Refactor gdb.base/disp-step-syscall.exp for general step over test

This patch moves some code out of disp_step_cross_syscall to a new proc
check_pc_after_cross_syscall and setup.  Procedure setup is to start a
fresh GDB and compute the syscall instruction address.

gdb/testsuite:

2016-03-03  Yao Qi  <yao.qi@linaro.org>

	* gdb.base/disp-step-syscall.exp (check_pc_after_cross_syscall): New
	proc.
	(setup): New proc.
	(disp_step_cross_syscall): Move code to check_pc_after_cross_syscall
	and setup.

gdb/testsuite/ChangeLog

@@ -1,3 +1,11 @@
+2016-03-03  Yao Qi  <yao.qi@linaro.org>
+
+	* gdb.base/disp-step-syscall.exp (check_pc_after_cross_syscall): New
+	proc.
+	(setup): New proc.
+	(disp_step_cross_syscall): Move code to check_pc_after_cross_syscall
+	and setup.
+
 2016-03-02  Bernhard Heckel  <bernhard.heckel@intel.com>
 
 	* gdb.fortran/vla-history.exp: Remove breakpoint.

gdb/testsuite/gdb.base/disp-step-syscall.exp

@@ -32,6 +32,86 @@ if { [istarget "i\[34567\]86-*-linux*"] || [istarget "x86_64-*-linux*"] } {
     return -1
 }
 
+proc check_pc_after_cross_syscall { syscall syscall_insn_next_addr } {
+    set syscall_insn_next_addr_found [get_hexadecimal_valueof "\$pc" "0"]
+
+    set test "single step over $syscall final pc"
+    if {$syscall_insn_next_addr != 0
+	&& $syscall_insn_next_addr == $syscall_insn_next_addr_found} {
+	pass $test
+    } else {
+	fail $test
+    }
+}
+
+# Restart GDB and set up the test.  Return a list in which the first one
+# is the address of syscall instruction and the second one is the address
+# of the next instruction address of syscall instruction.  If anything
+# wrong, the two elements of list are -1.
+
+proc setup { syscall } {
+    global gdb_prompt syscall_insn
+
+    set testfile "disp-step-$syscall"
+
+    clean_restart $testfile
+
+    if { ![runto main] } then {
+	fail "run to main ($syscall)"
+	return -1
+    }
+
+    # Delete the breakpoint on main.
+    gdb_test_no_output "delete break 1"
+
+    gdb_test_no_output "set displaced-stepping off"
+
+    gdb_test "break $syscall" "Breakpoint \[0-9\]* at .*"
+
+    gdb_test "continue" "Continuing\\..*Breakpoint \[0-9\]+, (.* in |__libc_|)$syscall \\(\\).*" \
+	"continue to $syscall (1st time)"
+    # Hit the breakpoint on $syscall for the first time.  In this time,
+    # we will let PLT resolution done, and the number single steps we will
+    # do later will be reduced.
+
+    gdb_test "continue" "Continuing\\..*Breakpoint \[0-9\]+, (.* in |__libc_|)$syscall \\(\\).*" \
+	"continue to $syscall (2nd time)"
+    # Hit the breakpoint on $syscall for the second time.  In this time,
+    # the address of syscall insn and next insn of syscall are recorded.
+
+    gdb_test "display/i \$pc" ".*"
+
+    # Single step until we see a syscall insn or we reach the
+    # upper bound of loop iterations.
+    set msg "find syscall insn in $syscall"
+    set steps 0
+    set max_steps 1000
+    gdb_test_multiple "stepi" $msg {
+	-re ".*$syscall_insn.*$gdb_prompt $" {
+	    pass $msg
+	}
+	-re "x/i .*=>.*\r\n$gdb_prompt $" {
+	    incr steps
+	    if {$steps == $max_steps} {
+		fail $msg
+	    } else {
+		send_gdb "stepi\n"
+		exp_continue
+	    }
+	}
+    }
+
+    if {$steps == $max_steps} {
+	return { -1, -1 }
+    }
+
+    set syscall_insn_addr [get_hexadecimal_valueof "\$pc" "0"]
+    if {[gdb_test "stepi" "x/i .*=>.*" "stepi $syscall insn"] != 0} {
+	return { -1, -1 }
+    }
+    return [list $syscall_insn_addr [get_hexadecimal_valueof "\$pc" "0"]]
+}
+
 proc disp_step_cross_syscall { syscall } {
     with_test_prefix "$syscall" {
 	global syscall_insn
@@ -39,74 +119,19 @@ proc disp_step_cross_syscall { syscall } {
 
 	set testfile "disp-step-$syscall"
 
