Codegen: Copy and restore the ValueMap and ClastVars explicitly

When generating OpenMP or GPGPU code the original ValueMap and ClastVars must be
kept. We already recovered the original ClastVars by reverting the changes, but
we did not keep the content of the ValueMap. This patch keeps now an explicit
copy of both maps and restores them after generating OpenMP or GPGPU code.

This is an adapted version of a patch contributed by:
Armin Groesslinger  <armin.groesslinger@uni-passau.de>

llvm-svn: 167213

diff --git a/polly/lib/CodeGen/CodeGeneration.cpp b/polly/lib/CodeGen/CodeGeneration.cpp
index fcd2d52..d713ae4 100644 (file)
--- a/polly/lib/CodeGen/CodeGeneration.cpp
+++ b/polly/lib/CodeGen/CodeGeneration.cpp
@@ -285,12 +285,10 @@ private:
   /// structure.
   SetVector<Value*> getOMPValues();
 
-  /// @brief Update the internal structures according to a Value Map.
+  /// @brief Update ClastVars and ValueMap according to a value map.
   ///
-  /// @param VMap     A map from old to new values.
-  /// @param Reverse  If true, we assume the update should be reversed.
-  void updateWithValueMap(OMPGenerator::ValueToValueMapTy &VMap,
-                          bool Reverse);
+  /// @param VMap A map from old to new values.
+  void updateWithValueMap(OMPGenerator::ValueToValueMapTy &VMap);
 
   /// @brief Create an OpenMP parallel for loop.
   ///
@@ -484,37 +482,18 @@ SetVector<Value*> ClastStmtCodeGen::getOMPValues() {
   return Values;
 }
 
-void ClastStmtCodeGen::updateWithValueMap(OMPGenerator::ValueToValueMapTy &VMap,
-                                          bool Reverse) {
+void ClastStmtCodeGen::updateWithValueMap(
+  OMPGenerator::ValueToValueMapTy &VMap) {
   std::set<Value*> Inserted;
 
-  if (Reverse) {
-    OMPGenerator::ValueToValueMapTy ReverseMap;
-
-    for (std::map<Value*, Value*>::iterator I = VMap.begin(), E = VMap.end();
-         I != E; ++I)
-       ReverseMap.insert(std::make_pair(I->second, I->first));
-
-    for (CharMapT::iterator I = ClastVars.begin(), E = ClastVars.end();
-         I != E; I++) {
-      ClastVars[I->first] = ReverseMap[I->second];
-      Inserted.insert(I->second);
-    }
-
-    /// FIXME: At the moment we do not reverse the update of the ValueMap.
-    ///        This is incomplet, but the failure should be obvious, such that
-    ///        we can fix this later.
-    return;
-  }
-
   for (CharMapT::iterator I = ClastVars.begin(), E = ClastVars.end();
        I != E; I++) {
     ClastVars[I->first] = VMap[I->second];
     Inserted.insert(I->second);
   }
 
-  for (std::map<Value*, Value*>::iterator I = VMap.begin(), E = VMap.end();
-       I != E; ++I) {
+  for (OMPGenerator::ValueToValueMapTy::iterator I = VMap.begin(),
+       E = VMap.end(); I != E; ++I) {
     if (Inserted.count(I->first))
       continue;
 
@@ -552,14 +531,19 @@ void ClastStmtCodeGen::codegenForOpenMP(const clast_for *For) {
   BasicBlock::iterator AfterLoop = Builder.GetInsertPoint();
   Builder.SetInsertPoint(LoopBody);
 
-  updateWithValueMap(VMap, /* reverse */ false);
+  // Save the current values.
+  const ValueMapT ValueMapCopy = ValueMap;
+  const CharMapT ClastVarsCopy = ClastVars;
+
+  updateWithValueMap(VMap);
   ClastVars[For->iterator] = IV;
 
   if (For->body)
     codegen(For->body);
 
