Try to resolve symbol differences early, and if successful create a plain

data fragment. This reduces the time to assemble the test in 8711 from 60s to
54s.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@120767 91177308-0d34-0410-b5e6-96231b3b80d8

9 files changed, 116 insertions, 85 deletions

diff --git a/lib/MC/MCAsmStreamer.cpp b/lib/MC/MCAsmStreamer.cpp
index 49bcc93..217daed 100644
--- a/lib/MC/MCAsmStreamer.cpp
+++ b/lib/MC/MCAsmStreamer.cpp
@@ -121,6 +121,9 @@ public:
 
   virtual void EmitAssignment(MCSymbol *Symbol, const MCExpr *Value);
   virtual void EmitWeakReference(MCSymbol *Alias, const MCSymbol *Symbol);
+  virtual void EmitDwarfAdvanceLineAddr(int64_t LineDelta,
+                                        const MCSymbol *LastLabel,
+                                        const MCSymbol *Label);
 
   virtual void EmitSymbolAttribute(MCSymbol *Symbol, MCSymbolAttr Attribute);
 
@@ -298,6 +301,12 @@ void MCAsmStreamer::EmitWeakReference(MCSymbol *Alias, const MCSymbol *Symbol) {
   EmitEOL();
 }
 
+void MCAsmStreamer::EmitDwarfAdvanceLineAddr(int64_t LineDelta,
+                                             const MCSymbol *LastLabel,
+                                             const MCSymbol *Label) {
+  EmitDwarfSetLineAddr(LineDelta, Label, PointerSize);
+}
+
 void MCAsmStreamer::EmitSymbolAttribute(MCSymbol *Symbol,
                                         MCSymbolAttr Attribute) {
   switch (Attribute) {
@@ -885,10 +894,9 @@ void MCAsmStreamer::EmitRawText(StringRef String) {
 
 void MCAsmStreamer::Finish() {
   // Dump out the dwarf file & directory tables and line tables.
-  if (getContext().hasDwarfFiles() && TLOF) {
-    MCDwarfFileTable::Emit(this, TLOF->getDwarfLineSection(), NULL,
-                           PointerSize, TLOF->getTextSection());
-  }
+  if (getContext().hasDwarfFiles() && TLOF)
+    MCDwarfFileTable::Emit(this, TLOF->getDwarfLineSection(),
+                           TLOF->getTextSection());
 }
 
 MCStreamer *llvm::createAsmStreamer(MCContext &Context,
diff --git a/lib/MC/MCDwarf.cpp b/lib/MC/MCDwarf.cpp
index 5fe73e2..0916b05 100644
--- a/lib/MC/MCDwarf.cpp
+++ b/lib/MC/MCDwarf.cpp
@@ -117,21 +117,6 @@ static inline const MCExpr *MakeStartMinusEndExpr(MCStreamer *MCOS,
   return Res3;
 }
 
-// 
-// This emits an "absolute" address used in the start of a dwarf line number
-// table.  This will result in a relocatation entry for the address.
-//
-static inline void EmitDwarfSetAddress(MCStreamer *MCOS,
-                                       MCSymbol *Symbol,
-                                       int PointerSize) {
-  MCOS->EmitIntValue(dwarf::DW_LNS_extended_op, 1);
-
-  MCOS->EmitULEB128IntValue(PointerSize + 1);
-
-  MCOS->EmitIntValue(dwarf::DW_LNE_set_address, 1);
-  MCOS->EmitSymbolValue(Symbol, PointerSize);
-}
-
 //
 // This emits the Dwarf line table for the specified section from the entries
 // in the LineSection.
@@ -139,9 +124,7 @@ static inline void EmitDwarfSetAddress(MCStreamer *MCOS,
 static inline void EmitDwarfLineTable(MCStreamer *MCOS,
                                       const MCSection *Section,
                                       const MCLineSection *LineSection,
-                                      const MCSection *DwarfLineSection,
-                                      MCSectionData *DLS,
-                                      int PointerSize) {
+                                      const MCSection *DwarfLineSection) {
   unsigned FileNum = 1;
   unsigned LastLine = 1;
   unsigned Column = 0;
@@ -186,19 +169,7 @@ static inline void EmitDwarfLineTable(MCStreamer *MCOS,
     // At this point we want to emit/create the sequence to encode the delta in
     // line numbers and the increment of the address from the previous Label
     // and the current Label.
-    if (LastLabel == NULL || DLS == NULL) {
-      // emit the sequence to set the address
-      EmitDwarfSetAddress(MCOS, Label, PointerSize);
-      // emit the sequence for the LineDelta (from 1) and a zero address delta.
-      MCDwarfLineAddr::Emit(MCOS, LineDelta, 0);
-    }
-    else {
-      // Create an expression for the address delta from the LastLabel and
-      // this Label (plus 0).
-      const MCExpr *AddrDelta = MakeStartMinusEndExpr(MCOS, LastLabel, Label,0);
-      // Create a Dwarf Line fragment for the LineDelta and AddrDelta.
-      new MCDwarfLineAddrFragment(LineDelta, *AddrDelta, DLS);
-    }
+    MCOS->EmitDwarfAdvanceLineAddr(LineDelta, LastLabel, Label);
 
     LastLine = it->getLine();
     LastLabel = Label;
@@ -220,19 +191,7 @@ static inline void EmitDwarfLineTable(MCStreamer *MCOS,
   // Switch back the the dwarf line section.
   MCOS->SwitchSection(DwarfLineSection);
 
-  if (DLS == NULL) {
-    // emit the sequence to set the address
-    EmitDwarfSetAddress(MCOS, SectionEnd, PointerSize);
-    // emit the sequence for the LineDelta (from 1) and a zero address delta.
-    MCDwarfLineAddr::Emit(MCOS, INT64_MAX, 0);
-  } else {
-    // Create an expression for the address delta from the LastLabel and this
-    // SectionEnd label.
-    const MCExpr *AddrDelta = MakeStartMinusEndExpr(MCOS, LastLabel, SectionEnd,
-                                                    0);
-    // Create a Dwarf Line fragment for the LineDelta and AddrDelta.
-    new MCDwarfLineAddrFragment(INT64_MAX, *AddrDelta, DLS);
-  }
+  MCOS->EmitDwarfAdvanceLineAddr(INT64_MAX, LastLabel, SectionEnd);
 }
 
 //
@@ -240,8 +199,6 @@ static inline void EmitDwarfLineTable(MCStreamer *MCOS,
 //
 void MCDwarfFileTable::Emit(MCStreamer *MCOS,
                             const MCSection *DwarfLineSection,
-                            MCSectionData *DLS,
-                            int PointerSize,
                             const MCSection *TextSection) {
   // Switch to the section where the table will be emitted into.
   MCOS->SwitchSection(DwarfLineSection);
@@ -332,8 +289,7 @@ void MCDwarfFileTable::Emit(MCStreamer *MCOS,
        ++it) {
     const MCSection *Sec = *it;
     const MCLineSection *Line = MCLineSections.lookup(Sec);
-    EmitDwarfLineTable(MCOS, Sec, Line, DwarfLineSection, DLS,
-                       PointerSize);
+    EmitDwarfLineTable(MCOS, Sec, Line, DwarfLineSection);
 
     // Now delete the MCLineSections that were created in MCLineEntry::Make()
     // and used to emit the line table.
@@ -351,10 +307,7 @@ void MCDwarfFileTable::Emit(MCStreamer *MCOS,
     // Switch back the the dwarf line section.
     MCOS->SwitchSection(DwarfLineSection);
 
-    // emit the sequence to set the address
-    EmitDwarfSetAddress(MCOS, SectionEnd, PointerSize);
-    // emit the sequence for the LineDelta (from 1) and a zero address delta.
-    MCDwarfLineAddr::Emit(MCOS, INT64_MAX, 0);
+    MCOS->EmitDwarfAdvanceLineAddr(INT64_MAX, NULL, SectionEnd);
   }
 
   // This is the end of the section, so set the value of the symbol at the end
diff --git a/lib/MC/MCELFStreamer.cpp b/lib/MC/MCELFStreamer.cpp
index d98c9ef..f18c420 100644
--- a/lib/MC/MCELFStreamer.cpp
+++ b/lib/MC/MCELFStreamer.cpp
@@ -484,10 +484,7 @@ void MCELFStreamer::Finish() {
     const MCSection *DwarfLineSection =
       getContext().getELFSection(".debug_line", 0, 0,
                                  SectionKind::getDataRelLocal());
-    MCSectionData &DLS =
-      getAssembler().getOrCreateSectionData(*DwarfLineSection);
-    int PointerSize = getAssembler().getBackend().getPointerSize();
-    MCDwarfFileTable::Emit(this, DwarfLineSection, &DLS, PointerSize);
+    MCDwarfFileTable::Emit(this, DwarfLineSection);
   }
 
   for (std::vector<LocalCommon>::const_iterator i = LocalCommons.begin(),
diff --git a/lib/MC/MCExpr.cpp b/lib/MC/MCExpr.cpp
index 64c57b3..3d47608 100644
--- a/lib/MC/MCExpr.cpp
+++ b/lib/MC/MCExpr.cpp
@@ -237,7 +237,24 @@ void MCTargetExpr::Anchor() {}
 
 /* *** */
 
-bool MCExpr::EvaluateAsAbsolute(int64_t &Res, const MCAsmLayout *Layout) const {
+bool MCExpr::EvaluateAsAbsolute(int64_t &Res) const {
+  return EvaluateAsAbsolute(Res, 0, 0);
+}
+
+bool MCExpr::EvaluateAsAbsolute(int64_t &Res,
+                                const MCAsmLayout *Layout) const {
+  if (Layout)
+    return EvaluateAsAbsolute(Res, &Layout->getAssembler(), Layout);
+  else
+    return EvaluateAsAbsolute(Res, 0, 0);
+}
+
+bool MCExpr::EvaluateAsAbsolute(int64_t &Res, const MCAssembler *Asm) const {
+  return EvaluateAsAbsolute(Res, Asm, 0);
+}
+
+bool MCExpr::EvaluateAsAbsolute(int64_t &Res, const MCAssembler *Asm,
+                                const MCAsmLayout *Layout) const {
   MCValue Value;
 
   // Fast path constants.
@@ -246,7 +263,8 @@ bool MCExpr::EvaluateAsAbsolute(int64_t &Res, const MCAsmLayout *Layout) const {
     return true;
   }
 
-  if (!EvaluateAsRelocatable(Value, Layout) || !Value.isAbsolute()) {
+  if (!EvaluateAsRelocatableImpl(Value, Asm, Layout, false) ||
+      !Value.isAbsolute()) {
     // EvaluateAsAbsolute is defined to return the "current value" of
     // the expression if we are given a Layout object, even in cases
     // when the value is not fixed.
@@ -268,7 +286,9 @@ bool MCExpr::EvaluateAsAbsolute(int64_t &Res, const MCAsmLayout *Layout) const {
   return true;
 }
 
-static bool EvaluateSymbolicAdd(const MCAsmLayout *Layout, bool InSet,
+static bool EvaluateSymbolicAdd(const MCAsmLayout *Layout,
+                                const MCAssembler *Asm,
+                                bool InSet,
                                 const MCValue &LHS,const MCSymbolRefExpr *RHS_A,
                                 const MCSymbolRefExpr *RHS_B, int64_t RHS_Cst,
                                 MCValue &Res) {
@@ -291,14 +311,15 @@ static bool EvaluateSymbolicAdd(const MCAsmLayout *Layout, bool InSet,
   // Absolutize symbol differences between defined symbols when we have a
   // layout object and the target requests it.
 
-  if (Layout && A && B) {
+  assert(!(Layout && !Asm));
+
+  if ((Layout || Asm) && A && B) {
     const MCSymbol &SA = A->getSymbol();
     const MCSymbol &SB = B->getSymbol();
-    const MCAssembler &Asm = Layout->getAssembler();
-    const MCObjectFormat &F = Asm.getBackend().getObjectFormat();
+    const MCObjectFormat &F = Asm->getBackend().getObjectFormat();
     if (SA.isDefined() && SB.isDefined() && F.isAbsolute(InSet, SA, SB)) {
-      MCSymbolData &AD = Asm.getSymbolData(A->getSymbol());
-      MCSymbolData &BD = Asm.getSymbolData(B->getSymbol());
+      MCSymbolData &AD = Asm->getSymbolData(A->getSymbol());
+      MCSymbolData &BD = Asm->getSymbolData(B->getSymbol());
 
       if (AD.getFragment() == BD.getFragment()) {
         Res = MCValue::get(+ AD.getOffset()
@@ -308,25 +329,31 @@ static bool EvaluateSymbolicAdd(const MCAsmLayout *Layout, bool InSet,
         return true;
       }
 
-      Res = MCValue::get(+ Layout->getSymbolAddress(&AD)
-                         - Layout->getSymbolAddress(&BD)
-                         + LHS.getConstant()
-                         + RHS_Cst);
-      return true;
+      if (Layout) {
+        Res = MCValue::get(+ Layout->getSymbolAddress(&AD)
+                           - Layout->getSymbolAddress(&BD)
+                           + LHS.getConstant()
+                           + RHS_Cst);
+        return true;
+      }
     }
   }
 
-
   Res = MCValue::get(A, B, LHS.getConstant() + RHS_Cst);
   return true;
 }
 
 bool MCExpr::EvaluateAsRelocatable(MCValue &Res,
                                    const MCAsmLayout *Layout) const {
-  return EvaluateAsRelocatableImpl(Res, Layout, false);
+  if (Layout)
+    return EvaluateAsRelocatableImpl(Res, &Layout->getAssembler(), Layout,
+                                     false);
+  else
+    return EvaluateAsRelocatableImpl(Res, 0, 0, false);
 }
 
 bool MCExpr::EvaluateAsRelocatableImpl(MCValue &Res,
+                                       const MCAssembler *Asm,
                                        const MCAsmLayout *Layout,
                                        bool InSet) const {
   ++stats::MCExprEvaluate;
@@ -345,7 +372,8 @@ bool MCExpr::EvaluateAsRelocatableImpl(MCValue &Res,
 
     // Evaluate recursively if this is a variable.
     if (Sym.isVariable() && SRE->getKind() == MCSymbolRefExpr::VK_None) {
-      bool Ret = Sym.getVariableValue()->EvaluateAsRelocatableImpl(Res, Layout,
+      bool Ret = Sym.getVariableValue()->EvaluateAsRelocatableImpl(Res, Asm,
+                                                                   Layout,
                                                                    true);
       // If we failed to simplify this to a constant, let the target
       // handle it.
@@ -361,7 +389,8 @@ bool MCExpr::EvaluateAsRelocatableImpl(MCValue &Res,
     const MCUnaryExpr *AUE = cast<MCUnaryExpr>(this);
     MCValue Value;
 
-    if (!AUE->getSubExpr()->EvaluateAsRelocatableImpl(Value, Layout, InSet))
+    if (!AUE->getSubExpr()->EvaluateAsRelocatableImpl(Value, Asm, Layout,
+                                                      InSet))
       return false;
 
     switch (AUE->getOpcode()) {
@@ -394,8 +423,10 @@ bool MCExpr::EvaluateAsRelocatableImpl(MCValue &Res,
     const MCBinaryExpr *ABE = cast<MCBinaryExpr>(this);
     MCValue LHSValue, RHSValue;
 
-    if (!ABE->getLHS()->EvaluateAsRelocatableImpl(LHSValue, Layout, InSet) ||
-        !ABE->getRHS()->EvaluateAsRelocatableImpl(RHSValue, Layout, InSet))
+    if (!ABE->getLHS()->EvaluateAsRelocatableImpl(LHSValue, Asm, Layout,
+                                                  InSet) ||
+        !ABE->getRHS()->EvaluateAsRelocatableImpl(RHSValue, Asm, Layout,
+                                                  InSet))
       return false;
 
     // We only support a few operations on non-constant expressions, handle
@@ -406,13 +437,13 @@ bool MCExpr::EvaluateAsRelocatableImpl(MCValue &Res,
         return false;
       case MCBinaryExpr::Sub:
         // Negate RHS and add.
-        return EvaluateSymbolicAdd(Layout, InSet, LHSValue,
+        return EvaluateSymbolicAdd(Layout, Asm, InSet, LHSValue,
                                    RHSValue.getSymB(), RHSValue.getSymA(),
                                    -RHSValue.getConstant(),
                                    Res);
 
       case MCBinaryExpr::Add:
-        return EvaluateSymbolicAdd(Layout, InSet, LHSValue,
+        return EvaluateSymbolicAdd(Layout, Asm, InSet, LHSValue,
                                    RHSValue.getSymA(), RHSValue.getSymB(),
                                    RHSValue.getConstant(),
                                    Res);
diff --git a/lib/MC/MCLoggingStreamer.cpp b/lib/MC/MCLoggingStreamer.cpp
index 5191ac4..6cbef0b 100644
--- a/lib/MC/MCLoggingStreamer.cpp
+++ b/lib/MC/MCLoggingStreamer.cpp
@@ -84,6 +84,13 @@ public:
     return Child->EmitWeakReference(Alias, Symbol);
   }
 
+  virtual void EmitDwarfAdvanceLineAddr(int64_t LineDelta,
+                                        const MCSymbol *LastLabel,
+                                        const MCSymbol *Label) {
+    LogCall("EmitDwarfAdvanceLineAddr");
+    return Child->EmitDwarfAdvanceLineAddr(LineDelta, LastLabel, Label);
+  }
+
   virtual void EmitSymbolAttribute(MCSymbol *Symbol, MCSymbolAttr Attribute) {
     LogCall("EmitSymbolAttribute");
     return Child->EmitSymbolAttribute(Symbol, Attribute);
diff --git a/lib/MC/MCMachOStreamer.cpp b/lib/MC/MCMachOStreamer.cpp
index 71bd407..1ee2d48 100644
--- a/lib/MC/MCMachOStreamer.cpp
+++ b/lib/MC/MCMachOStreamer.cpp
@@ -357,10 +357,7 @@ void MCMachOStreamer::Finish() {
                                          "__debug_line",
                                          MCSectionMachO::S_ATTR_DEBUG,
                                          0, SectionKind::getDataRelLocal());
-    MCSectionData &DLS =
-      getAssembler().getOrCreateSectionData(*DwarfLineSection);
-    int PointerSize = getAssembler().getBackend().getPointerSize();
-    MCDwarfFileTable::Emit(this, DwarfLineSection, &DLS, PointerSize);
+    MCDwarfFileTable::Emit(this, DwarfLineSection);
   }
 
   // We have to set the fragment atom associations so we can relax properly for
diff --git a/lib/MC/MCNullStreamer.cpp b/lib/MC/MCNullStreamer.cpp
index c79793c..86ab628 100644
--- a/lib/MC/MCNullStreamer.cpp
+++ b/lib/MC/MCNullStreamer.cpp
@@ -44,6 +44,9 @@ namespace {
 
     virtual void EmitAssignment(MCSymbol *Symbol, const MCExpr *Value) {}
     virtual void EmitWeakReference(MCSymbol *Alias, const MCSymbol *Symbol){}
+    virtual void EmitDwarfAdvanceLineAddr(int64_t LineDelta,
+                                          const MCSymbol *LastLabel,
+                                          const MCSymbol *Label) {}
 
     virtual void EmitSymbolAttribute(MCSymbol *Symbol, MCSymbolAttr Attribute){}
 
diff --git a/lib/MC/MCObjectStreamer.cpp b/lib/MC/MCObjectStreamer.cpp
index a514858..506c963 100644
--- a/lib/MC/MCObjectStreamer.cpp
+++ b/lib/MC/MCObjectStreamer.cpp
@@ -179,6 +179,30 @@ void MCObjectStreamer::EmitInstToFragment(const MCInst &Inst) {
   getAssembler().getEmitter().EncodeInstruction(Inst, VecOS, IF->getFixups());
 }
 
+void MCObjectStreamer::EmitDwarfAdvanceLineAddr(int64_t LineDelta,
+                                                const MCSymbol *LastLabel,
+                                                const MCSymbol *Label) {
+  if (!LastLabel) {
+    int PointerSize = getAssembler().getBackend().getPointerSize();
+    EmitDwarfSetLineAddr(LineDelta, Label, PointerSize);
+    return;
+  }
+  MCSymbolRefExpr::VariantKind Variant = MCSymbolRefExpr::VK_None;
+  const MCExpr *LabelRef =
+    MCSymbolRefExpr::Create(Label, Variant, getContext());
+  const MCExpr *LastLabelRef =
+    MCSymbolRefExpr::Create(LastLabel, Variant, getContext());
+  const MCExpr *AddrDelta =
+    MCBinaryExpr::Create(MCBinaryExpr::Sub, LabelRef, LastLabelRef,
+                         getContext());
+  int64_t Res;
+  if (AddrDelta->EvaluateAsAbsolute(Res, &getAssembler())) {
+    MCDwarfLineAddr::Emit(this, LineDelta, Res);
+    return;
+  }
+  new MCDwarfLineAddrFragment(LineDelta, *AddrDelta, getCurrentSectionData());
+}
+
 void MCObjectStreamer::EmitValueToOffset(const MCExpr *Offset,
                                         unsigned char Value) {
   new MCOrgFragment(*Offset, Value, getCurrentSectionData());
diff --git a/lib/MC/MCStreamer.cpp b/lib/MC/MCStreamer.cpp
index 7921957..9fe719a 100644
--- a/lib/MC/MCStreamer.cpp
+++ b/lib/MC/MCStreamer.cpp
@@ -30,6 +30,17 @@ raw_ostream &MCStreamer::GetCommentOS() {
   return nulls();
 }
 
+void MCStreamer::EmitDwarfSetLineAddr(int64_t LineDelta,
+                                      const MCSymbol *Label, int PointerSize) {
+  // emit the sequence to set the address
+  EmitIntValue(dwarf::DW_LNS_extended_op, 1);
+  EmitULEB128IntValue(PointerSize + 1);
+  EmitIntValue(dwarf::DW_LNE_set_address, 1);
+  EmitSymbolValue(Label, PointerSize);
+
+  // emit the sequence for the LineDelta (from 1) and a zero address delta.
+  MCDwarfLineAddr::Emit(this, LineDelta, 0);
+}
 
 /// EmitIntValue - Special case of EmitValue that avoids the client having to
 /// pass in a MCExpr for constant integers.