[PATCH] Bad DWARF2 line information for MIPS16

[PATCH] Bad DWARF2 line information for MIPS16

[Maciej W. Rozycki]

Hello,

 Investigating a problem with gdb setting up breakpoints in a middle of 
MIPS16 extended instructions I've discovered incorrect DWARF2 line 
information is output for relaxed frags.  The culprit is address offsets 
are calculated relating to instruction ends and relaxed frags are 
initially set up for standard instructions.  Then when an extended 
alternative is used, occupying twice as much space, the address offset 
points to a middle of that instruction.

 Apparently other ports have encountered similar problems in the past and 
the solution is to calculate address offsets relating to instruction 
beginnings.  Here is a corresponding update for MIPS.  I've tested it for 
mips64-linux-gnu, mipsel-linux-gnu, mips64el-elf and mips64-elf with no 
regressions (I've run the gdb testsuite under sim for one of our 
configurations involving MIPS64 just in case as well; standard MIPS should 
be unaffected by this change).  I've prepared a DWARF2 test case to check 
we get line information right.

gas/:
2005-02-21  Maciej W. Rozycki  <macro@mips.com>

	* config/tc-mips.c (append_insn): Call dwarf2_emit_insn() before 
	emitting insn.

gas/testsuite/:
2005-02-21  Maciej W. Rozycki  <macro@mips.com>

	* gas/mips/mips16-dwarf2.d: New test to check DWARF2 line 
	information for MIPS16.
	* gas/mips/mips16-dwarf2.s: Source for the new test.
	* gas/mips/mips.exp: Run the new test.

 OK to apply?

  Maciej

binutils-2.15.94-20050221-mips16-dwarf2.patch
diff -up --recursive --new-file binutils-2.15.94-20050221.macro/gas/config/tc-mips.c binutils-2.15.94-20050221/gas/config/tc-mips.c
--- binutils-2.15.94-20050221.macro/gas/config/tc-mips.c	2005-02-21 17:55:54.000000000 +0000
+++ binutils-2.15.94-20050221/gas/config/tc-mips.c	2005-02-21 21:25:58.000000000 +0000
@@ -2009,6 +2009,15 @@ append_insn (struct mips_cl_insn *ip, ex
 	}
     }
 
+#ifdef OBJ_ELF
+  /* The value passed to dwarf2_emit_insn is the distance between
+     the beginning of the current instruction and the address that
+     should be recorded in the debug tables.  For MIPS16 debug info
+     we want to use ISA-encoded addresses, so we pass -1 for an
+     address higher by one than the current.  */
+  dwarf2_emit_insn (mips_opts.mips16 ? -1 : 0);
+#endif
+
   /* Record the frag type before frag_var.  */
   if (prev_insn_frag)
     prev_insn_frag_type = prev_insn_frag->fr_type;
@@ -2243,24 +2252,11 @@ append_insn (struct mips_cl_insn *ip, ex
     }
 
   if (! mips_opts.mips16)
-    {
       md_number_to_chars (f, ip->insn_opcode, 4);
-#ifdef OBJ_ELF
-      dwarf2_emit_insn (4);
-#endif
-    }
   else if (*reloc_type == BFD_RELOC_MIPS16_JMP)
     {
       md_number_to_chars (f, ip->insn_opcode >> 16, 2);
       md_number_to_chars (f + 2, ip->insn_opcode & 0xffff, 2);
-#ifdef OBJ_ELF
-      /* The value passed to dwarf2_emit_insn is the distance between
-	 the end of the current instruction and the address that should
-	 be recorded in the debug tables.  Since we want to use ISA-encoded
-	 addresses in MIPS16 debug info, the value is one byte less than
-	 the real instruction length.  */
-      dwarf2_emit_insn (3);
-#endif
     }
   else
     {
@@ -2270,9 +2266,6 @@ append_insn (struct mips_cl_insn *ip, ex
 	  f += 2;
 	}
       md_number_to_chars (f, ip->insn_opcode, 2);
-#ifdef OBJ_ELF
-      dwarf2_emit_insn (ip->use_extend ? 3 : 1);
-#endif
     }
 
   /* Update the register mask information.  */
diff -up --recursive --new-file binutils-2.15.94-20050221.macro/gas/testsuite/gas/mips/mips.exp binutils-2.15.94-20050221/gas/testsuite/gas/mips/mips.exp
--- binutils-2.15.94-20050221.macro/gas/testsuite/gas/mips/mips.exp	2005-02-21 17:55:58.000000000 +0000
+++ binutils-2.15.94-20050221/gas/testsuite/gas/mips/mips.exp	2005-02-21 21:26:36.000000000 +0000
@@ -746,4 +746,8 @@ if { [istarget mips*-*-*] } then {
     run_list_test "noat-5" ""
     run_list_test "noat-6" ""
     run_list_test "noat-7" ""
+
+    if { $elf && !$no_mips16 } {
+	run_dump_test "mips16-dwarf2"
+    }
 }
diff -up --recursive --new-file binutils-2.15.94-20050221.macro/gas/testsuite/gas/mips/mips16-dwarf2.d binutils-2.15.94-20050221/gas/testsuite/gas/mips/mips16-dwarf2.d
--- binutils-2.15.94-20050221.macro/gas/testsuite/gas/mips/mips16-dwarf2.d	1970-01-01 00:00:00.000000000 +0000
+++ binutils-2.15.94-20050221/gas/testsuite/gas/mips/mips16-dwarf2.d	2005-02-21 21:01:56.000000000 +0000
@@ -0,0 +1,47 @@
+#readelf: -wl
+#name: MIPS16 DWARF2
+#as: -mips16 -no-mdebug -g0
+#source: mips16-dwarf2.s
+
+Dump of debug contents of section \.debug_line:
+
+  Length:                      64
+  DWARF Version:               2
+  Prologue Length:             35
+  Minimum Instruction Length:  1
+  Initial value of 'is_stmt':  1
+  Line Base:                   -5
+  Line Range:                  14
+  Opcode Base:                 10
+  \(Pointer size:               4\)
+
+ Opcodes:
+  Opcode 1 has 0 args
+  Opcode 2 has 1 args
+  Opcode 3 has 1 args
+  Opcode 4 has 1 args
+  Opcode 5 has 1 args
+  Opcode 6 has 0 args
+  Opcode 7 has 0 args
+  Opcode 8 has 0 args
+  Opcode 9 has 1 args
+
+ The Directory Table is empty\.
+
+ The File Name Table:
+  Entry	Dir	Time	Size	Name
+  1	0	0	0	mips16-dwarf2\.s
+
+ Line Number Statements:
+  Extended opcode 2: set Address to 0x1
+  Special opcode 5: advance Address by 0 to 0x1 and Line by 0 to 1
+  Special opcode 34: advance Address by 2 to 0x3 and Line by 1 to 2
+  Special opcode 34: advance Address by 2 to 0x5 and Line by 1 to 3
+  Special opcode 62: advance Address by 4 to 0x9 and Line by 1 to 4
+  Special opcode 34: advance Address by 2 to 0xb and Line by 1 to 5
+  Special opcode 62: advance Address by 4 to 0xf and Line by 1 to 6
+  Special opcode 62: advance Address by 4 to 0x13 and Line by 1 to 7
+  Advance PC by 2286 to 901
+  Special opcode 6: advance Address by 0 to 0x901 and Line by 1 to 8
+  Advance PC by 15 to 910
+  Extended opcode 1: End of Sequence
diff -up --recursive --new-file binutils-2.15.94-20050221.macro/gas/testsuite/gas/mips/mips16-dwarf2.s binutils-2.15.94-20050221/gas/testsuite/gas/mips/mips16-dwarf2.s
--- binutils-2.15.94-20050221.macro/gas/testsuite/gas/mips/mips16-dwarf2.s	1970-01-01 00:00:00.000000000 +0000
+++ binutils-2.15.94-20050221/gas/testsuite/gas/mips/mips16-dwarf2.s	2005-02-21 21:19:29.000000000 +0000
@@ -0,0 +1,66 @@
+# Source file used to test DWARF2 information for MIPS16.
+
+	.set	mips16
+
+	.text
+.Ltext0:
+	.p2align 2
+
+	.file	1 "mips16-dwarf2.s"
+stuff:
+	.loc	1 1 0
+	nop
+	.loc	1 2 0
+	li	$2, 0
+	.loc	1 3 0
+	li	$2, 0x1234
+	.loc	1 4 0
+	lw	$2, 0f
+	.loc	1 5 0
+	lw	$2, 1f
+	.loc	1 6 0
+	b	0f
+	nop
+	.loc	1 7 0
+	b	1f
+	nop
+	.loc	1 8 0
+
+	.p2align 8
+0:
+	.space	2048
+1:
+	nop
+# align section end to 16-byte boundary for easier testing on multiple targets
+	.p2align 4
+.Letext0:
+
+	.section .debug_info,"",@progbits
+.Ldebug_info0:
+	.4byte	.Ledebug_info0 - .L1debug_info0	# length
+.L1debug_info0:
+	.2byte	2				# version
+	.4byte	.Ldebug_abbrev0			# abbrev offset
+	.byte	4				# address size
+	.uleb128 1				# abbrev code
+	.4byte	.Ldebug_line0			# DW_AT_stmt_list
+	.4byte	.Ltext0				# DW_AT_low_pc
+	.4byte	.Letext0			# DW_AT_high_pc
+.Ledebug_info0:
+
+	.section .debug_abbrev,"",@progbits
+.Ldebug_abbrev0:
+	.uleb128 0x1				# abbrev code
+	.uleb128 0x11				# DW_TAG_compile_unit
+	.byte	0x0				# DW_CHILDREN_no
+	.uleb128 0x10				# DW_AT_stmt_list
+	.uleb128 0x6				# DW_FORM_data4
+	.uleb128 0x11				# DW_AT_low_pc
+	.uleb128 0x1				# DW_FORM_addr
+	.uleb128 0x12				# DW_AT_high_pc
+	.uleb128 0x1				# DW_FORM_addr
+	.byte	0x0
+	.byte	0x0
+
+	.section .debug_line,"",@progbits
+.Ldebug_line0:

