PR2049: support arbitrary $target-array indexing

Rather than just numeric literals, we can now support arbitrary
expressions for the index value.  Note that loc2c won't allow this for
noncontiguous arrays, as the access methods need to be statically
computed, but for contiguous arrays and pointers-as-arrays it works
just fine.

* staptree.h (target_symbol::component): Add expression_array_index.
* staptree.cxx (target_symbol::visit_components): New helper.
  (target_symbol::assert_no_components): Recognize new array type.
  (target_symbol::component::print): Print subexpressions.
  (traversing_visitor::visit_target_symbol, visit_cast_op): Visit the
  indexing components too.
  (varuse_collecting_visitor::visit_target_symbol): Ditto.
  (update_visitor::visit_target_symbol, visit_cast_op): Ditto.
* elaborate.cxx (void_statement_reducer::visit_target_symbol): New.
  (void_statement_reducer::visit_cast_op): Save indexes too.
* parse.cxx (parser::parse_target_symbol_components): Parse expressions.
* tapsets.cxx (dwarf_var_expanding_visitor::visit_target_symbol): Pass
  expression-indexes as parameters (indexN) to the dwarf function.
  (dwarf_cast_expanding_visitor::visit_cast_op): Ditto.
  (tracepoint_var_expanding_visitor::visit_target_symbol_arg): Ditto.
  (sdt_var_expanding_visitor::visit_target_symbol): Visit the new @cast.
* dwflpp.cxx (dwflpp::translate_components): Use THIS->indexN.
* translate.cxx (c_unparser::visit_target_symbol): Correct error msg.
* testsuite/systemtap.base/pointer_array.stp: Use a simple index.

1 files changed, 2 insertions, 9 deletions

diff --git a/testsuite/systemtap.base/pointer_array.stp b/testsuite/systemtap.base/pointer_array.stp
index 1d15ebf4..cd420604 100644
--- a/testsuite/systemtap.base/pointer_array.stp
+++ b/testsuite/systemtap.base/pointer_array.stp
@@ -2,15 +2,8 @@ probe syscall.execve
 {
     if (pid() == target()) {
         println(user_string($argv[0]))
-        printf("%c\n", $argv[0][0])
-        printf("%c\n", $argv[0][1])
-        printf("%c\n", $argv[0][2])
-        printf("%c\n", $argv[0][3])
-        printf("%c\n", $argv[0][4])
-        printf("%c\n", $argv[0][5])
-        printf("%c\n", $argv[0][6])
-        printf("%c\n", $argv[0][7])
-        printf("%c\n", $argv[0][8])
+        for (i=0; i<9; ++i)
+            printf("%c\n", $argv[0][i])
         println($argv[0][9])
     }
 }