readelf: Remove show_op_index variable

advance_pc() uses show_op_index to save whether the current op_index is
> 0 OR the new op_index is > 0.

The new op index is calculated via

new_op_index = (op_index + op_advance) % max_ops_per_instr;

since all of the variables involved are unsigned,
new_op_index >= op_index is always true.

So...

if op_index > 0, then new_op_index > 0
if op_index == 0, then new_op_index >= 0

and if the new_op_index is > 0, then the old one was as well.

In any case, we only need to check the new_op_index, since show_op_index
used to OR the two comparisons.

In other words:

 op_index > 0  |  new_op_index > 0  || show_op_index
 ------------------------------------------------
      true           true                true
     false           true                true
      true          false                true     xx
     false          false                false

... but since the third line (marked with xx) is not possible,
the table becomes:

 op_index > 0  |  new_op_index > 0  || show_op_index
 ------------------------------------------------
      true           true                true
     false           true                true
     false          false                false

... and show_op_index is equal to (new_op_index > 0).
So, remove the show_op_index variable and simply replace it by comparing
the new op_index > 0.

diff --git a/src/ChangeLog b/src/ChangeLog
index 1f53ca7bcf9f05f5e45356d6a57f51b1093e5607..9e30df31c20026d5ae9056d2cb7adef05a81bcc4 100644 (file)
--- a/src/ChangeLog
+++ b/src/ChangeLog
@@ -1,3 +1,8 @@
+2021-02-02 Timm Bäder <tbaeder@redhat.com>
+
+       * readelf.c (print_debug_line_section): Remove unnecessary
+       show_op_index variable, replace with (op_index > 0).
+
 2021-01-08  Timm Bäder  <tbaeder@redhat.com>
 
        * readelf.c (print_cfa_program): Lift regname function to...

diff --git a/src/readelf.c b/src/readelf.c
index 9943c21148a74d71d0259f510f9539c4fa73bbe2..11692bb5bba539bb9ffb11b42dc8fa1bd912d444 100644 (file)
--- a/src/readelf.c
+++ b/src/readelf.c
@@ -8752,14 +8752,11 @@ print_debug_line_section (Dwfl_Module *dwflmod, Ebl *ebl, GElf_Ehdr *ehdr,
       /* Apply the "operation advance" from a special opcode
         or DW_LNS_advance_pc (as per DWARF4 6.2.5.1).  */
       unsigned int op_addr_advance;
-      bool show_op_index;
       inline void advance_pc (unsigned int op_advance)
       {
        op_addr_advance = minimum_instr_len * ((op_index + op_advance)
                                               / max_ops_per_instr);
        address += op_addr_advance;
-       show_op_index = (op_index > 0 ||
-                        (op_index + op_advance) % max_ops_per_instr > 0);
        op_index = (op_index + op_advance) % max_ops_per_instr;
       }
 
@@ -8803,7 +8800,7 @@ print_debug_line_section (Dwfl_Module *dwflmod, Ebl *ebl, GElf_Ehdr *ehdr,
              printf (_(" special opcode %u: address+%u = "),
                      opcode, op_addr_advance);
              print_dwarf_addr (dwflmod, 0, address, address);
-             if (show_op_index)
+             if (op_index > 0)
                printf (_(", op_index = %u, line%+d = %zu\n"),
                        op_index, line_increment, line);
              else
@@ -8921,7 +8918,7 @@ print_debug_line_section (Dwfl_Module *dwflmod, Ebl *ebl, GElf_Ehdr *ehdr,
                    printf (_(" advance address by %u to "),
                            op_addr_advance);
                    print_dwarf_addr (dwflmod, 0, address, address);
-                   if (show_op_index)
+                   if (op_index > 0)
                      printf (_(", op_index to %u"), op_index);
                    printf ("\n");
                  }
@@ -8982,7 +8979,7 @@ print_debug_line_section (Dwfl_Module *dwflmod, Ebl *ebl, GElf_Ehdr *ehdr,
                    printf (_(" advance address by constant %u to "),
                            op_addr_advance);
                    print_dwarf_addr (dwflmod, 0, address, address);
-                   if (show_op_index)
+                   if (op_index > 0)
                      printf (_(", op_index to %u"), op_index);
                    printf ("\n");
                  }