[SCEVExpander] Don't hoist divisions

Fixes PR30942.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@286437 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 42 insertions, 32 deletions

diff --git a/lib/Analysis/ScalarEvolutionExpander.cpp b/lib/Analysis/ScalarEvolutionExpander.cpp
index 6ad766b4bd7..d94782ab899 100644
--- a/lib/Analysis/ScalarEvolutionExpander.cpp
+++ b/lib/Analysis/ScalarEvolutionExpander.cpp
@@ -198,14 +198,21 @@ Value *SCEVExpander::InsertBinop(Instruction::BinaryOps Opcode,
   DebugLoc Loc = Builder.GetInsertPoint()->getDebugLoc();
   SCEVInsertPointGuard Guard(Builder, this);
 
-  // Move the insertion point out of as many loops as we can.
-  while (const Loop *L = SE.LI.getLoopFor(Builder.GetInsertBlock())) {
-    if (!L->isLoopInvariant(LHS) || !L->isLoopInvariant(RHS)) break;
-    BasicBlock *Preheader = L->getLoopPreheader();
-    if (!Preheader) break;
-
-    // Ok, move up a level.
-    Builder.SetInsertPoint(Preheader->getTerminator());
+  if (Opcode != Instruction::UDiv) {
+    // FIXME: There is alredy similar logic in expandCodeFor, we should see if
+    // this is actually needed here.
+
+    // Move the insertion point out of as many loops as we can.
+    while (const Loop *L = SE.LI.getLoopFor(Builder.GetInsertBlock())) {
+      if (!L->isLoopInvariant(LHS) || !L->isLoopInvariant(RHS))
+        break;
+      BasicBlock *Preheader = L->getLoopPreheader();
+      if (!Preheader)
+        break;
+
+      // Ok, move up a level.
+      Builder.SetInsertPoint(Preheader->getTerminator());
+    }
   }
 
   // If we haven't found this binop, insert it.
@@ -1663,31 +1670,34 @@ Value *SCEVExpander::expand(const SCEV *S) {
   // Compute an insertion point for this SCEV object. Hoist the instructions
   // as far out in the loop nest as possible.
   Instruction *InsertPt = &*Builder.GetInsertPoint();
-  for (Loop *L = SE.LI.getLoopFor(Builder.GetInsertBlock());;
-       L = L->getParentLoop())
-    if (SE.isLoopInvariant(S, L)) {
-      if (!L) break;
-      if (BasicBlock *Preheader = L->getLoopPreheader())
-        InsertPt = Preheader->getTerminator();
-      else {
-        // LSR sets the insertion point for AddRec start/step values to the
-        // block start to simplify value reuse, even though it's an invalid
-        // position. SCEVExpander must correct for this in all cases.
-        InsertPt = &*L->getHeader()->getFirstInsertionPt();
-      }
-    } else {
-      // If the SCEV is computable at this level, insert it into the header
-      // after the PHIs (and after any other instructions that we've inserted
-      // there) so that it is guaranteed to dominate any user inside the loop.
-      if (L && SE.hasComputableLoopEvolution(S, L) && !PostIncLoops.count(L))
-        InsertPt = &*L->getHeader()->getFirstInsertionPt();
-      while (InsertPt->getIterator() != Builder.GetInsertPoint() &&
-             (isInsertedInstruction(InsertPt) ||
-              isa<DbgInfoIntrinsic>(InsertPt))) {
-        InsertPt = &*std::next(InsertPt->getIterator());
+  if (!isa<SCEVUDivExpr>(S)) {
+    for (Loop *L = SE.LI.getLoopFor(Builder.GetInsertBlock());;
+         L = L->getParentLoop())
+      if (SE.isLoopInvariant(S, L)) {
+        if (!L)
+          break;
+        if (BasicBlock *Preheader = L->getLoopPreheader())
+          InsertPt = Preheader->getTerminator();
+        else {
+          // LSR sets the insertion point for AddRec start/step values to the
+          // block start to simplify value reuse, even though it's an invalid
+          // position. SCEVExpander must correct for this in all cases.
+          InsertPt = &*L->getHeader()->getFirstInsertionPt();
+        }
+      } else {
+        // If the SCEV is computable at this level, insert it into the header
+        // after the PHIs (and after any other instructions that we've inserted
+        // there) so that it is guaranteed to dominate any user inside the loop.
+        if (L && SE.hasComputableLoopEvolution(S, L) && !PostIncLoops.count(L))
+          InsertPt = &*L->getHeader()->getFirstInsertionPt();
+        while (InsertPt->getIterator() != Builder.GetInsertPoint() &&
+               (isInsertedInstruction(InsertPt) ||
+                isa<DbgInfoIntrinsic>(InsertPt))) {
+          InsertPt = &*std::next(InsertPt->getIterator());
+        }
+        break;
       }
-      break;
-    }
+  }
 
   // Check to see if we already expanded this here.
   auto I = InsertedExpressions.find(std::make_pair(S, InsertPt));