print: Print single map values

Allows indexing a map with key(s) to print single map values while
using the print() function.

CHANGELOG.md

@@ -13,6 +13,8 @@ and this project adheres to
   - [#2958](https://github.com/bpftrace/bpftrace/pull/2958)
 - Add ability to list all probes in a program
   - [#2969](https://github.com/bpftrace/bpftrace/pull/2969)
+- Add ability to call print() with indexed maps to print single map values
+  - [#3027](https://github.com/bpftrace/bpftrace/pull/3027)
 #### Changed
 #### Deprecated
 #### Removed

src/ast/passes/codegen_llvm.cpp

@@ -983,9 +983,14 @@ void CodegenLLVM::visit(Call &call)
                                               b_.GetInsertBlock()->getParent());
     b_.SetInsertPoint(deadcode);
   } else if (call.func == "print") {
-    if (call.vargs->at(0)->is_map)
-      createPrintMapCall(call);
-    else
+    if (call.vargs->at(0)->is_map) {
+      auto &arg = *call.vargs->at(0);
+      auto &map = static_cast<Map &>(arg);
+      if (!map.vargs)
+        createPrintMapCall(call);
+      else
+        createPrintNonMapCall(call, non_map_print_id_);
+    } else
       createPrintNonMapCall(call, non_map_print_id_);
   } else if (call.func == "cgroup_path") {
     auto elements = AsyncEvent::CgroupPath().asLLVMType(b_);

src/ast/passes/resource_analyser.cpp

@@ -154,6 +154,11 @@ void ResourceAnalyser::visit(Call &call)
     auto &arg = *call.vargs->at(0);
     if (!arg.is_map)
       resources_.non_map_print_args.push_back(arg.type);
+    else {
+      auto &map = static_cast<Map &>(arg);
+      if (map.vargs)
+        resources_.non_map_print_args.push_back(map.type);
+    }
   } else if (call.func == "kstack" || call.func == "ustack") {
     resources_.stackid_maps.insert(call.type.stack_type);
   } else if (call.func == "cgroup_path") {

src/ast/passes/semantic_analyser.cpp

@@ -472,9 +472,11 @@ void SemanticAnalyser::visit(Call &call)
       auto &expr = *(*call.vargs)[i];
       func_arg_idx_ = i;
 
-      if (expr.is_map && skip_key_validation(call)) {
+      if (expr.is_map) {
         Map &map = static_cast<Map &>(expr);
-        map.skip_key_validation = true;
+        // If the map is indexed, don't skip key validation
+        if (!map.vargs && skip_key_validation(call))
+          map.skip_key_validation = true;
       }
 
       expr.accept(*this);
@@ -930,9 +932,10 @@ void SemanticAnalyser::visit(Call &call)
       if (arg.is_map) {
         Map &map = static_cast<Map &>(arg);
         if (map.vargs != nullptr) {
-          LOG(ERROR, call.loc, err_)
-              << "The map passed to " << call.func << "() should not be "
-              << "indexed by a key";
+          if (call.vargs->size() != 1)
+            LOG(ERROR, call.loc, err_)
+                << "Single-value (i.e. indexed) map print cannot take top "
+                   "or div arguments.";
         }
 
         if (is_final_pass()) {

tests/runtime/call

@@ -352,6 +352,16 @@ REQUIRES_FEATURE kfunc
 TIMEOUT 5
 AFTER ./testprogs/syscall open
 
+NAME print_map_item
+PROG BEGIN { @x[1] = 5; print(@x[1]); exit() }
+EXPECT 5
+TIMEOUT 1
+
+NAME print_map_item_tuple
+PROG BEGIN { @x[1] = "hi"; print((1, 2, @x[1])); exit() }
+EXPECT (1, 2, hi)
+TIMEOUT 1
+
 NAME strftime
 PROG BEGIN { $ts = strftime("%m/%d/%y", nsecs); printf("%s\n", $ts); exit(); }
 EXPECT_REGEX [0-9]{2}\/[0-9]{2}\/[0-9]{2}

tests/semantic_analyser.cpp

@@ -569,7 +569,6 @@ TEST(semantic_analyser, call_print)
 
   test("kprobe:f { print(@x); @x[1,2] = count(); }", 0);
   test("kprobe:f { @x[1,2] = count(); print(@x); }", 0);
-  test("kprobe:f { @x[1,2] = count(); print(@x[3,4]); }", 1);
 
   test("kprobe:f { @x = count(); @ = print(@x); }", 1);
   test("kprobe:f { @x = count(); $y = print(@x); }", 1);
@@ -583,6 +582,31 @@ TEST(semantic_analyser, call_print)
                    "top and div arguments are ignored");
 }
 
+TEST(semantic_analyser, call_print_map_item)
+{
+  test(R"_(BEGIN { @x[1] = 1; print(@x[1]); })_", 0);
+  test(R"_(BEGIN { @x[1] = 1; @x[2] = 2; print(@x[2]); })_", 0);
+  test(R"_(BEGIN { @x[1] = 1; print(@x[2]); })_", 0);
+  test(R"_(BEGIN { @x[3, 5] = 1; print(@x[3, 5]); })_", 0);
+  test(R"_(BEGIN { @x[1,2] = "asdf"; print((1, 2, @x[1,2])); })_", 0);
+
+  test_error("BEGIN { @x[1] = 1; print(@x[\"asdf\"]); }", R"(
+stdin:1:20-36: ERROR: Argument mismatch for @x: trying to access with arguments: [string[5]] when map expects arguments: [unsigned int64]
+BEGIN { @x[1] = 1; print(@x["asdf"]); }
+                   ~~~~~~~~~~~~~~~~
+)");
+  test_error("BEGIN { print(@x[2]); }", R"(
+stdin:1:9-20: ERROR: Undefined map: @x
+BEGIN { print(@x[2]); }
+        ~~~~~~~~~~~
+)");
+  test_error("BEGIN { @x[1] = 1; print(@x[1], 10, 3); }", R"(
+stdin:1:20-39: ERROR: Single-value (i.e. indexed) map print cannot take top or div arguments.
+BEGIN { @x[1] = 1; print(@x[1], 10, 3); }
+                   ~~~~~~~~~~~~~~~~~~~
+)");
+}
+
 TEST(semantic_analyser, call_print_non_map)
 {
   test(R"_(BEGIN { print(1) })_", 0);