py: Add compile option to enable/disable source line numbers.
diff --git a/py/emitbc.c b/py/emitbc.c
index 6d9523f..d74b065 100644
--- a/py/emitbc.c
+++ b/py/emitbc.c
@@ -249,6 +249,7 @@
 
 static void emit_bc_set_source_line(emit_t *emit, int source_line) {
     //printf("source: line %d -> %d  offset %d -> %d\n", emit->last_source_line, source_line, emit->last_source_line_offset, emit->byte_code_offset);
+#if MICROPY_ENABLE_SOURCE_LINE
     if (source_line > emit->last_source_line) {
         uint bytes_to_skip = emit->byte_code_offset - emit->last_source_line_offset;
         uint lines_to_skip = source_line - emit->last_source_line;
@@ -257,6 +258,7 @@
         emit->last_source_line_offset = emit->byte_code_offset;
         emit->last_source_line = source_line;
     }
+#endif
 }
 
 static void emit_bc_load_id(emit_t *emit, qstr qstr) {
diff --git a/py/mpconfig.h b/py/mpconfig.h
index 97e4b13..38b74b7 100644
--- a/py/mpconfig.h
+++ b/py/mpconfig.h
@@ -76,6 +76,12 @@
 typedef long long mp_longint_impl_t;
 #endif
 
+// Whether to include information in the byte code to determine source
+// line number (increases RAM usage, but doesn't slow byte code execution)
+#ifndef MICROPY_ENABLE_SOURCE_LINE
+#define MICROPY_ENABLE_SOURCE_LINE (0)
+#endif
+
 // Whether to support float and complex types
 #ifndef MICROPY_ENABLE_FLOAT
 #define MICROPY_ENABLE_FLOAT (0)
diff --git a/py/obj.c b/py/obj.c
index 76a4d8f..ce555ef 100644
--- a/py/obj.c
+++ b/py/obj.c
@@ -57,7 +57,11 @@
         if (n > 0) {
             printf("Traceback (most recent call last):\n");
             for (int i = n - 3; i >= 0; i -= 3) {
+#if MICROPY_ENABLE_SOURCE_LINE
                 printf("  File \"%s\", line %d, in %s\n", qstr_str(values[i]), (int)values[i + 1], qstr_str(values[i + 2]));
+#else
+                printf("  File \"%s\", in %s\n", qstr_str(values[i]), qstr_str(values[i + 2]));
+#endif
             }
         }
     }