diff options
| -rw-r--r-- | lib/CodeGen/TailDuplication.cpp | 5 |
1 files changed, 3 insertions, 2 deletions
diff --git a/lib/CodeGen/TailDuplication.cpp b/lib/CodeGen/TailDuplication.cpp index 83706deb3f..04d3d311b4 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; |