Refactor some code out of MachineSink into a MachineInstr query.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@48311 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/CodeGen/MachineInstr.cpp b/lib/CodeGen/MachineInstr.cpp
index b396382..265a330 100644
--- a/lib/CodeGen/MachineInstr.cpp
+++ b/lib/CodeGen/MachineInstr.cpp
@@ -628,16 +628,46 @@
/// copyPredicates - Copies predicate operand(s) from MI.
void MachineInstr::copyPredicates(const MachineInstr *MI) {
const TargetInstrDesc &TID = MI->getDesc();
- if (TID.isPredicable()) {
- for (unsigned i = 0, e = MI->getNumOperands(); i != e; ++i) {
- if (TID.OpInfo[i].isPredicate()) {
- // Predicated operands must be last operands.
- addOperand(MI->getOperand(i));
- }
+ if (!TID.isPredicable())
+ return;
+ for (unsigned i = 0, e = MI->getNumOperands(); i != e; ++i) {
+ if (TID.OpInfo[i].isPredicate()) {
+ // Predicated operands must be last operands.
+ addOperand(MI->getOperand(i));
}
}
}
+/// isSafeToMove - Return true if it is safe to this instruction. If SawStore
+/// true, it means there is a store (or call) between the instruction the
+/// localtion and its intended destination.
+bool MachineInstr::isSafeToMove(const TargetInstrInfo *TII, bool &SawStore) {
+ // Ignore stuff that we obviously can't move.
+ if (TID->mayStore() || TID->isCall()) {
+ SawStore = true;
+ return false;
+ }
+ if (TID->isReturn() || TID->isBranch() || TID->hasUnmodeledSideEffects())
+ return false;
+
+ // See if this instruction does a load. If so, we have to guarantee that the
+ // loaded value doesn't change between the load and the its intended
+ // destination. The check for isInvariantLoad gives the targe the chance to
+ // classify the load as always returning a constant, e.g. a constant pool
+ // load.
+ if (TID->mayLoad() && !TII->isInvariantLoad(this)) {
+ // Otherwise, this is a real load. If there is a store between the load and
+ // end of block, we can't sink the load.
+ //
+ // FIXME: we can't do this transformation until we know that the load is
+ // not volatile, and machineinstrs don't keep this info. :(
+ //
+ //if (SawStore)
+ return false;
+ }
+ return true;
+}
+
void MachineInstr::dump() const {
cerr << " " << *this;
}