[mlir][IR][NFC] PostDominanceInfo: Mark all functions as const

Same as `DominanceInfo`, all functions should be `const`.

Depends on #115587.

Author: matthias-springer

mlir/include/mlir/IR/Dominance.h

@@ -196,18 +196,18 @@ class PostDominanceInfo : public detail::DominanceInfoBase</*IsPostDom=*/true> {
 
   /// Return true if operation A properly postdominates operation B.
   bool properlyPostDominates(Operation *a, Operation *b,
-                             bool enclosingOpOk = true);
+                             bool enclosingOpOk = true) const;
 
   /// Return true if operation A postdominates operation B.
-  bool postDominates(Operation *a, Operation *b) {
+  bool postDominates(Operation *a, Operation *b) const {
     return a == b || properlyPostDominates(a, b);
   }
 
   /// Return true if the specified block A properly postdominates block B.
-  bool properlyPostDominates(Block *a, Block *b);
+  bool properlyPostDominates(Block *a, Block *b) const;
 
   /// Return true if the specified block A postdominates block B.
-  bool postDominates(Block *a, Block *b) {
+  bool postDominates(Block *a, Block *b) const {
     return a == b || properlyPostDominates(a, b);
   }
 };

mlir/lib/IR/Dominance.cpp

@@ -352,13 +352,13 @@ bool DominanceInfo::properlyDominates(Value a, Operation *b) const {
 //===----------------------------------------------------------------------===//
 
 bool PostDominanceInfo::properlyPostDominates(Operation *a, Operation *b,
-                                              bool enclosingOpOk) {
+                                              bool enclosingOpOk) const {
   return super::properlyDominatesImpl(a->getBlock(), a->getIterator(),
                                       b->getBlock(), b->getIterator(),
                                       enclosingOpOk);
 }
 
-bool PostDominanceInfo::properlyPostDominates(Block *a, Block *b) {
+bool PostDominanceInfo::properlyPostDominates(Block *a, Block *b) const {
   return super::properlyDominatesImpl(a, a->end(), b, b->end(),
                                       /*enclosingOk=*/true);
 }