[llvm] df77ce7 - [SCEV] Extract code to collect conditions to lambda (NFC).

[Florian Hahn via llvm-commits]

Author: Florian Hahn
Date: 2020-09-25T15:12:42+01:00
New Revision: df77ce7cad081bf55042cf098b61b118dcdfc7e9

URL: https://github.com/llvm/llvm-project/commit/df77ce7cad081bf55042cf098b61b118dcdfc7e9
DIFF: https://github.com/llvm/llvm-project/commit/df77ce7cad081bf55042cf098b61b118dcdfc7e9.diff

LOG: [SCEV] Extract code to collect conditions to lambda (NFC).

This makes re-using the common functionality easier in follow-up
patches.

Added: 
    

Modified: 
    llvm/lib/Analysis/ScalarEvolution.cpp

Removed: 
    


################################################################################
diff  --git a/llvm/lib/Analysis/ScalarEvolution.cpp b/llvm/lib/Analysis/ScalarEvolution.cpp
index c4e639e54e42..980c75f3073b 100644
--- a/llvm/lib/Analysis/ScalarEvolution.cpp
+++ b/llvm/lib/Analysis/ScalarEvolution.cpp
@@ -12591,6 +12591,32 @@ const SCEV* ScalarEvolution::computeMaxBackedgeTakenCount(const Loop *L) {
 }
 
 const SCEV *ScalarEvolution::applyLoopGuards(const SCEV *Expr, const Loop *L) {
+  auto CollectCondition = [&](ICmpInst::Predicate Predicate, const SCEV *LHS,
+                              const SCEV *RHS, ValueToSCEVMapTy &RewriteMap) {
+    // For now, limit to conditions that provide information about unknown
+    // expressions.
+    auto *LHSUnknown = dyn_cast<SCEVUnknown>(LHS);
+    if (!LHSUnknown)
+      return;
+
+    // TODO: use information from more predicates.
+    switch (Predicate) {
+    case CmpInst::ICMP_ULT: {
+      if (!containsAddRecurrence(RHS)) {
+        const SCEV *Base = LHS;
+        auto I = RewriteMap.find(LHSUnknown->getValue());
+        if (I != RewriteMap.end())
+          Base = I->second;
+
+        RewriteMap[LHSUnknown->getValue()] =
+            getUMinExpr(Base, getMinusSCEV(RHS, getOne(RHS->getType())));
+      }
+      break;
+    }
+    default:
+      break;
+    }
+  };
   // Starting at the loop predecessor, climb up the predecessor chain, as long
   // as there are predecessors that can be found that have unique successors
   // leading to the original header.
@@ -12613,26 +12639,8 @@ const SCEV *ScalarEvolution::applyLoopGuards(const SCEV *Expr, const Loop *L) {
     auto Predicate = Cmp->getPredicate();
     if (LoopEntryPredicate->getSuccessor(1) == Pair.second)
       Predicate = CmpInst::getInversePredicate(Predicate);
-    // TODO: use information from more predicates.
-    switch (Predicate) {
-    case CmpInst::ICMP_ULT: {
-      const SCEV *LHS = getSCEV(Cmp->getOperand(0));
-      const SCEV *RHS = getSCEV(Cmp->getOperand(1));
-      if (isa<SCEVUnknown>(LHS) && !isa<UndefValue>(Cmp->getOperand(0)) &&
-          !containsAddRecurrence(RHS)) {
-        const SCEV *Base = LHS;
-        auto I = RewriteMap.find(Cmp->getOperand(0));
-        if (I != RewriteMap.end())
-          Base = I->second;
-
-        RewriteMap[Cmp->getOperand(0)] =
-            getUMinExpr(Base, getMinusSCEV(RHS, getOne(RHS->getType())));
-      }
-      break;
-    }
-    default:
-      break;
-    }
+    CollectCondition(Predicate, getSCEV(Cmp->getOperand(0)),
+                     getSCEV(Cmp->getOperand(1)), RewriteMap);
   }
 
   if (RewriteMap.empty())