Revert 131172 as it is causing clang to miscompile itself. I will try

[oota-llvm.git] / lib / CodeGen / TailDuplication.cpp

diff --git a/lib/CodeGen/TailDuplication.cpp b/lib/CodeGen/TailDuplication.cpp
index 15aed3436c7771569eede7b3241f75a74ea28d70..04d3d311b416e7d7864f7e821a1d1516643eec49 100644 (file)
--- a/lib/CodeGen/TailDuplication.cpp
+++ b/lib/CodeGen/TailDuplication.cpp
@@ -459,7 +459,8 @@ TailDuplicatePass::TailDuplicate(MachineBasicBlock *TailBB, MachineFunction &MF,
   // duplicate only one, because one branch instruction can be eliminated to
   // compensate for the duplication.
   unsigned MaxDuplicateCount;
-  if (MF.getFunction()->hasFnAttr(Attribute::OptimizeForSize))
+  if (TailDuplicateSize.getNumOccurrences() == 0 &&
+      MF.getFunction()->hasFnAttr(Attribute::OptimizeForSize))
     MaxDuplicateCount = 1;
   else
     MaxDuplicateCount = TailDuplicateSize;
@@ -503,8 +504,9 @@ TailDuplicatePass::TailDuplicate(MachineBasicBlock *TailBB, MachineFunction &MF,
     if (!I->isPHI() && !I->isDebugValue())
       InstrCount += 1;
   }
-  // Heuristically, don't tail-duplicate calls if it would expand code size,
-  // as it's less likely to be worth the extra cost.
+  // Don't tail-duplicate calls before register allocation. Calls presents a
+  // barrier to register allocation so duplicating them may end up increasing
+  // spills.
   if (InstrCount > 1 && (PreRegAlloc && HasCall))
     return false;