[llvm] fd773e8 - Re-land [MC] Fix quadratic behavior in addPendingLabel

[Alexandre Ganea via llvm-commits]

Author: Alexandre Ganea
Date: 2020-04-26T10:39:42-04:00
New Revision: fd773e8a51b82775f411061117173a21b500642a

URL: https://github.com/llvm/llvm-project/commit/fd773e8a51b82775f411061117173a21b500642a
DIFF: https://github.com/llvm/llvm-project/commit/fd773e8a51b82775f411061117173a21b500642a.diff

LOG: Re-land [MC] Fix quadratic behavior in addPendingLabel

This was discovered when compiling large unity/blob/jumbo files.

Differential Revision: https://reviews.llvm.org/D78775

Added: 
    

Modified: 
    llvm/include/llvm/MC/MCObjectStreamer.h
    llvm/lib/MC/MCObjectStreamer.cpp

Removed: 
    


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diff  --git a/llvm/include/llvm/MC/MCObjectStreamer.h b/llvm/include/llvm/MC/MCObjectStreamer.h
index 48d00fab2fa9..f37f2ad76002 100644
--- a/llvm/include/llvm/MC/MCObjectStreamer.h
+++ b/llvm/include/llvm/MC/MCObjectStreamer.h
@@ -9,6 +9,7 @@
 #ifndef LLVM_MC_MCOBJECTSTREAMER_H
 #define LLVM_MC_MCOBJECTSTREAMER_H
 
+#include "llvm/ADT/SetVector.h"
 #include "llvm/ADT/SmallVector.h"
 #include "llvm/MC/MCAssembler.h"
 #include "llvm/MC/MCSection.h"
@@ -38,7 +39,7 @@ class MCObjectStreamer : public MCStreamer {
   bool EmitEHFrame;
   bool EmitDebugFrame;
   SmallVector<MCSymbol *, 2> PendingLabels;
-  SmallVector<MCSection*, 2> PendingLabelSections;
+  SmallSetVector<MCSection *, 4> PendingLabelSections;
   unsigned CurSubsectionIdx;
   struct PendingMCFixup {
     const MCSymbol *Sym;

diff  --git a/llvm/lib/MC/MCObjectStreamer.cpp b/llvm/lib/MC/MCObjectStreamer.cpp
index 5bb8e76713fb..fd4422fc368c 100644
--- a/llvm/lib/MC/MCObjectStreamer.cpp
+++ b/llvm/lib/MC/MCObjectStreamer.cpp
@@ -59,12 +59,8 @@ void MCObjectStreamer::addPendingLabel(MCSymbol* S) {
     CurSection->addPendingLabel(S, CurSubsectionIdx);
 
     // Add this Section to the list of PendingLabelSections.
-    auto SecIt = std::find(PendingLabelSections.begin(),
-                           PendingLabelSections.end(), CurSection);
-    if (SecIt == PendingLabelSections.end())
-      PendingLabelSections.push_back(CurSection);
-  }
-  else
+    PendingLabelSections.insert(CurSection);
+  } else
     // There is no Section / Subsection for this label yet.
     PendingLabels.push_back(S);
 }