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Evaluating DWARF expressions (such as location expressions) requires
knowing about the current objfile. For example, it may call functions
like dwarf2_fetch_die_loc_sect_off, which currently obtain the
dwarf2_per_objfile object it needs from the dwarf2_per_cu_data object.
However, since we are going to remove this
dwarf2_per_cu_data::dwarf2_per_objfile link, these functions will need
to obtain the current dwarf2_per_objfile by parmeter.
If we go up the stack, we see that the DWARF expression contexts
(dwarf_expr_context and the classes that derive from it) need to store
the dwarf2_per_objfile, to be able to pass it to those functions that
will need it.
This patch adds a constructor to all these dwarf_expr_context variants,
accepting a dwarf2_per_objfile parameter. This dwarf2_per_objfile
generally comes from a symbol baton created earlier.
For frame-related expressions, the dwarf2_per_objfile object must be
passed through the dwarf2_frame_cache object. This lead to the
dwarf2_frame_find_fde function returning (by parameter) a
dwarf2_per_objfile object. I then realized that this made the existing
"out_offset" parameter redundant. This offset is
`objfile->text_section_offset ()`, so it can be recomputed from the
dwarf2_per_objfile object at any time. I therefore opted to remove this
output parameter, as well as the offset field of dwarf2_frame_cache.
*Note*, there's one spot I'm particularly unsure about. In
dwarf_evaluate_loc_desc::push_dwarf_reg_entry_value, we would save and
overwrite the offset value in the context, along with a bunch of other
state. This is because we might be about to evaluate something in a
different CU that the current one. If the two CUs are in the same
objfile, then the text_offset is the same, as it's a property of the
objfile. However, if the two CUs are possibly in different objfiles,
then it means the text_offsets are different. It would also mean we
would need to save and restore the dwarf2_per_objfile in the context.
Is that even possible?
gdb/ChangeLog:
* dwarf2/expr.h (struct dwarf_expr_context)
<dwarf_expr_context>: Add dwarf2_per_objfile parameter.
<offset>: Remove.
<per_objfile>: New member.
* dwarf2/expr.c (dwarf_expr_context::dwarf_expr_context): Add
dwarf2_per_objfile parameter. Don't set offset, set
per_objfile.
(dwarf_expr_context::execute_stack_op): Use offset from objfile.
* dwarf2/frame.c (dwarf2_frame_find_fde): Return (by parameter)
a dwarf2_per_objfile object instead of an offset.
(class dwarf_expr_executor) <dwarf_expr_executor>: Add
constructor.
(execute_stack_op): Add dwarf2_per_objfile parameter, pass it
to dwarf2_expr_executor constructor. Don't set offset.
(dwarf2_fetch_cfa_info): Update.
(struct dwarf2_frame_cache) <text_offset>: Remove.
<per_objfile>: New field.
(dwarf2_frame_cache): Update.
(dwarf2_frame_prev_register): Update.
* dwarf2/loc.c (class dwarf_evaluate_loc_desc)
<dwarf_evaluate_loc_desc>: Add constructor.
(dwarf2_evaluate_loc_desc_full): Update.
(dwarf2_locexpr_baton_eval): Update.
(class symbol_needs_eval_context) <symbol_needs_eval_context>:
Add constructor.
(dwarf2_loc_desc_get_symbol_read_needs): Update.
Change-Id: I14df060669cc36ad04759f1708c6d7b1fda77727
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This moves all the remaining DWARF code to the new dwarf2
subdirectory. This is just a simple renaming, with updates to
includes as needed.
gdb/ChangeLog
2020-02-08 Tom Tromey <tom@tromey.com>
* dwarf2/expr.c: Rename from dwarf2expr.c.
* dwarf2/expr.h: Rename from dwarf2expr.h.
* dwarf2/frame-tailcall.c: Rename from dwarf2-frame-tailcall.c.
* dwarf2/frame-tailcall.h: Rename from dwarf2-frame-tailcall.h.
* dwarf2/frame.c: Rename from dwarf2-frame.c.
* dwarf2/frame.h: Rename from dwarf2-frame.h.
* dwarf2/index-cache.c: Rename from dwarf-index-cache.c.
* dwarf2/index-cache.h: Rename from dwarf-index-cache.h.
* dwarf2/index-common.c: Rename from dwarf-index-common.c.
* dwarf2/index-common.h: Rename from dwarf-index-common.h.
* dwarf2/index-write.c: Rename from dwarf-index-write.c.
* dwarf2/index-write.h: Rename from dwarf-index-write.h.
* dwarf2/loc.c: Rename from dwarf2loc.c.
* dwarf2/loc.h: Rename from dwarf2loc.h.
* dwarf2/read.c: Rename from dwarf2read.c.
* dwarf2/read.h: Rename from dwarf2read.h.
* dwarf2/abbrev.c, aarch64-tdep.c, alpha-tdep.c,
amd64-darwin-tdep.c, arc-tdep.c, arm-tdep.c, bfin-tdep.c,
compile/compile-c-symbols.c, compile/compile-cplus-symbols.c,
compile/compile-loc2c.c, cris-tdep.c, csky-tdep.c, findvar.c,
gdbtypes.c, guile/scm-type.c, h8300-tdep.c, hppa-bsd-tdep.c,
hppa-linux-tdep.c, i386-darwin-tdep.c, i386-linux-tdep.c,
i386-tdep.c, iq2000-tdep.c, m32c-tdep.c, m68hc11-tdep.c,
m68k-tdep.c, microblaze-tdep.c, mips-tdep.c, mn10300-tdep.c,
msp430-tdep.c, nds32-tdep.c, nios2-tdep.c, or1k-tdep.c,
riscv-tdep.c, rl78-tdep.c, rs6000-tdep.c, rx-tdep.c, s12z-tdep.c,
s390-tdep.c, score-tdep.c, sh-tdep.c, sparc-linux-tdep.c,
sparc-tdep.c, sparc64-linux-tdep.c, sparc64-tdep.c, tic6x-tdep.c,
tilegx-tdep.c, v850-tdep.c, xstormy16-tdep.c, xtensa-tdep.c:
Update.
* Makefile.in (COMMON_SFILES): Update.
(HFILES_NO_SRCDIR): Update.
Change-Id: Ied9ce1436cd27ac4a4cffef10ec92e396f181928
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