Add loc() tests and relax convert op verification

Author: ashermancinelli

flang/include/flang/Optimizer/Dialect/FIROps.td

@@ -2756,7 +2756,7 @@ def fir_AddrOfOp : fir_OneResultOp<"address_of", [NoMemoryEffect]> {
   let assemblyFormat = "`(` $symbol `)` attr-dict `:` type($resTy)";
 }
 
-def fir_VolatileCastOp : fir_SimpleOneResultOp<"volatile_cast", [NoMemoryEffect]> {
+def fir_VolatileCastOp : fir_SimpleOneResultOp<"volatile_cast", [Pure]> {
   let summary = "cast between volatile and non-volatile types";
   let description = [{
     Cast between volatile and non-volatile types. The types must be otherwise

flang/lib/Optimizer/Dialect/FIROps.cpp

@@ -1529,12 +1529,14 @@ bool fir::ConvertOp::canBeConverted(mlir::Type inType, mlir::Type outType) {
 llvm::LogicalResult fir::ConvertOp::verify() {
   mlir::Type inType = getValue().getType();
   mlir::Type outType = getType();
-  // If we're converting to an LLVM pointer type in code generation, we don't
+  // If we're converting to an LLVM pointer type or an integer, we don't
   // need to check for volatility mismatch - volatility will be handled by the
-  // memory operations themselves at that point.
+  // memory operations themselves in llvm code generation and ptr-to-int can't
+  // represent volatility.
   const bool toLLVMPointer = mlir::isa<mlir::LLVM::LLVMPointerType>(outType);
+  const bool toInteger = fir::isa_integer(outType);
   if (fir::isa_volatile_type(inType) != fir::isa_volatile_type(outType) &&
-      !toLLVMPointer)
+      !toLLVMPointer && !toInteger)
     return emitOpError("cannot convert between volatile and non-volatile "
                        "types, use fir.volatile_cast instead ")
            << inType << " / " << outType;

flang/test/Lower/volatile4.f90

@@ -4,6 +4,7 @@ program p
   integer,volatile::i,arr(10)
   integer,volatile,target::tgt(10)
   integer,volatile,pointer,dimension(:)::ptr
+  i = loc(i)
   ptr => tgt
   i=0
   arr=1