Add EbreakTest. (#380)

* Add EbreakTest.

Confirm correct behavior when somebody bakes an ebreak instruction into
their code.

* Forgot to commit ebreak.c

2 files changed, 62 insertions, 0 deletions

diff --git a/debug/gdbserver.py b/debug/gdbserver.py
index 96ba326..c75267d 100755
--- a/debug/gdbserver.py
+++ b/debug/gdbserver.py
@@ -1735,6 +1735,37 @@ class VectorTest(GdbSingleHartTest):
         assertIn("_exit", output)
         assertEqual(self.gdb.p("status"), 0)
 
+class EbreakTest(GdbSingleHartTest):
+    """Test that we work correctly when somebody puts an ebreak directly into
+    their code."""
+    compile_args = ("programs/ebreak.c", )
+
+    def setup(self):
+        self.gdb.load()
+        self.gdb.b("_exit")
+
+    def test(self):
+        # Should hit ebreak in the code.
+        output = self.gdb.c()
+        assertIn("ebreak", output)
+        ebreak_pc = self.gdb.p("$pc")
+
+        # Simple resume, we should hit the same ebreak again.
+        output = self.gdb.c()
+        assertIn("ebreak", output)
+        assertEqual(ebreak_pc, self.gdb.p("$pc"))
+
+        # Test getting past the ebreak by changing the PC.
+        for _ in range(2):
+            self.gdb.p("$pc=$pc+4")
+            output = self.gdb.c()
+            assertIn("ebreak", output)
+            assertEqual(ebreak_pc, self.gdb.p("$pc"))
+
+        self.gdb.p("$pc=$pc+4")
+        output = self.gdb.c()
+        assertIn("_exit", output)
+
 class FreeRtosTest(GdbTest):
     def early_applicable(self):
         return self.target.freertos_binary
diff --git a/debug/programs/ebreak.c b/debug/programs/ebreak.c
new file mode 100644
index 0000000..466c4e7
--- /dev/null
+++ b/debug/programs/ebreak.c
@@ -0,0 +1,31 @@
+#include <stdint.h>
+
+void ebreak()
+{
+    asm volatile("ebreak");
+}
+
+unsigned int fib(unsigned int n)
+{
+    if (n == 0) {
+        return 0;
+    }
+
+    unsigned int a = 0;
+    unsigned int b = 1;
+
+    for (unsigned int i = 1; i < n; i++) {
+        unsigned int next = a + b;
+        a = b;
+        b = next;
+        ebreak();
+    }
+
+    return b;
+}
+
+int main()
+{
+begin:
+    fib(4);
+}