Add a new SCEV representing signed division.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@60407 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 9 insertions, 0 deletions

diff --git a/lib/Analysis/ScalarEvolutionExpander.cpp b/lib/Analysis/ScalarEvolutionExpander.cpp
index 30df087cef..211f013c25 100644
--- a/lib/Analysis/ScalarEvolutionExpander.cpp
+++ b/lib/Analysis/ScalarEvolutionExpander.cpp
@@ -143,6 +143,15 @@ Value *SCEVExpander::visitUDivExpr(SCEVUDivExpr *S) {
   return InsertBinop(Instruction::UDiv, LHS, RHS, InsertPt);
 }
 
+Value *SCEVExpander::visitSDivExpr(SCEVSDivExpr *S) {
+  // Do not fold sdiv into ashr, unless you know that LHS is positive. On
+  // negative values, it rounds the wrong way.
+
+  Value *LHS = expand(S->getLHS());
+  Value *RHS = expand(S->getRHS());
+  return InsertBinop(Instruction::SDiv, LHS, RHS, InsertPt);
+}
+
 Value *SCEVExpander::visitAddRecExpr(SCEVAddRecExpr *S) {
   const Type *Ty = S->getType();
   const Loop *L = S->getLoop();