[llvm] 4e04a53 - [TableGen] Avoid a couple vector copies in ExpandHwModeBasedTypes.

[Craig Topper via llvm-commits]

Author: Craig Topper
Date: 2021-01-30T13:16:39-08:00
New Revision: 4e04a535d8f836804d39e8861ae17d7817293c5a

URL: https://github.com/llvm/llvm-project/commit/4e04a535d8f836804d39e8861ae17d7817293c5a
DIFF: https://github.com/llvm/llvm-project/commit/4e04a535d8f836804d39e8861ae17d7817293c5a.diff

LOG: [TableGen] Avoid a couple vector copies in ExpandHwModeBasedTypes.

Use vector::swap instead of copying to a local vector and clearing
the original. We can just swap into the just created local vector
instead which will move the pointers and not the data.

Use std::move in another place to avoid a copy.

Added: 
    

Modified: 
    llvm/utils/TableGen/CodeGenDAGPatterns.cpp

Removed: 
    


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diff  --git a/llvm/utils/TableGen/CodeGenDAGPatterns.cpp b/llvm/utils/TableGen/CodeGenDAGPatterns.cpp
index 1ca4a68eb155..d4409db2837e 100644
--- a/llvm/utils/TableGen/CodeGenDAGPatterns.cpp
+++ b/llvm/utils/TableGen/CodeGenDAGPatterns.cpp
@@ -4282,8 +4282,8 @@ static void collectModes(std::set<unsigned> &Modes, const TreePatternNode *N) {
 void CodeGenDAGPatterns::ExpandHwModeBasedTypes() {
   const CodeGenHwModes &CGH = getTargetInfo().getHwModes();
   std::map<unsigned,std::vector<Predicate>> ModeChecks;
-  std::vector<PatternToMatch> Copy = PatternsToMatch;
-  PatternsToMatch.clear();
+  std::vector<PatternToMatch> Copy;
+  PatternsToMatch.swap(Copy);
 
   auto AppendPattern = [this, &ModeChecks](PatternToMatch &P, unsigned Mode) {
     TreePatternNodePtr NewSrc = P.SrcPattern->clone();
@@ -4295,8 +4295,9 @@ void CodeGenDAGPatterns::ExpandHwModeBasedTypes() {
     std::vector<Predicate> Preds = P.Predicates;
     const std::vector<Predicate> &MC = ModeChecks[Mode];
     llvm::append_range(Preds, MC);
-    PatternsToMatch.emplace_back(P.getSrcRecord(), Preds, std::move(NewSrc),
-                                 std::move(NewDst), P.getDstRegs(),
+    PatternsToMatch.emplace_back(P.getSrcRecord(), std::move(Preds),
+                                 std::move(NewSrc), std::move(NewDst),
+                                 P.getDstRegs(),
                                  P.getAddedComplexity(), Record::getNewUID(),
                                  Mode);
   };