[intel-pt] Implement a basic test case

* This is a reattempted commit due to a previous builtbot failure

- Now using a env var to determine whether to run the test, as
someone might have built liblldbIntelFeatures.so without intelPT
support, which would make this test fail.

Summary:
Depends on D76872.

There was no test for the Intel PT support on LLDB, so I'm creating one, which
will help making progress on solid grounds.

The test is skipped if the Intel PT plugin library is not built.

Reviewers: clayborg, labath, kusmour, aadsm

Subscribers: lldb-commits

Tags: #lldb

Differential Revision: https://reviews.llvm.org/D77107

lldb/test/API/tools/intel-features/intel-pt/test/Makefile

@@ -0,0 +1,3 @@
+CXX_SOURCES := main.cpp
+
+include Makefile.rules

lldb/test/API/tools/intel-features/intel-pt/test/TestIntelPTSimpleBinary.py

@@ -0,0 +1,60 @@
+from __future__ import print_function
+
+import os
+import lldb
+import time
+
+from lldbsuite.test.decorators import *
+from lldbsuite.test.lldbtest import *
+from lldbsuite.test import lldbutil
+
+
+class TestIntelPTSimpleBinary(TestBase):
+
+    mydir = TestBase.compute_mydir(__file__)
+    NO_DEBUG_INFO_TESTCASE = True
+
+    @skipIf(oslist=no_match(['linux']))
+    @skipIf(archs=no_match(['i386', 'x86_64']))
+    @skipIfRemote
+    def test_basic_flow(self):
+        """Test collection, decoding, and dumping instructions"""
+        if os.environ.get('TEST_INTEL_PT') != '1':
+            self.skipTest("The environment variable TEST_INTEL_PT=1 is needed to run this test.")
+
+        lldb_exec_dir = os.environ["LLDB_IMPLIB_DIR"]
+        lldb_lib_dir = os.path.join(lldb_exec_dir, os.pardir, "lib")
+        plugin_file = os.path.join(lldb_lib_dir, "liblldbIntelFeatures.so")
+
+        self.build()
+
+        self.runCmd("plugin load " + plugin_file)
+
+        exe = self.getBuildArtifact("a.out")
+        lldbutil.run_to_name_breakpoint(self, "main", exe_name=exe)
+        # We start tracing from main
+        self.runCmd("processor-trace start all")
+
+        # We check the trace after the for loop
+        self.runCmd("b " + str(line_number('main.cpp', '// Break 1')))
+        self.runCmd("c")
+
+        # We wait a little bit to ensure the processor has send the PT packets to
+        # the memory
+        time.sleep(.1)
+
+        # We find the start address of the 'fun' function for a later check
+        target = self.dbg.GetSelectedTarget()
+        fun_start_adddress = target.FindFunctions("fun")[0].GetSymbol() \
+            .GetStartAddress().GetLoadAddress(target)
+
+        # We print the last instructions
+        self.expect("processor-trace show-instr-log -c 100",
+            patterns=[
+                # We expect to have seen the first instruction of 'fun'
+                hex(fun_start_adddress),  
+                # We expect to see the exit condition of the for loop
+                "at main.cpp:" + str(line_number('main.cpp', '// Break for loop')) 
+            ])
+
+        self.runCmd("processor-trace stop")

lldb/test/API/tools/intel-features/intel-pt/test/main.cpp

@@ -0,0 +1,10 @@
+int fun(int a) { return a * a + 1; }
+
+int main() {
+  int z = 0;
+  for (int i = 0; i < 10000; i++) { // Break for loop
+    z += fun(z);
+  }
+
+  return 0; // Break 1
+}

lldb/tools/intel-features/intel-pt/cli-wrapper-pt.cpp

@@ -191,6 +191,7 @@ public:
       result.SetStatus(lldb::eReturnStatusFailed);
       return false;
     }
+    result.SetStatus(lldb::eReturnStatusSuccessFinishResult);
     return true;
   }
 
@@ -290,6 +291,7 @@ public:
                  s.GetData());
       result.AppendMessage(res.GetOutput());
     }
+    result.SetStatus(lldb::eReturnStatusSuccessFinishResult);
     return true;
   }
 
@@ -428,6 +430,7 @@ public:
       }
       result.AppendMessage(res.GetOutput());
     }
+    result.SetStatus(lldb::eReturnStatusSuccessFinishResult);
     return true;
   }
 
@@ -480,6 +483,7 @@ public:
       result.SetStatus(lldb::eReturnStatusFailed);
       return false;
     }
+    result.SetStatus(lldb::eReturnStatusSuccessFinishResult);
     return true;
   }