[DebugInfo] Fix verbose printing of rows added via DW_LNE_end_sequence

[jhenderson]

Summary

The debug line verbose printing was printing the wrong values for rows added via DW_LNE_end_sequence, because the row was being printed AFTER its state had been reset following it being appended to the line table. This patch fixes this issue by printing the row before appending it.

[dblaikie]

Looks good - thanks!

[MaskRay]

appendRowToMatrix after dumping looks good (D60364 made a similar change to DW_LNS_copy).

llvm/test/tools/llvm-dwarfdump/X86/debug-line-dw-lne-end-sequence.s

4

We may delete -pc-linux
This is not specific to Linux.

llvm/lib/DebugInfo/DWARF/DWARFDebugLine.cpp

if (Opcode == 0) {
         // Set the end_sequence register of the state machine to true and
         // append a row to the matrix using the current values of the
         // state-machine registers. Then reset the registers to the initial
         // values specified above. Every statement program sequence must end
         // with a DW_LNE_end_sequence instruction which creates a row whose
         // address is that of the byte after the last target machine instruction
         // of the sequence.
         State.Row.EndSequence = true;
-        State.appendRowToMatrix();
         if (OS) {
           *OS << "\n";
           OS->indent(12);
           State.Row.dump(*OS);
         }
+        State.appendRowToMatrix();
         State.resetRowAndSequence();
         break;
 
       case DW_LNE_set_address:
         // Takes a single relocatable address as an operand. The size of the
         // operand is the size appropriate to hold an address on the target
         // machine. Set the address register to the value given by the
         // relocatable address. All of the other statement program opcodes

llvm/test/tools/llvm-dwarfdump/X86/debug-line-dw-lne-end-sequence.s

+## Show that the DW_LNE_end_sequence opcode resets the line state
+## properly and the rows are printed correctly.
+
+# RUN: llvm-mc -filetype obj -triple x86_64-pc-linux %s -o %t.o
+# RUN: llvm-dwarfdump --debug-line %t.o | FileCheck %s --check-prefixes=HEADER,ROWS
+# RUN: llvm-dwarfdump --debug-line %t.o --verbose | FileCheck %s --check-prefix=ROWS
+
+# HEADER:      Address            Line   Column File   ISA Discriminator Flags
+# HEADER-NEXT: ------------------ ------ ------ ------ --- ------------- -------------
+# ROWS:        0x0000000012345678      1      0      1   0             1  is_stmt basic_block prologue_end epilogue_begin end_sequence
+# ROWS:        0x0000000000000001      2      0      1   0             0  is_stmt
+# ROWS:        0x0000000000000001      2      0      1   0             0  is_stmt end_sequence
+
+.section .debug_line,"",@progbits
+.Line_table_start0:
+  .long   .Line_table_end0-.Line_table_start0-4   # Length of Unit
+  .short  5               # DWARF version number
+  .byte   8               # Address Size
+  .byte   0               # Segment Selector Size
+  .long   .Line_table_header_end0-.Line_table_params0     # Length of Prologue
+.Line_table_params0:
+  .byte   1               # Minimum Instruction Length
+  .byte   1               # Maximum Operations per Instruction
+  .byte   1               # Default is_stmt
+  .byte   -5              # Line Base
+  .byte   14              # Line Range
+  .byte   13              # Opcode Base
+  .byte   0, 1, 1, 1, 1, 0, 0, 0, 1, 0, 0, 1 # Standard Opcode Lengths
+  # Directory table format
+  .byte   1               # One element per directory entry
+  .byte   1               # DW_LNCT_path
+  .byte   0x08            # DW_FORM_string
+  # Directory table entries
+  .byte   1               # 1 directory
+  .asciz  "/tmp"
+  # File table format
+  .byte   2               # 2 elements per file entry
+  .byte   1               # DW_LNCT_path
+  .byte   0x08            # DW_FORM_string
+  .byte   2               # DW_LNCT_directory_index
+  .byte   0x0b            # DW_FORM_data1
+  # File table entries
+  .byte   1               # 1 file
+  .asciz  "a.c"
+  .byte   0
+.Line_table_header_end0:
+  .byte   0,9,2           # DW_LNE_set_address
+  .quad   0x12345678
+  .byte   7               # DW_LNS_set_basic_block
+  .byte   10              # DW_LNS_set_prologue_end
+  .byte   11              # DW_LNS_set_epilogue_begin
+  .byte   0,2,4,1         # DW_LNE_set_discriminator 1
+  .byte   0,1,1           # DW_LNE_end_sequence
+  .byte   33              # address += 1, line += 1
+  .byte   0,1,1           # DW_LNE_end_sequence
+.Line_table_end0: