[flang] AliasAnalysis: Handle fir.load on hlfir.designate (#127107)

For example, determine that the address in `obj%p` below cannot alias
the address of `v`:

```
module m
  type :: ty
    real, pointer :: p
  end type ty
end module m
subroutine test()
  use m
  real, target :: t
  real :: v
  type(ty) :: obj
  obj%p => t
  v = obj%p
end subroutine test
```

Author: jdenny-ornl

flang/include/flang/Optimizer/Analysis/AliasAnalysis.h

@@ -211,14 +211,14 @@ struct AliasAnalysis {
   fir::AliasAnalysis::Source getSource(mlir::Value,
                                        bool getLastInstantiationPoint = false);
 
+  /// Return true, if `ty` is a reference type to a boxed
+  /// POINTER object or a raw fir::PointerType.
+  static bool isPointerReference(mlir::Type ty);
+
 private:
   /// Return true, if `ty` is a reference type to an object of derived type
   /// that contains a component with POINTER attribute.
   static bool isRecordWithPointerComponent(mlir::Type ty);
-
-  /// Return true, if `ty` is a reference type to a boxed
-  /// POINTER object or a raw fir::PointerType.
-  static bool isPointerReference(mlir::Type ty);
 };
 
 inline bool operator==(const AliasAnalysis::Source::SourceOrigin &lhs,

flang/lib/Optimizer/Analysis/AliasAnalysis.cpp

@@ -54,10 +54,11 @@ static bool hasGlobalOpTargetAttr(mlir::Value v, fir::AddrOfOp op) {
 static mlir::Value
 getOriginalDef(mlir::Value v,
                fir::AliasAnalysis::Source::Attributes &attributes,
-               bool &isCapturedInInternalProcedure) {
+               bool &isCapturedInInternalProcedure, bool &approximateSource) {
   mlir::Operation *defOp;
   bool breakFromLoop = false;
   while (!breakFromLoop && (defOp = v.getDefiningOp())) {
+    mlir::Type ty = defOp->getResultTypes()[0];
     llvm::TypeSwitch<Operation *>(defOp)
         .Case<fir::ConvertOp>([&](fir::ConvertOp op) { v = op.getValue(); })
         .Case<fir::DeclareOp, hlfir::DeclareOp>([&](auto op) {
@@ -67,6 +68,18 @@ getOriginalDef(mlir::Value v,
           isCapturedInInternalProcedure |=
               varIf.isCapturedInInternalProcedure();
         })
+        .Case<fir::CoordinateOp>([&](auto op) {
+          if (fir::AliasAnalysis::isPointerReference(ty))
+            attributes.set(fir::AliasAnalysis::Attribute::Pointer);
+          v = op->getOperand(0);
+          approximateSource = true;
+        })
+        .Case<hlfir::DesignateOp>([&](hlfir::DesignateOp op) {
+          auto varIf = llvm::cast<fir::FortranVariableOpInterface>(defOp);
+          attributes |= getAttrsFromVariable(varIf);
+          v = op.getMemref();
+          approximateSource = true;
+        })
         .Default([&](auto op) { breakFromLoop = true; });
   }
   return v;
@@ -609,7 +622,8 @@ AliasAnalysis::Source AliasAnalysis::getSource(mlir::Value v,
               attributes.set(Attribute::Pointer);
 
             auto def = getOriginalDef(op.getMemref(), attributes,
-                                      isCapturedInInternalProcedure);
+                                      isCapturedInInternalProcedure,
+                                      approximateSource);
             if (auto addrOfOp = def.template getDefiningOp<fir::AddrOfOp>()) {
               global = addrOfOp.getSymbol();