Recognize virtual tail call frames.
* Makefile.in (SFILES): Add dwarf2-frame-tailcall.c.
(HFILES_NO_SRCDIR): Add dwarf2-frame-tailcall.h.
(COMMON_OBS): Add dwarf2-frame-tailcall.o.
* dwarf2-frame-tailcall.c: New file.
* dwarf2-frame-tailcall.h: New file.
* dwarf2-frame.c: Include dwarf2-frame-tailcall.h.
(execute_cfa_program): New function comment. Return INSN_PTR. Reset
REGS.PREV only after CIE execution.
(struct dwarf2_frame_cache): New field tailcall_cache.
(dwarf2_frame_cache): New variables entry_pc, entry_cfa_sp_offset,
entry_cfa_sp_offset_p and instr. Execute FDE instructions in two
parts, try to find entry_cfa_sp_offset. Call
dwarf2_tailcall_sniffer_first.
(dwarf2_frame_prev_register): Call dwarf2_tailcall_prev_register_first
when appropriate.
(dwarf2_frame_dealloc_cache): New function.
(dwarf2_frame_sniffer): Preinitialize cache by dwarf2_frame_cache.
(dwarf2_frame_unwind): Install dwarf2_frame_dealloc_cache.
(dwarf2_signal_frame_unwind): Do not install dwarf2_frame_dealloc_cache.
(dwarf2_append_unwinders): Add dwarf2_tailcall_frame_unwind.
(dwarf2_frame_cfa): Support also dwarf2_tailcall_frame_unwind.
* dwarf2loc.c (func_addr_to_tail_call_list)
(tailcall_dump, call_sitep, VEC (call_sitep), chain_candidate)
(call_site_find_chain_1, call_site_find_chain): New.
* dwarf2loc.h (struct call_site_chain): New.
(call_site_find_chain): New declaration.
* frame.c (get_frame_address_in_block): Support also TAILCALL_FRAME.
* frame.h (enum frame_type): New entry TAILCALL_FRAME.
* python/py-frame.c (gdbpy_initialize_frames): Add TAILCALL_FRAME.
* stack.c (frame_info): Support also TAILCALL_FRAME.
gdb/doc/
Recognize virtual tail call frames.
* gdb.texinfo (Optimized Code): Add reference to Tail Call Frames.
(Tail Call Frames): New node.
(Frames In Python): Add gdb.TAILCALL_FRAME.
gdb/testsuite/
Recognize virtual tail call frames.
* gdb.arch/amd64-entry-value.cc (c, a, b, amb_z, amb_y, amb_x, amb)
(amb_b, amb_a): New.
(main): Call a and b.
* gdb.arch/amd64-entry-value.exp (tailcall: breakhere, tailcall: bt)
(tailcall: p i, tailcall: p j, set $sp0=$sp, up, p $sp0 == $sp, frame 3)
(p $sp0 + sizeof (void *) == $sp, ambiguous: breakhere, ambiguous: bt):
New tests.
2011-10-09 Jan Kratochvil <jan.kratochvil@redhat.com>
+ Recognize virtual tail call frames.
+ * Makefile.in (SFILES): Add dwarf2-frame-tailcall.c.
+ (HFILES_NO_SRCDIR): Add dwarf2-frame-tailcall.h.
+ (COMMON_OBS): Add dwarf2-frame-tailcall.o.
+ * dwarf2-frame-tailcall.c: New file.
+ * dwarf2-frame-tailcall.h: New file.
+ * dwarf2-frame.c: Include dwarf2-frame-tailcall.h.
+ (execute_cfa_program): New function comment. Return INSN_PTR. Reset
+ REGS.PREV only after CIE execution.
+ (struct dwarf2_frame_cache): New field tailcall_cache.
+ (dwarf2_frame_cache): New variables entry_pc, entry_cfa_sp_offset,
+ entry_cfa_sp_offset_p and instr. Execute FDE instructions in two
+ parts, try to find entry_cfa_sp_offset. Call
+ dwarf2_tailcall_sniffer_first.
+ (dwarf2_frame_prev_register): Call dwarf2_tailcall_prev_register_first
+ when appropriate.
+ (dwarf2_frame_dealloc_cache): New function.
+ (dwarf2_frame_sniffer): Preinitialize cache by dwarf2_frame_cache.
+ (dwarf2_frame_unwind): Install dwarf2_frame_dealloc_cache.
+ (dwarf2_signal_frame_unwind): Do not install dwarf2_frame_dealloc_cache.
+ (dwarf2_append_unwinders): Add dwarf2_tailcall_frame_unwind.
+ (dwarf2_frame_cfa): Support also dwarf2_tailcall_frame_unwind.
+ * dwarf2loc.c (func_addr_to_tail_call_list)
+ (tailcall_dump, call_sitep, VEC (call_sitep), chain_candidate)
+ (call_site_find_chain_1, call_site_find_chain): New.
+ * dwarf2loc.h (struct call_site_chain): New.
+ (call_site_find_chain): New declaration.
+ * frame.c (get_frame_address_in_block): Support also TAILCALL_FRAME.
+ * frame.h (enum frame_type): New entry TAILCALL_FRAME.
