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.

llvm-svn: 282285

lld/ELF/LinkerScript.cpp

@@ -383,10 +383,13 @@ template <class ELFT> void LinkerScript<ELFT>::output(InputSection<ELFT> *S) {
 }
 
 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<ELFT>::process(BaseCommand &Base) {
     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(OutputSectionCommand *Cmd) {
                .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()); });
 }

lld/test/ELF/linkerscript/double-bss.s

@@ -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: