Form reform for MCDwarf

[probinson]

Summary

MCDwarf emits a canned abbreviation table, but was not emitting proper
forms for DWARF version 4, which is the default after r249655.

Note: test/MC/MachO/gen-dwarf.s was modified to look for the new
forms, even though Darwin normally wants to default to DWARF 2.
But I think only llvm-mc works this way; if you compile an assembler
file with Clang, it gets the target-based default, because the
driver always passes -dwarf-version and does target defaulting.

FTR the line table produced by MCDwarf is hard-coded to DWARF 2,
regardless of what's requested.

[echristo]

Can you add a test to make sure we're doing the right thing for dwarf2 still? (I mean, looking at the code it's obvious that we are, but it'd be good to not break it).

Otherwise LGTM.

-eric

[probinson]

I think test/MC/ARM/dwarf-asm-multiple-sections-dwarf-2.s is sufficient to prove V2 works?

[echristo]

Sure, I didn't look.

llvm/trunk/lib/MC/MCDwarf.cpp

 static void EmitGenDwarfAbbrev(MCStreamer *MCOS) {
   MCContext &context = MCOS->getContext();
   MCOS->SwitchSection(context.getObjectFileInfo()->getDwarfAbbrevSection());
 
   // DW_TAG_compile_unit DIE abbrev (1).
   MCOS->EmitULEB128IntValue(1);
   MCOS->EmitULEB128IntValue(dwarf::DW_TAG_compile_unit);
   MCOS->EmitIntValue(dwarf::DW_CHILDREN_yes, 1);
-  EmitAbbrev(MCOS, dwarf::DW_AT_stmt_list, dwarf::DW_FORM_data4);
-  if (MCOS->getContext().getGenDwarfSectionSyms().size() > 1 &&
-      MCOS->getContext().getDwarfVersion() >= 3) {
-    EmitAbbrev(MCOS, dwarf::DW_AT_ranges, dwarf::DW_FORM_data4);
+  EmitAbbrev(MCOS, dwarf::DW_AT_stmt_list,
+             context.getDwarfVersion() >= 4 ? dwarf::DW_FORM_sec_offset
+                                            : dwarf::DW_FORM_data4);
+  if (context.getGenDwarfSectionSyms().size() > 1 &&
+      context.getDwarfVersion() >= 3) {
+    EmitAbbrev(MCOS, dwarf::DW_AT_ranges,
+               context.getDwarfVersion() >= 4 ? dwarf::DW_FORM_sec_offset
+                                              : dwarf::DW_FORM_data4);
   } else {
     EmitAbbrev(MCOS, dwarf::DW_AT_low_pc, dwarf::DW_FORM_addr);
     EmitAbbrev(MCOS, dwarf::DW_AT_high_pc, dwarf::DW_FORM_addr);
   }
   EmitAbbrev(MCOS, dwarf::DW_AT_name, dwarf::DW_FORM_string);
   if (!context.getCompilationDir().empty())
     EmitAbbrev(MCOS, dwarf::DW_AT_comp_dir, dwarf::DW_FORM_string);
   StringRef DwarfDebugFlags = context.getDwarfDebugFlags();

llvm/trunk/test/MC/ARM/dwarf-asm-multiple-sections-dwarf-2.s

 // DWARF:         DW_AT_high_pc   DW_FORM_addr
 // DWARF:         DW_AT_name      DW_FORM_string
 // DWARF:         DW_AT_comp_dir  DW_FORM_string
 // DWARF:         DW_AT_producer  DW_FORM_string
 // DWARF:         DW_AT_language  DW_FORM_data2
 
 // DWARF: .debug_info contents:
 // DWARF: 0x{{[0-9a-f]+}}: DW_TAG_compile_unit [1]
-// CHECK-NOT-DWARF: DW_TAG_
+// DWARF-NOT: DW_TAG_
 // DWARF:               DW_AT_low_pc [DW_FORM_addr]       (0x0000000000000000)
 // DWARF:               DW_AT_high_pc [DW_FORM_addr]      (0x0000000000000004)
 
 // DWARF: 0x{{[0-9a-f]+}}:   DW_TAG_label [2] *
 // DWARF-NEXT: DW_AT_name [DW_FORM_string]     ("a")
 
 
 // DWARF: .debug_aranges contents:

llvm/trunk/test/MC/ARM/dwarf-asm-multiple-sections.s

 // RUN: llvm-mc < %s -triple=armv7-linux-gnueabi -filetype=obj -o %t -g -fdebug-compilation-dir=/tmp
-// RUN: llvm-dwarfdump %t | FileCheck -check-prefix DWARF %s
+// RUN: llvm-dwarfdump %t | FileCheck -check-prefix DWARF -check-prefix DWARF4 %s
 // RUN: llvm-objdump -r %t | FileCheck -check-prefix RELOC %s
+// RUN: llvm-mc < %s -triple=armv7-linux-gnueabi -filetype=obj -o %t -g -dwarf-version 3 -fdebug-compilation-dir=/tmp
+// RUN: llvm-dwarfdump %t | FileCheck -check-prefix DWARF -check-prefix DWARF3 %s
 // RUN: llvm-mc < %s -triple=armv7-linux-gnueabi -filetype=obj -o %t -g -dwarf-version 2 2>&1 | FileCheck -check-prefix VERSION %s
 // RUN: not llvm-mc < %s -triple=armv7-linux-gnueabi -filetype=obj -o %t -g -dwarf-version 1 2>&1 | FileCheck -check-prefix DWARF1 %s
 // RUN: not llvm-mc < %s -triple=armv7-linux-gnueabi -filetype=obj -o %t -g -dwarf-version 5 2>&1 | FileCheck -check-prefix DWARF5 %s
   .section .text, "ax"
 a:
   mov r0, r0
 
   .section foo, "ax"
 b:
   mov r1, r1
 
 // DWARF: .debug_abbrev contents:
 // DWARF: Abbrev table for offset: 0x00000000
 // DWARF: [1] DW_TAG_compile_unit DW_CHILDREN_yes
-// DWARF:         DW_AT_stmt_list DW_FORM_data4
-// DWARF:         DW_AT_ranges    DW_FORM_data4
+// DWARF3:        DW_AT_stmt_list DW_FORM_data4
+// DWARF4:        DW_AT_stmt_list DW_FORM_sec_offset
+// DWARF3:        DW_AT_ranges    DW_FORM_data4
+// DWARF4:        DW_AT_ranges    DW_FORM_sec_offset
 // DWARF:         DW_AT_name      DW_FORM_string
 // DWARF:         DW_AT_comp_dir  DW_FORM_string
 // DWARF:         DW_AT_producer  DW_FORM_string
 // DWARF:         DW_AT_language  DW_FORM_data2
 
 // DWARF: .debug_info contents:
 // DWARF: 0x{{[0-9a-f]+}}: DW_TAG_compile_unit [1]
-// CHECK-NOT-DWARF: DW_TAG_
-// DWARF: DW_AT_ranges [DW_FORM_data4]      (0x00000000
+// DWARF-NOT: DW_TAG_
+// DWARF3: DW_AT_ranges [DW_FORM_data4]           (0x00000000
+// DWARF4: DW_AT_ranges [DW_FORM_sec_offset]      (0x00000000
 
 // DWARF: 0x{{[0-9a-f]+}}:   DW_TAG_label [2] *
 // DWARF-NEXT: DW_AT_name [DW_FORM_string]     ("a")
 
 // DWARF: 0x{{[0-9a-f]+}}:   DW_TAG_label [2] *
 // DWARF-NEXT: DW_AT_name [DW_FORM_string]     ("b")
 
 
 // DWARF: .debug_aranges contents:
 // DWARF-NEXT: Address Range Header: length = 0x00000024, version = 0x0002, cu_offset = 0x00000000, addr_size = 0x04, seg_size = 0x00
 // DWARF-NEXT: [0x00000000 - 0x00000004)
 // DWARF-NEXT: [0x00000000 - 0x00000004)
 
 
 // DWARF: .debug_line contents:
-// DWARF:      0x0000000000000000      9      0      1   0   0  is_stmt
-// DWARF-NEXT: 0x0000000000000004      9      0      1   0   0  is_stmt end_sequence
-// DWARF-NEXT: 0x0000000000000000     13      0      1   0   0  is_stmt
-// DWARF-NEXT: 0x0000000000000004     13      0      1   0   0  is_stmt end_sequence
+// DWARF:      0x0000000000000000     11      0      1   0   0  is_stmt
+// DWARF-NEXT: 0x0000000000000004     11      0      1   0   0  is_stmt end_sequence
+// DWARF-NEXT: 0x0000000000000000     15      0      1   0   0  is_stmt
+// DWARF-NEXT: 0x0000000000000004     15      0      1   0   0  is_stmt end_sequence
 
 
 // DWARF: .debug_ranges contents:
 // DWARF: 00000000 ffffffff 00000000
 // DWARF: 00000000 00000000 00000004
 // DWARF: 00000000 ffffffff 00000000
 // DWARF: 00000000 00000000 00000004
 // DWARF: 00000000 <End of list>

llvm/trunk/test/MC/ARM/dwarf-asm-nonstandard-section.s

 // RUN: llvm-mc < %s -triple=armv7-linux-gnueabi -filetype=obj -o %t -g -fdebug-compilation-dir=/tmp
 // RUN: llvm-dwarfdump %t | FileCheck -check-prefix DWARF %s
 // RUN: llvm-objdump -r %t | FileCheck -check-prefix RELOC %s
 