+ * python/py-frame.c (gdbpy_initialize_frames): Add TAILCALL_FRAME.
+ * stack.c (frame_info): Support also TAILCALL_FRAME.
+
+2011-10-09 Jan Kratochvil <jan.kratochvil@redhat.com>
+
Tail call sites reader implementation.
* dwarf2read.c (read_call_site_scope): Recognize DW_AT_GNU_tail_call,
fill in TYPE_TAIL_CALL_LIST.
cp-name-parser.y \
dbxread.c demangle.c dictionary.c disasm.c doublest.c dummy-frame.c \
dwarf2expr.c dwarf2loc.c dwarf2read.c dwarf2-frame.c \
+ dwarf2-frame-tailcall.c \
elfread.c environ.c eval.c event-loop.c event-top.c \
exceptions.c expprint.c \
f-exp.y f-lang.c f-typeprint.c f-valprint.c filesystem.c \
cli/cli-script.h macrotab.h symtab.h version.h gnulib/wchar.in.h \
gnulib/string.in.h gnulib/str-two-way.h \
gnulib/stdint.in.h remote.h gdb.h sparc-nat.h \
-gdbthread.h dwarf2-frame.h nbsd-nat.h dcache.h \
+gdbthread.h dwarf2-frame.h dwarf2-frame-tailcall.h nbsd-nat.h dcache.h \
amd64-nat.h s390-tdep.h arm-linux-tdep.h exceptions.h macroscope.h \
gdbarch.h bsd-uthread.h gdb_stat.h memory-map.h memrange.h \
mdebugread.h m88k-tdep.h stabsread.h hppa-linux-offsets.h linux-fork.h \
bcache.o objfiles.o observer.o minsyms.o maint.o demangle.o \
dbxread.o coffread.o coff-pe-read.o \
dwarf2read.o mipsread.o stabsread.o corefile.o \
- dwarf2expr.o dwarf2loc.o dwarf2-frame.o \
+ dwarf2expr.o dwarf2loc.o dwarf2-frame.o dwarf2-frame-tailcall.o \
ada-lang.o c-lang.o d-lang.o f-lang.o objc-lang.o \
ada-tasks.o \
ui-out.o cli-out.o \
+2011-10-09 Jan Kratochvil <jan.kratochvil@redhat.com>
+ Eli Zaretskii <eliz@gnu.org>
+
+ Recognize virtual tail call frames.
+ * gdb.texinfo (Optimized Code): Add reference to Tail Call Frames.
+ (Tail Call Frames): New node.
+ (Frames In Python): Add gdb.TAILCALL_FRAME.
+
2011-10-07 Doug Evans <dje@google.com>
* gdb.texinfo (gdb.printing): Document new `replace' arg to
@menu
* Inline Functions:: How @value{GDBN} presents inlining
+* Tail Call Frames:: @value{GDBN} analysis of jumps to functions
@end menu
@node Inline Functions
@end itemize
+@node Tail Call Frames
+@section Tail Call Frames
+@cindex tail call frames, debugging
+
+Function @code{B} can call function @code{C} in its very last statement. In
+unoptimized compilation the call of @code{C} is immediately followed by return
+instruction at the end of @code{B} code. Optimizing compiler may replace the
+call and return in function @code{B} into one jump to function @code{C}
+instead. Such use of a jump instruction is called @dfn{tail call}.
+
+During execution of function @code{C}, there will be no indication in the
+function call stack frames that it was tail-called from @code{B}. If function
+@code{A} regularly calls function @code{B} which tail-calls function @code{C},
+then @value{GDBN} will see @code{A} as the caller of @code{C}. However, in
+some cases @value{GDBN} can determine that @code{C} was tail-called from
+@code{B}, and it will then create fictitious call frame for that, with the
+return address set up as if @code{B} called @code{C} normally.
+
+This functionality is currently supported only by DWARF 2 debugging format and
+the compiler has to produce @samp{DW_TAG_GNU_call_site} tags. With
+@value{NGCC}, you need to specify @option{-O -g} during compilation, to get
+this information.
+
+@kbd{info frame} command (@pxref{Frame Info}) will indicate the tail call frame
+kind by text @code{tail call frame} such as in this sample @value{GDBN} output:
+
+@smallexample
+(gdb) x/i $pc - 2
+ 0x40066b <b(int, double)+11>: jmp 0x400640 <c(int, double)>
+(gdb) info frame
+Stack level 1, frame at 0x7fffffffda30:
+ rip = 0x40066d in b (amd64-entry-value.cc:59); saved rip 0x4004c5
+ tail call frame, caller of frame at 0x7fffffffda30
+ source language c++.
+ Arglist at unknown address.
+ Locals at unknown address, Previous frame's sp is 0x7fffffffda30
+@end smallexample
+
+The detection of all the possible code path executions can find them ambiguous.
+There is no execution history stored (possible @ref{Reverse Execution} is never
+used for this purpose) and the last known caller could have reached the known
+callee by multiple different jump sequences. In such case @value{GDBN} still
+tries to show at least all the unambiguous top tail callers and all the
+unambiguous bottom tail calees, if any.
