[llvm-branch-commits] [flang] [flang] handle fir.call in AliasAnalysis::getModRef (PR #117164)

[Tom Eccles via llvm-branch-commits]

================
@@ -329,14 +341,92 @@ AliasResult AliasAnalysis::alias(Source lhsSrc, Source rhsSrc, mlir::Value lhs,
 // AliasAnalysis: getModRef
 //===----------------------------------------------------------------------===//
 
+static bool isSavedLocal(const fir::AliasAnalysis::Source &src) {
+  if (auto symRef = llvm::dyn_cast<mlir::SymbolRefAttr>(src.origin.u)) {
+    auto [nameKind, deconstruct] =
+        fir::NameUniquer::deconstruct(symRef.getLeafReference().getValue());
+    return nameKind == fir::NameUniquer::NameKind::VARIABLE &&
+           !deconstruct.procs.empty();
+  }
+  return false;
+}
+
+static bool isCallToFortranUserProcedure(fir::CallOp call) {
+  // TODO: indirect calls are excluded by these checks. Maybe some attribute is
+  // needed to flag user calls in this case.
+  if (fir::hasBindcAttr(call))
+    return true;
+  if (std::optional<mlir::SymbolRefAttr> callee = call.getCallee())
+    return fir::NameUniquer::deconstruct(callee->getLeafReference().getValue())
+               .first == fir::NameUniquer::NameKind::PROCEDURE;
+  return false;
+}
+
+static ModRefResult getCallModRef(fir::CallOp call, mlir::Value var) {
+  // TODO: limit to Fortran functions??
+  // 1. Detect variables that can be accessed indirectly.
+  fir::AliasAnalysis aliasAnalysis;
+  fir::AliasAnalysis::Source varSrc = aliasAnalysis.getSource(var);
+  // If the variable is not a user variable, we cannot safely assume that
+  // Fortran semantics apply (e.g., a bare alloca/allocmem result may very well
+  // be placed in an allocatable/pointer descriptor and escape).
+
+  // All the logic bellows are based on Fortran semantics and only holds if this
+  // is a call to a procedure form the Fortran source and this is a variable
----------------
tblah wrote:

```suggestion
  // is a call to a procedure from the Fortran source and this is a variable
```
nit

https://github.com/llvm/llvm-project/pull/117164