[llvm] r343686 - [RA CopyHints] Fix compile-time regression

[Jonas Paulsson via llvm-commits]

Author: jonpa
Date: Wed Oct  3 05:51:19 2018
New Revision: 343686

URL: http://llvm.org/viewvc/llvm-project?rev=343686&view=rev
Log:
[RA CopyHints] Fix compile-time regression

This patch makes sure that a register is only hinted once to RA. In extreme
cases the same register can otherwise be hinted numerous times and cause a
compile time slowdown.

Review: Simon Pilgrim
https://reviews.llvm.org/D52826

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

Modified: llvm/trunk/lib/CodeGen/CalcSpillWeights.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/CodeGen/CalcSpillWeights.cpp?rev=343686&r1=343685&r2=343686&view=diff
==============================================================================
--- llvm/trunk/lib/CodeGen/CalcSpillWeights.cpp (original)
+++ llvm/trunk/lib/CodeGen/CalcSpillWeights.cpp Wed Oct  3 05:51:19 2018
@@ -287,9 +287,11 @@ float VirtRegAuxInfo::weightCalcHelper(L
     if (TargetHint.first == 0 && TargetHint.second)
       mri.clearSimpleHint(li.reg);
 
+    std::set<unsigned> HintedRegs;
     for (auto &Hint : CopyHints) {
-      if (TargetHint.first != 0 && Hint.Reg == TargetHint.second)
-        // Don't add again the target-type hint.
+      if (!HintedRegs.insert(Hint.Reg).second ||
+          (TargetHint.first != 0 && Hint.Reg == TargetHint.second))
+        // Don't add the same reg twice or the target-type hint again.
         continue;
       mri.addRegAllocationHint(li.reg, Hint.Reg);
       if (!tri.enableMultipleCopyHints())