-	if [prepare_for_testing ${testfile}.exp ${testfile} ${testfile}.c {debug}] {
+	if [build_executable ${testfile}.exp ${testfile} ${testfile}.c {debug}] {
 	    untested ${testfile}.exp
 	    return -1
 	}
 
-	if { ![runto main] } then {
+	set ret [setup $syscall]
-	    fail "run to main ($syscall)"
-	    return
-	}
 
-	# Delete the breakpoint on main.
+	set syscall_insn_addr [lindex $ret 0]
-	gdb_test_no_output "delete break 1"
+	set syscall_insn_next_addr [lindex $ret 1]
-
+	if { $syscall_insn_addr == -1 } {
-	gdb_test "break marker" "Breakpoint.*at.* file .*${testfile}.c, line.*"
-	gdb_test_no_output "set displaced-stepping off"
-
-	set syscall_bp 0
-	gdb_test_multiple "break $syscall"  "break $syscall" {
-	    -re "Breakpoint (\[0-9\]*) at .*$gdb_prompt $" {
-		set syscall_bp $expect_out(1,string)
-		pass "break $syscall"
-	    }
-	}
-
-	gdb_test "continue" "Continuing\\..*Breakpoint \[0-9\]+, (.* in |__libc_|)$syscall \\(\\).*" \
-	    "continue to $syscall (1st time)"
-	# Hit the breakpoint on $syscall for the first time.  In this time, we will let PLT
-	# resolution done, and the number single steps we will do later will be
-	# reduced.
-
-	gdb_test "continue" "Continuing\\..*Breakpoint \[0-9\]+, (.* in |__libc_|)$syscall \\(\\).*" \
-	    "continue to $syscall (2nd time)"
-	# Hit the breakpoint on $syscall for the second time.  In this time, the address
-	# of syscall insn and next insn of syscall are recorded.
-
-	gdb_test "display/i \$pc" ".*"
-
-
-	# Single step until we see a syscall insn or we reach the
-	# upper bound of loop iterations.
-	set msg "find syscall insn in $syscall"
-	set steps 0
-	set max_steps 1000
-	gdb_test_multiple "stepi" $msg {
-	    -re ".*$syscall_insn.*$gdb_prompt $" {
-		pass $msg
-	    }
-	    -re "x/i .*=>.*\r\n$gdb_prompt $" {
-		incr steps
-		if {$steps == $max_steps} {
-		    fail $msg
-		} else {
-		    send_gdb "stepi\n"
-		    exp_continue
-		}
-	    }
-	}
-
-	if {$steps == $max_steps} {
 	    return -1
 	}
 
-	set syscall_insn_addr [get_hexadecimal_valueof "\$pc" "0"]
-	if {[gdb_test "stepi" "x/i .*=>.*" "stepi $syscall insn"] != 0} {
-	    return -1
-	}
-	set syscall_insn_next_addr [get_hexadecimal_valueof "\$pc" "0"]
-
 	gdb_test "continue" "Continuing\\..*Breakpoint \[0-9\]+, (.* in |__libc_|)$syscall \\(\\).*" \
 	    "continue to $syscall (3rd time)"
 
@@ -120,7 +145,6 @@ proc disp_step_cross_syscall { syscall } {
 		pass "break on syscall insns"
 	    }
 	}
-	gdb_test_no_output "delete $syscall_bp" "delete break $syscall"
 
 	gdb_test "continue" "Continuing\\..*Breakpoint \[0-9\]+, .*" \
 	    "continue to syscall insn $syscall"
@@ -132,19 +156,12 @@ proc disp_step_cross_syscall { syscall } {
 	    return -1
 	}
 
-	set syscall_insn_next_addr_found [get_hexadecimal_valueof "\$pc" "0"]
+	check_pc_after_cross_syscall $syscall $syscall_insn_next_addr
-
-	set test "single step over $syscall final pc"
-	if {$syscall_insn_next_addr != 0
-	    && $syscall_insn_next_addr == $syscall_insn_next_addr_found} {
-	    pass $test
-	} else {
-	    fail $test
-	}
 
 	# Delete breakpoint syscall insns to avoid interference to other syscalls.
-	gdb_test_no_output "delete $syscall_insn_bp" "delete break $syscall insn"
+	delete_breakpoints
 
+	gdb_test "break marker" "Breakpoint.*at.* file .*${testfile}.c, line.*"
 	gdb_test "continue" "Continuing\\..*Breakpoint \[0-9\]+, marker \\(\\) at.*" \
 	    "continue to marker ($syscall)"
     }