Re: [patch] Do not skip prologue for asm (.S) files

[Jan Kratochvil <jan.kratochvil@redhat.com>]

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On Tue, 23 Jun 2015 22:35:01 +0200, Jan Kratochvil wrote:
> On Tue, 23 Jun 2015 01:46:08 +0200, Doug Evans wrote:
> > static void
> > minsym_found (struct linespec_state *self, struct objfile *objfile,
> >               struct minimal_symbol *msymbol,
> >               struct symtabs_and_lines *result)
> > {
> >   struct gdbarch *gdbarch = get_objfile_arch (objfile);
> >   CORE_ADDR pc;
> >   struct symtab_and_line sal;
> > 
> >   sal = find_pc_sect_line (MSYMBOL_VALUE_ADDRESS (objfile, msymbol),
> >                            (struct obj_section *) 0, 0);
> >   sal.section = MSYMBOL_OBJ_SECTION (objfile, msymbol);
> > 
> >   /* The minimal symbol might point to a function descriptor;
> >      resolve it to the actual code address instead.  */
> >   pc = gdbarch_convert_from_func_ptr_addr (gdbarch, sal.pc, &current_target);
> >   if (pc != sal.pc)
> >     sal = find_pc_sect_line (pc, NULL, 0);
> > 
> >   if (self->funfirstline)
> >     skip_prologue_sal (&sal);
> > 
> >   if (maybe_add_address (self->addr_set, objfile->pspace, sal.pc))
> >     add_sal_to_sals (self, result, &sal, MSYMBOL_NATURAL_NAME (msymbol), 0);
> > }
> > 
> > With the patch added, we're using the value of
> > MSYMBOL_VALUE_ADDRESS twice
> > and calling gdbarch_convert_from_func_ptr_addr twice.
> > [I'm not micro-optimizing here, my goal is code readability.]
> > 
> > Plus the patch does:
> > 
> >       sal.pc = MSYMBOL_VALUE_ADDRESS (objfile, msymbol);
> >       sal.pc = gdbarch_convert_from_func_ptr_addr (gdbarch, sal.pc,
> >                                                   &current_target);
> > 
> > but it doesn't update sal.section nor sal.line.
> 
> OK, I agree that seems wrong.

I do not agree, it seems correct to me.

I have only added a comment to the code.  Is it enough this way?

I am sorry I cannot write it much cleanly as the data structures and functions
involved are not much clean.


Jan

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gdb/ChangeLog
2015-06-20  Jan Kratochvil  <jan.kratochvil@redhat.com>

	* dwarf2read.c (process_full_comp_unit): Set LOCATIONS_VALID also for
	language_asm.
	* linespec.c (minsym_found): Reset sal.PC forCOMPUNIT_LOCATIONS_VALID.

gdb/testsuite/ChangeLog
2015-06-20  Jan Kratochvil  <jan.kratochvil@redhat.com>

	* gdb.arch/amd64-prologue-skip.S: New file.
	* gdb.arch/amd64-prologue-skip.exp: New file.

diff --git a/gdb/dwarf2read.c b/gdb/dwarf2read.c
index 496b74f..8bfd034 100644
--- a/gdb/dwarf2read.c
+++ b/gdb/dwarf2read.c
@@ -8094,7 +8094,7 @@ process_full_comp_unit (struct dwarf2_per_cu_data *per_cu,
 	 Still one can confuse GDB by using non-standard GCC compilation
 	 options - this waits on GCC PR other/32998 (-frecord-gcc-switches).
 	 */ 
-      if (cu->has_loclist && gcc_4_minor >= 5)
+      if ((cu->has_loclist && gcc_4_minor >= 5) || cu->language == language_asm)
 	cust->locations_valid = 1;
 
       if (gcc_4_minor >= 5)
diff --git a/gdb/linespec.c b/gdb/linespec.c
index d2089b5..e5b4c56 100644
--- a/gdb/linespec.c
+++ b/gdb/linespec.c
@@ -3454,7 +3454,22 @@ minsym_found (struct linespec_state *self, struct objfile *objfile,
     sal = find_pc_sect_line (pc, NULL, 0);
 
   if (self->funfirstline)
-    skip_prologue_sal (&sal);
+    {
+      if (sal.symtab != NULL
+	  && COMPUNIT_LOCATIONS_VALID (SYMTAB_COMPUNIT (sal.symtab)))
+	{
+	  /* If gdbarch_convert_from_func_ptr_addr does not apply then
+	     sal.SECTION, sal.LINE&co. will stay correct from above.
+	     If gdbarch_convert_from_func_ptr_addr applies then
+	     sal.SECTION is cleared from above and sal.LINE&co. will
+	     stay correct from the last find_pc_sect_line above.  */
+	  sal.pc = MSYMBOL_VALUE_ADDRESS (objfile, msymbol);
+	  sal.pc = gdbarch_convert_from_func_ptr_addr (gdbarch, sal.pc,
+						       &current_target);
+	}
+      else
+	skip_prologue_sal (&sal);
+    }
 
   if (maybe_add_address (self->addr_set, objfile->pspace, sal.pc))
     add_sal_to_sals (self, result, &sal, MSYMBOL_NATURAL_NAME (msymbol), 0);
diff --git a/gdb/testsuite/gdb.arch/amd64-prologue-skip.S b/gdb/testsuite/gdb.arch/amd64-prologue-skip.S
new file mode 100644
index 0000000..66b806a
--- /dev/null
+++ b/gdb/testsuite/gdb.arch/amd64-prologue-skip.S
@@ -0,0 +1,28 @@
+/* This testcase is part of GDB, the GNU debugger.
+
+   Copyright 2015 Free Software Foundation, Inc.
+
+   This program is free software; you can redistribute it and/or modify
+   it under the terms of the GNU General Public License as published by
+   the Free Software Foundation; either version 3 of the License, or
+   (at your option) any later version.
+
+   This program is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+   GNU General Public License for more details.
+
+   You should have received a copy of the GNU General Public License
+   along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
+
+	.text
+/*0*/	hlt
+pushrbp: .globl pushrbp
+#define PUSHRBP push %rbp; mov %rsp, %rbp; nop
+/*1*/	PUSHRBP
+/*6*/	hlt
+
+/*7*/	hlt
+#define MINSYM nop; .globl minsym; minsym: nop
+/*8*/	MINSYM
+/*a*/	hlt
diff --git a/gdb/testsuite/gdb.arch/amd64-prologue-skip.exp b/gdb/testsuite/gdb.arch/amd64-prologue-skip.exp
new file mode 100644
index 0000000..015cd69
--- /dev/null
+++ b/gdb/testsuite/gdb.arch/amd64-prologue-skip.exp
@@ -0,0 +1,35 @@
+# Copyright 2010-2015 Free Software Foundation, Inc.
+
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 3 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+standard_testfile .S
+set binfile ${binfile}.o
+
+if { ![istarget x86_64-*-* ] || ![is_lp64_target] } {
+    verbose "Skipping ${testfile}."
+    return
+}
+
+if { [gdb_compile "${srcdir}/${subdir}/${srcfile}" "${binfile}" object {debug}] != "" } {
+    untested ${testfile}
+    return
+}
+
+clean_restart ${binfile}
+
+gdb_test "break *pushrbp" " at 0x1: file .*"
+gdb_test "break pushrbp" " at 0x1: file .*"
+
+gdb_test "break *minsym" " at 0x9: file .*"
+gdb_test "break minsym" " at 0x9: file .*"