7 files changed, 101 insertions, 3 deletions
diff --git a/polly/include/polly/CodeGen/IslAst.h b/polly/include/polly/CodeGen/IslAst.h
index 79335be524b..c1d3305e430 100644
--- a/polly/include/polly/CodeGen/IslAst.h
+++ b/polly/include/polly/CodeGen/IslAst.h
@@ -67,6 +67,8 @@ public:
 
   __isl_give isl_ast_node *getAst();
 
+  const std::shared_ptr<isl_ctx> getSharedIslCtx() const { return Ctx; }
+
   /// Get the run-time conditions for the Scop.
   __isl_give isl_ast_expr *getRunCondition();
 
@@ -131,6 +133,9 @@ private:
 public:
   IslAstInfo(Scop &S, const Dependences &D) : S(S), Ast(IslAst::create(S, D)) {}
 
+  /// Return the isl AST computed by this IslAstInfo.
+  IslAst &getIslAst() { return Ast; }
+
   /// Return a copy of the AST root node.
   __isl_give isl_ast_node *getAst();
 
diff --git a/polly/include/polly/DependenceInfo.h b/polly/include/polly/DependenceInfo.h
index d440dd54e7f..89c3205a437 100644
--- a/polly/include/polly/DependenceInfo.h
+++ b/polly/include/polly/DependenceInfo.h
@@ -92,6 +92,8 @@ struct Dependences {
     TYPE_TC_RED = 1 << 4,
   };
 
+  const std::shared_ptr<isl_ctx> &getSharedIslCtx() const { return IslCtx; }
+
   /// Get the dependences of type @p Kinds.
   ///
   /// @param Kinds This integer defines the different kinds of dependences
diff --git a/polly/lib/CodeGen/CodeGeneration.cpp b/polly/lib/CodeGen/CodeGeneration.cpp
index 240ce23c1b4..41a3b2fcf6a 100644
--- a/polly/lib/CodeGen/CodeGeneration.cpp
+++ b/polly/lib/CodeGen/CodeGeneration.cpp
@@ -182,8 +182,27 @@ static void removeLifetimeMarkers(Region *R) {
 
 static bool CodeGen(Scop &S, IslAstInfo &AI, LoopInfo &LI, DominatorTree &DT,
                     ScalarEvolution &SE, RegionInfo &RI) {
+  // Check whether IslAstInfo uses the same isl_ctx. Since -polly-codegen
+  // reports itself to preserve DependenceInfo and IslAstInfo, we might get
+  // those analysis that were computed by a different ScopInfo for a different
+  // Scop structure. When the ScopInfo/Scop object is freed, there is a high
+  // probability that the new ScopInfo/Scop object will be created at the same
+  // heap position with the same address. Comparing whether the Scop or ScopInfo
+  // address is the expected therefore is unreliable.
+  // Instead, we compare the address of the isl_ctx object. Both, DependenceInfo
+  // and IslAstInfo must hold a reference to the isl_ctx object to ensure it is
+  // not freed before the destruction of those analyses which might happen after
+  // the destruction of the Scop/ScopInfo they refer to.  Hence, the isl_ctx
+  // will not be freed and its space not reused as long there is a
+  // DependenceInfo or IslAstInfo around.
+  IslAst &Ast = AI.getIslAst();
+  if (Ast.getSharedIslCtx() != S.getSharedIslCtx()) {
+    DEBUG(dbgs() << "Got an IstAst for a different Scop/isl_ctx\n");
+    return false;
+  }
+
   // Check if we created an isl_ast root node, otherwise exit.
-  isl_ast_node *AstRoot = AI.getAst();
+  isl_ast_node *AstRoot = Ast.getAst();
   if (!AstRoot)
     return false;
 
diff --git a/polly/lib/CodeGen/IslAst.cpp b/polly/lib/CodeGen/IslAst.cpp
index 3c67cc7ed10..346e14f496b 100644
--- a/polly/lib/CodeGen/IslAst.cpp
+++ b/polly/lib/CodeGen/IslAst.cpp
@@ -806,6 +806,12 @@ bool IslAstInfoWrapperPass::runOnScop(Scop &Scop) {
   const Dependences &D =
       getAnalysis<DependenceInfo>().getDependences(Dependences::AL_Statement);
 
+  if (D.getSharedIslCtx() != Scop.getSharedIslCtx()) {
+    DEBUG(dbgs() << "Got dependence analysis for different SCoP/isl_ctx\n");
+    Ast.reset();
+    return false;
+  }
+
   Ast.reset(new IslAstInfo(Scop, D));
 
