- Add TargetInstrInfo::isIdentical(). It's similar to MachineInstr::isIdentical

  except it doesn't care if the definitions' virtual registers differ. This is
  used by machine LICM and other MI passes to perform CSE.
- Teach Thumb2InstrInfo::isIdentical() to check two t2LDRpci_pic are identical.
  Since pc relative constantpool entries are always different, this requires it
  it check if the values can actually the same.

llvm-svn: 86328

1 files changed, 20 insertions, 2 deletions

diff --git a/llvm/lib/Target/ARM/ARMConstantPoolValue.cpp b/llvm/lib/Target/ARM/ARMConstantPoolValue.cpp
index efa941a677c..90dd0c7fd96 100644
--- a/llvm/lib/Target/ARM/ARMConstantPoolValue.cpp
+++ b/llvm/lib/Target/ARM/ARMConstantPoolValue.cpp
@@ -62,9 +62,10 @@ int ARMConstantPoolValue::getExistingMachineCPValue(MachineConstantPool *CP,
       ARMConstantPoolValue *CPV =
         (ARMConstantPoolValue *)Constants[i].Val.MachineCPVal;
       if (CPV->CVal == CVal &&
-          CPV->S == S &&
           CPV->LabelId == LabelId &&
-          CPV->PCAdjust == PCAdjust)
+          CPV->PCAdjust == PCAdjust &&
+          (CPV->S == S || strcmp(CPV->S, S) == 0) &&
+          (CPV->Modifier == Modifier || strcmp(CPV->Modifier, Modifier) == 0))
         return i;
     }
   }
@@ -84,6 +85,23 @@ ARMConstantPoolValue::AddSelectionDAGCSEId(FoldingSetNodeID &ID) {
   ID.AddInteger(PCAdjust);
 }
 
+bool
+ARMConstantPoolValue::hasSameValue(ARMConstantPoolValue *ACPV) {
+  if (ACPV->Kind == Kind &&
+      ACPV->CVal == CVal &&
+      ACPV->PCAdjust == PCAdjust &&
+      (ACPV->S == S || strcmp(ACPV->S, S) == 0) &&
+      (ACPV->Modifier == Modifier || strcmp(ACPV->Modifier, Modifier) == 0)) {
+    if (ACPV->LabelId == LabelId)
+      return true;
+    // Two PC relative constpool entries containing the same GV address or
+    // external symbols. FIXME: What about blockaddress?
+    if (Kind == ARMCP::CPValue || Kind == ARMCP::CPExtSymbol)
+      return true;
+  }
+  return false;
+}
+
 void ARMConstantPoolValue::dump() const {
   errs() << "  " << *this;
 }