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2003-06-07 Andrew Cagney <cagney@redhat.com>

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* dwarf2-frame.c (dwarf2_frame_cache): Add comments on PC_REGNUM.
	Assert that PC_REGNUM is valid.
	(dwarf2_frame_prev_register): Add comments on SP_REGNUM.
This commit is contained in:
Andrew Cagney 2003-06-07 19:05:51 +00:00
parent bd1ce8ba9b
commit a42e117c79
2 changed files with 39 additions and 1 deletions
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6
gdb/ChangeLog
View File

@ -1,3 +1,9 @@
2003-06-07 Andrew Cagney <cagney@redhat.com>
* dwarf2-frame.c (dwarf2_frame_cache): Add comments on PC_REGNUM.
Assert that PC_REGNUM is valid.
(dwarf2_frame_prev_register): Add comments on SP_REGNUM.
2003-06-07 Andrew Cagney <cagney@redhat.com>
* gdbarch.sh (TARGET_READ_SP): Add predicate, delete default.

34
gdb/dwarf2-frame.c
View File

@ -544,6 +544,13 @@ dwarf2_frame_cache (struct frame_info *next_frame, void **this_cache)
/* Skip the return address column. */
if (reg == fs->retaddr_column)
/* NOTE: cagney/2003-06-07: Is this right? What if the
RETADDR_COLUM corresponds to a real register (and, worse,
that isn't the PC_REGNUM)? I'm guessing that the PC_REGNUM
further down is trying to handle this. That can't be right
though - PC_REGNUM may not be valid (it can be -ve). I
think, instead when RETADDR_COLUM isn't a real register, it
should map itself onto frame_pc_unwind. */
continue;
/* Use the GDB register number as index. */
@ -558,12 +565,22 @@ dwarf2_frame_cache (struct frame_info *next_frame, void **this_cache)
implies a copy from the ra column register. */
if (fs->retaddr_column < fs->regs.num_regs
&& fs->regs.reg[fs->retaddr_column].how != REG_UNSAVED)
cache->reg[PC_REGNUM] = fs->regs.reg[fs->retaddr_column];
{
/* See comment above about a possibly -ve PC_REGNUM. If this
assertion fails, it's a problem with this code and not the
architecture. */
gdb_assert (PC_REGNUM >= 0);
cache->reg[PC_REGNUM] = fs->regs.reg[fs->retaddr_column];
}
else
{
reg = DWARF2_REG_TO_REGNUM (fs->retaddr_column);
if (reg != PC_REGNUM)
{
/* See comment above about PC_REGNUM being -ve. If this
assertion fails, it's a problem with this code and not
the architecture. */
gdb_assert (PC_REGNUM >= 0);
cache->reg[PC_REGNUM].loc.reg = reg;
cache->reg[PC_REGNUM].how = REG_SAVED_REG;
}
@ -606,6 +623,21 @@ dwarf2_frame_prev_register (struct frame_info *next_frame, void **this_cache,
/* GCC defines the CFA as the value of the stack pointer
just before the call instruction is executed. Do other
compilers use the same definition? */
/* DWARF V3 Draft 7 p102: Typically, the CFA is defined to
be the value of the stack pointer at the call site in the
previous frame (which may be different from its value on
entry to the current frame). */
/* DWARF V3 Draft 7 p103: The first column of the rules
defines the rule which computes the CFA value; it may be
either a register and a signed offset that are added
together or a DWARF expression that is evaluated. */
/* FIXME: cagney/2003-07-07: I don't understand this. The
CFI info should have provided unwind information for the
SP register and then pointed ->cfa_reg at it, not the
reverse. Assuming that SP_REGNUM is !-ve, there is a
very real posibility that CFA is an offset from some
other register, having nothing to do with the unwound SP
value. */
*optimizedp = 0;
if (valuep)
{