From 53c803871ef355d7caee38d9ef2c913b51215a89 Mon Sep 17 00:00:00 2001
From: Philip Pfaffe <philip.pfaffe@gmail.com>
Date: Sun, 29 Oct 2017 21:36:34 +0000
Subject: [PATCH] [Acc] Do not statically dispatch into IslNodeBuilder's
 createFor

Summary:
When GPUNodeBuilder creates loops inside the kernel, it dispatches to
IslNodeBuilder. This however is surprisingly dangerous, since it accesses the
AST Node's user through the wrong type. This patch fixes this problem by
overriding createFor correctly.

This fixes PR35010.

Reviewers: grosser, bollu, Meinersbur

Reviewed By: Meinersbur

Subscribers: Meinersbur, nemanjai, pollydev, llvm-commits, kbarton

Differential Revision: https://reviews.llvm.org/D39364

llvm-svn: 316872
---
 polly/include/polly/CodeGen/IslNodeBuilder.h |  2 +-
 polly/lib/CodeGen/IslNodeBuilder.cpp         | 14 ++++++--------
 polly/lib/CodeGen/PPCGCodeGeneration.cpp     |  7 +++++++
 3 files changed, 14 insertions(+), 9 deletions(-)

diff --git a/polly/include/polly/CodeGen/IslNodeBuilder.h b/polly/include/polly/CodeGen/IslNodeBuilder.h
index 7b3ce6cdeb83..cae93eef6a7b 100644
--- a/polly/include/polly/CodeGen/IslNodeBuilder.h
+++ b/polly/include/polly/CodeGen/IslNodeBuilder.h
@@ -351,7 +351,7 @@ protected:
   bool preloadInvariantEquivClass(InvariantEquivClassTy &IAClass);
 
   void createForVector(__isl_take isl_ast_node *For, int VectorWidth);
-  void createForSequential(__isl_take isl_ast_node *For, bool KnownParallel);
+  void createForSequential(__isl_take isl_ast_node *For, bool MarkParallel);
 
   /// Create LLVM-IR that executes a for node thread parallel.
   ///
diff --git a/polly/lib/CodeGen/IslNodeBuilder.cpp b/polly/lib/CodeGen/IslNodeBuilder.cpp
index 35210b714be2..d6dafcbcb4a2 100644
--- a/polly/lib/CodeGen/IslNodeBuilder.cpp
+++ b/polly/lib/CodeGen/IslNodeBuilder.cpp
@@ -530,7 +530,7 @@ static bool IsLoopVectorizerDisabled(isl::ast_node Node) {
 }
 
 void IslNodeBuilder::createForSequential(__isl_take isl_ast_node *For,
-                                         bool KnownParallel) {
+                                         bool MarkParallel) {
   isl_ast_node *Body;
   isl_ast_expr *Init, *Inc, *Iterator, *UB;
   isl_id *IteratorID;
@@ -539,10 +539,6 @@ void IslNodeBuilder::createForSequential(__isl_take isl_ast_node *For,
   BasicBlock *ExitBlock;
   Value *IV;
   CmpInst::Predicate Predicate;
-  bool Parallel;
-
-  Parallel = KnownParallel || (IslAstInfo::isParallel(For) &&
-                               !IslAstInfo::isReductionParallel(For));
 
   bool LoopVectorizerDisabled =
       IsLoopVectorizerDisabled(isl::manage(isl_ast_node_copy(For)));
@@ -582,13 +578,13 @@ void IslNodeBuilder::createForSequential(__isl_take isl_ast_node *For,
   bool UseGuardBB =
       !SE.isKnownPredicate(Predicate, SE.getSCEV(ValueLB), SE.getSCEV(ValueUB));
   IV = createLoop(ValueLB, ValueUB, ValueInc, Builder, LI, DT, ExitBlock,
-                  Predicate, &Annotator, Parallel, UseGuardBB,
+                  Predicate, &Annotator, MarkParallel, UseGuardBB,
                   LoopVectorizerDisabled);
   IDToValue[IteratorID] = IV;
 
   create(Body);
 
-  Annotator.popLoop(Parallel);
+  Annotator.popLoop(MarkParallel);
 
   IDToValue.erase(IDToValue.find(IteratorID));
 
@@ -795,7 +791,9 @@ void IslNodeBuilder::createFor(__isl_take isl_ast_node *For) {
     createForParallel(For);
     return;
   }
-  createForSequential(For, false);
+  bool Parallel =
+      (IslAstInfo::isParallel(For) && !IslAstInfo::isReductionParallel(For));
+  createForSequential(For, Parallel);
 }
 
 void IslNodeBuilder::createIf(__isl_take isl_ast_node *If) {
diff --git a/polly/lib/CodeGen/PPCGCodeGeneration.cpp b/polly/lib/CodeGen/PPCGCodeGeneration.cpp
index ed45e0738ffb..720e2564d3e9 100644
--- a/polly/lib/CodeGen/PPCGCodeGeneration.cpp
+++ b/polly/lib/CodeGen/PPCGCodeGeneration.cpp
@@ -415,6 +415,8 @@ private:
   /// @param UserStmt The ast node to generate code for.
   virtual void createUser(__isl_take isl_ast_node *UserStmt);
 
+  virtual void createFor(__isl_take isl_ast_node *Node);
+
   enum DataDirection { HOST_TO_DEVICE, DEVICE_TO_HOST };
 
   /// Create code for a data transfer statement
@@ -1286,6 +1288,11 @@ void GPUNodeBuilder::createUser(__isl_take isl_ast_node *UserStmt) {
   isl_ast_node_free(UserStmt);
   return;
 }
+
+void GPUNodeBuilder::createFor(__isl_take isl_ast_node *Node) {
+  createForSequential(Node, false);
+}
+
 void GPUNodeBuilder::createKernelCopy(ppcg_kernel_stmt *KernelStmt) {
   isl_ast_expr *LocalIndex = isl_ast_expr_copy(KernelStmt->u.c.local_index);
   LocalIndex = isl_ast_expr_address_of(LocalIndex);