[llvm] r327721 - This patch fixes the invalid usage of OptSize in Machine Combiner.

[Andrew V. Tischenko via llvm-commits]

Author: avt77
Date: Fri Mar 16 09:06:24 2018
New Revision: 327721

URL: http://llvm.org/viewvc/llvm-project?rev=327721&view=rev
Log:
This patch fixes the invalid usage of OptSize in Machine Combiner.
Differential Revision: https://reviews.llvm.org/D43813

Modified:
    llvm/trunk/lib/CodeGen/MachineCombiner.cpp

Modified: llvm/trunk/lib/CodeGen/MachineCombiner.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/CodeGen/MachineCombiner.cpp?rev=327721&r1=327720&r2=327721&view=diff
==============================================================================
--- llvm/trunk/lib/CodeGen/MachineCombiner.cpp (original)
+++ llvm/trunk/lib/CodeGen/MachineCombiner.cpp Fri Mar 16 09:06:24 2018
@@ -407,8 +407,8 @@ bool MachineCombiner::preservesResourceL
 /// \returns true when new instruction sequence should be generated
 /// independent if it lengthens critical path or not
 bool MachineCombiner::doSubstitute(unsigned NewSize, unsigned OldSize) {
-  if (OptSize && (NewSize < OldSize))
-    return true;
+  if (OptSize)                   // First of all check OptSize option
+    return (NewSize < OldSize);  // Only substitute if new size < old size
   if (!TSchedModel.hasInstrSchedModelOrItineraries())
     return true;
   return false;
@@ -588,7 +588,7 @@ bool MachineCombiner::combineInstruction
         // Eagerly stop after the first pattern fires.
         Changed = true;
         break;
-      } else {
+      } else if (!OptSize || (NewInstCount <= OldInstCount)) {
         // For big basic blocks, we only compute the full trace the first time
         // we hit this. We do not invalidate the trace, but instead update the
         // instruction depths incrementally.