diff options
Diffstat (limited to 'lib/CodeGen/MachineSink.cpp')
| -rw-r--r-- | lib/CodeGen/MachineSink.cpp | 24 |
1 files changed, 13 insertions, 11 deletions
diff --git a/lib/CodeGen/MachineSink.cpp b/lib/CodeGen/MachineSink.cpp index b83d844a16..dc3e364e8a 100644 --- a/lib/CodeGen/MachineSink.cpp +++ b/lib/CodeGen/MachineSink.cpp @@ -133,19 +133,21 @@ bool MachineSinking::SinkInstruction(MachineInstr *MI) { const TargetInstrDesc &TID = MI->getDesc(); // Ignore stuff that we obviously can't sink. - if (TID.mayStore() || TID.isCall() || TID.isReturn() || TID.isBranch()) + if (TID.mayStore() || TID.isCall() || TID.isReturn() || TID.isBranch() || + TID.hasUnmodeledSideEffects()) return false; - if (TID.mayLoad()) - return false; - - // Don't sink things with side-effects we don't understand. - if (TII->hasUnmodelledSideEffects(MI)) - return false; - - // FIXME: we should be able to sink loads with no other side effects if there - // is nothing that can change memory from here until the end of block. This - // is a trivial form of alias analysis. + if (TID.mayLoad()) { + // Okay, this instruction does a load. As a refinement, allow the target + // to decide whether the loaded value is actually a constant. If so, we + // can actually use it as a load. + if (!TII->isInvariantLoad(MI)) { + // FIXME: we should be able to sink loads with no other side effects if + // there is nothing that can change memory from here until the end of + // block. This is a trivial form of alias analysis. + return false; + } + } // FIXME: This should include support for sinking instructions within the // block they are currently in to shorten the live ranges. We often get |