+
+@table @code
+@item set debug entry-values
+@kindex set debug entry-values
+When set to on, enables printing of analysis messages for both frame argument
+values at function entry and tail calls. It will show all the possible valid
+tail calls code paths it has considered. It will also print the intersection
+of them with the final unambiguous (possibly partial or even empty) code path
+result.
+
+@item show debug entry-values
+@kindex show debug entry-values
+Show the current state of analysis messages printing for both frame argument
+values at function entry and tail calls.
+@end table
+
+The analysis messages for tail calls can for example show why the virtual tail
+call frame for function @code{c} has not been recognized (due to the indirect
+reference by variable @code{x}):
+
+@smallexample
+static void __attribute__((noinline, noclone)) c (void);
+void (*x) (void) = c;
+static void __attribute__((noinline, noclone)) a (void) @{ x++; @}
+static void __attribute__((noinline, noclone)) c (void) @{ a (); @}
+int main (void) @{ x (); return 0; @}
+
+Breakpoint 1, DW_OP_GNU_entry_value resolving cannot find
+DW_TAG_GNU_call_site 0x40039a in main
+a () at t.c:3
+3 static void __attribute__((noinline, noclone)) a (void) @{ x++; @}
+(gdb) bt
+#0 a () at t.c:3
+#1 0x000000000040039a in main () at t.c:5
+@end smallexample
+
+Another possibility is an ambiguous virtual tail call frames resolution:
+
+@smallexample
+int i;
+static void __attribute__((noinline, noclone)) f (void) @{ i++; @}
+static void __attribute__((noinline, noclone)) e (void) @{ f (); @}
+static void __attribute__((noinline, noclone)) d (void) @{ f (); @}
+static void __attribute__((noinline, noclone)) c (void) @{ d (); @}
+static void __attribute__((noinline, noclone)) b (void)
+@{ if (i) c (); else e (); @}
+static void __attribute__((noinline, noclone)) a (void) @{ b (); @}
+int main (void) @{ a (); return 0; @}
+
+tailcall: initial: 0x4004d2(a) 0x4004ce(b) 0x4004b2(c) 0x4004a2(d)
+tailcall: compare: 0x4004d2(a) 0x4004cc(b) 0x400492(e)
+tailcall: reduced: 0x4004d2(a) |
+(gdb) bt
+#0 f () at t.c:2
+#1 0x00000000004004d2 in a () at t.c:8
+#2 0x0000000000400395 in main () at t.c:9
+@end smallexample
+
+Frames #0 and #2 are real, #1 is a virtual tail call frame. The code can have
+possible execution paths
+@code{main@arrow{}a@arrow{}b@arrow{}c@arrow{}d@arrow{}f} or
+@code{main@arrow{}a@arrow{}b@arrow{}e@arrow{}f}, @value{GDBN} cannot find which
+one from the inferior state.
+
+@code{initial:} state shows some random possible calling sequence @value{GDBN}
+has found. It then finds another possible calling sequcen - that one is
+prefixed by @code{compare:}. The non-ambiguous intersection of these two is
+printed as the @code{reduced:} calling sequence. That one could have many
+futher @code{compare:} and @code{reduced:} statements as long as there remain
+any non-ambiguous sequence entries.
+
+For the frame of function @code{b} in both cases there are different possible
+@code{$pc} values (@code{0x4004cc} or @code{0x4004ce}), therefore this frame is
+also ambigous. The only non-ambiguous frame is the one for function @code{a},
+therefore this one is displayed to the user while the ambiguous frames are
+omitted.
@node Macros
@chapter C Preprocessor Macros
A frame representing an inlined function. The function was inlined
into a @code{gdb.NORMAL_FRAME} that is older than this one.
+@item gdb.TAILCALL_FRAME
+A frame representing a tail call. @xref{Tail Call Frames}.
+
@item gdb.SIGTRAMP_FRAME
A signal trampoline frame. This is the frame created by the OS when
it calls into a signal handler.
#include "ax.h"
#include "dwarf2loc.h"
#include "exceptions.h"
+#include "dwarf2-frame-tailcall.h"
struct comp_unit;
}
\f
-static void
+/* Execute FDE program from INSN_PTR possibly up to INSN_END or up to inferior
+ PC. Modify FS state accordingly. Return current INSN_PTR where the
+ execution has stopped, one can resume it on the next call. */
+
+static const gdb_byte *
execute_cfa_program (struct dwarf2_fde *fde, const gdb_byte *insn_ptr,
const gdb_byte *insn_end, struct gdbarch *gdbarch,
CORE_ADDR pc, struct dwarf2_frame_state *fs)
}
}
- /* Don't allow remember/restore between CIE and FDE programs. */
- dwarf2_frame_state_free_regs (fs->regs.prev);
- fs->regs.prev = NULL;
+ if (fs->initial.reg == NULL)
+ {
+ /* Don't allow remember/restore between CIE and FDE programs. */
+ dwarf2_frame_state_free_regs (fs->regs.prev);
+ fs->regs.prev = NULL;
+ }
+
+ return insn_ptr;
}
\f
/* The .text offset. */
CORE_ADDR text_offset;
+
+ /* If not NULL then this frame is the bottom frame of a TAILCALL_FRAME
+ sequence. If NULL then it is a normal case with no TAILCALL_FRAME
+ involved. Non-bottom frames of a virtual tail call frames chain use
+ dwarf2_tailcall_frame_unwind unwinder so this field does not apply for
+ them. */
+ void *tailcall_cache;
};
static struct dwarf2_frame_cache *
struct dwarf2_frame_state *fs;
struct dwarf2_fde *fde;
volatile struct gdb_exception ex;
+ CORE_ADDR entry_pc;
+ LONGEST entry_cfa_sp_offset;
+ int entry_cfa_sp_offset_p = 0;
+ const gdb_byte *instr;
if (*this_cache)
return *this_cache;
fs->initial = fs->regs;
fs->initial.reg = dwarf2_frame_state_copy_regs (&fs->regs);
+ if (get_frame_func_if_available (this_frame, &entry_pc))
+ {
+ /* Decode the insns in the FDE up to the entry PC. */
+ instr = execute_cfa_program (fde, fde->instructions, fde->end, gdbarch,
+ entry_pc, fs);
+
+ if (fs->regs.cfa_how == CFA_REG_OFFSET
+ && (gdbarch_dwarf2_reg_to_regnum (gdbarch, fs->regs.cfa_reg)
+ == gdbarch_sp_regnum (gdbarch)))
+ {
+ entry_cfa_sp_offset = fs->regs.cfa_offset;
+ entry_cfa_sp_offset_p = 1;
+ }
+ }
+ else
+ instr = fde->instructions;
+
/* Then decode the insns in the FDE up to our target PC. */
- execute_cfa_program (fde, fde->instructions, fde->end, gdbarch,
+ execute_cfa_program (fde, instr, fde->end, gdbarch,
get_frame_pc (this_frame), fs);
TRY_CATCH (ex, RETURN_MASK_ERROR)
do_cleanups (old_chain);
+ /* Try to find a virtual tail call frames chain with bottom (callee) frame
+ starting at THIS_FRAME. */
+ dwarf2_tailcall_sniffer_first (this_frame, &cache->tailcall_cache,
+ (entry_cfa_sp_offset_p
+ ? &entry_cfa_sp_offset : NULL));
+
return cache;
}
CORE_ADDR addr;
int realnum;
+ /* Non-bottom frames of a virtual tail call frames chain use
+ dwarf2_tailcall_frame_unwind unwinder so this code does not apply for
+ them. If dwarf2_tailcall_prev_register_first does not have specific value
+ unwind the register, tail call frames are assumed to have the register set
+ of the top caller. */
+ if (cache->tailcall_cache)
+ {
+ struct value *val;
+
+ val = dwarf2_tailcall_prev_register_first (this_frame,
+ &cache->tailcall_cache,
+ regnum);
+ if (val)
+ return val;
+ }
+
switch (cache->reg[regnum].how)
{
case DWARF2_FRAME_REG_UNDEFINED:
}
}
+/* Proxy for tailcall_frame_dealloc_cache for bottom frame of a virtual tail
+ call frames chain. */
+
+static void
+dwarf2_frame_dealloc_cache (struct frame_info *self, void *this_cache)
+{
+ struct dwarf2_frame_cache *cache = dwarf2_frame_cache (self, &this_cache);
+
+ if (cache->tailcall_cache)
+ dwarf2_tailcall_frame_unwind.dealloc_cache (self, cache->tailcall_cache);
+}
+
static int
dwarf2_frame_sniffer (const struct frame_unwind *self,
struct frame_info *this_frame, void **this_cache)
this_frame))
return self->type == SIGTRAMP_FRAME;
- return self->type != SIGTRAMP_FRAME;
+ if (self->type != NORMAL_FRAME)
+ return 0;
+
+ /* Preinitializa the cache so that TAILCALL_FRAME can find the record by
+ dwarf2_tailcall_sniffer_first. */
+ dwarf2_frame_cache (this_frame, this_cache);
+
+ return 1;
}
static const struct frame_unwind dwarf2_frame_unwind =
dwarf2_frame_this_id,
dwarf2_frame_prev_register,
NULL,
- dwarf2_frame_sniffer
+ dwarf2_frame_sniffer,
+ dwarf2_frame_dealloc_cache
};
static const struct frame_unwind dwarf2_signal_frame_unwind =
dwarf2_frame_this_id,
dwarf2_frame_prev_register,
NULL,
- dwarf2_frame_sniffer
+ dwarf2_frame_sniffer,
+
