From d4eff4c122e06e913452e2039e29e8db6b15b1dd Mon Sep 17 00:00:00 2001 From: Tom Tromey Date: Mon, 8 Mar 2021 07:27:57 -0700 Subject: [PATCH] Introduce repeat_operation This adds class repeat_operation, which implements BINOP_REPEAT. gdb/ChangeLog 2021-03-08 Tom Tromey * expop.h (class repeat_operation): New. * eval.c (eval_op_repeat): No longer static. Remove "op" parameter. (evaluate_subexp_standard): Update. * ax-gdb.c (repeat_operation::do_generate_ax): New method. --- gdb/ChangeLog | 8 ++++++++ gdb/ax-gdb.c | 50 ++++++++++++++++++++++++++++++++++++++++++++++++++ gdb/eval.c | 6 +++--- gdb/expop.h | 20 ++++++++++++++++++++ 4 files changed, 81 insertions(+), 3 deletions(-) diff --git a/gdb/ChangeLog b/gdb/ChangeLog index 1f3287aefb3..b93ca086eb5 100644 --- a/gdb/ChangeLog +++ b/gdb/ChangeLog @@ -1,3 +1,11 @@ +2021-03-08 Tom Tromey + + * expop.h (class repeat_operation): New. + * eval.c (eval_op_repeat): No longer static. Remove "op" + parameter. + (evaluate_subexp_standard): Update. + * ax-gdb.c (repeat_operation::do_generate_ax): New method. + 2021-03-08 Tom Tromey * expop.h (class comparison_operation): New. diff --git a/gdb/ax-gdb.c b/gdb/ax-gdb.c index 87aa2107872..332840456fe 100644 --- a/gdb/ax-gdb.c +++ b/gdb/ax-gdb.c @@ -2419,6 +2419,56 @@ ternop_cond_operation::do_generate_ax (struct expression *exp, value->kind = value2.kind; } +/* Generate code for GDB's magical `repeat' operator. + LVALUE @ INT creates an array INT elements long, and whose elements + have the same type as LVALUE, located in memory so that LVALUE is + its first element. For example, argv[0]@argc gives you the array + of command-line arguments. + + Unfortunately, because we have to know the types before we actually + have a value for the expression, we can't implement this perfectly + without changing the type system, having values that occupy two + stack slots, doing weird things with sizeof, etc. So we require + the right operand to be a constant expression. */ +void +repeat_operation::do_generate_ax (struct expression *exp, + struct agent_expr *ax, + struct axs_value *value, + struct type *cast_type) +{ + struct axs_value value1; + + /* We don't want to turn this into an rvalue, so no conversions + here. */ + std::get<0> (m_storage)->generate_ax (exp, ax, &value1); + if (value1.kind != axs_lvalue_memory) + error (_("Left operand of `@' must be an object in memory.")); + + /* Evaluate the length; it had better be a constant. */ + if (!std::get<1> (m_storage)->constant_p ()) + error (_("Right operand of `@' must be a " + "constant, in agent expressions.")); + + struct value *v + = std::get<1> (m_storage)->evaluate (nullptr, exp, + EVAL_AVOID_SIDE_EFFECTS); + if (value_type (v)->code () != TYPE_CODE_INT) + error (_("Right operand of `@' must be an integer.")); + int length = value_as_long (v); + if (length <= 0) + error (_("Right operand of `@' must be positive.")); + + /* The top of the stack is already the address of the object, so + all we need to do is frob the type of the lvalue. */ + /* FIXME-type-allocation: need a way to free this type when we are + done with it. */ + struct type *array + = lookup_array_range_type (value1.type, 0, length - 1); + + value->kind = axs_lvalue_memory; + value->type = array; +} + } /* This handles the middle-to-right-side of code generation for binary diff --git a/gdb/eval.c b/gdb/eval.c index 83d0147f96e..2d2f881746c 100644 --- a/gdb/eval.c +++ b/gdb/eval.c @@ -1732,9 +1732,9 @@ eval_op_leq (struct type *expect_type, struct expression *exp, /* A helper function for BINOP_REPEAT. */ -static struct value * +struct value * eval_op_repeat (struct type *expect_type, struct expression *exp, - enum noside noside, + enum noside noside, enum exp_opcode op, struct value *arg1, struct value *arg2) { if (noside == EVAL_SKIP) @@ -2946,7 +2946,7 @@ evaluate_subexp_standard (struct type *expect_type, case BINOP_REPEAT: arg1 = evaluate_subexp (nullptr, exp, pos, noside); arg2 = evaluate_subexp (nullptr, exp, pos, noside); - return eval_op_repeat (expect_type, exp, noside, arg1, arg2); + return eval_op_repeat (expect_type, exp, noside, op, arg1, arg2); case BINOP_COMMA: evaluate_subexp (nullptr, exp, pos, noside); diff --git a/gdb/expop.h b/gdb/expop.h index af378d011f8..4bf32f538e1 100644 --- a/gdb/expop.h +++ b/gdb/expop.h @@ -135,6 +135,11 @@ extern struct value *eval_op_leq (struct type *expect_type, enum noside noside, enum exp_opcode op, struct value *arg1, struct value *arg2); +extern struct value *eval_op_repeat (struct type *expect_type, + struct expression *exp, + enum noside noside, enum exp_opcode op, + struct value *arg1, + struct value *arg2); namespace expr { @@ -1188,6 +1193,21 @@ using gtr_operation = comparison_operation; using geq_operation = comparison_operation; using leq_operation = comparison_operation; +/* Implement the GDB '@' repeat operator. */ +class repeat_operation + : public binop_operation +{ + using binop_operation::binop_operation; + +protected: + + void do_generate_ax (struct expression *exp, + struct agent_expr *ax, + struct axs_value *value, + struct type *cast_type) + override; +}; + } /* namespace expr */ #endif /* EXPOP_H */ -- 2.30.2