-  ClastVars.erase(For->iterator);
-  updateWithValueMap(VMap, /* reverse */ true);
+  // Restore the original values.
+  ValueMap = ValueMapCopy;
+  ClastVars = ClastVarsCopy;
 
   clearDomtree((*LoopBody).getParent()->getParent(),
                P->getAnalysis<DominatorTree>());
@@ -698,9 +682,16 @@ void ClastStmtCodeGen::codegenForGPGPU(const clast_for *F) {
     VMap.insert(std::make_pair<Value*, Value*>(OldIV, IV));
   }
 
-  updateWithValueMap(VMap, /* reverse */ false);
+  // Preserve the current values.
+  const ValueMapT ValueMapCopy = ValueMap;
+  const CharMapT ClastVarsCopy = ClastVars;
+  updateWithVMap(VMap);
+
   BlockGenerator::generate(Builder, *Statement, ValueMap, P);
-  updateWithValueMap(VMap, /* reverse */ true);
+
+  // Restore the original values.
+  ValueMap = ValueMapCopy;
+  ClastVars = ClastVarsCopy;
 
   if (AfterBB)
     Builder.SetInsertPoint(AfterBB->begin());

diff --git a/polly/test/CodeGen/OpenMP/clastvar_after_parallel_loop.ll b/polly/test/CodeGen/OpenMP/clastvar_after_parallel_loop.ll
new file mode 100644 (file)
index 0000000..3e44784
--- /dev/null
+++ b/polly/test/CodeGen/OpenMP/clastvar_after_parallel_loop.ll
@@ -0,0 +1,56 @@
+; RUN: opt %loadPolly -basicaa -polly-cloog -analyze -S < %s | FileCheck %s -check-prefix=CLOOG
+; RUN: opt %loadPolly -basicaa -polly-codegen -enable-polly-openmp -S < %s | FileCheck %s
+;
+; Test case that checks that after the parallel loop on j the value for i is
+; taken from the right temporary (in particular, _not_ the temporary used for i
+; in the OpenMP subfunction for the loop on j).
+;
+; void f(long * restrict A) {
+;     long i, j;
+;     for (i=0; i<100; ++i) {
+;         #pragma omp parallel
+;         for (j=0; j<100; ++j)
+;             A[j] += i;
+;         A[i] = 42;
+;     }
+; }
+target datalayout = "e-p:64:64:64-i1:8:8-i8:8:8-i16:16:16-i32:32:32-i64:64:64-f32:32:32-f64:64:64-v64:64:64-v128:128:128-a0:0:64-s0:64:64-f80:128:128-n8:16:32:64-S128"
+target triple = "x86_64-unknown-linux-gnu"
+
+define void @f(i64* noalias nocapture %A) {
+entry:
+  br label %for.i
+
+for.i:
+  %i = phi i64 [ %i.next, %for.end ], [ 0, %entry ]
+  br label %for.j
+
+for.j:                                     ; preds = %for.j, %for.i
+  %j = phi i64 [ 0, %for.i ], [ %j.next, %for.j ]
+  %i.arrayidx = getelementptr inbounds i64* %A, i64 %j
+  %load = load i64* %i.arrayidx
+  %add = add nsw i64 %load, %i
+  store i64 %add, i64* %i.arrayidx
+  %j.next = add i64 %j, 1
+  %j.exitcond = icmp eq i64 %j.next, 100
+  br i1 %j.exitcond, label %for.end, label %for.j
+
+for.end:                                       ; preds = %for.j
+  %j.arrayidx = getelementptr inbounds i64* %A, i64 %i
+  store i64 42, i64* %j.arrayidx
+  %i.next = add i64 %i, 1
+  %i.exitcond = icmp eq i64 %i.next, 100
+  br i1 %i.exitcond, label %end, label %for.i
+
+end:                                         ; preds = %for.end, %entry
+  ret void
+}
+
+; CLOOG: for (c2=0;c2<=99;c2++) {
+; CLOOG:   for (c4=0;c4<=99;c4++) {
+; CLOOG:     Stmt_for_j(c2,c4);
+; CLOOG:   }
+; CLOOG:   Stmt_for_end(c2);
+; CLOOG: }
+
+; CHECK: @f.omp_subfn