+ /* TAILCALL_CACHE can never be in such frame to need dealloc_cache. */
+ NULL
};
/* Append the DWARF-2 frame unwinders to GDBARCH's list. */
void
dwarf2_append_unwinders (struct gdbarch *gdbarch)
{
+ /* TAILCALL_FRAME must be first to find the record by
+ dwarf2_tailcall_sniffer_first. */
+ frame_unwind_append_unwinder (gdbarch, &dwarf2_tailcall_frame_unwind);
+
frame_unwind_append_unwinder (gdbarch, &dwarf2_frame_unwind);
frame_unwind_append_unwinder (gdbarch, &dwarf2_signal_frame_unwind);
}
/* This restriction could be lifted if other unwinders are known to
compute the frame base in a way compatible with the DWARF
unwinder. */
- if (! frame_unwinder_is (this_frame, &dwarf2_frame_unwind))
+ if (!frame_unwinder_is (this_frame, &dwarf2_frame_unwind)
+ && !frame_unwinder_is (this_frame, &dwarf2_tailcall_frame_unwind))
error (_("can't compute CFA for this frame"));
return get_frame_base (this_frame);
}
}
}
+/* Convert function entry point exact address ADDR to the function which is
+ compliant with TAIL_CALL_LIST_COMPLETE condition. Throw
+ NO_ENTRY_VALUE_ERROR otherwise. */
+
+static struct symbol *
+func_addr_to_tail_call_list (struct gdbarch *gdbarch, CORE_ADDR addr)
+{
+ struct symbol *sym = find_pc_function (addr);
+ struct type *type;
+
+ if (sym == NULL || BLOCK_START (SYMBOL_BLOCK_VALUE (sym)) != addr)
+ throw_error (NO_ENTRY_VALUE_ERROR,
+ _("DW_TAG_GNU_call_site resolving failed to find function "
+ "name for address %s"),
+ paddress (gdbarch, addr));
+
+ type = SYMBOL_TYPE (sym);
+ gdb_assert (TYPE_CODE (type) == TYPE_CODE_FUNC);
+ gdb_assert (TYPE_SPECIFIC_FIELD (type) == TYPE_SPECIFIC_FUNC);
+
+ return sym;
+}
+
+/* Print user readable form of CALL_SITE->PC to gdb_stdlog. Used only for
+ ENTRY_VALUES_DEBUG. */
+
+static void
+tailcall_dump (struct gdbarch *gdbarch, const struct call_site *call_site)
+{
+ CORE_ADDR addr = call_site->pc;
+ struct minimal_symbol *msym = lookup_minimal_symbol_by_pc (addr - 1);
+
+ fprintf_unfiltered (gdb_stdlog, " %s(%s)", paddress (gdbarch, addr),
+ msym == NULL ? "???" : SYMBOL_PRINT_NAME (msym));
+
+}
+
+/* vec.h needs single word type name, typedef it. */
+typedef struct call_site *call_sitep;
+
+/* Define VEC (call_sitep) functions. */
+DEF_VEC_P (call_sitep);
+
+/* Intersect RESULTP with CHAIN to keep RESULTP unambiguous, keep in RESULTP
+ only top callers and bottom callees which are present in both. GDBARCH is
+ used only for ENTRY_VALUES_DEBUG. RESULTP is NULL after return if there are
+ no remaining possibilities to provide unambiguous non-trivial result.
+ RESULTP should point to NULL on the first (initialization) call. Caller is
+ responsible for xfree of any RESULTP data. */
+
+static void
+chain_candidate (struct gdbarch *gdbarch, struct call_site_chain **resultp,
+ VEC (call_sitep) *chain)
+{
+ struct call_site_chain *result = *resultp;
+ long length = VEC_length (call_sitep, chain);
+ int callers, callees, idx;
+
+ if (result == NULL)
+ {
+ /* Create the initial chain containing all the passed PCs. */
+
+ result = xmalloc (sizeof (*result) + sizeof (*result->call_site)
+ * (length - 1));
+ result->length = length;
+ result->callers = result->callees = length;
+ memcpy (result->call_site, VEC_address (call_sitep, chain),
+ sizeof (*result->call_site) * length);
+ *resultp = result;
+
+ if (entry_values_debug)
+ {
+ fprintf_unfiltered (gdb_stdlog, "tailcall: initial:");
+ for (idx = 0; idx < length; idx++)
+ tailcall_dump (gdbarch, result->call_site[idx]);
+ fputc_unfiltered ('\n', gdb_stdlog);
+ }
+
+ return;
+ }
+
+ if (entry_values_debug)
+ {
+ fprintf_unfiltered (gdb_stdlog, "tailcall: compare:");
+ for (idx = 0; idx < length; idx++)
+ tailcall_dump (gdbarch, VEC_index (call_sitep, chain, idx));
+ fputc_unfiltered ('\n', gdb_stdlog);
+ }
+
+ /* Intersect callers. */
+
+ callers = min (result->callers, length);
+ for (idx = 0; idx < callers; idx++)
+ if (result->call_site[idx] != VEC_index (call_sitep, chain, idx))
+ {
+ result->callers = idx;
+ break;
+ }
+
+ /* Intersect callees. */
+
+ callees = min (result->callees, length);
+ for (idx = 0; idx < callees; idx++)
+ if (result->call_site[result->length - 1 - idx]
+ != VEC_index (call_sitep, chain, length - 1 - idx))
+ {
+ result->callees = idx;
+ break;
+ }
+
+ if (entry_values_debug)
+ {
+ fprintf_unfiltered (gdb_stdlog, "tailcall: reduced:");
+ for (idx = 0; idx < result->callers; idx++)
