From c8b90e22a8f2987126a7e2e841adc8db9776521c Mon Sep 17 00:00:00 2001 From: Evan Cheng Date: Fri, 4 Feb 2011 01:10:12 +0000 Subject: [PATCH] Update comments. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@124843 91177308-0d34-0410-b5e6-96231b3b80d8 --- lib/CodeGen/TailDuplication.cpp | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-) diff --git a/lib/CodeGen/TailDuplication.cpp b/lib/CodeGen/TailDuplication.cpp index 83706deb3f7..04d3d311b41 100644 --- a/lib/CodeGen/TailDuplication.cpp +++ b/lib/CodeGen/TailDuplication.cpp @@ -504,8 +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; -- 2.34.1