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

1 files changed, 4 insertions, 6 deletions

diff --git a/lib/Transforms/Utils/BasicBlockUtils.cpp b/lib/Transforms/Utils/BasicBlockUtils.cpp
index c705cc5109..92464e8cf1 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();
 }