[CodeGen] Split out the notions of MI invariance and MI dereferenceability.

Summary:
An IR load can be invariant, dereferenceable, neither, or both.  But
currently, MI's notion of invariance is IR-invariant &&
IR-dereferenceable.

This patch splits up the notions of invariance and dereferenceability at
the MI level.  It's NFC, so adds some probably-unnecessary
"is-dereferenceable" checks, which we can remove later if desired.

Reviewers: chandlerc, tstellarAMD

Subscribers: jholewinski, arsenm, nemanjai, llvm-commits

Differential Revision: https://reviews.llvm.org/D23371

llvm-svn: 281151

1 files changed, 4 insertions, 3 deletions

diff --git a/llvm/lib/CodeGen/MachineInstr.cpp b/llvm/lib/CodeGen/MachineInstr.cpp
index 90ebf2c532f..fb9bd8f6ec3 100644
--- a/llvm/lib/CodeGen/MachineInstr.cpp
+++ b/llvm/lib/CodeGen/MachineInstr.cpp
@@ -650,10 +650,10 @@ void MachineMemOperand::print(raw_ostream &OS, ModuleSlotTracker &MST) const {
     OS << ")";
   }
 
-  // Print nontemporal info.
   if (isNonTemporal())
     OS << "(nontemporal)";
-
+  if (isDereferenceable())
+    OS << "(dereferenceable)";
   if (isInvariant())
     OS << "(invariant)";
 }
@@ -1580,7 +1580,8 @@ bool MachineInstr::isDereferenceableInvariantLoad(AliasAnalysis *AA) const {
   for (MachineMemOperand *MMO : memoperands()) {
     if (MMO->isVolatile()) return false;
     if (MMO->isStore()) return false;
-    if (MMO->isInvariant()) continue;
+    if (MMO->isInvariant() && MMO->isDereferenceable())
+      continue;
 
     // A load from a constant PseudoSourceValue is invariant.
     if (const PseudoSourceValue *PSV = MMO->getPseudoValue())