[Polly] Switch DT/LI in RegionGenerator for parallel subfn (#120413)

The patch #102460 already implements separate DT/LI/SE for parallel sub
function. Crashes have been reported while region generator tries using
oringinal function's DT while creating new parallel sub function due to
checks in #101198. This patch aims at fixing those cases by switching
the DT/LI while generating parallel function using Region Generator.

Fixes #117877

Author: kartcq

polly/include/polly/CodeGen/BlockGenerators.h

@@ -632,7 +632,7 @@ class BlockGenerator {
 };
 
 /// Generator for new versions of polyhedral region statements.
-class RegionGenerator final : BlockGenerator {
+class RegionGenerator final : public BlockGenerator {
 public:
   /// Create a generator for regions.
   ///

polly/lib/CodeGen/BlockGenerators.cpp

@@ -1000,7 +1000,7 @@ BasicBlock *RegionGenerator::repairDominance(BasicBlock *BB,
   BasicBlock *BBCopyIDom = EndBlockMap.lookup(BBIDom);
 
   if (BBCopyIDom)
-    DT.changeImmediateDominator(BBCopy, BBCopyIDom);
+    GenDT->changeImmediateDominator(BBCopy, BBCopyIDom);
 
   return StartBlockMap.lookup(BBIDom);
 }
@@ -1069,8 +1069,8 @@ void RegionGenerator::copyStmt(ScopStmt &Stmt, LoopToScevMapT &LTS,
   // Create a dedicated entry for the region where we can reload all demoted
   // inputs.
   BasicBlock *EntryBB = R->getEntry();
-  BasicBlock *EntryBBCopy = SplitBlock(Builder.GetInsertBlock(),
-                                       &*Builder.GetInsertPoint(), &DT, &LI);
+  BasicBlock *EntryBBCopy = SplitBlock(
+      Builder.GetInsertBlock(), &*Builder.GetInsertPoint(), GenDT, GenLI);
   EntryBBCopy->setName("polly.stmt." + EntryBB->getName() + ".entry");
   Builder.SetInsertPoint(&EntryBBCopy->front());
 
@@ -1136,7 +1136,7 @@ void RegionGenerator::copyStmt(ScopStmt &Stmt, LoopToScevMapT &LTS,
 
   // Now create a new dedicated region exit block and add it to the region map.
   BasicBlock *ExitBBCopy = SplitBlock(Builder.GetInsertBlock(),
-                                      &*Builder.GetInsertPoint(), &DT, &LI);
+                                      &*Builder.GetInsertPoint(), GenDT, GenLI);
   ExitBBCopy->setName("polly.stmt." + R->getExit()->getName() + ".exit");
   StartBlockMap[R->getExit()] = ExitBBCopy;
   EndBlockMap[R->getExit()] = ExitBBCopy;
@@ -1145,7 +1145,7 @@ void RegionGenerator::copyStmt(ScopStmt &Stmt, LoopToScevMapT &LTS,
   assert(ExitDomBBCopy &&
          "Common exit dominator must be within region; at least the entry node "
          "must match");
-  DT.changeImmediateDominator(ExitBBCopy, ExitDomBBCopy);
+  GenDT->changeImmediateDominator(ExitBBCopy, ExitDomBBCopy);
 
   // As the block generator doesn't handle control flow we need to add the
   // region control flow by hand after all blocks have been copied.

polly/lib/CodeGen/IslNodeBuilder.cpp

@@ -612,6 +612,7 @@ void IslNodeBuilder::createForParallel(__isl_take isl_ast_node *For) {
   GenLI = SubLI;
   GenSE = SubSE.get();
   BlockGen.switchGeneratedFunc(SubFn, GenDT, GenLI, GenSE);
+  RegionGen.switchGeneratedFunc(SubFn, GenDT, GenLI, GenSE);
   ExprBuilder.switchGeneratedFunc(SubFn, GenDT, GenLI, GenSE);
   Builder.SetInsertPoint(&*LoopBody);
 
@@ -681,6 +682,7 @@ void IslNodeBuilder::createForParallel(__isl_take isl_ast_node *For) {
   IDToValue = std::move(IDToValueCopy);
   ValueMap = std::move(CallerGlobals);
   ExprBuilder.switchGeneratedFunc(CallerFn, CallerDT, CallerLI, CallerSE);
+  RegionGen.switchGeneratedFunc(CallerFn, CallerDT, CallerLI, CallerSE);
   BlockGen.switchGeneratedFunc(CallerFn, CallerDT, CallerLI, CallerSE);
   Builder.SetInsertPoint(&*AfterLoop);
 

polly/test/CodeGen/reggen_domtree_crash.ll

@@ -0,0 +1,41 @@
+; RUN: opt %loadNPMPolly -passes=polly-codegen -polly-parallel -S < %s | FileCheck %s
+
+; CHECK: define ptr @ham(ptr %arg, i64 %arg1, i1 %arg2)
+
+; This test is added to verify if the following IR does not crash on using different Dominator Tree when using polly parallel flag.
+
+; ModuleID = '<stdin>'
+source_filename = "<stdin>"
+
+define ptr @ham(ptr %arg, i64 %arg1, i1 %arg2) {
+bb:
+  br label %bb3
+
+bb3:                                              ; preds = %bb8, %bb
+  %phi = phi i64 [ 0, %bb ], [ %add9, %bb8 ]
+  %getelementptr = getelementptr [64 x i16], ptr %arg, i64 %phi
+  br label %bb4
+
+bb4:                                              ; preds = %bb7, %bb3
+  %phi5 = phi i64 [ %add, %bb7 ], [ 0, %bb3 ]
+  %load = load i16, ptr null, align 2
+  br i1 %arg2, label %bb7, label %bb6
+
+bb6:                                              ; preds = %bb4
+  store i16 0, ptr %getelementptr, align 2
+  br label %bb7
+
+bb7:                                              ; preds = %bb6, %bb4
+  %add = add i64 %phi5, 1
+  %icmp = icmp ne i64 %phi5, 64
+  br i1 %icmp, label %bb4, label %bb8
+
+bb8:                                              ; preds = %bb7
+  %add9 = add i64 %phi, 1
+  %icmp10 = icmp ult i64 %phi, %arg1
+  br i1 %icmp10, label %bb3, label %bb11
+
+bb11:                                             ; preds = %bb8
+  ret ptr null
+}
+