+ tailcall_dump (gdbarch, result->call_site[idx]);
+ fputs_unfiltered (" |", gdb_stdlog);
+ for (idx = 0; idx < result->callees; idx++)
+ tailcall_dump (gdbarch, result->call_site[result->length
+ - result->callees + idx]);
+ fputc_unfiltered ('\n', gdb_stdlog);
+ }
+
+ if (result->callers == 0 && result->callees == 0)
+ {
+ /* There are no common callers or callees. It could be also a direct
+ call (which has length 0) with ambiguous possibility of an indirect
+ call - CALLERS == CALLEES == 0 is valid during the first allocation
+ but any subsequence processing of such entry means ambiguity. */
+ xfree (result);
+ *resultp = NULL;
+ return;
+ }
+
+ /* See call_site_find_chain_1 why there is no way to reach the bottom callee
+ PC again. In such case there must be two different code paths to reach
+ it, therefore some of the former determined intermediate PCs must differ
+ and the unambiguous chain gets shortened. */
+ gdb_assert (result->callers + result->callees < result->length);
+}
+
+/* Create and return call_site_chain for CALLER_PC and CALLEE_PC. All the
+ assumed frames between them use GDBARCH. Use depth first search so we can
+ keep single CHAIN of call_site's back to CALLER_PC. Function recursion
+ would have needless GDB stack overhead. Caller is responsible for xfree of
+ the returned result. Any unreliability results in thrown
+ NO_ENTRY_VALUE_ERROR. */
+
+static struct call_site_chain *
+call_site_find_chain_1 (struct gdbarch *gdbarch, CORE_ADDR caller_pc,
+ CORE_ADDR callee_pc)
+{
+ struct func_type *func_specific;
+ struct obstack addr_obstack;
+ struct cleanup *back_to_retval, *back_to_workdata;
+ struct call_site_chain *retval = NULL;
+ struct call_site *call_site;
+
+ /* Mark CALL_SITEs so we do not visit the same ones twice. */
+ htab_t addr_hash;
+
+ /* CHAIN contains only the intermediate CALL_SITEs. Neither CALLER_PC's
+ call_site nor any possible call_site at CALLEE_PC's function is there.
+ Any CALL_SITE in CHAIN will be iterated to its siblings - via
+ TAIL_CALL_NEXT. This is inappropriate for CALLER_PC's call_site. */
+ VEC (call_sitep) *chain = NULL;
+
+ /* We are not interested in the specific PC inside the callee function. */
+ callee_pc = get_pc_function_start (callee_pc);
+ if (callee_pc == 0)
+ throw_error (NO_ENTRY_VALUE_ERROR, _("Unable to find function for PC %s"),
+ paddress (gdbarch, callee_pc));
+
+ back_to_retval = make_cleanup (free_current_contents, &retval);
+
+ obstack_init (&addr_obstack);
+ back_to_workdata = make_cleanup_obstack_free (&addr_obstack);
+ addr_hash = htab_create_alloc_ex (64, core_addr_hash, core_addr_eq, NULL,
+ &addr_obstack, hashtab_obstack_allocate,
+ NULL);
+ make_cleanup_htab_delete (addr_hash);
+
+ make_cleanup (VEC_cleanup (call_sitep), &chain);
+
+ /* Do not push CALL_SITE to CHAIN. Push there only the first tail call site
+ at the target's function. All the possible tail call sites in the
+ target's function will get iterated as already pushed into CHAIN via their
+ TAIL_CALL_NEXT. */
+ call_site = call_site_for_pc (gdbarch, caller_pc);
+
+ while (call_site)
+ {
+ CORE_ADDR target_func_addr;
+ struct call_site *target_call_site;
+
+ /* CALLER_FRAME with registers is not available for tail-call jumped
+ frames. */
+ target_func_addr = call_site_to_target_addr (gdbarch, call_site, NULL);
+
+ if (target_func_addr == callee_pc)
+ {
+ chain_candidate (gdbarch, &retval, chain);
+ if (retval == NULL)
+ break;
+
+ /* There is no way to reach CALLEE_PC again as we would prevent
+ entering it twice as being already marked in ADDR_HASH. */
+ target_call_site = NULL;
+ }
+ else
+ {
+ struct symbol *target_func;
+
+ target_func = func_addr_to_tail_call_list (gdbarch, target_func_addr);
+ target_call_site = TYPE_TAIL_CALL_LIST (SYMBOL_TYPE (target_func));
+ }
+
+ do
+ {
+ /* Attempt to visit TARGET_CALL_SITE. */
+
+ if (target_call_site)
+ {
+ void **slot;
+
+ slot = htab_find_slot (addr_hash, &target_call_site->pc, INSERT);
+ if (*slot == NULL)
+ {
+ /* Successfully entered TARGET_CALL_SITE. */
+
+ *slot = &target_call_site->pc;
+ VEC_safe_push (call_sitep, chain, target_call_site);
+ break;
+ }
+ }
+
+ /* Backtrack (without revisiting the originating call_site). Try the
+ callers's sibling; if there isn't any try the callers's callers's
+ sibling etc. */
+
+ target_call_site = NULL;
+ while (!VEC_empty (call_sitep, chain))
+ {
+ call_site = VEC_pop (call_sitep, chain);
