[SCEVExpander] Support cost evaluation of several SCEVs with same budget

This is a follow-up from discussion in D138412. Sometimes we want to evaluate
the cost of expansion of several SCEVs together with same budget. For example,
if one of them is a bit above cheap limit, and the second one is free, then
we still want to expand. Checking each of them with "cheap" limit is a bit more
pessimistic.

Differential Revision: https://reviews.llvm.org/D138475
Reviewed By: lebedev.ri

1 files changed, 2 insertions, 5 deletions

diff --git a/llvm/lib/Transforms/Utils/SimplifyIndVar.cpp b/llvm/lib/Transforms/Utils/SimplifyIndVar.cpp
index 84adb6a..9f0ad99 100644
--- a/llvm/lib/Transforms/Utils/SimplifyIndVar.cpp
+++ b/llvm/lib/Transforms/Utils/SimplifyIndVar.cpp
@@ -221,11 +221,8 @@ bool SimplifyIndvar::makeIVComparisonInvariant(ICmpInst *ICmp,
 
   // Do not generate something ridiculous.
   auto *PHTerm = Preheader->getTerminator();
-  if (Rewriter.isHighCostExpansion(InvariantLHS, L, SCEVCheapExpansionBudget,
-                                   TTI, PHTerm))
-    return false;
-  if (Rewriter.isHighCostExpansion(InvariantRHS, L, SCEVCheapExpansionBudget,
-                                   TTI, PHTerm))
+  if (Rewriter.isHighCostExpansion({ InvariantLHS, InvariantRHS }, L,
+                                   2 * SCEVCheapExpansionBudget, TTI, PHTerm))
     return false;
   auto *NewLHS =
       Rewriter.expandCodeFor(InvariantLHS, IVOperand->getType(), PHTerm);