Implement compareOperand() API for G4_Reloc_Imm

This is useful
for checking equivalence of 2 relocatable imm operands. Without this
change, we fall back to invoking G4_Imm::compareOperand() that returns Rel_eq for 2 relocatable immediates as they're always
initialized to same imm magic value. This bug is fixed by checking
symbol equivalence in G4_Reloc_Imm::compareOperand() now.

Author: pratikashar

visa/G4_IR.cpp

@@ -5580,6 +5580,22 @@ int64_t G4_Imm::typecastVals(int64_t value, G4_Type type) {
   return retVal;
 }
 
+G4_CmpRelation G4_Reloc_Imm::compareOperand(G4_Operand *opnd,
+                                            const IR_Builder &builder) {
+  if (!opnd->isRelocImm())
+    return Rel_disjoint;
+
+  const auto *relocImmOpnd = opnd->asRelocImm();
+  if (llvm::StringRef(symbol) != llvm::StringRef(relocImmOpnd->symbol))
+    return Rel_disjoint;
+  if (relocKind != relocImmOpnd->relocKind)
+    return Rel_disjoint;
+  if (getType() != opnd->getType())
+    return Rel_disjoint;
+
+  return Rel_eq;
+}
+
 void G4_Reloc_Imm::emit(std::ostream &output) {
   // @RelocTy(Symbol):OpType
   // @RelocTy(Symbol+Imm):OpType

visa/G4_Operand.h

@@ -121,6 +121,7 @@ class G4_InstDpas;
 // Forward declarations for the concrete operand classes. We need them here
 // because the base class has APIs that perform downcasts to the concrete type.
 class G4_Imm;
+class G4_Reloc_Imm;
 class G4_Label;
 class G4_AddrExp;
 class G4_DstRegRegion;
@@ -303,6 +304,18 @@ class G4_Operand {
     return const_cast<G4_Imm *>(((const G4_Operand *)this)->asImm());
   }
 
+  const G4_Reloc_Imm *asRelocImm() const {
+#ifdef _DEBUG
+    if (!isRelocImm()) {
+      return nullptr;
+    }
+#endif
+    return reinterpret_cast<const G4_Reloc_Imm *>(this);
+  }
+  G4_Reloc_Imm *asRelocImm() {
+    return const_cast<G4_Reloc_Imm *>(((const G4_Operand *)this)->asRelocImm());
+  }
+
   const G4_Predicate *asPredicate() const {
 #ifdef _DEBUG
     if (!isPredicate()) {
@@ -478,6 +491,9 @@ class G4_Reloc_Imm : public G4_Imm {
   void *operator new(size_t sz, Mem_Manager &m) { return m.alloc(sz); }
 public:
 
+  G4_CmpRelation compareOperand(G4_Operand *opnd,
+                                const IR_Builder &builder) override;
+
   bool isRelocImm() const override { return true; }
 
   void emit(std::ostream &output) override;