[PATCH v3 3/4] gdb/testsuite: fix testing gdb.reverse/step-reverse.exp with clang

[Guinevere Larsen <blarsen@redhat.com>]

When testing using reverse-stepi to fully step through a function, the
code checks for an infinite loop by seeing if we land on the line that
contains the return statement multiple times. This assumption only works
if there is only one instruction associated with that line, which is how
GCC handles line information, but other compilers may handle it differently.
Clang-15, for instance, associates 6. Because of this, the inferior used
to get seriously out of sync with the test expectations, and result in 13
spurious failures. The same issue occurs with gdb.reverse/step-precsave.exp.

This commit changes the test so that we check for PC instead of line
number. The test still only happens when the same line is detected, to
simplify the resulting log. With this change, no new failures are
emitted when using clang.

It also adds a new parameter to get_hexadecimal_valueof, so that we can
use it without generating new passes, otherwise we'd get multiple
duplicate test names. This change shouldn't affect any other test using
this proc.
---
 gdb/testsuite/gdb.reverse/step-precsave.exp | 10 +++++++++-
 gdb/testsuite/gdb.reverse/step-reverse.exp  | 12 +++++++++++-
 2 files changed, 20 insertions(+), 2 deletions(-)

diff --git a/gdb/testsuite/gdb.reverse/step-precsave.exp b/gdb/testsuite/gdb.reverse/step-precsave.exp
index 19cd5d9930e..e2971621c57 100644
--- a/gdb/testsuite/gdb.reverse/step-precsave.exp
+++ b/gdb/testsuite/gdb.reverse/step-precsave.exp
@@ -209,11 +209,19 @@ gdb_test_multiple "stepi" "$test_message" {
 
 # stepi backward out of a function call
 
+set start_pc [get_hexadecimal_valueof "\$pc" 0 "getting PC at start of stepi backwards"]
+set step_count 0
 set stepi_location  [gdb_get_line_number "STEPI TEST" "$srcfile"]
 set test_message "reverse stepi from a function call"
 gdb_test_multiple "stepi" "$test_message" {
     -re "ARRIVED IN CALLEE.*$gdb_prompt $" {
-	fail "$test_message (start statement)"
+	incr step_count
+	if { [get_hexadecimal_valueof "\$pc" 0 "getting PC after $step_count steps"] == $start_pc } {
+	    fail "$test_message (start statement)"
+	} else {
+	    send_gdb "stepi\n"
+	    exp_continue
+	}
     }
     -re "ENTER CALLEE.*$gdb_prompt $" {
 	send_gdb "stepi\n" 
diff --git a/gdb/testsuite/gdb.reverse/step-reverse.exp b/gdb/testsuite/gdb.reverse/step-reverse.exp
index 4b78a8f8fb7..b7d00fb4bd3 100644
--- a/gdb/testsuite/gdb.reverse/step-reverse.exp
+++ b/gdb/testsuite/gdb.reverse/step-reverse.exp
@@ -174,11 +174,21 @@ gdb_test_multiple "stepi" "$test_message" {
 
 # stepi backward out of a function call
 
+# When testing stepi, we dont want to infinitely step if we're not moving
+# so we store the starting PC, in case we land on the same line as above
+set start_pc [get_hexadecimal_valueof "\$pc" 0 "get PC at start"]
+set get_pc_count 0
 set stepi_location  [gdb_get_line_number "STEPI TEST" "$srcfile"]
 set test_message "reverse stepi from a function call"
 gdb_test_multiple "stepi" "$test_message" {
     -re "ARRIVED IN CALLEE.*$gdb_prompt $" {
-	fail "$test_message (start statement)"
+	incr get_pc_count
+	if { [get_hexadecimal_valueof "\$pc" 0 "get PC again $get_pc_count"] == $start_pc } {
+	    fail "$test_message (start statement)"
+	} else {
+	    send_gdb "stepi\n"
+	    exp_continue
+	}
     }
     -re "ENTER CALLEE.*$gdb_prompt $" {
 	send_gdb "stepi\n" 
-- 
2.41.0