[PATCH] D18818: [FIX] Adjust execution context of hoisted loads wrt. error domains

[Johannes Doerfert via llvm-commits]

jdoerfert created this revision.
jdoerfert added reviewers: grosser, Meinersbur.
jdoerfert added a subscriber: Polly.

This is a fix for PR26683 that lacks a test case but allows to start a
discussion.

Personally I do not like this solution and will therefor look into another one.
Nevertheless, it might help to compare them.

http://reviews.llvm.org/D18818

Files:
  include/polly/ScopInfo.h
  lib/Analysis/ScopInfo.cpp

Index: lib/Analysis/ScopInfo.cpp
===================================================================
--- lib/Analysis/ScopInfo.cpp
+++ lib/Analysis/ScopInfo.cpp
@@ -2127,7 +2127,10 @@
       auto *CurrentDomain = DomainMap[ErrorChildBlock];
       auto *Empty = isl_set_empty(isl_set_get_space(CurrentDomain));
       DomainMap[ErrorChildBlock] = Empty;
-      isl_set_free(CurrentDomain);
+      if (!ErrorDomainMap.count(ErrorChildBlock))
+        ErrorDomainMap[ErrorChildBlock] = CurrentDomain;
+      else
+        isl_set_free(CurrentDomain);
     }
   };
 
@@ -2932,6 +2935,8 @@
 
   for (auto It : DomainMap)
     isl_set_free(It.second);
+  for (auto It : ErrorDomainMap)
+    isl_set_free(It.second);
 
   // Free the alias groups
   for (MinMaxVectorPairTy &MinMaxAccessPair : MinMaxAliasGroups) {
@@ -3044,10 +3049,35 @@
   return nullptr;
 }
 
+isl_set *Scop::getErrorCtxReachingStmt(ScopStmt &Stmt) {
+  auto *ErrorCtx = isl_set_empty(getParamSpace());
+
+  SmallPtrSet<BasicBlock *, 32> FinishedBlocks;
+  SmallVector<BasicBlock *, 32> RemainingBlocks;
+  RemainingBlocks.push_back(Stmt.getEntryBlock());
+  while (!RemainingBlocks.empty()) {
+    auto *BB = RemainingBlocks.pop_back_val();
+    if (!R.contains(BB) || !FinishedBlocks.insert(BB).second)
+      continue;
+    RemainingBlocks.append(pred_begin(BB), pred_end(BB));
+
+    auto It = ErrorDomainMap.find(BB);
+    if (It == ErrorDomainMap.end())
+      continue;
+
+    auto *ErrorDomain = isl_set_copy(It->second);
+    ErrorCtx = isl_set_union(ErrorCtx, isl_set_params(ErrorDomain));
+  }
+
+  return ErrorCtx;
+}
+
 void Scop::addInvariantLoads(ScopStmt &Stmt, MemoryAccessList &InvMAs) {
 
-  // Get the context under which the statement is executed.
+  // Get the context under which the statement is executed but remove error
+  // block domains that reach this statement.
   isl_set *DomainCtx = isl_set_params(Stmt.getDomain());
+  DomainCtx = isl_set_subtract(DomainCtx, getErrorCtxReachingStmt(Stmt));
   DomainCtx = isl_set_remove_redundancies(DomainCtx);
   DomainCtx = isl_set_detect_equalities(DomainCtx);
   DomainCtx = isl_set_coalesce(DomainCtx);
Index: include/polly/ScopInfo.h
===================================================================
--- include/polly/ScopInfo.h
+++ include/polly/ScopInfo.h
@@ -1317,6 +1317,9 @@
   /// @brief A map from basic blocks to their domains.
   DenseMap<BasicBlock *, isl_set *> DomainMap;
 
+  /// @brief A map from error blocks to their domains.
+  DenseMap<BasicBlock *, isl_set *> ErrorDomainMap;
+
   /// Constraints on parameters.
   isl_set *Context;
 
@@ -1537,6 +1540,9 @@
   /// @see isIgnored()
   void simplifySCoP(bool RemoveIgnoredStmts, DominatorTree &DT, LoopInfo &LI);
 
+  /// @brief TODO
+  __isl_give isl_set *getErrorCtxReachingStmt(ScopStmt &Stmt);
+
   /// @brief Create equivalence classes for required invariant accesses.
   ///
   /// These classes will consolidate multiple required invariant loads from the


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