Track assumptions and restrictions separatly

  In order to speed up compile time and to avoid random timeouts we now
  separately track assumptions and restrictions. In this context
  assumptions describe parameter valuations we need and restrictions
  describe parameter valuations we do not allow. During AST generation
  we create a runtime check for both, whereas the one for the
  restrictions is negated before a conjunction is build.

  Except the In-Bounds assumptions we currently only track restrictions.

Differential Revision: http://reviews.llvm.org/D17247

llvm-svn: 262328

polly/include/polly/ScopInfo.h

@@ -27,6 +27,7 @@
 #include "llvm/Analysis/RegionPass.h"
 #include "isl/aff.h"
 #include "isl/ctx.h"
+#include "isl/set.h"
 
 #include <deque>
 #include <forward_list>
@@ -81,6 +82,9 @@ enum AssumptionKind {
   ERROR_DOMAINCONJUNCTS,
 };
 
+/// @brief Enum to distinguish between assumptions and restrictions.
+enum AssumptionSign { AS_ASSUMPTION, AS_RESTRICTION };
+
 /// Maps from a loop to the affine function expressing its backedge taken count.
 /// The backedge taken count already enough to express iteration domain as we
 /// only allow loops with canonical induction variable.
@@ -1334,16 +1338,13 @@ class Scop {
   /// this scop and that need to be code generated as a run-time test.
   isl_set *AssumedContext;
 
-  /// @brief The boundary assumptions under which this scop was built.
+  /// @brief The restrictions under which this SCoP was built.
   ///
-  /// The boundary context is similar to the assumed context as it contains
-  /// constraints over the parameters we assume to be true. However, the
-  /// boundary context is less useful for dependence analysis and
-  /// simplification purposes as it contains only constraints that affect the
-  /// boundaries of the parameter ranges. As these constraints can become quite
-  /// complex, the boundary context and the assumed context are separated as a
-  /// meassure to save compile time.
-  isl_set *BoundaryContext;
+  /// The invalid context is similar to the assumed context as it contains
+  /// constraints over the parameters. However, while we need the constraints
+  /// in the assumed context to be "true" the constraints in the invalid context
+  /// need to be "false". Otherwise they behave the same.
+  isl_set *InvalidContext;
 
   /// @brief The schedule of the SCoP
   ///
@@ -1550,8 +1551,8 @@ class Scop {
   /// @brief Build the Context of the Scop.
   void buildContext();
 
-  /// @brief Build the BoundaryContext based on the wrapping of expressions.
-  void buildBoundaryContext();
+  /// @brief Add the restrictions based on the wrapping of expressions.
+  void addWrappingContext();
 
   /// @brief Add user provided parameter constraints to context (source code).
   void addUserAssumptions(AssumptionCache &AC, DominatorTree &DT, LoopInfo &LI);
@@ -1562,7 +1563,7 @@ class Scop {
   /// @brief Add the bounds of the parameters to the context.
   void addParameterBounds();
 
-  /// @brief Simplify the assumed and boundary context.
+  /// @brief Simplify the assumed and invalid context.
   void simplifyContexts();
 
   /// @brief Get the representing SCEV for @p S if applicable, otherwise @p S.
@@ -1790,14 +1791,6 @@ class Scop {
   /// @return The assumed context of this Scop.
   __isl_give isl_set *getAssumedContext() const;
 
-  /// @brief Get the runtime check context for this Scop.
-  ///
-  /// The runtime check context contains all constraints that have to
-  /// hold at runtime for the optimized version to be executed.
-  ///
-  /// @return The runtime check context of this Scop.
-  __isl_give isl_set *getRuntimeCheckContext() const;
-
   /// @brief Return true if the optimized SCoP can be executed.
   ///
   /// In addition to the runtime check context this will also utilize the domain
@@ -1808,14 +1801,18 @@ class Scop {
 
   /// @brief Track and report an assumption.
   ///
-  /// Use 'clang -Rpass-analysis=polly-scops' or 'opt -pass-remarks=polly-scops'
-  /// to output the assumptions.
+  /// Use 'clang -Rpass-analysis=polly-scops' or 'opt
+  /// -pass-remarks-analysis=polly-scops' to output the assumptions.
   ///
   /// @param Kind The assumption kind describing the underlying cause.
   /// @param Set  The relations between parameters that are assumed to hold.
   /// @param Loc  The location in the source that caused this assumption.
-  void trackAssumption(AssumptionKind Kind, __isl_keep isl_set *Set,
-                       DebugLoc Loc);
+  /// @param Sign Enum to indicate if the assumptions in @p Set are positive
+  ///             (needed/assumptions) or negative (invalid/restrictions).
+  ///
+  /// @returns True if the assumption is not trivial.
+  bool trackAssumption(AssumptionKind Kind, __isl_keep isl_set *Set,
+                       DebugLoc Loc, AssumptionSign Sign);
 
   /// @brief Add assumptions to assumed context.
   ///
@@ -1831,8 +1828,10 @@ class Scop {
   /// @param Kind The assumption kind describing the underlying cause.
   /// @param Set  The relations between parameters that are assumed to hold.
   /// @param Loc  The location in the source that caused this assumption.
-  void addAssumption(AssumptionKind Kind, __isl_take isl_set *Set,
-                     DebugLoc Loc);
+  /// @param Sign Enum to indicate if the assumptions in @p Set are positive
+  ///             (needed/assumptions) or negative (invalid/restrictions).
+  void addAssumption(AssumptionKind Kind, __isl_take isl_set *Set, DebugLoc Loc,
+                     AssumptionSign Sign);
 
   /// @brief Mark the scop as invalid.
   ///
@@ -1845,10 +1844,15 @@ class Scop {
   /// @param Loc  The location in the source that triggered .
   void invalidate(AssumptionKind Kind, DebugLoc Loc);
 
-  /// @brief Get the boundary context for this Scop.
+  /// @brief Get the invalid context for this Scop.
   ///
-  /// @return The boundary context of this Scop.
-  __isl_give isl_set *getBoundaryContext() const;
+  /// @return The invalid context of this Scop.
+  __isl_give isl_set *getInvalidContext() const;
+
+  /// @brief Return true if and only if the InvalidContext is trivial (=empty).
+  bool hasTrivialInvalidContext() const {
+    return isl_set_is_empty(InvalidContext);
+  }
 
   /// @brief Build the alias checks for this SCoP.
   void buildAliasChecks(AliasAnalysis &AA);
@@ -1869,8 +1873,8 @@ class Scop {
   /// @brief Get an isl string representing the assumed context.
   std::string getAssumedContextStr() const;
 
-  /// @brief Get an isl string representing the boundary context.
-  std::string getBoundaryContextStr() const;
+  /// @brief Get an isl string representing the invalid context.
+  std::string getInvalidContextStr() const;
 
   /// @brief Return the ScopStmt for the given @p BB or nullptr if there is
   ///        none.