[llvm] r270165 - Fix pr27728.

[Rafael Espindola via llvm-commits]

Author: rafael
Date: Thu May 19 19:38:28 2016
New Revision: 270165

URL: http://llvm.org/viewvc/llvm-project?rev=270165&view=rev
Log:
Fix pr27728.

Sorry for the lack testcase. There is one in the pr, but it depends on
std::sort and the .ll version is 110 lines, so I don't think it is
wort it.

The bug was that we were sorting after adding a terminator, and the
sorting algorithm could end up putting the terminator in the middle of
the List vector.

With that we would create a Spans map entry keyed on nullptr which would
then be added to CUs and fail in that sorting.

Modified:
    llvm/trunk/lib/CodeGen/AsmPrinter/DwarfDebug.cpp

Modified: llvm/trunk/lib/CodeGen/AsmPrinter/DwarfDebug.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/CodeGen/AsmPrinter/DwarfDebug.cpp?rev=270165&r1=270164&r2=270165&view=diff
==============================================================================
--- llvm/trunk/lib/CodeGen/AsmPrinter/DwarfDebug.cpp (original)
+++ llvm/trunk/lib/CodeGen/AsmPrinter/DwarfDebug.cpp Thu May 19 19:38:28 2016
@@ -1554,24 +1554,12 @@ void DwarfDebug::emitDebugARanges() {
     }
   }
 
-  // Add terminating symbols for each section.
-  for (const auto &I : SectionMap) {
-    MCSection *Section = I.first;
-    MCSymbol *Sym = nullptr;
-
-    if (Section)
-      Sym = Asm->OutStreamer->endSection(Section);
-
-    // Insert a final terminator.
-    SectionMap[Section].push_back(SymbolCU(nullptr, Sym));
-  }
-
   DenseMap<DwarfCompileUnit *, std::vector<ArangeSpan>> Spans;
 
   for (auto &I : SectionMap) {
-    const MCSection *Section = I.first;
+    MCSection *Section = I.first;
     SmallVector<SymbolCU, 8> &List = I.second;
-    if (List.size() < 2)
+    if (List.size() < 1)
       continue;
 
     // If we have no section (e.g. common), just write out
@@ -1581,8 +1569,8 @@ void DwarfDebug::emitDebugARanges() {
         ArangeSpan Span;
         Span.Start = Cur.Sym;
         Span.End = nullptr;
-        if (Cur.CU)
-          Spans[Cur.CU].push_back(Span);
+        assert(Cur.CU);
+        Spans[Cur.CU].push_back(Span);
       }
       continue;
     }
@@ -1602,6 +1590,9 @@ void DwarfDebug::emitDebugARanges() {
           return IA < IB;
         });
 
+    // Insert a final terminator.
+    List.push_back(SymbolCU(nullptr, Asm->OutStreamer->endSection(Section)));
+
     // Build spans between each label.
     const MCSymbol *StartSym = List[0].Sym;
     for (size_t n = 1, e = List.size(); n < e; n++) {
@@ -1613,6 +1604,7 @@ void DwarfDebug::emitDebugARanges() {
         ArangeSpan Span;
         Span.Start = StartSym;
         Span.End = Cur.Sym;
+        assert(Prev.CU);
         Spans[Prev.CU].push_back(Span);
         StartSym = Cur.Sym;
       }