gdb.perf/: FAIL on Python errors, avoid "ERROR: internal buffer is full"

Currently, if you run make check-perf on a system with Python 3.8,
tests seen to PASS, but they actually test a lot less than intended,
due to:

 PerfTest::assemble, run ...
 python BackTrace(64).run()
 Traceback (most recent call last):
   File "<string>", line 1, in <module>
   File "/home/pedro/rocm/gdb/src/gdb/testsuite/gdb.perf/lib/perftest/perftest.py", line 65, in run
     self.execute_test()
   File "<string>", line 49, in execute_test
   File "/home/pedro/rocm/gdb/src/gdb/testsuite/gdb.perf/lib/perftest/measure.py", line 45, in measure
     m.start(id)
   File "/home/pedro/rocm/gdb/src/gdb/testsuite/gdb.perf/lib/perftest/measure.py", line 102, in start
     self.start_time = time.clock()
 AttributeError: module 'time' has no attribute 'clock'
 Error while executing Python code.
 (gdb) PASS: gdb.perf/backtrace.exp: python BackTrace(64).run()

And then, after fixing the above Python compatibility issues (which
will be a separate patch), I get 86 instances of overflowing expect's
buffer, like:

  ERROR: internal buffer is full.
  UNRESOLVED: gdb.perf/single-step.exp: python SingleStep(1000).run()

This patch fixes both problems by adding & using a gdb_test_python_run
routine that:

 - checks for Python errors
 - consumes output line by line

gdb/testsuite/ChangeLog:
yyyy-mm-dd  Pedro Alves  <pedro@palves.net>

	* gdb.perf/backtrace.exp: Use gdb_test_python_run.
	* gdb.perf/disassemble.exp: Use gdb_test_python_run.
	* gdb.perf/single-step.exp: Use gdb_test_python_run.
	* gdb.perf/skip-command.exp: Use gdb_test_python_run.
	* gdb.perf/skip-prologue.exp: Use gdb_test_python_run.
	* gdb.perf/solib.exp: Use gdb_test_python_run.
	* gdb.perf/template-breakpoints.exp: Use gdb_test_python_run.
	* lib/perftest.exp (gdb_test_python_run): New.

Change-Id: I007af36f164b3f4cda41033616eaaa4e268dfd2f

gdb/testsuite/gdb.perf/backtrace.exp

@@ -63,7 +63,7 @@ PerfTest::assemble {
 } {
     global BACKTRACE_DEPTH
 
-    gdb_test "python BackTrace\($BACKTRACE_DEPTH\).run()"
+    gdb_test_python_run "BackTrace\($BACKTRACE_DEPTH\)"
 
     return 0
 }

gdb/testsuite/gdb.perf/disassemble.exp

@@ -55,6 +55,6 @@ PerfTest::assemble {
 
     return 0
 } {
-    gdb_test "python Disassemble\(\).run()"
+    gdb_test_python_run "Disassemble\(\)"
     return 0
 }

gdb/testsuite/gdb.perf/single-step.exp

@@ -51,7 +51,7 @@ PerfTest::assemble {
 } {
     global SINGLE_STEP_COUNT
 
-    gdb_test_no_output "python SingleStep\(${SINGLE_STEP_COUNT}\).run()"
+    gdb_test_python_run "SingleStep\(${SINGLE_STEP_COUNT}\)"
     # Terminate the loop.
     gdb_test "set variable flag = 0"
     return 0

gdb/testsuite/gdb.perf/skip-command.exp

@@ -103,7 +103,7 @@ proc run_skip_bench { kind text } {
     for { set i 0 } { $i < 5 } { incr i } {
 	set nr_skips [expr $i * $SKIP_DIRECTIVE_COUNT]
 	install_skips $kind $text $nr_skips
-	gdb_test_no_output "python SkipCommand\(\"skip-$kind-$nr_skips\", ${SKIP_STEP_COUNT}\).run()"
+	gdb_test_python_run "SkipCommand\(\"skip-$kind-$nr_skips\", ${SKIP_STEP_COUNT}\)"
     }
 
     gdb_test "set variable flag = 0"

gdb/testsuite/gdb.perf/skip-prologue.exp

@@ -63,16 +63,6 @@ PerfTest::assemble {
 } {
     global SKIP_PROLOGUE_COUNT
 
-    set test "run"
-    gdb_test_multiple "python SkipPrologue\($SKIP_PROLOGUE_COUNT\).run()" $test {
-	-re "Breakpoint $decimal at \[^\n\]*\n" {
-	    # GDB prints some messages on breakpoint creation.
-	    # Consume the output to avoid internal buffer full.
-	    exp_continue
-	}
-	-re ".*$gdb_prompt $" {
-	    pass $test
-	}
-    }
+    gdb_test_python_run "SkipPrologue\($SKIP_PROLOGUE_COUNT\)" "run"
     return 0
 }

gdb/testsuite/gdb.perf/solib.exp

@@ -84,6 +84,6 @@ PerfTest::assemble {
 } {
     global SOLIB_COUNT
 
-    gdb_test_no_output "python SolibLoadUnload\($SOLIB_COUNT\).run()"
+    gdb_test_python_run "SolibLoadUnload\($SOLIB_COUNT\)"
     return 0
 }

gdb/testsuite/gdb.perf/template-breakpoints.exp

@@ -59,7 +59,7 @@ PerfTest::assemble {
 	return 0
 } {
 
-	gdb_test "python TemplateBreakpoints().run()"
+	gdb_test_python_run "TemplateBreakpoints()"
 
 	return 0
 }

gdb/testsuite/lib/perftest.exp

@@ -155,3 +155,28 @@ proc tcl_string_list_to_python_list { l } {
     }
     return "([join $quoted_list {, }])"
 }
+
+# Helper routine for PerfTest::assemble "run" step implementations.
+# Issues the "python ${OBJ}.run()" command, and consumes GDB output
+# line by line.  Issues a FAIL if the command fails with a Python
+# error.  Issues a PASS on success.  MESSAGE is an optional message to
+# be printed.  If this is omitted, then the pass/fail messages use the
+# command string as the message.
+
+proc gdb_test_python_run {obj {message ""}} {
+    global gdb_prompt
+
+    set saw_error 0
+    gdb_test_multiple "python ${obj}.run()" $message {
+	-re "Error while executing Python code\\." {
+	    set saw_error 1
+	    exp_continue
+	}
+	-re "\[^\r\n\]*\r\n" {
+	    exp_continue
+	}
+	-re "$gdb_prompt $" {
+	    gdb_assert {!$saw_error} $gdb_test_name
+	}
+    }
+}