+
+ gdb_assert (htab_find_slot (addr_hash, &call_site->pc,
+ NO_INSERT) != NULL);
+ htab_remove_elt (addr_hash, &call_site->pc);
+
+ target_call_site = call_site->tail_call_next;
+ if (target_call_site)
+ break;
+ }
+ }
+ while (target_call_site);
+
+ if (VEC_empty (call_sitep, chain))
+ call_site = NULL;
+ else
+ call_site = VEC_last (call_sitep, chain);
+ }
+
+ if (retval == NULL)
+ {
+ struct minimal_symbol *msym_caller, *msym_callee;
+
+ msym_caller = lookup_minimal_symbol_by_pc (caller_pc);
+ msym_callee = lookup_minimal_symbol_by_pc (callee_pc);
+ throw_error (NO_ENTRY_VALUE_ERROR,
+ _("There are no unambiguously determinable intermediate "
+ "callers or callees between caller function \"%s\" at %s "
+ "and callee function \"%s\" at %s"),
+ (msym_caller == NULL
+ ? "???" : SYMBOL_PRINT_NAME (msym_caller)),
+ paddress (gdbarch, caller_pc),
+ (msym_callee == NULL
+ ? "???" : SYMBOL_PRINT_NAME (msym_callee)),
+ paddress (gdbarch, callee_pc));
+ }
+
+ do_cleanups (back_to_workdata);
+ discard_cleanups (back_to_retval);
+ return retval;
+}
+
+/* Create and return call_site_chain for CALLER_PC and CALLEE_PC. All the
+ assumed frames between them use GDBARCH. If valid call_site_chain cannot be
+ constructed return NULL. Caller is responsible for xfree of the returned
+ result. */
+
+struct call_site_chain *
+call_site_find_chain (struct gdbarch *gdbarch, CORE_ADDR caller_pc,
+ CORE_ADDR callee_pc)
+{
+ volatile struct gdb_exception e;
+ struct call_site_chain *retval = NULL;
+
+ TRY_CATCH (e, RETURN_MASK_ERROR)
+ {
+ retval = call_site_find_chain_1 (gdbarch, caller_pc, callee_pc);
+ }
+ if (e.reason < 0)
+ {
+ if (e.error == NO_ENTRY_VALUE_ERROR)
+ {
+ if (entry_values_debug)
+ exception_print (gdb_stdout, e);
+
+ return NULL;
+ }
+ else
+ throw_exception (e);
+ }
+ return retval;
+}
+
/* Fetch call_site_parameter from caller matching the parameters. FRAME is for
callee. See DWARF_REG and FB_OFFSET description at struct
dwarf_expr_context_funcs->push_dwarf_reg_entry_value.
const gdb_byte *op_end,
struct dwarf2_per_cu_data *per_cu);
+/* Determined tail calls for constructing virtual tail call frames. */
+
+struct call_site_chain
+ {
+ /* Initially CALLERS == CALLEES == LENGTH. For partially ambiguous result
+ CALLERS + CALLEES < LENGTH. */
+ int callers, callees, length;
+
+ /* Variably sized array with LENGTH elements. Later [0..CALLERS-1] contain
+ top (GDB "prev") sites and [LENGTH-CALLEES..LENGTH-1] contain bottom
+ (GDB "next") sites. One is interested primarily in the PC field. */
+ struct call_site *call_site[1];
+ };
+
+struct call_site_stuff;
+extern struct call_site_chain *call_site_find_chain (struct gdbarch *gdbarch,
+ CORE_ADDR caller_pc,
+ CORE_ADDR callee_pc);
+
#endif /* dwarf2loc.h */
while (get_frame_type (next_frame) == INLINE_FRAME)
next_frame = next_frame->next;
- if (get_frame_type (next_frame) == NORMAL_FRAME
+ if ((get_frame_type (next_frame) == NORMAL_FRAME
+ || get_frame_type (next_frame) == TAILCALL_FRAME)
&& (get_frame_type (this_frame) == NORMAL_FRAME
+ || get_frame_type (this_frame) == TAILCALL_FRAME
|| get_frame_type (this_frame) == INLINE_FRAME))
return pc - 1;
/* A frame representing an inlined function, associated with an
upcoming (prev, outer, older) NORMAL_FRAME. */
INLINE_FRAME,
+ /* A virtual frame of a tail call - see dwarf2_tailcall_frame_unwind. */
+ TAILCALL_FRAME,
/* In a signal handler, various OSs handle this in various ways.
The main thing is that the frame may be far from normal. */
SIGTRAMP_FRAME,
PyModule_AddIntConstant (gdb_module, "NORMAL_FRAME", NORMAL_FRAME);
PyModule_AddIntConstant (gdb_module, "DUMMY_FRAME", DUMMY_FRAME);
PyModule_AddIntConstant (gdb_module, "INLINE_FRAME", INLINE_FRAME);
+ PyModule_AddIntConstant (gdb_module, "TAILCALL_FRAME", TAILCALL_FRAME);
PyModule_AddIntConstant (gdb_module, "SIGTRAMP_FRAME", SIGTRAMP_FRAME);
PyModule_AddIntConstant (gdb_module, "ARCH_FRAME", ARCH_FRAME);
PyModule_AddIntConstant (gdb_module, "SENTINEL_FRAME", SENTINEL_FRAME);
printf_filtered (_(" Outermost frame: %s\n"),
frame_stop_reason_string (reason));
}
+ else if (get_frame_type (fi) == TAILCALL_FRAME)
+ puts_filtered (" tail call frame");
else if (get_frame_type (fi) == INLINE_FRAME)
printf_filtered (" inlined into frame %d",
frame_relative_level (get_prev_frame (fi)));
2011-10-09 Jan Kratochvil <jan.kratochvil@redhat.com>
+ Recognize virtual tail call frames.
