[FIX] Don't consider reductions which are partially outside the SCoP

  + Test case

llvm-svn: 212080

2 files changed, 71 insertions, 2 deletions

diff --git a/polly/lib/Analysis/ScopInfo.cpp b/polly/lib/Analysis/ScopInfo.cpp
index abd865670db..4cc1e80b73f 100644
--- a/polly/lib/Analysis/ScopInfo.cpp
+++ b/polly/lib/Analysis/ScopInfo.cpp
@@ -732,6 +732,10 @@ void ScopStmt::collectCandiateReductionLoads(
   if (!BinOp->isCommutative() || !BinOp->isAssociative())
     return;
 
+  // Skip if the binary operator is outside the current SCoP
+  if (BinOp->getParent() != Store->getParent())
+    return;
+
   // Skip if it is a multiplicative reduction and we disabled them
   if (DisableMultiplicativeReductions &&
       (BinOp->getOpcode() == Instruction::Mul ||
@@ -746,9 +750,11 @@ void ScopStmt::collectCandiateReductionLoads(
 
   // A load is only a candidate if it cannot escape (thus has only this use)
   if (PossibleLoad0 && PossibleLoad0->getNumUses() == 1)
-    Loads.push_back(lookupAccessFor(PossibleLoad0));
+    if (PossibleLoad0->getParent() == Store->getParent())
+      Loads.push_back(lookupAccessFor(PossibleLoad0));
   if (PossibleLoad1 && PossibleLoad1->getNumUses() == 1)
-    Loads.push_back(lookupAccessFor(PossibleLoad1));
+    if (PossibleLoad1->getParent() == Store->getParent())
+      Loads.push_back(lookupAccessFor(PossibleLoad1));
 }
 
 /// @brief Check for reductions in this ScopStmt
diff --git a/polly/test/ScopInfo/reduction_chain_partially_outside_the_scop.ll b/polly/test/ScopInfo/reduction_chain_partially_outside_the_scop.ll
new file mode 100644
index 00000000000..248d29e3502
--- /dev/null
+++ b/polly/test/ScopInfo/reduction_chain_partially_outside_the_scop.ll
@@ -0,0 +1,63 @@
+; RUN: opt %loadPolly -polly-scops -analyze < %s | FileCheck %s
+;
+; CHECK-NOT: Reduction like: 1
+;
+;    int c, d;
+;    void f(int *sum) {
+;      for (int i = 0; i < 1024; i++)
+;        *sum = c + d;
+;    }
+;
+target datalayout = "e-m:e-p:32:32-i64:64-v128:64:128-n32-S64"
+
+@c = common global i32 0, align 4
+@d = common global i32 0, align 4
+
+define void @loads_outside_scop(i32* %sum) {
+entry:
+  %tmp = load i32* @c, align 4
+  %tmp1 = load i32* @d, align 4
+  br label %for.cond
+
+for.cond:                                         ; preds = %for.inc, %entry
+  %i.0 = phi i32 [ 0, %entry ], [ %inc, %for.inc ]
+  %exitcond = icmp ne i32 %i.0, 1024
+  br i1 %exitcond, label %for.body, label %for.end
+
+for.body:                                         ; preds = %for.cond
+  %add = add nsw i32 %tmp, %tmp1
+  store i32 %add, i32* %sum, align 4
+  br label %for.inc
+
+for.inc:                                          ; preds = %for.body
+  %inc = add nsw i32 %i.0, 1
+  br label %for.cond
+
+for.end:                                          ; preds = %for.cond
+  ret void
+}
+
+
+define void @binop_outside_scop(i32* %sum) {
+entry:
+  %tmp = load i32* @c, align 4
+  %tmp1 = load i32* @d, align 4
+  %add = add nsw i32 %tmp, %tmp1
+  br label %for.cond
+
+for.cond:                                         ; preds = %for.inc, %entry
+  %i.0 = phi i32 [ 0, %entry ], [ %inc, %for.inc ]
+  %exitcond = icmp ne i32 %i.0, 1024
+  br i1 %exitcond, label %for.body, label %for.end
+
+for.body:                                         ; preds = %for.cond
+  store i32 %add, i32* %sum, align 4
+  br label %for.inc
+
+for.inc:                                          ; preds = %for.body
+  %inc = add nsw i32 %i.0, 1
+  br label %for.cond
+
+for.end:                                          ; preds = %for.cond
+  ret void
+}