[PATCH] [DWARF] Fix a bug in line info handling

[Keno Fischer]

Hi echristo, friss, dblaikie,

This fixes a bug in the line info handling in the dwarf code, based on a
problem I when implementing RelocVisitor support for MachO.
Since addr+size will give the first address past the end of the function,
we need to back up one line table entry. However, if we are doing the
comparison with < rather than <=, we actually end up with the second
entry past the end of the current function, if the next function
starts at exactly addr+size (the first entry for the next
function is at addr+size, so the next entry greater than it
is the second entry for the next function).
This comes up on MachO much more than on ELF, since MachO
doesn't store the symbol size separately, hence making
said situation always occur.

REPOSITORY
  rL LLVM

http://reviews.llvm.org/D9925

Files:
  include/llvm/DebugInfo/DWARF/DWARFDebugLine.h
  lib/DebugInfo/DWARF/DWARFDebugLine.cpp
  test/DebugInfo/debuglineinfo-macho.test

Index: include/llvm/DebugInfo/DWARF/DWARFDebugLine.h
===================================================================
--- include/llvm/DebugInfo/DWARF/DWARFDebugLine.h
+++ include/llvm/DebugInfo/DWARF/DWARFDebugLine.h
@@ -94,6 +94,10 @@
       return LHS.Address < RHS.Address;
     }
 
+    static bool orderByAddressLeq(const Row& LHS, const Row& RHS) {
+      return LHS.Address <= RHS.Address;
+    }
+
     // The program-counter value corresponding to a machine instruction
     // generated by the compiler.
     uint64_t Address;
Index: lib/DebugInfo/DWARF/DWARFDebugLine.cpp
===================================================================
--- lib/DebugInfo/DWARF/DWARFDebugLine.cpp
+++ lib/DebugInfo/DWARF/DWARFDebugLine.cpp
@@ -605,13 +605,10 @@
       RowIter first_row = Rows.begin() + cur_seq.FirstRowIndex;
       RowIter last_row = Rows.begin() + cur_seq.LastRowIndex;
       RowIter row_pos = std::upper_bound(first_row, last_row, row,
-                                         DWARFDebugLine::Row::orderByAddress);
+                                         DWARFDebugLine::Row::orderByAddressLeq);
       // The 'row_pos' iterator references the first row that is greater than
-      // our start address. Unless that's the first row, we want to start at
-      // the row before that.
+      // our or equal to start address.
       first_row_index = cur_seq.FirstRowIndex + (row_pos - first_row);
-      if (row_pos != first_row)
-        --first_row_index;
     } else
       first_row_index = cur_seq.FirstRowIndex;
 
@@ -623,9 +620,11 @@
       RowIter first_row = Rows.begin() + cur_seq.FirstRowIndex;
       RowIter last_row = Rows.begin() + cur_seq.LastRowIndex;
       RowIter row_pos = std::upper_bound(first_row, last_row, row,
-                                         DWARFDebugLine::Row::orderByAddress);
+                                         DWARFDebugLine::Row::orderByAddressLeq);
       // The 'row_pos' iterator references the first row that is greater than
-      // our end address.  The row before that is the last row we want.
+      // or equal our end address. The row before that is the last row we want,
+      // since end_address is the first address past the end of the range we're
+      // looking up.
       last_row_index = cur_seq.FirstRowIndex + (row_pos - first_row) - 1;
     } else
       // Contrary to what you might expect, DWARFDebugLine::SequenceLastRowIndex
Index: test/DebugInfo/debuglineinfo-macho.test
===================================================================
--- test/DebugInfo/debuglineinfo-macho.test
+++ test/DebugInfo/debuglineinfo-macho.test
@@ -3,3 +3,39 @@
 RUN: llvm-dwarfdump %p/Inputs/test-multiple-macho.o | FileCheck %s
 
 CHECK-NOT: error: failed to compute relocation: X86_64_RELOC_UNSIGNED
+
+# Check that relocations get applied correctly
+RUN: llvm-rtdyld -printobjline %p/Inputs/test-simple-macho.o \
+RUN:   | FileCheck %s -check-prefix TEST_SIMPLE
+RUN: llvm-rtdyld -printline %p/Inputs/test-simple-macho.o \
+RUN:   | FileCheck %s -check-prefix TEST_SIMPLE
+RUN: llvm-rtdyld -printobjline %p/Inputs/test-multiple-macho.o \
+RUN:   | FileCheck %s -check-prefix TEST_MULTIPLE
+RUN: llvm-rtdyld -printline %p/Inputs/test-multiple-macho.o \
+RUN:   | FileCheck %s -check-prefix TEST_MULTIPLE
+
+TEST_SIMPLE:      Function: _foo, Size = 11
+TEST_SIMPLE-NEXT:  Line info @ 0: simple.c, line:1
+TEST_SIMPLE-NEXT:  Line info @ 7: simple.c, line:2
+TEST_SIMPLE-NEXT:  Line info @ 11: simple.c, line:2
+
+TEST_MULTIPLE:      Function: _bar, Size = 48
+TEST_MULTIPLE-NEXT:   Line info @ 0: multiple.c, line:5
+TEST_MULTIPLE-NEXT:   Line info @ 7: multiple.c, line:6
+TEST_MULTIPLE-NEXT:   Line info @ 16: multiple.c, line:9
+TEST_MULTIPLE-NEXT:   Line info @ 21: multiple.c, line:9
+TEST_MULTIPLE-NEXT:   Line info @ 26: multiple.c, line:7
+TEST_MULTIPLE-NEXT:   Line info @ 33: multiple.c, line:10
+TEST_MULTIPLE-NOT:    Line info @ 48: multiple.c, line:12
+TEST_MULTIPLE-NEXT: Function: _foo, Size = 16
+TEST_MULTIPLE-NEXT:   Line info @ 0: multiple.c, line:1
+TEST_MULTIPLE-NEXT:   Line info @ 7: multiple.c, line:2
+TEST_MULTIPLE-NOT:    Line info @ 16: multiple.c, line:5
+TEST_MULTIPLE-NEXT: Function: _fubar, Size = 46
+TEST_MULTIPLE-NEXT:   Line info @ 0: multiple.c, line:12
+TEST_MULTIPLE-NEXT:   Line info @ 7: multiple.c, line:13
+TEST_MULTIPLE-NEXT:   Line info @ 12: multiple.c, line:17
+TEST_MULTIPLE-NEXT:   Line info @ 25: multiple.c, line:15
+TEST_MULTIPLE-NEXT:   Line info @ 34: multiple.c, line:19
+TEST_MULTIPLE-NEXT:   Line info @ 41: multiple.c, line:21
+TEST_MULTIPLE-NEXT:   Line info @ 46: multiple.c, line:21

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