[llvm] Allow SMLoc to be used in constexpr context

Since `StringRef::empty` can be used in constexpr context, it seems reasonable that `SMLoc::isValid` should be too.  The default-ctor and `operator==` are made constexpr for consistency.

In particular, the `constexpr` keyword is needed for silencing warnings on Windows (whereas Linux allows constexpr usage without the keyword).

Reviewed By: jpienaar

Differential Revision: https://reviews.llvm.org/D154741

diff --git a/llvm/include/llvm/Support/SMLoc.h b/llvm/include/llvm/Support/SMLoc.h
index 60b052a..d7dde81 100644 (file)
--- a/llvm/include/llvm/Support/SMLoc.h
+++ b/llvm/include/llvm/Support/SMLoc.h
@@ -24,14 +24,14 @@ class SMLoc {
   const char *Ptr = nullptr;
 
 public:
-  SMLoc() = default;
+  constexpr SMLoc() = default;
 
-  bool isValid() const { return Ptr != nullptr; }
+  constexpr bool isValid() const { return Ptr != nullptr; }
 
-  bool operator==(const SMLoc &RHS) const { return RHS.Ptr == Ptr; }
-  bool operator!=(const SMLoc &RHS) const { return RHS.Ptr != Ptr; }
+  constexpr bool operator==(const SMLoc &RHS) const { return RHS.Ptr == Ptr; }
+  constexpr bool operator!=(const SMLoc &RHS) const { return RHS.Ptr != Ptr; }
 
-  const char *getPointer() const { return Ptr; }
+  constexpr const char *getPointer() const { return Ptr; }
 
   static SMLoc getFromPointer(const char *Ptr) {
     SMLoc L;

diff --git a/mlir/lib/Dialect/SparseTensor/IR/Detail/Var.h b/mlir/lib/Dialect/SparseTensor/IR/Detail/Var.h
index 24dd631..f381d46 100644 (file)
--- a/mlir/lib/Dialect/SparseTensor/IR/Detail/Var.h
+++ b/mlir/lib/Dialect/SparseTensor/IR/Detail/Var.h
@@ -361,9 +361,9 @@ public:
                     std::optional<Var::Num> n = {})
       : name(name), loc(loc), id(id), num(n), kind(vk) {
     assert(!name.empty() && "null StringRef");
+    assert(loc.isValid() && "null SMLoc");
     assert(isWF(vk) && "unknown VarKind");
     assert((!n || Var::isWF_Num(*n)) && "Var::Num is too large");
-    // NOTE TO Wren: windows did not like loc.isValid constexpr
   }
 
   constexpr StringRef getName() const { return name; }