From d7dc225888b7f6925099cdb0fe4da77a62dd74d4 Mon Sep 17 00:00:00 2001
From: Rafael Espindola <rafael.espindola@gmail.com>
Date: Wed, 10 May 2017 19:13:38 +0000
Subject: [PATCH] Use a DenseMap in LinkerScript::getCmd.

This improves many-sections.s with a linker script from 22s to 0.9s.

llvm-svn: 302708
---
 lld/ELF/LinkerScript.cpp     | 16 ++++++++++------
 lld/ELF/LinkerScript.h       |  3 ++-
 lld/test/ELF/many-sections.s |  5 +++++
 3 files changed, 17 insertions(+), 7 deletions(-)

diff --git a/lld/ELF/LinkerScript.cpp b/lld/ELF/LinkerScript.cpp
index 3277e65..161909a 100644
--- a/lld/ELF/LinkerScript.cpp
+++ b/lld/ELF/LinkerScript.cpp
@@ -415,6 +415,7 @@ void LinkerScript::processCommands(OutputSectionFactory &Factory) {
       if (OutputSection *Sec = Cmd->Sec) {
         assert(Sec->SectionIndex == INT_MAX);
         Sec->SectionIndex = I;
+        SecToCommand[Sec] = Cmd;
       }
     }
   }
@@ -444,6 +445,7 @@ void LinkerScript::fabricateDefaultCommands() {
 
     auto *OSCmd = make<OutputSectionCommand>(Sec->Name);
     OSCmd->Sec = Sec;
+    SecToCommand[Sec] = OSCmd;
 
     // Prefer user supplied address over additional alignment constraint
     auto I = Config->SectionStartMap.find(Sec->Name);
@@ -488,6 +490,7 @@ void LinkerScript::addOrphanSections(OutputSectionFactory &Factory) {
       auto *Cmd = cast<OutputSectionCommand>(*I);
       Factory.addInputSec(S, Name, Cmd->Sec);
       if (OutputSection *Sec = Cmd->Sec) {
+        SecToCommand[Sec] = Cmd;
         unsigned Index = std::distance(Opt.Commands.begin(), I);
         assert(Sec->SectionIndex == INT_MAX || Sec->SectionIndex == Index);
         Sec->SectionIndex = Index;
@@ -703,6 +706,7 @@ void LinkerScript::adjustSectionsBeforeSorting() {
     OutSec->SectionIndex = I;
     OutputSections->push_back(OutSec);
     Cmd->Sec = OutSec;
+    SecToCommand[OutSec] = Cmd;
   }
 }
 
@@ -833,6 +837,7 @@ void LinkerScript::placeOrphanSections() {
       ++CmdIndex;
 
       Cmd->Sec = Sec;
+      SecToCommand[Sec] = Cmd;
       auto *ISD = make<InputSectionDescription>("");
       for (InputSection *IS : Sec->Sections)
         ISD->Sections.push_back(IS);
@@ -1025,12 +1030,11 @@ bool LinkerScript::ignoreInterpSection() {
   return true;
 }
 
-OutputSectionCommand *LinkerScript::getCmd(OutputSection *Sec) {
-  for (BaseCommand *Base : Opt.Commands)
-    if (auto *Cmd = dyn_cast<OutputSectionCommand>(Base))
-      if (Cmd->Sec == Sec)
-        return Cmd;
-  return nullptr;
+OutputSectionCommand *LinkerScript::getCmd(OutputSection *Sec) const {
+  auto I = SecToCommand.find(Sec);
+  if (I == SecToCommand.end())
+    return nullptr;
+  return I->second;
 }
 
 Optional<uint32_t> LinkerScript::getFiller(OutputSection *Sec) {
diff --git a/lld/ELF/LinkerScript.h b/lld/ELF/LinkerScript.h
index ef7ecba..d0a4d83 100644
--- a/lld/ELF/LinkerScript.h
+++ b/lld/ELF/LinkerScript.h
@@ -212,7 +212,8 @@ struct ScriptConfiguration {
 };
 
 class LinkerScript final {
-  OutputSectionCommand *getCmd(OutputSection *Sec);
+  llvm::DenseMap<OutputSection *, OutputSectionCommand *> SecToCommand;
+  OutputSectionCommand *getCmd(OutputSection *Sec) const;
   void assignSymbol(SymbolAssignment *Cmd, bool InSec);
   void setDot(Expr E, const Twine &Loc, bool InSec);
 
diff --git a/lld/test/ELF/many-sections.s b/lld/test/ELF/many-sections.s
index 77e76c2..ae82868 100644
--- a/lld/test/ELF/many-sections.s
+++ b/lld/test/ELF/many-sections.s
@@ -14,6 +14,11 @@
 // RUN: ld.lld %t -o %t2
 // RUN: llvm-readobj -t %t2 | FileCheck --check-prefix=LINKED %s
 
+// Test also with a linker script.
+// RUN: echo "SECTIONS { . = SIZEOF_HEADERS; .text : { *(.text) } }" > %t.script
+// RUN: ld.lld -T %t.script %t -o %t2
+// RUN: llvm-readobj -t %t2 | FileCheck --check-prefix=LINKED %s
+
 // Test that _start is in the correct section.
 // LINKED:      Name: _start
 // LINKED-NEXT: Value: 0x0
-- 
2.7.4