[CodeGen] Rename MachineInstr::isInvariantLoad to isDereferenceableInvariantLoad. NFC

Summary:
I want to separate out the notions of invariance and dereferenceability
at the MI level, so that they correspond to the equivalent concepts at
the IR level.  (Currently an MI load is MI-invariant iff it's
IR-invariant and IR-dereferenceable.)

First step is renaming this function.

Reviewers: chandlerc

Subscribers: MatzeB, jfb, llvm-commits

Differential Revision: https://reviews.llvm.org/D23370

llvm-svn: 281125

1 files changed, 5 insertions, 7 deletions

diff --git a/llvm/lib/CodeGen/MachineInstr.cpp b/llvm/lib/CodeGen/MachineInstr.cpp
index d79c32e9ca9..90ebf2c532f 100644
--- a/llvm/lib/CodeGen/MachineInstr.cpp
+++ b/llvm/lib/CodeGen/MachineInstr.cpp
@@ -1531,7 +1531,7 @@ bool MachineInstr::isSafeToMove(AliasAnalysis *AA, bool &SawStore) const {
   // 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 (mayLoad() && !isInvariantLoad(AA))
+  if (mayLoad() && !isDereferenceableInvariantLoad(AA))
     // Otherwise, this is a real load.  If there is a store between the load and
     // end of block, we can't move it.
     return !SawStore;
@@ -1562,12 +1562,10 @@ bool MachineInstr::hasOrderedMemoryRef() const {
   });
 }
 
-/// isInvariantLoad - Return true if this instruction is loading from a
-/// location whose value is invariant across the function.  For example,
-/// loading a value from the constant pool or from the argument area
-/// of a function if it does not change.  This should only return true of
-/// *all* loads the instruction does are invariant (if it does multiple loads).
-bool MachineInstr::isInvariantLoad(AliasAnalysis *AA) const {
+/// isDereferenceableInvariantLoad - Return true if this instruction will never
+/// trap and is loading from a location whose value is invariant across a run of
+/// this function.
+bool MachineInstr::isDereferenceableInvariantLoad(AliasAnalysis *AA) const {
   // If the instruction doesn't load at all, it isn't an invariant load.
   if (!mayLoad())
     return false;