[PATCH] Support DWARF discriminators in object streamer.

Diego Novillo dnovillo at google.com
Fri Feb 14 07:28:45 PST 2014


  I still haven't woken up. I need -g in *both* cases:

  1- llvm-dwarfdump needs a -g .o or it will not generate its report.
  2- If I do not use -g, I need to write a .file directive so .loc won't
     get confused.
  3- I cannot write a .file directive if I'm using -g.

  So, the only way to get both tests here is to always run llvm-mc with
  -g.

Hi echristo,

http://llvm-reviews.chandlerc.com/D2794

CHANGE SINCE LAST DIFF
  http://llvm-reviews.chandlerc.com/D2794?vs=7129&id=7131#toc

Files:
  lib/DebugInfo/DWARFDebugLine.cpp
  lib/DebugInfo/DWARFDebugLine.h
  lib/MC/MCDwarf.cpp
  test/DebugInfo/X86/ending-run.ll
  test/DebugInfo/X86/line-info.ll
  test/MC/ELF/discriminator.s
  test/MC/MachO/gen-dwarf-cpp.s
  test/MC/MachO/gen-dwarf.s

Index: lib/DebugInfo/DWARFDebugLine.cpp
===================================================================
--- lib/DebugInfo/DWARFDebugLine.cpp
+++ lib/DebugInfo/DWARFDebugLine.cpp
@@ -62,6 +62,7 @@
   Column = 0;
   File = 1;
   Isa = 0;
+  Discriminator = 0;
   IsStmt = default_is_stmt;
   BasicBlock = false;
   EndSequence = false;
@@ -71,7 +72,7 @@
 
 void DWARFDebugLine::Row::dump(raw_ostream &OS) const {
   OS << format("0x%16.16" PRIx64 " %6u %6u", Address, Line, Column)
-     << format(" %6u %3u ", File, Isa)
+     << format(" %6u %3u %13u ", File, Isa, Discriminator)
      << (IsStmt ? " is_stmt" : "")
      << (BasicBlock ? " basic_block" : "")
      << (PrologueEnd ? " prologue_end" : "")
@@ -85,8 +86,9 @@
   OS << '\n';
 
   if (!Rows.empty()) {
-    OS << "Address            Line   Column File   ISA Flags\n"
-       << "------------------ ------ ------ ------ --- -------------\n";
+    OS << "Address            Line   Column File   ISA Discriminator Flags\n"
+       << "------------------ ------ ------ ------ --- ------------- "
+          "-------------\n";
     for (std::vector<Row>::const_iterator pos = Rows.begin(),
          end = Rows.end(); pos != end; ++pos)
       pos->dump(OS);
@@ -311,6 +313,10 @@
         }
         break;
 
+      case DW_LNE_set_discriminator:
+        state.Discriminator = debug_line_data.getULEB128(offset_ptr);
+        break;
+
       default:
         // Length doesn't include the zero opcode byte or the length itself, but
         // it does include the sub_opcode, so we have to adjust for that below
Index: lib/DebugInfo/DWARFDebugLine.h
===================================================================
--- lib/DebugInfo/DWARFDebugLine.h
+++ lib/DebugInfo/DWARFDebugLine.h
@@ -112,6 +112,9 @@
     // An unsigned integer whose value encodes the applicable instruction set
     // architecture for the current instruction.
     uint8_t Isa;
+    // An unsigned integer representing the DWARF path discriminator value
+    // for this location.
+    uint32_t Discriminator;
     // A boolean indicating that the current instruction is the beginning of a
     // statement.
     uint8_t IsStmt:1,
Index: lib/MC/MCDwarf.cpp
===================================================================
--- lib/MC/MCDwarf.cpp
+++ lib/MC/MCDwarf.cpp
@@ -137,6 +137,7 @@
   unsigned Column = 0;
   unsigned Flags = DWARF2_LINE_DEFAULT_IS_STMT ? DWARF2_FLAG_IS_STMT : 0;
   unsigned Isa = 0;
+  unsigned Discriminator = 0;
   MCSymbol *LastLabel = NULL;
 
   // Loop through each MCLineEntry and encode the dwarf line number table.
@@ -154,6 +155,15 @@
       MCOS->EmitIntValue(dwarf::DW_LNS_set_column, 1);
       MCOS->EmitULEB128IntValue(Column);
     }
+    if (Discriminator != it->getDiscriminator()) {
+      Discriminator = it->getDiscriminator();
+      unsigned Size =
+          MCOS->getContext().getAsmInfo()->getULEB128Size(Discriminator);
+      MCOS->EmitIntValue(dwarf::DW_LNS_extended_op, 1);
+      MCOS->EmitULEB128IntValue(Size + 1);
+      MCOS->EmitIntValue(dwarf::DW_LNE_set_discriminator, 1);
+      MCOS->EmitULEB128IntValue(Discriminator);
+    }
     if (Isa != it->getIsa()) {
       Isa = it->getIsa();
       MCOS->EmitIntValue(dwarf::DW_LNS_set_isa, 1);
Index: test/DebugInfo/X86/ending-run.ll
===================================================================
--- test/DebugInfo/X86/ending-run.ll
+++ test/DebugInfo/X86/ending-run.ll
@@ -4,9 +4,9 @@
 ; Check that the line table starts at 7, not 4, but that the first
 ; statement isn't until line 8.
 