+ * gdb.arch/amd64-entry-value.cc (c, a, b, amb_z, amb_y, amb_x, amb)
+ (amb_b, amb_a): New.
+ (main): Call a and b.
+ * gdb.arch/amd64-entry-value.exp (tailcall: breakhere, tailcall: bt)
+ (tailcall: p i, tailcall: p j, set $sp0=$sp, up, p $sp0 == $sp, frame 3)
+ (p $sp0 + sizeof (void *) == $sp, ambiguous: breakhere, ambiguous: bt):
+ New tests.
+
+2011-10-09 Jan Kratochvil <jan.kratochvil@redhat.com>
+
Implement basic support for DW_TAG_GNU_call_site.
* gdb.arch/Makefile.in (EXECUTABLES): Add amd64-entry-value.
* gdb.arch/amd64-entry-value.cc: New file.
e (v, v);
}
+static void __attribute__((noinline, noclone))
+c (int i, double j)
+{
+ d (i * 10, j * 10);
+}
+
+static void __attribute__((noinline, noclone))
+a (int i, double j)
+{
+ c (i + 1, j + 1);
+}
+
+static void __attribute__((noinline, noclone))
+b (int i, double j)
+{
+ c (i + 2, j + 2);
+}
+
+static void __attribute__((noinline, noclone))
+amb_z (int i)
+{
+ d (i + 7, i + 7.5);
+}
+
+static void __attribute__((noinline, noclone))
+amb_y (int i)
+{
+ amb_z (i + 6);
+}
+
+static void __attribute__((noinline, noclone))
+amb_x (int i)
+{
+ amb_y (i + 5);
+}
+
+static void __attribute__((noinline, noclone))
+amb (int i)
+{
+ if (i < 0)
+ amb_x (i + 3);
+ else
+ amb_x (i + 4);
+}
+
+static void __attribute__((noinline, noclone))
+amb_b (int i)
+{
+ amb (i + 2);
+}
+
+static void __attribute__((noinline, noclone))
+amb_a (int i)
+{
+ amb_b (i + 1);
+}
+
int
main ()
{
d (30, 30.5);
+ if (v)
+ a (1, 1.25);
+ else
+ b (5, 5.25);
+ amb_a (100);
return 0;
}
"entry: bt"
gdb_test "p i" " = 31" "entry: p i"
gdb_test "p j" { = 31\.5} "entry: p j"
+
+
+# Test virtual tail call frames.
+
+gdb_continue_to_breakpoint "tailcall: breakhere"
+
+gdb_test "bt" "^bt\r\n#0 +d *\\(i=71, j=73\\.5\\) \[^\r\n\]*\r\n#1 +0x\[0-9a-f\]+ in c \\(i=7, j=7\\.25\\) \[^\r\n\]*\r\n#2 +0x\[0-9a-f\]+ in b \\(i=5, j=5\\.25\\) \[^\r\n\]*\r\n#3 +0x\[0-9a-f\]+ in main \[^\r\n\]*" \
+ "tailcall: bt"
+gdb_test "p i" " = 71" "tailcall: p i"
+gdb_test "p j" " = 73\\.5" "tailcall: p j"
+
+# Test $sp simulation for tail call frames.
+#gdb_test {p/x $sp} " = 0x.*"
+#gdb_test {p/x $pc} " = 0x.*"
+gdb_test_no_output {set $sp0=$sp}
+gdb_test "up" "\r\n#1 .*"
+#gdb_test {p/x $sp} " = 0x.*"
+gdb_test {p $sp0 == $sp} " = true"
+gdb_test "frame 3" "\r\n#3 .*"
+gdb_test {p $sp0 + sizeof (void *) == $sp} " = true"
+
+
+# Test partial-ambiguous virtual tail call frames chain.
+
+gdb_continue_to_breakpoint "ambiguous: breakhere"
+
+gdb_test "bt" "^bt\r\n#0 +d \\(i=<optimized out>, j=<optimized out>\\)\[^\r\n\]*\r\n#1 +0x\[0-9a-f\]+ in amb_z \\(i=<optimized out>\\)\[^\r\n\]*\r\n#2 +0x\[0-9a-f\]+ in amb_y \\(i=<optimized out>\\)\[^\r\n\]*\r\n#3 +0x\[0-9a-f\]+ in amb_x \\(i=<optimized out>\\)\[^\r\n\]*\r\n#4 +0x\[0-9a-f\]+ in amb_b \\(i=101\\)\[^\r\n\]*\r\n#5 +0x\[0-9a-f\]+ in amb_a \\(i=100\\)\[^\r\n\]*\r\n#6 +0x\[0-9a-f\]+ in main \\(\\)\[^\r\n\]*" \
+ "ambiguous: bt"
projects / platform / upstream / binutils.git / commitdiff