[Dominators] Make IsPostDominator a template parameter

Summary:
DominatorTreeBase used to have IsPostDominators (bool) member to indicate if the tree is a dominator or a postdominator tree. This made it possible to switch between the two 'modes' at runtime, but it isn't used in practice anywhere.

This patch makes IsPostDominator a template argument. This way, it is easier to switch between different algorithms at compile-time based on this argument and design external utilities around it. It also makes it impossible to incidentally assign a postdominator tree to a dominator tree (and vice versa), and to further simplify template code in GenericDominatorTreeConstruction.

Reviewers: dberlin, sanjoy, davide, grosser

Reviewed By: dberlin

Subscribers: mzolotukhin, llvm-commits

Differential Revision: https://reviews.llvm.org/D35315

llvm-svn: 308040

1 files changed, 10 insertions, 11 deletions

diff --git a/llvm/unittests/IR/DominatorTreeTest.cpp b/llvm/unittests/IR/DominatorTreeTest.cpp
index fa3dad8a2ab..89c1297dc0d 100644
--- a/llvm/unittests/IR/DominatorTreeTest.cpp
+++ b/llvm/unittests/IR/DominatorTreeTest.cpp
@@ -19,18 +19,19 @@
 
 using namespace llvm;
 
+struct PostDomTree : PostDomTreeBase<BasicBlock> {
+  PostDomTree(Function &F) { recalculate(F); }
+};
+
 /// Build the dominator tree for the function and run the Test.
-static void
-runWithDomTree(Module &M, StringRef FuncName,
-               function_ref<void(Function &F, DominatorTree *DT,
-                                 DominatorTreeBase<BasicBlock> *PDT)>
-                   Test) {
+static void runWithDomTree(
+    Module &M, StringRef FuncName,
+    function_ref<void(Function &F, DominatorTree *DT, PostDomTree *PDT)> Test) {
   auto *F = M.getFunction(FuncName);
   ASSERT_NE(F, nullptr) << "Could not find " << FuncName;
   // Compute the dominator tree for the function.
   DominatorTree DT(*F);
-  DominatorTreeBase<BasicBlock> PDT(/*isPostDom*/ true);
-  PDT.recalculate(*F);
+  PostDomTree PDT(*F);
   Test(*F, &DT, &PDT);
 }
 
@@ -72,8 +73,7 @@ TEST(DominatorTree, Unreachable) {
   std::unique_ptr<Module> M = makeLLVMModule(Context, ModuleString);
 
   runWithDomTree(
-      *M, "f",
-      [&](Function &F, DominatorTree *DT, DominatorTreeBase<BasicBlock> *PDT) {
+      *M, "f", [&](Function &F, DominatorTree *DT, PostDomTree *PDT) {
         Function::iterator FI = F.begin();
 
         BasicBlock *BB0 = &*FI++;
@@ -293,8 +293,7 @@ TEST(DominatorTree, NonUniqueEdges) {
   std::unique_ptr<Module> M = makeLLVMModule(Context, ModuleString);
 
   runWithDomTree(
-      *M, "f",
-      [&](Function &F, DominatorTree *DT, DominatorTreeBase<BasicBlock> *PDT) {
+      *M, "f", [&](Function &F, DominatorTree *DT, PostDomTree *PDT) {
         Function::iterator FI = F.begin();
 
         BasicBlock *BB0 = &*FI++;