[Polly] Introduce list of statements in Scop::StmtMap. NFC

[nandini12396]

Summary

Once statements are split, a Basic Block will comprise of multiple statements. To prepare for this change in future, we introduce a list of statements in the statement map.

[Meinersbur]

I intended to commit, but r307907 seems to have broken the unit tests. I'll wait until it is green again.

[grosser]

The buildbots are green for me (except one older before-vectorizer issue) I can see.

[nandini12396]

sure, thank you.

[bollu]

@Meinersbur - Could you please tell me what breaks with r307907?

[grosser]

@Meinersbur: If you find time, would be great to check if the unit tests are still broken under windows.

[Meinersbur]

@bollu: It wss fixed by 'r308215'. Somewhat strange, it looked like the change in ScopInfo.cpp was active already before that commit, but not its changed test cases, so they failed. For example:

FAIL: Polly :: DeLICM/reduction_looprotate_load.ll (16 of 959)
******************** TEST 'Polly :: DeLICM/reduction_looprotate_load.ll' FAILED ********************
Script:
--
opt  -polly-process-unprofitable  -polly-remarks-minimal  -polly-use-llvm-names  -polly-import-jscop-dir=C:\Users\Meinersbur\src\llvm\tools\polly\test\DeLICM  -polly-flatten-schedule -polly-delicm-overapproximate-writes=true -polly-delicm-compute-known=true -polly-delicm -analyze < C:\Users\Meinersbur\src\llvm\tools\polly\test\DeLICM\reduction_looprotate_load.ll | FileCheck C:\Users\Meinersbur\src\llvm\tools\polly\test\DeLICM\reduction_looprotate_load.ll
--
Exit Code: 1

Command Output (stdout):
--
$ "opt" "-polly-process-unprofitable" "-polly-remarks-minimal" "-polly-use-llvm-names" "-polly-import-jscop-dir=C:\Users\Meinersbur\src\llvm\tools\polly\test\DeLICM" "-polly-flatten-schedule" "-polly-delicm-overapproximate-writes=true" "-polly-delicm-compute-known=true" "-polly-delicm" "-analyze"
$ "FileCheck" "C:\Users\Meinersbur\src\llvm\tools\polly\test\DeLICM\reduction_looprotate_load.ll"
# command stderr:
C:\Users\Meinersbur\src\llvm\tools\polly\test\DeLICM\reduction_looprotate_load.ll:71:15: error: expected string not found in input
; CHECK-NEXT: new: { Stmt_reduction_preheader[i0] -> MemRef_A[i0] : 0 <= i0 <= 1 };
              ^
<stdin>:35:2: note: scanning from here
 new: { Stmt_reduction_preheader[i0] -> MemRef_A[i0] };
 ^

error: command failed with exit status: 1

I am able to reproduce it under Windows, lxss (Bash on Windows) and Linux. SHA1 collision?

include/polly/ScopInfo.h

private:
   ///
   /// We need a shared_ptr with reference counter to delete the context when all
   /// isl objects are deleted. We will distribute the shared_ptr to all objects
   /// that use the context to create isl objects, and increase the reference
   /// counter. By doing this, we guarantee that the context is deleted when we
   /// delete the last object that creates isl objects with the context.
   std::shared_ptr<isl_ctx> IslCtx;
 
-  /// A map from basic blocks to SCoP statements.
-  DenseMap<BasicBlock *, ScopStmt *> StmtMap;
+  /// A map from basic blocks to vector of SCoP statements. Currently this
+  /// vector comprises only of a single statement.
+  DenseMap<BasicBlock *, std::vector<ScopStmt *>> StmtMap;
 
   /// A map from basic blocks to their domains.
   DenseMap<BasicBlock *, isl_set *> DomainMap;
 
   /// Constraints on parameters.
   isl_set *Context;
 
   /// The affinator used to translate SCEVs to isl expressions.

lib/Analysis/ScopInfo.cpp

static isl::multi_union_pw_aff mapToDimension(isl::union_set USet, int N) {
   return isl::multi_union_pw_aff(isl::union_pw_multi_aff(Result));
 }
 
 void Scop::addScopStmt(BasicBlock *BB, Loop *SurroundingLoop,
                        std::vector<Instruction *> Instructions) {
   assert(BB && "Unexpected nullptr!");
   Stmts.emplace_back(*this, *BB, SurroundingLoop, Instructions);
   auto *Stmt = &Stmts.back();
-  StmtMap[BB] = Stmt;
+  StmtMap[BB].push_back(Stmt);
 }
 
 void Scop::addScopStmt(Region *R, Loop *SurroundingLoop) {
   assert(R && "Unexpected nullptr!");
   Stmts.emplace_back(*this, *R, SurroundingLoop);
   auto *Stmt = &Stmts.back();
   for (BasicBlock *BB : R->blocks())
-    StmtMap[BB] = Stmt;
+    StmtMap[BB].push_back(Stmt);
 }
 
 ScopStmt *Scop::addScopStmt(__isl_take isl_map *SourceRel,
                             __isl_take isl_map *TargetRel,
                             __isl_take isl_set *Domain) {
 #ifndef NDEBUG
   isl_set *SourceDomain = isl_map_domain(isl_map_copy(SourceRel));
   isl_set *TargetDomain = isl_map_domain(isl_map_copy(TargetRel));
while (LoopData.L &&
     LoopData = NextLoopData;
   }
 }
 
 ScopStmt *Scop::getStmtFor(BasicBlock *BB) const {
   auto StmtMapIt = StmtMap.find(BB);
   if (StmtMapIt == StmtMap.end())
     return nullptr;
-  return StmtMapIt->second;
+  assert(StmtMapIt->second.size() == 1);
+  return StmtMapIt->second.front();
 }
 
 ScopStmt *Scop::getStmtFor(RegionNode *RN) const {
   if (RN->isSubRegion())
     return getStmtFor(RN->getNodeAs<Region>());
   return getStmtFor(RN->getNodeAs<BasicBlock>());
 }