-; CHECK-NOT: 0x0000000000000000      7      0      1   0  is_stmt
+; CHECK-NOT: 0x0000000000000000      7      0      1   0  0  is_stmt
 ; CHECK: 0x0000000000000000      7      0      1   0
-; CHECK: 0x0000000000000004      8     18      1   0  is_stmt prologue_end
+; CHECK: 0x0000000000000004      8     18      1   0  0  is_stmt prologue_end
 
 define i32 @callee(i32 %x) nounwind uwtable ssp {
 entry:
Index: test/DebugInfo/X86/line-info.ll
===================================================================
--- test/DebugInfo/X86/line-info.ll
+++ test/DebugInfo/X86/line-info.ll
@@ -2,7 +2,7 @@
 ; RUN: llvm-dwarfdump %t | FileCheck %s
 
 ; CHECK: [[FILEID:[0-9]+]]]{{.*}}list0.h
-; CHECK: [[FILEID]]      0      1   0  is_stmt{{$}}
+; CHECK: [[FILEID]]      0      1   0  0 is_stmt{{$}}
 
 ; IR generated from clang -g -emit-llvm with the following source:
 ; list0.h:
Index: test/MC/ELF/discriminator.s
===================================================================
--- /dev/null
+++ test/MC/ELF/discriminator.s
@@ -0,0 +1,20 @@
+# RUN: llvm-mc -g -triple i386-unknown-unknown %s -filetype=obj -o - | llvm-readobj -r | FileCheck %s
+# RUN: llvm-mc -g -triple i386-unknown-unknown %s -filetype=obj -o - | llvm-dwarfdump -debug-dump=line - | FileCheck %s -check-prefix=DWARF-DUMP
+
+    .text
+    .globl foo
+    .type foo, @function
+    .align 4
+foo:
+    .loc 1 2 discriminator 1
+    ret
+    .size foo, .-foo
+
+# CHECK:      Relocations [
+# CHECK:        Section ({{[^ ]+}}) .rel.debug_line {
+# CHECK-NEXT:     0x5B R_386_32 .text 0x0
+# CHECK-NEXT:   }
+
+# DWARF-DUMP: Address            Line   Column File   ISA Discriminator Flags
+# DWARF-DUMP: ------------------ ------ ------ ------ --- ------------- -------------
+# DWARF-DUMP: 0x0000000000000000      2      0      1   0             1  is_stmt
Index: test/MC/MachO/gen-dwarf-cpp.s
===================================================================
--- test/MC/MachO/gen-dwarf-cpp.s
+++ test/MC/MachO/gen-dwarf-cpp.s
@@ -17,6 +17,6 @@
 // CHECK: file_names[  2]    0 0x00000000 0x00000000 t.s
 
 // We check that the source line number 100 is picked up before the "movl"
-// CHECK: Address            Line   Column File   ISA Flags
-// CHECK: ------------------ ------ ------ ------ --- -------------
-// CHECK: 0x0000000000000000    102      0      2   0  is_stmt
+// CHECK: Address            Line   Column File   ISA Discriminator Flags
+// CHECK: ------------------ ------ ------ ------ --- ------------- -------------
+// CHECK: 0x0000000000000000    102      0      2   0             0  is_stmt
Index: test/MC/MachO/gen-dwarf.s
===================================================================
--- test/MC/MachO/gen-dwarf.s
+++ test/MC/MachO/gen-dwarf.s
@@ -113,10 +113,10 @@
 // CHECK:                 ---- ---------- ---------- ---------------------------
 // CHECK: file_names[  1]    1 0x00000000 0x00000000 gen-dwarf.s
 
-// CHECK: Address            Line   Column File   ISA Flags
-// CHECK: ------------------ ------ ------ ------ --- -------------
-// CHECK: 0x0000000000000000      6      0      1   0  is_stmt
-// CHECK: 0x0000000000000005      7      0      1   0  is_stmt
-// CHECK: 0x0000000000000006      8      0      1   0  is_stmt
-// CHECK: 0x0000000000000007     11      0      1   0  is_stmt
-// CHECK: 0x0000000000000008     11      0      1   0  is_stmt end_sequence
+// CHECK: Address            Line   Column File   ISA Discriminator Flags
+// CHECK: ------------------ ------ ------ ------ --- ------------- -------------
+// CHECK: 0x0000000000000000      6      0      1   0             0  is_stmt
+// CHECK: 0x0000000000000005      7      0      1   0             0  is_stmt
+// CHECK: 0x0000000000000006      8      0      1   0             0  is_stmt
+// CHECK: 0x0000000000000007     11      0      1   0             0  is_stmt
+// CHECK: 0x0000000000000008     11      0      1   0             0  is_stmt end_sequence
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