[flang] [clang-tools-extra] [clang] [llvm] [flang] add SYSTEM runtime and lowering intrinsics support (PR #74309)

[Tom Eccles via cfe-commits]

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@@ -5934,6 +5938,40 @@ IntrinsicLibrary::genSum(mlir::Type resultType,
                       resultType, args);
 }
 
+// SYSTEM
+void IntrinsicLibrary::genSystem(llvm::ArrayRef<fir::ExtendedValue> args) {
+  assert(args.size() == 2);
+  mlir::Value command = fir::getBase(args[0]);
+  const fir::ExtendedValue &exitstat = args[1];
+
+  if (!command)
+    fir::emitFatalError(loc, "expected COMMAND parameter");
+
+  mlir::Type boxNoneTy = fir::BoxType::get(builder.getNoneType());
+
+  mlir::Value waitBool = builder.createBool(loc, true);
+  mlir::Value exitstatBox =
+      isStaticallyPresent(exitstat)
+          ? fir::getBase(exitstat)
+          : builder.create<fir::AbsentOp>(loc, boxNoneTy).getResult();
+
+  // Create a dummmy cmdstat to prevent EXECUTE_COMMAND_LINE terminate itself
+  // when cmdstat is assigned with a non-zero value but not present
+  mlir::Value tempValue =
+      builder.createIntegerConstant(loc, builder.getI2Type(), 0);
+  mlir::Value temp = builder.createTemporary(loc, builder.getI2Type());
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tblah wrote:

Why i2? Doesn't this need to support -2 to 4? 

https://github.com/llvm/llvm-project/pull/74309