Add TargetInstrInfo::isSafeToMoveRegisterClassDefs. It returns true if it's safe to move an instruction which defines a value in the register class. Replace pre-splitting specific IgnoreRegisterClassBarriers with this new hook.
llvm-svn: 63936
diff --git a/llvm/lib/CodeGen/PreAllocSplitting.cpp b/llvm/lib/CodeGen/PreAllocSplitting.cpp
index dfff87a..ef2cfdb 100644
--- a/llvm/lib/CodeGen/PreAllocSplitting.cpp
+++ b/llvm/lib/CodeGen/PreAllocSplitting.cpp
@@ -1128,7 +1128,10 @@
// by the current barrier.
SmallVector<LiveInterval*, 8> Intervals;
for (const TargetRegisterClass **RC = RCs; *RC; ++RC) {
- if (TII->IgnoreRegisterClassBarriers(*RC))
+ // FIXME: If it's not safe to move any instruction that defines the barrier
+ // register class, then it means there are some special dependencies which
+ // codegen is not modelling. Ignore these barriers for now.
+ if (!TII->isSafeToMoveRegClassDefs(*RC))
continue;
std::vector<unsigned> &VRs = MRI->getRegClassVirtRegs(*RC);
for (unsigned i = 0, e = VRs.size(); i != e; ++i) {