a Mon Sep 17 00:00:00 2001
From: Devang Patel <dpatel@apple.com>
Date: Mon, 2 May 2011 21:57:00 +0000
Subject: [PATCH] Scanning entire basic block may be too expensive in terms of
 compile time. Instead, just use whatever location info first non-phi
 instruction has.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@130729 91177308-0d34-0410-b5e6-96231b3b80d8
---
 lib/Transforms/Utils/BasicBlockUtils.cpp | 10 ++++------
 1 file changed, 4 insertions(+), 6 deletions(-)

diff --git a/lib/Transforms/Utils/BasicBlockUtils.cpp b/lib/Transforms/Utils/BasicBlockUtils.cpp
index c705cc51094..92464e8cf13 100644
--- a/lib/Transforms/Utils/BasicBlockUtils.cpp
+++ b/lib/Transforms/Utils/BasicBlockUtils.cpp
@@ -542,11 +542,9 @@ ReturnInst *llvm::FoldReturnIntoUncondBranch(ReturnInst *RI, BasicBlock *BB,
 /// GetFirstDebugLocInBasicBlock - Return first valid DebugLoc entry in a 
 /// given basic block.
 DebugLoc llvm::GetFirstDebugLocInBasicBlock(const BasicBlock *BB) {
-  for (BasicBlock::const_iterator BI = BB->begin(), BE = BB->end(); 
-       BI != BE; ++BI) {
-    DebugLoc DL = BI->getDebugLoc();
-    if (!DL.isUnknown())
-      return DL;
-  }
+  if (const Instruction *I = BB->getFirstNonPHI())
+    return I->getDebugLoc();
+  // Scanning entire block may be too expensive, if the first instruction
+  // does not have valid location info.
   return DebugLoc();
 }