Re: [PATCH] Bad DWARF2 line information for MIPS16

[Eric Christopher]

> gas/:
> 2005-02-21  Maciej W. Rozycki  <macro@mips.com>
> 
> 	* config/tc-mips.c (append_insn): Call dwarf2_emit_insn() before 
> 	emitting insn.
> 
> gas/testsuite/:
> 2005-02-21  Maciej W. Rozycki  <macro@mips.com>
> 
> 	* gas/mips/mips16-dwarf2.d: New test to check DWARF2 line 
> 	information for MIPS16.
> 	* gas/mips/mips16-dwarf2.s: Source for the new test.
> 	* gas/mips/mips.exp: Run the new test.
> 
>  OK to apply?

OK.

-eric

Re: [PATCH] Bad DWARF2 line information for MIPS16

[Maciej W. Rozycki]

On Mon, 21 Feb 2005, Eric Christopher wrote:

> OK.

 Well, I had applied it, but then I discovered it failed for NewABI 
targets, like mips64*-linux-gnu, due to RELA relocations being involved.  
Shame on me...

 I've prepared the obvious fix of forcing the o32 ABI, but rather than 
stopping at that, I've decided to keep n32 tested, too, so I've made 
another test for the latter and covered relocation setup as well.  Here's 
the result.  Tested for mipsel-linux-gnu, mips64-elf, mips64el-elf, 
mips64-linux-gnu, mips64el-linux-gnu with no regressions and the two 
latters fixed.

2005-02-22  Maciej W. Rozycki  <macro@mips.com>

	* gas/mips/mips16-dwarf2.d: Pass -mabi=32.  Include relocation 
	information.
	* gas/mips/mips16-dwarf2-n32.d: New test to check DWARF2 line
	information for MIPS16 for the n32 ABI.
	* gas/mips/mips.exp. Run the new test.

 OK to apply?

  Maciej

binutils-2.15.94-20050222-mips16-dwarf2-newabi.patch
diff -up --recursive --new-file binutils-2.15.94-20050222.macro/gas/testsuite/gas/mips/mips.exp binutils-2.15.94-20050222/gas/testsuite/gas/mips/mips.exp
--- binutils-2.15.94-20050222.macro/gas/testsuite/gas/mips/mips.exp	2005-02-22 14:32:13.000000000 +0000
+++ binutils-2.15.94-20050222/gas/testsuite/gas/mips/mips.exp	2005-02-22 18:56:37.000000000 +0000
@@ -749,5 +749,8 @@ if { [istarget mips*-*-*] } then {
 
