commit 284a750c5ff95a29cd8cc9130d3eb7ec6d25e352
author Rafael Espindola <rafael.espindola@gmail.com> Fri Jun 19 12:16:55 2015 +0000
committer Rafael Espindola <rafael.espindola@gmail.com> Fri Jun 19 12:16:55 2015 +0000
tree 38c934be221f58276592baa899f0514b9ac2d46b
parent 9fb676a2543434ed0df96649195a0529b23a8dea

Make all temporary symbols unnamed.

What this does is make all symbols that would otherwise start with a .L
(or L on MachO) unnamed.

Some of these symbols still show up in the symbol table, but we can just
make them unnamed.

In order to make sure we produce identical results when going thought assembly,
all .L (not just the compiler produced ones), are now unnamed.

Running llc on llvm-as.opt.bc, the peak memory usage goes from 208.24MB to
205.57MB.

llvm-svn: 240130

llvm/lib/MC/ELFObjectWriter.cpp

diff --git a/llvm/lib/MC/ELFObjectWriter.cpp b/llvm/lib/MC/ELFObjectWriter.cpp
index 0765937..bbf0b2b 100644
--- a/llvm/lib/MC/ELFObjectWriter.cpp
+++ b/llvm/lib/MC/ELFObjectWriter.cpp
@@ -786,10 +786,15 @@
                     Renames.count(&Symbol)))
       continue;
 
+    if (Symbol.isTemporary() && Symbol.isUndefined())
+      Ctx.reportFatalError(SMLoc(), "Undefined temporary");
+
     ELFSymbolData MSD;
     MSD.Symbol = cast<MCSymbolELF>(&Symbol);
 
     bool Local = Symbol.getBinding() == ELF::STB_LOCAL;
+    assert(Local || !Symbol.isTemporary());
+
     if (Symbol.isAbsolute()) {
       MSD.SectionIndex = ELF::SHN_ABS;
     } else if (Symbol.isCommon()) {
@@ -888,9 +893,11 @@
   unsigned Index = FileNames.size() + 1;
 
   for (ELFSymbolData &MSD : LocalSymbolData) {
-    unsigned StringIndex = MSD.Symbol->getType() == ELF::STT_SECTION
-                               ? 0
-                               : StrTabBuilder.getOffset(MSD.Name);
+    unsigned StringIndex;
+    if (MSD.Symbol->getType() == ELF::STT_SECTION || MSD.Name.empty())
+      StringIndex = 0;
+    else
+      StringIndex = StrTabBuilder.getOffset(MSD.Name);
     MSD.Symbol->setIndex(Index++);
     writeSymbol(Writer, StringIndex, MSD, Layout);
   }

llvm/lib/MC/MCContext.cpp

diff --git a/llvm/lib/MC/MCContext.cpp b/llvm/lib/MC/MCContext.cpp
index c601c56..01074eb 100644
--- a/llvm/lib/MC/MCContext.cpp
+++ b/llvm/lib/MC/MCContext.cpp
@@ -116,7 +116,7 @@
 
   MCSymbol *&Sym = Symbols[NameRef];
   if (!Sym)
-    Sym = createSymbol(NameRef, false, false);
+    Sym = createSymbol(NameRef, false);
 
   return Sym;
 }
@@ -175,17 +175,16 @@
                                     IsTemporary);
 }
 
-MCSymbol *MCContext::createSymbol(StringRef Name, bool AlwaysAddSuffix,
-                                  bool CanBeUnnamed) {
-  if (CanBeUnnamed && !UseNamesOnTempLabels)
-    return createSymbolImpl(nullptr, true);
-
+MCSymbol *MCContext::createSymbol(StringRef Name, bool AlwaysAddSuffix) {
   // Determine whether this is an user writter assembler temporary or normal
   // label, if used.
-  bool IsTemporary = CanBeUnnamed;
-  if (AllowTemporaryLabels && !IsTemporary)
+  bool IsTemporary = false;
+  if (AllowTemporaryLabels)
     IsTemporary = Name.startswith(MAI->getPrivateGlobalPrefix());
 
+  if (IsTemporary && !UseNamesOnTempLabels)
+    return createSymbolImpl(nullptr, true);
+
   SmallString<128> NewName = Name;
   bool AddSuffix = AlwaysAddSuffix;
   unsigned &NextUniqueID = NextID[Name];
@@ -206,21 +205,20 @@
   llvm_unreachable("Infinite loop");
 }
 
-MCSymbol *MCContext::createTempSymbol(const Twine &Name, bool AlwaysAddSuffix,
-                                      bool CanBeUnnamed) {
+MCSymbol *MCContext::createTempSymbol(const Twine &Name, bool AlwaysAddSuffix) {
   SmallString<128> NameSV;
   raw_svector_ostream(NameSV) << MAI->getPrivateGlobalPrefix() << Name;
-  return createSymbol(NameSV, AlwaysAddSuffix, CanBeUnnamed);
+  return createSymbol(NameSV, AlwaysAddSuffix);
 }
 
 MCSymbol *MCContext::createLinkerPrivateTempSymbol() {
   SmallString<128> NameSV;
   raw_svector_ostream(NameSV) << MAI->getLinkerPrivateGlobalPrefix() << "tmp";
-  return createSymbol(NameSV, true, false);
+  return createSymbol(NameSV, true);
 }
 
-MCSymbol *MCContext::createTempSymbol(bool CanBeUnnamed) {
-  return createTempSymbol("tmp", true, CanBeUnnamed);
+MCSymbol *MCContext::createTempSymbol() {
+  return createTempSymbol("tmp", true);
 }
 
 unsigned MCContext::NextInstance(unsigned LocalLabelVal) {
@@ -241,7 +239,7 @@
                                                        unsigned Instance) {
   MCSymbol *&Sym = LocalSymbols[std::make_pair(LocalLabelVal, Instance)];
   if (!Sym)
-    Sym = createTempSymbol(false);
+    Sym = createTempSymbol();
   return Sym;
 }
 

llvm/lib/MC/MachObjectWriter.cpp

diff --git a/llvm/lib/MC/MachObjectWriter.cpp b/llvm/lib/MC/MachObjectWriter.cpp
index 8ce6127..d7934ad 100644
--- a/llvm/lib/MC/MachObjectWriter.cpp
+++ b/llvm/lib/MC/MachObjectWriter.cpp
@@ -565,7 +565,8 @@
 
     MachSymbolData MSD;
     MSD.Symbol = &Symbol;
-    MSD.StringIndex = StringTable.getOffset(Symbol.getName());
+    StringRef Name = Symbol.getName();
+    MSD.StringIndex = Name.empty() ? 0 : StringTable.getOffset(Name);
 
     if (Symbol.isAbsolute()) {
       MSD.SectionIndex = 0;