[PATCH][gdb/testsuite] Fix count usage in gdb.reverse/insn-reverse.exp

[Tom de Vries <tdevries@suse.de>]

Hi,

Consider the test-case gdb.reverse/insn-reverse.exp.

After the loop setting count, the valid entries in various arrays range from 0
to $count - 1 inclusive.

Then $count is decremented:
...
       incr count -1
...
after which the valid entries range from 0 to $count inclusive.

The first subsequent loop handles that properly:
...
       for {set i $count} {$i >= 0} {incr i -1} {
...
but the following loop does not, because it treats $count as exclusive bound:
...
	for {set i 0} {$i < $count} {incr i} {
...

Fix this by removing the incr, and using $count - 1 as starting value in the
first loop.

Any comments?

Thanks,
- Tom

[gdb/testsuite] Fix count usage in gdb.reverse/insn-reverse.exp

gdb/testsuite/ChangeLog:

2020-11-25  Tom de Vries  <tdevries@suse.de>

	* gdb.reverse/insn-reverse.exp: Fix count handling.

---
 gdb/testsuite/gdb.reverse/insn-reverse.exp | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/gdb/testsuite/gdb.reverse/insn-reverse.exp b/gdb/testsuite/gdb.reverse/insn-reverse.exp
index 5627f9d2605..39e276964f9 100644
--- a/gdb/testsuite/gdb.reverse/insn-reverse.exp
+++ b/gdb/testsuite/gdb.reverse/insn-reverse.exp
@@ -102,9 +102,8 @@ proc test { func testcase_nr } {
 	    gdb_test "si" "" ""
 	}
 
-	incr count -1
 	# Registers contents after each backward single step.
-	for {set i $count} {$i >= 0} {incr i -1} {
+	for {set i [expr $count - 1]} {$i >= 0} {incr i -1} {
 	    gdb_test "reverse-stepi" "" ""
 	    set post_regs($i) [capture_command_output "info all-registers" ""]
 	}