Simplify the side effect stuff a bit more and make licm/sinking
both work right according to the new flags.
This removes the TII::isReallySideEffectFree predicate, and adds
TII::isInvariantLoad.
It removes NeverHasSideEffects+MayHaveSideEffects and adds
UnmodeledSideEffects as machine instr flags. Now the clients
can decide everything they need.
I think isRematerializable can be implemented in terms of the
flags we have now, though I will let others tackle that.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@45843 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/CodeGen/MachineSink.cpp b/lib/CodeGen/MachineSink.cpp
index b83d844..dc3e364 100644
--- a/lib/CodeGen/MachineSink.cpp
+++ b/lib/CodeGen/MachineSink.cpp
@@ -133,19 +133,21 @@
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