   .section foo, "ax"
 b:
   mov r1, r1
 
 // DWARF: .debug_abbrev contents:
 // DWARF: Abbrev table for offset: 0x00000000
 // DWARF: [1] DW_TAG_compile_unit DW_CHILDREN_yes
-// DWARF:         DW_AT_stmt_list DW_FORM_data4
+// DWARF:         DW_AT_stmt_list DW_FORM_sec_offset
 // DWARF:         DW_AT_low_pc    DW_FORM_addr
 // DWARF:         DW_AT_high_pc   DW_FORM_addr
 // DWARF:         DW_AT_name      DW_FORM_string
 // DWARF:         DW_AT_comp_dir  DW_FORM_string
 // DWARF:         DW_AT_producer  DW_FORM_string
 // DWARF:         DW_AT_language  DW_FORM_data2
 
 // DWARF: .debug_info contents:

llvm/trunk/test/MC/ARM/dwarf-asm-single-section.s

 // RUN: llvm-mc < %s -triple=armv7-linux-gnueabi -filetype=obj -o %t -g -fdebug-compilation-dir=/tmp
 // RUN: llvm-dwarfdump %t | FileCheck -check-prefix DWARF %s
 // RUN: llvm-objdump -r %t | FileCheck -check-prefix RELOC %s
 
   .section .text, "ax"
 a:
   mov r0, r0
 
 
 // DWARF: .debug_abbrev contents:
 // DWARF: Abbrev table for offset: 0x00000000
 // DWARF: [1] DW_TAG_compile_unit DW_CHILDREN_yes
-// DWARF:         DW_AT_stmt_list DW_FORM_data4
+// DWARF:         DW_AT_stmt_list DW_FORM_sec_offset
 // DWARF:         DW_AT_low_pc    DW_FORM_addr
 // DWARF:         DW_AT_high_pc   DW_FORM_addr
 // DWARF:         DW_AT_name      DW_FORM_string
 // DWARF:         DW_AT_comp_dir  DW_FORM_string
 // DWARF:         DW_AT_producer  DW_FORM_string
 // DWARF:         DW_AT_language  DW_FORM_data2
 
 // DWARF: .debug_info contents:
 // DWARF: 0x{{[0-9a-f]+}}: DW_TAG_compile_unit [1]
-// CHECK-NOT-DWARF: DW_TAG_
+// DWARF-NOT: DW_TAG_
 // DWARF:               DW_AT_low_pc [DW_FORM_addr]       (0x0000000000000000)
 // DWARF:               DW_AT_high_pc [DW_FORM_addr]      (0x0000000000000004)
 
 // DWARF: 0x{{[0-9a-f]+}}:   DW_TAG_label [2] *
 // DWARF-NEXT: DW_AT_name [DW_FORM_string]     ("a")
 
 
 // DWARF: .debug_aranges contents:

llvm/trunk/test/MC/MachO/gen-dwarf.s

 .data
 _x: .long 1
 
 // CHECK: file format Mach-O 32-bit i386
 
 // CHECK: .debug_abbrev contents:
 // CHECK: Abbrev table for offset: 0x00000000
 // CHECK: [1] DW_TAG_compile_unit DW_CHILDREN_yes
-// CHECK:   DW_AT_stmt_list DW_FORM_data4
+// CHECK:   DW_AT_stmt_list DW_FORM_sec_offset
 // CHECK:   DW_AT_low_pc  DW_FORM_addr
 // CHECK:   DW_AT_high_pc DW_FORM_addr
 // CHECK:   DW_AT_name  DW_FORM_string
 // CHECK:   DW_AT_comp_dir  DW_FORM_string
 // CHECK:   DW_AT_producer  DW_FORM_string
 // CHECK:   DW_AT_language  DW_FORM_data2
 
 // CHECK: [2] DW_TAG_label  DW_CHILDREN_yes
 // CHECK:   DW_AT_name  DW_FORM_string
 // CHECK:   DW_AT_decl_file DW_FORM_data4
 // CHECK:   DW_AT_decl_line DW_FORM_data4
 // CHECK:   DW_AT_low_pc  DW_FORM_addr
 // CHECK:   DW_AT_prototyped  DW_FORM_flag
 
 // CHECK: [3] DW_TAG_unspecified_parameters DW_CHILDREN_no
 
 
 // CHECK: .debug_info contents:
 
 // We don't check the leading addresses these are at.
 // CHECK:  DW_TAG_compile_unit [1] *
-// CHECK:    DW_AT_stmt_list [DW_FORM_data4]  (0x00000000)
+// CHECK:    DW_AT_stmt_list [DW_FORM_sec_offset] (0x00000000)
 // CHECK:    DW_AT_low_pc [DW_FORM_addr]  (0x0000000000000000)
 // CHECK:    DW_AT_high_pc [DW_FORM_addr] (0x0000000000000008)
 // We don't check the file name as it is a temp directory
 // CHECK:    DW_AT_name [DW_FORM_string]
 // We don't check the DW_AT_comp_dir which is the current working directory
 // CHECK:    DW_AT_producer [DW_FORM_string]  ("llvm-mc (based on {{.*}})")
 // CHECK:    DW_AT_language [DW_FORM_data2] (DW_LANG_Mips_Assembler)