From f9e4ed8baa9eeebc71be88f863c52f81e42bed34 Mon Sep 17 00:00:00 2001 From: Zoran Zaric Date: Tue, 15 Sep 2020 12:35:56 +0100 Subject: [PATCH] Merge evaluate_for_locexpr_baton evaluator The evaluate_for_locexpr_baton is the last derived class from the dwarf_expr_context class. It's purpose is to support the passed in buffer functionality. Although, it is not really necessary to merge this class with it's base class, doing that simplifies new expression evaluator design. Considering that this functionality is going around the DWARF standard, it is also reasonable to expect that with a new evaluator design and extending the push object address functionality to accept any location description, there will be no need to support passed in buffers. Alternatively, it would also makes sense to abstract the interaction between the evaluator and a given resource in the near future. The passed in buffer would then be a specialization of that abstraction. gdb/ChangeLog: * dwarf2/expr.c (dwarf_expr_context::read_mem): Merge with evaluate_for_locexpr_baton implementation. * dwarf2/loc.c (class evaluate_for_locexpr_baton): Remove class. (evaluate_for_locexpr_baton::read_mem): Move to dwarf_expr_context. (dwarf2_locexpr_baton_eval): Instantiate dwarf_expr_context instead of evaluate_for_locexpr_baton class. --- gdb/dwarf2/expr.c | 20 ++++++++++++++++++-- gdb/dwarf2/expr.h | 18 ++++++++---------- gdb/dwarf2/loc.c | 45 ++------------------------------------------- 3 files changed, 28 insertions(+), 55 deletions(-) diff --git a/gdb/dwarf2/expr.c b/gdb/dwarf2/expr.c index 5224ed0efbd..f9ac77160f6 100644 --- a/gdb/dwarf2/expr.c +++ b/gdb/dwarf2/expr.c @@ -242,6 +242,19 @@ void dwarf_expr_context::read_mem (gdb_byte *buf, CORE_ADDR addr, size_t length) { + if (length == 0) + return; + + /* Prefer the passed-in memory, if it exists. */ + CORE_ADDR offset = addr - this->obj_address; + + if (offset < this->data_view.size () + && offset + length <= this->data_view.size ()) + { + memcpy (buf, this->data_view.data (), length); + return; + } + read_memory (addr, buf, length); } @@ -1573,8 +1586,11 @@ dwarf_expr_context::execute_stack_op (const gdb_byte *op_ptr, case DW_OP_push_object_address: /* Return the address of the object we are currently observing. */ - result = this->get_object_address (); - result_val = value_from_ulongest (address_type, result); + if (this->data_view.data () == nullptr + && this->obj_address == 0) + error (_("Location address is not set.")); + + result_val = value_from_ulongest (address_type, this->obj_address); break; default: diff --git a/gdb/dwarf2/expr.h b/gdb/dwarf2/expr.h index 9dc9257abd8..76c073cf38f 100644 --- a/gdb/dwarf2/expr.h +++ b/gdb/dwarf2/expr.h @@ -191,16 +191,8 @@ struct dwarf_expr_context /* Object address used for the evaluation. */ CORE_ADDR obj_address = 0; - /* Read LENGTH bytes at ADDR into BUF. */ - virtual void read_mem (gdb_byte *buf, CORE_ADDR addr, size_t length); - - /* Return the `object address' for DW_OP_push_object_address. */ - virtual CORE_ADDR get_object_address () - { - if (obj_address == 0) - error (_("Location address is not set.")); - return obj_address; - } + /* The data that was passed in. */ + gdb::array_view data_view; private: @@ -234,6 +226,12 @@ struct dwarf_expr_context void push_dwarf_reg_entry_value (call_site_parameter_kind kind, call_site_parameter_u kind_u, int deref_size); + + /* Read LENGTH bytes at ADDR into BUF. This method also handles the + case where a caller of the evaluator passes in some data, + but with the address being 0. In this situation, we arrange for + memory reads to come from the passed-in buffer. */ + void read_mem (gdb_byte *buf, CORE_ADDR addr, size_t length); }; /* Return the value of register number REG (a DWARF register number), diff --git a/gdb/dwarf2/loc.c b/gdb/dwarf2/loc.c index b985f91c8da..6b9fc19ec05 100644 --- a/gdb/dwarf2/loc.c +++ b/gdb/dwarf2/loc.c @@ -2262,45 +2262,6 @@ dwarf2_evaluate_loc_desc (struct type *type, struct frame_info *frame, per_objfile, NULL, 0); } -/* A specialization of dwarf_expr_context that is used by - dwarf2_locexpr_baton_eval. This subclass exists to handle the case - where a caller of dwarf2_locexpr_baton_eval passes in some data, - but with the address being 0. In this situation, we arrange for - memory reads to come from the passed-in buffer. */ - -struct evaluate_for_locexpr_baton : public dwarf_expr_context -{ - evaluate_for_locexpr_baton (dwarf2_per_objfile *per_objfile) - : dwarf_expr_context (per_objfile) - {} - - /* The data that was passed in. */ - gdb::array_view data_view; - - CORE_ADDR get_object_address () override - { - if (data_view.data () == nullptr && obj_address == 0) - error (_("Location address is not set.")); - return obj_address; - } - - void read_mem (gdb_byte *buf, CORE_ADDR addr, size_t len) override - { - if (len == 0) - return; - - /* Prefer the passed-in memory, if it exists. */ - CORE_ADDR offset = addr - obj_address; - if (offset < data_view.size () && offset + len <= data_view.size ()) - { - memcpy (buf, data_view.data (), len); - return; - } - - read_memory (addr, buf, len); - } -}; - /* Evaluates a dwarf expression and stores the result in VAL, expecting that the dwarf expression only produces a single CORE_ADDR. FRAME is the frame in which the expression is @@ -2324,13 +2285,11 @@ dwarf2_locexpr_baton_eval (const struct dwarf2_locexpr_baton *dlbaton, return 0; dwarf2_per_objfile *per_objfile = dlbaton->per_objfile; - evaluate_for_locexpr_baton ctx (per_objfile); + dwarf_expr_context ctx (per_objfile); ctx.frame = frame; ctx.per_cu = dlbaton->per_cu; - if (addr_stack == nullptr) - ctx.obj_address = 0; - else + if (addr_stack != nullptr) { ctx.obj_address = addr_stack->addr; ctx.data_view = addr_stack->valaddr;