     if { $elf && !$no_mips16 } {
 	run_dump_test "mips16-dwarf2"
+	if $has_newabi {
+	    run_dump_test "mips16-dwarf2-n32"
+	}
     }
 }
diff -up --recursive --new-file binutils-2.15.94-20050222.macro/gas/testsuite/gas/mips/mips16-dwarf2-n32.d binutils-2.15.94-20050222/gas/testsuite/gas/mips/mips16-dwarf2-n32.d
--- binutils-2.15.94-20050222.macro/gas/testsuite/gas/mips/mips16-dwarf2-n32.d	1970-01-01 00:00:00.000000000 +0000
+++ binutils-2.15.94-20050222/gas/testsuite/gas/mips/mips16-dwarf2-n32.d	2005-02-22 20:00:02.000000000 +0000
@@ -0,0 +1,58 @@
+#readelf: -r -wl
+#name: MIPS16 DWARF2
+#as: -march=mips3 -mabi=n32 -mips16 -no-mdebug -g0
+#source: mips16-dwarf2.s
+
+Relocation section '\.rela\.debug_info' at offset .* contains 4 entries:
+ *Offset * Info * Type * Sym\.Value * Sym\. Name \+ Addend
+0+0006 * 0+..02 * R_MIPS_32 * 0+0000 * \.debug_abbrev \+ 0
+0+000c * 0+..02 * R_MIPS_32 * 0+0000 * \.debug_line \+ 0
+0+0010 * 0+..02 * R_MIPS_32 * 0+0000 * \.text \+ 0
+0+0014 * 0+..02 * R_MIPS_32 * 0+0000 * \.text \+ 910
+
+Relocation section '\.rela\.debug_line' at offset .* contains 1 entries:
+ *Offset * Info * Type * Sym\.Value * Sym\. Name \+ Addend
+0+0030 * 0+..02 * R_MIPS_32 * 0+0000 * .text \+ 1
+
+Dump of debug contents of section \.debug_line:
+
+  Length:                      64
+  DWARF Version:               2
+  Prologue Length:             35
+  Minimum Instruction Length:  1
+  Initial value of 'is_stmt':  1
+  Line Base:                   -5
+  Line Range:                  14
+  Opcode Base:                 10
+  \(Pointer size:               4\)
+
+ Opcodes:
+  Opcode 1 has 0 args
+  Opcode 2 has 1 args
+  Opcode 3 has 1 args
+  Opcode 4 has 1 args
+  Opcode 5 has 1 args
+  Opcode 6 has 0 args
+  Opcode 7 has 0 args
+  Opcode 8 has 0 args
+  Opcode 9 has 1 args
+
+ The Directory Table is empty\.
+
+ The File Name Table:
+  Entry	Dir	Time	Size	Name
+  1	0	0	0	mips16-dwarf2\.s
+
+ Line Number Statements:
+  Extended opcode 2: set Address to 0x0
+  Special opcode 5: advance Address by 0 to 0x0 and Line by 0 to 1
+  Special opcode 34: advance Address by 2 to 0x2 and Line by 1 to 2
+  Special opcode 34: advance Address by 2 to 0x4 and Line by 1 to 3
+  Special opcode 62: advance Address by 4 to 0x8 and Line by 1 to 4
+  Special opcode 34: advance Address by 2 to 0xa and Line by 1 to 5
+  Special opcode 62: advance Address by 4 to 0xe and Line by 1 to 6
+  Special opcode 62: advance Address by 4 to 0x12 and Line by 1 to 7
+  Advance PC by 2286 to 900
+  Special opcode 6: advance Address by 0 to 0x900 and Line by 1 to 8
+  Advance PC by 15 to 90f
+  Extended opcode 1: End of Sequence
diff -up --recursive --new-file binutils-2.15.94-20050222.macro/gas/testsuite/gas/mips/mips16-dwarf2.d binutils-2.15.94-20050222/gas/testsuite/gas/mips/mips16-dwarf2.d
--- binutils-2.15.94-20050222.macro/gas/testsuite/gas/mips/mips16-dwarf2.d	2005-02-22 12:32:26.000000000 +0000
+++ binutils-2.15.94-20050222/gas/testsuite/gas/mips/mips16-dwarf2.d	2005-02-22 20:00:11.000000000 +0000
@@ -1,8 +1,19 @@
-#readelf: -wl
+#readelf: -r -wl
 #name: MIPS16 DWARF2
-#as: -mips16 -no-mdebug -g0
+#as: -mabi=32 -mips16 -no-mdebug -g0
 #source: mips16-dwarf2.s
 
+Relocation section '\.rel\.debug_info' at offset .* contains 4 entries:
+ *Offset * Info * Type * Sym\.Value * Sym\. Name
+0+0006 * 0+..02 * R_MIPS_32 * 0+0000 * \.debug_abbrev
+0+000c * 0+..02 * R_MIPS_32 * 0+0000 * \.debug_line
+0+0010 * 0+..02 * R_MIPS_32 * 0+0000 * \.text
+0+0014 * 0+..02 * R_MIPS_32 * 0+0000 * \.text
+
+Relocation section '\.rel\.debug_line' at offset .* contains 1 entries:
+ *Offset * Info * Type * Sym\.Value * Sym\. Name
+0+0030 * 0+..02 * R_MIPS_32 * 0+0000 * \.text
+
 Dump of debug contents of section \.debug_line:
 
   Length:                      64

Re: [PATCH] Bad DWARF2 line information for MIPS16

[Eric Christopher]

> the result.  Tested for mipsel-linux-gnu, mips64-elf, mips64el-elf, 
> mips64-linux-gnu, mips64el-linux-gnu with no regressions and the two 
> latters fixed.
> 
> 2005-02-22  Maciej W. Rozycki  <macro@mips.com>
> 
> 	* gas/mips/mips16-dwarf2.d: Pass -mabi=32.  Include relocation 
> 	information.
> 	* gas/mips/mips16-dwarf2-n32.d: New test to check DWARF2 line
> 	information for MIPS16 for the n32 ABI.
> 	* gas/mips/mips.exp. Run the new test.
> 
>  OK to apply?

OK.

-eric