[flang-commits] [flang] [flang][FIR] allow mem2reg over fir.declare (PR #181848)

[Abid Qadeer via flang-commits]

================
@@ -3473,6 +3476,42 @@ def fir_DeclareOp
   let hasVerifier = 1;
 }
 
+def fir_DeclareValueOp
+    : fir_Op<"declare_value", [MemoryEffects<[MemAlloc<DebuggingResource>]>]> {
+  let summary = "declare a value";
+
+  let description = [{
+    Tie the properties of a simple scalar Fortran variable to a value.
+    The value must be a scalar integer, real, complex, or logical.
+    This is the value based version of fir.declare. It is used to keep track
+    of variable properties and debug info after mem2reg promotion.
+
+    Note that there is currently nothing that allows pinning this operation
+    relatively to the operation using the value of the variable,
+    this means that the when a mem2reg variable was assigned several
+    values, the variable value printed in the debugger at a given code
+    point main not be the actual value the variable had at that code point
----------------
abidh wrote:

```suggestion
    point may not be the actual value the variable had at that code point
```

https://github.com/llvm/llvm-project/pull/181848