[lld] r282285 - Avoid counting sections twice.

[Rafael Espindola via llvm-commits]

Author: rafael
Date: Fri Sep 23 15:10:47 2016
New Revision: 282285

URL: http://llvm.org/viewvc/llvm-project?rev=282285&view=rev
Log:
Avoid counting sections twice.

We were counting the size of the bss section holding common symbols twice:

    Dot += CurOutSec->getSize();
    flush();

The new code is also simpler as now flush is the only function that
inserts in AlreadyOutputOS, which makes sense since the set hold fully
output sections.

Modified:
    lld/trunk/ELF/LinkerScript.cpp
    lld/trunk/test/ELF/linkerscript/double-bss.s

Modified: lld/trunk/ELF/LinkerScript.cpp
URL: http://llvm.org/viewvc/llvm-project/lld/trunk/ELF/LinkerScript.cpp?rev=282285&r1=282284&r2=282285&view=diff
==============================================================================
--- lld/trunk/ELF/LinkerScript.cpp (original)
+++ lld/trunk/ELF/LinkerScript.cpp Fri Sep 23 15:10:47 2016
@@ -383,10 +383,13 @@ template <class ELFT> void LinkerScript<
 }
 
 template <class ELFT> void LinkerScript<ELFT>::flush() {
-  if (auto *OutSec = dyn_cast_or_null<OutputSection<ELFT>>(CurOutSec)) {
+  if (!CurOutSec || !AlreadyOutputOS.insert(CurOutSec).second)
+    return;
+  if (auto *OutSec = dyn_cast<OutputSection<ELFT>>(CurOutSec)) {
     for (InputSection<ELFT> *I : OutSec->Sections)
       output(I);
-    AlreadyOutputOS.insert(CurOutSec);
+  } else {
+    Dot += CurOutSec->getSize();
   }
 }
 
@@ -421,8 +424,8 @@ template <class ELFT> void LinkerScript<
     switchTo(IB->OutSec);
     if (auto *I = dyn_cast<InputSection<ELFT>>(IB))
       output(I);
-    else if (AlreadyOutputOS.insert(CurOutSec).second)
-      Dot += CurOutSec->getSize();
+    else
+      flush();
   }
 }
 
@@ -454,14 +457,9 @@ void LinkerScript<ELFT>::assignOffsets(O
                .base();
   for (auto I = Cmd->Commands.begin(); I != E; ++I)
     process(**I);
-  flush();
-  for (OutputSectionBase<ELFT> *Base : Sections) {
-    if (AlreadyOutputOS.count(Base))
-      continue;
+  for (OutputSectionBase<ELFT> *Base : Sections)
     switchTo(Base);
-    Dot += CurOutSec->getSize();
-    flush();
-  }
+  flush();
   std::for_each(E, Cmd->Commands.end(),
                 [this](std::unique_ptr<BaseCommand> &B) { process(*B.get()); });
 }

Modified: lld/trunk/test/ELF/linkerscript/double-bss.s
URL: http://llvm.org/viewvc/llvm-project/lld/trunk/test/ELF/linkerscript/double-bss.s?rev=282285&r1=282284&r2=282285&view=diff
==============================================================================
--- lld/trunk/test/ELF/linkerscript/double-bss.s (original)
+++ lld/trunk/test/ELF/linkerscript/double-bss.s Fri Sep 23 15:10:47 2016
@@ -4,7 +4,7 @@
 # RUN: ld.lld -o %t1 --script %t.script %t
 # RUN: llvm-objdump -section-headers %t1 | FileCheck %s
 # CHECK:      .bss          00000004 0000000000000122 BSS
-# CHECK-NEXT: .bss          00000100 0000000000000128 BSS
+# CHECK-NEXT: .bss          00000080 0000000000000128 BSS
 
 .globl _start
 _start: