DebugInfo: Remove unnecessary zero-size check

[oota-llvm.git] / lib / CodeGen / AsmPrinter / DwarfDebug.cpp

diff --git a/lib/CodeGen/AsmPrinter/DwarfDebug.cpp b/lib/CodeGen/AsmPrinter/DwarfDebug.cpp
index e396ff9a7f4e356904faf468fee001547172f03f..792a9c48cdfc4a287d081435edc8a96d0bf3b2d4 100644 (file)
--- a/lib/CodeGen/AsmPrinter/DwarfDebug.cpp
+++ b/lib/CodeGen/AsmPrinter/DwarfDebug.cpp
@@ -456,8 +456,15 @@ void DwarfDebug::addScopeRangeList(DwarfCompileUnit *TheCU, DIE *ScopeDIE,
   // Emit offset in .debug_range as a relocatable label. emitDIE will handle
   // emitting it appropriately.
   MCSymbol *RangeSym = Asm->GetTempSymbol("debug_ranges", GlobalRangeCount++);
-  addSectionLabel(Asm, TheCU, ScopeDIE, dwarf::DW_AT_ranges, RangeSym,
-                  DwarfDebugRangeSectionSym);
+
+  // Under fission, ranges are specified by constant offsets relative to the
+  // CU's DW_AT_GNU_ranges_base.
+  if (useSplitDwarf())
+    TheCU->addSectionDelta(ScopeDIE, dwarf::DW_AT_ranges, RangeSym,
+                           DwarfDebugRangeSectionSym);
+  else
+    addSectionLabel(Asm, TheCU, ScopeDIE, dwarf::DW_AT_ranges, RangeSym,
+                    DwarfDebugRangeSectionSym);
 
   RangeSpanList List(RangeSym);
   for (const InsnRange &R : Range) {
@@ -1253,6 +1260,7 @@ DwarfDebug::collectVariableInfo(SmallPtrSet<const MDNode *, 16> &Processed) {
     // Handle multiple DBG_VALUE instructions describing one variable.
     RegVar->setDotDebugLocOffset(DotDebugLocEntries.size());
 
+    SmallVector<DebugLocEntry, 4> DebugLoc;
     for (SmallVectorImpl<const MachineInstr *>::const_iterator
              HI = History.begin(),
              HE = History.end();
@@ -1290,10 +1298,11 @@ DwarfDebug::collectVariableInfo(SmallPtrSet<const MDNode *, 16> &Processed) {
       // The value is valid until the next DBG_VALUE or clobber.
       LexicalScope *FnScope = LScopes.getCurrentFunctionScope();
       DwarfCompileUnit *TheCU = SPMap.lookup(FnScope->getScopeNode());
-      DotDebugLocEntries.push_back(
-          getDebugLocEntry(Asm, FLabel, SLabel, Begin, TheCU));
+      DebugLocEntry Loc = getDebugLocEntry(Asm, FLabel, SLabel, Begin, TheCU);
+      if (DebugLoc.empty() || !DebugLoc.back().Merge(Loc))
+        DebugLoc.push_back(std::move(Loc));
     }
-    DotDebugLocEntries.push_back(DebugLocEntry());
+    DotDebugLocEntries.push_back(std::move(DebugLoc));
   }
 
   // Collect info for variables that were optimized out.
@@ -2368,37 +2377,14 @@ void DwarfDebug::emitDebugLocEntry(ByteStreamer &Streamer,
 
 // Emit locations into the debug loc section.
 void DwarfDebug::emitDebugLoc() {
-  if (DotDebugLocEntries.empty())
-    return;
-
-  for (SmallVectorImpl<DebugLocEntry>::iterator
-           I = DotDebugLocEntries.begin(),
-           E = DotDebugLocEntries.end();
-       I != E; ++I) {
-    DebugLocEntry &Entry = *I;
-    if (I + 1 != DotDebugLocEntries.end())
-      Entry.Merge(I + 1);
-  }
-
   // Start the dwarf loc section.
   Asm->OutStreamer.SwitchSection(
       Asm->getObjFileLowering().getDwarfLocSection());
   unsigned char Size = Asm->getDataLayout().getPointerSize();
-  Asm->OutStreamer.EmitLabel(Asm->GetTempSymbol("debug_loc", 0));
-  unsigned index = 1;
-  for (SmallVectorImpl<DebugLocEntry>::const_iterator
-           I = DotDebugLocEntries.begin(),
-           E = DotDebugLocEntries.end();
-       I != E; ++I, ++index) {
-    const DebugLocEntry &Entry = *I;
-    if (Entry.isMerged())
-      continue;
-
-    if (Entry.isEmpty()) {
-      Asm->OutStreamer.EmitIntValue(0, Size);
-      Asm->OutStreamer.EmitIntValue(0, Size);
-      Asm->OutStreamer.EmitLabel(Asm->GetTempSymbol("debug_loc", index));
-    } else {
+  unsigned index = 0;
+  for (const auto &DebugLoc : DotDebugLocEntries) {
+    Asm->OutStreamer.EmitLabel(Asm->GetTempSymbol("debug_loc", index));
+    for (const auto &Entry : DebugLoc) {
       // Set up the range. This range is relative to the entry point of the
       // compile unit. This is a hard coded 0 for low_pc when we're emitting
       // ranges, or the DW_AT_low_pc on the compile unit otherwise.
@@ -2423,6 +2409,9 @@ void DwarfDebug::emitDebugLoc() {
       // Close the range.
       Asm->OutStreamer.EmitLabel(end);
     }
+    Asm->OutStreamer.EmitIntValue(0, Size);
+    Asm->OutStreamer.EmitIntValue(0, Size);
+    ++index;
   }
 }
 
@@ -2644,8 +2633,7 @@ void DwarfDebug::initSkeletonUnit(const DwarfUnit *U, DIE *Die,
 
 // This DIE has the following attributes: DW_AT_comp_dir, DW_AT_stmt_list,
 // DW_AT_low_pc, DW_AT_high_pc, DW_AT_ranges, DW_AT_dwo_name, DW_AT_dwo_id,
-// DW_AT_ranges_base, DW_AT_addr_base.
-// TODO: Implement DW_AT_ranges_base.
+// DW_AT_addr_base, DW_AT_ranges_base.
 DwarfCompileUnit *DwarfDebug::constructSkeletonCU(const DwarfCompileUnit *CU) {
 
   DIE *Die = new DIE(dwarf::DW_TAG_compile_unit);
@@ -2660,10 +2648,16 @@ DwarfCompileUnit *DwarfDebug::constructSkeletonCU(const DwarfCompileUnit *CU) {
 
   // Relocate to the beginning of the addr_base section, else 0 for the
   // beginning of the one for this compile unit.
-  if (Asm->MAI->doesDwarfUseRelocationsAcrossSections())
+  // We could shave off some space if we deferred adding these attributes until
+  // the end of the CU to see if we have a non-empty debug_addr and debug_ranges
+  // sections so we don't bother with extra attributes and relocations.
+  if (Asm->MAI->doesDwarfUseRelocationsAcrossSections()) {
     NewCU->addSectionLabel(Die, dwarf::DW_AT_GNU_addr_base, DwarfAddrSectionSym);
-  else
+    NewCU->addSectionLabel(Die, dwarf::DW_AT_GNU_ranges_base, DwarfDebugRangeSectionSym);
+  } else {
     NewCU->addSectionOffset(Die, dwarf::DW_AT_GNU_addr_base, 0);
+    NewCU->addSectionOffset(Die, dwarf::DW_AT_GNU_ranges_base, 0);
+  }
 
   return NewCU;
 }
@@ -2690,7 +2684,7 @@ DwarfTypeUnit *DwarfDebug::constructSkeletonTU(DwarfTypeUnit *TU) {
 // compile units that would normally be in debug_info.
 void DwarfDebug::emitDebugInfoDWO() {
   assert(useSplitDwarf() && "No split dwarf debug info?");
-  InfoHolder.emitUnits(this, DwarfAbbrevDWOSectionSym);
+  InfoHolder.emitUnits(this, nullptr);
 }
 
 // Emit the .debug_abbrev.dwo section for separated dwarf. This contains the