[FIX] Look through div & srem instructions in SCEVs

  The findValues() function did not look through div & srem instructions
  that were part of the argument SCEV. However, in different other
  places we already look through it. This mismatch caused us to preload
  values in the wrong order.

llvm-svn: 265775

1 files changed, 29 insertions, 5 deletions

diff --git a/polly/lib/Support/SCEVValidator.cpp b/polly/lib/Support/SCEVValidator.cpp
index 0bece55de0a..4b91025fd0e 100644
--- a/polly/lib/Support/SCEVValidator.cpp
+++ b/polly/lib/Support/SCEVValidator.cpp
@@ -560,21 +560,45 @@ void findLoops(const SCEV *Expr, SetVector<const Loop *> &Loops) {
 
 /// Find all values referenced in SCEVUnknowns.
 class SCEVFindValues {
+  ScalarEvolution &SE;
   SetVector<Value *> &Values;
 
 public:
-  SCEVFindValues(SetVector<Value *> &Values) : Values(Values) {}
+  SCEVFindValues(ScalarEvolution &SE, SetVector<Value *> &Values)
+      : SE(SE), Values(Values) {}
 
   bool follow(const SCEV *S) {
-    if (const SCEVUnknown *Unknown = dyn_cast<SCEVUnknown>(S))
+    const SCEVUnknown *Unknown = dyn_cast<SCEVUnknown>(S);
+    if (!Unknown)
+      return true;
+
+    Instruction *Inst = dyn_cast<Instruction>(Unknown->getValue());
+    if (!Inst || (Inst->getOpcode() != Instruction::SRem &&
+                  Inst->getOpcode() != Instruction::SDiv)) {
       Values.insert(Unknown->getValue());
-    return true;
+      return false;
+    }
+
+    auto *Dividend = SE.getSCEV(Inst->getOperand(1));
+    if (!isa<SCEVConstant>(Dividend)) {
+      Values.insert(Unknown->getValue());
+      return false;
+    }
+
+    auto *Divisor = SE.getSCEV(Inst->getOperand(0));
+    SCEVFindValues FindValues(SE, Values);
+    SCEVTraversal<SCEVFindValues> ST(FindValues);
+    ST.visitAll(Dividend);
+    ST.visitAll(Divisor);
+
+    return false;
   }
   bool isDone() { return false; }
 };
 
-void findValues(const SCEV *Expr, SetVector<Value *> &Values) {
-  SCEVFindValues FindValues(Values);
+void findValues(const SCEV *Expr, ScalarEvolution &SE,
+                SetVector<Value *> &Values) {
+  SCEVFindValues FindValues(SE, Values);
   SCEVTraversal<SCEVFindValues> ST(FindValues);
   ST.visitAll(Expr);
 }