   DEBUG(printScop(dbgs(), Scop));
@@ -815,7 +821,7 @@ bool IslAstInfoWrapperPass::runOnScop(Scop &Scop) {
 void IslAstInfoWrapperPass::getAnalysisUsage(AnalysisUsage &AU) const {
   // Get the Common analysis usage of ScopPasses.
   ScopPass::getAnalysisUsage(AU);
-  AU.addRequired<ScopInfoRegionPass>();
+  AU.addRequiredTransitive<ScopInfoRegionPass>();
   AU.addRequired<DependenceInfo>();
 
   AU.addPreserved<DependenceInfo>();
diff --git a/polly/lib/Transform/ScheduleOptimizer.cpp b/polly/lib/Transform/ScheduleOptimizer.cpp
index 0a2fe8b6897..899f1c06830 100644
--- a/polly/lib/Transform/ScheduleOptimizer.cpp
+++ b/polly/lib/Transform/ScheduleOptimizer.cpp
@@ -1485,6 +1485,11 @@ bool IslScheduleOptimizer::runOnScop(Scop &S) {
   const Dependences &D =
       getAnalysis<DependenceInfo>().getDependences(Dependences::AL_Statement);
 
+  if (D.getSharedIslCtx() != S.getSharedIslCtx()) {
+    DEBUG(dbgs() << "DependenceInfo for another SCoP/isl_ctx\n");
+    return false;
+  }
+
   if (!D.hasValidDependences())
     return false;
 
diff --git a/polly/test/Isl/CodeGen/multiple-codegens.ll b/polly/test/Isl/CodeGen/multiple-codegens.ll
new file mode 100644
index 00000000000..b9bfb55e041
--- /dev/null
+++ b/polly/test/Isl/CodeGen/multiple-codegens.ll
@@ -0,0 +1,61 @@
+; RUN: opt %loadPolly -polly-scops -polly-opt-isl -polly-codegen -polly-scops -polly-codegen -S < %s | FileCheck %s
+;
+; llvm.org/PR34441
+; Properly handle multiple -polly-scops/-polly-codegen in the same
+; RegionPassManager. -polly-codegen must not reuse the -polly-ast analysis the
+; was created for the first -polly-scops pass.
+; The current solution is that only the first -polly-codegen is allowed to
+; generate code, the second detects it is re-using an IslAst that belongs to a
+; different ScopInfo.
+;
+; int a, b, c;
+;
+; int main () {
+;  while (a++)
+;    while (b) {
+;        c = 0;
+;        break;
+;      }
+;  return 0;
+; }
+;
+target datalayout = "e-m:w-i64:64-f80:128-n8:16:32:64-S128"
+
+@a = common global i32 0, align 4
+@b = common global i32 0, align 4
+@c = common global i32 0, align 4
+
+; Function Attrs: nounwind uwtable
+define i32 @main() {
+entry:
+  %retval = alloca i32, align 4
+  store i32 0, i32* %retval, align 4
+  %.pre = load i32, i32* @a, align 4
+  br label %while.cond
+
+while.cond:                                       ; preds = %while.end, %entry
+  %0 = phi i32 [ %inc, %while.end ], [ %.pre, %entry ]
+  %inc = add nsw i32 %0, 1
+  store i32 %inc, i32* @a, align 4
+  %tobool = icmp ne i32 %0, 0
+  br i1 %tobool, label %while.body, label %while.end4
+
+while.body:                                       ; preds = %while.cond
+  %1 = load i32, i32* @b, align 4
+  %tobool2 = icmp ne i32 %1, 0
+  br i1 %tobool2, label %while.body3, label %while.end
+
+while.body3:                                      ; preds = %while.body
+  store i32 0, i32* @c, align 4
+  br label %while.end
+
+while.end:                                        ; preds = %while.body3, %while.body
+  br label %while.cond
+
+while.end4:                                       ; preds = %while.cond
+  ret i32 0
+}
+
+
+; CHECK: polly.start:
+; CHECK-NOT: polly.start:
diff --git a/polly/test/ScopDetect/base_pointer_load_setNewAccessRelation.ll b/polly/test/ScopDetect/base_pointer_load_setNewAccessRelation.ll
index bc965526b4f..3561a49a271 100644
--- a/polly/test/ScopDetect/base_pointer_load_setNewAccessRelation.ll
+++ b/polly/test/ScopDetect/base_pointer_load_setNewAccessRelation.ll
@@ -1,4 +1,4 @@
-; RUN: opt %loadPolly -polly-ignore-aliasing -polly-invariant-load-hoisting=true -polly-import-jscop -polly-scops -polly-codegen -analyze < %s | FileCheck %s
+; RUN: opt %loadPolly -polly-ignore-aliasing -polly-invariant-load-hoisting=true -polly-scops -polly-import-jscop -polly-codegen -analyze < %s | FileCheck %s
 ;
 ; This violated an assertion in setNewAccessRelation that assumed base pointers
 ; to be load-hoisted. Without this assertion, it codegen would generate invalid