2003-09-08 Andrew Cagney <cagney@redhat.com>
* dwarf2-frame.c (enum dwarf2_reg_rule): New, replace anonymous enum. Add REG_UNSPECIFIED, rename REG_UNSAVED to REG_UNDEFINED and REG_UNMODIFIED to REG_SAME_VALUE. (execute_cfa_program): Update. (dwarf2_frame_cache): Update. Initialize table to REG_UNSPECIFIED, complain if CFI fails to specify a register's location. (dwarf2_frame_prev_register): Update. Handle REG_UNSPECIFIED.
This commit is contained in:
Andrew Cagney
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39efb398a9
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3e2c403395
@ -1,3 +1,14 @@
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2003-09-08 Andrew Cagney <cagney@redhat.com>
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* dwarf2-frame.c (enum dwarf2_reg_rule): New, replace anonymous
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enum. Add REG_UNSPECIFIED, rename REG_UNSAVED to REG_UNDEFINED
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and REG_UNMODIFIED to REG_SAME_VALUE.
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(execute_cfa_program): Update.
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(dwarf2_frame_cache): Update. Initialize table to
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REG_UNSPECIFIED, complain if CFI fails to specify a register's
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location.
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(dwarf2_frame_prev_register): Update. Handle REG_UNSPECIFIED.
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2003-09-08 Andrew Cagney <cagney@redhat.com>
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* gnu-nat.c: Remove "inline" function attribute.
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@ -97,6 +97,28 @@ static struct dwarf2_fde *dwarf2_frame_find_fde (CORE_ADDR *pc);
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/* Structure describing a frame state. */
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enum dwarf2_reg_rule
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{
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/* Make certain that 0 maps onto the correct enum value - the
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corresponding structure is being initialized using memset zero.
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This indicates that CFI didn't provide any information at all
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about a register - leaving how to obtain it's value totally
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unspecified. */
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REG_UNSPECIFIED = 0,
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/* The term "undefined" comes from the DWARF2 CFI spec which this
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code is moddeling - it indicates that the register's value is
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"undefined". */
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/* NOTE: cagney/2003-09-08: GCC uses the less formal term "unsaved"
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- it's definition is a combination of REG_UNDEFINED and
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REG_UNSPECIFIED - the failure to differentiate the two helps
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explain a few problems with the CFI GCC outputs. */
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REG_UNDEFINED,
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REG_SAVED_OFFSET,
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REG_SAVED_REG,
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REG_SAVED_EXP,
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REG_SAME_VALUE
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};
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struct dwarf2_frame_state
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{
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/* Each register save state can be described in terms of a CFA slot,
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@ -111,13 +133,7 @@ struct dwarf2_frame_state
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unsigned char *exp;
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} loc;
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ULONGEST exp_len;
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enum {
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REG_UNSAVED,
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REG_SAVED_OFFSET,
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REG_SAVED_REG,
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REG_SAVED_EXP,
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REG_UNMODIFIED
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} how;
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enum dwarf2_reg_rule how;
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} *reg;
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int num_regs;
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@ -354,13 +370,13 @@ execute_cfa_program (unsigned char *insn_ptr, unsigned char *insn_end,
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case DW_CFA_undefined:
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insn_ptr = read_uleb128 (insn_ptr, insn_end, ®);
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dwarf2_frame_state_alloc_regs (&fs->regs, reg + 1);
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fs->regs.reg[reg].how = REG_UNSAVED;
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fs->regs.reg[reg].how = REG_UNDEFINED;
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break;
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case DW_CFA_same_value:
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insn_ptr = read_uleb128 (insn_ptr, insn_end, ®);
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dwarf2_frame_state_alloc_regs (&fs->regs, reg + 1);
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fs->regs.reg[reg].how = REG_UNMODIFIED;
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fs->regs.reg[reg].how = REG_SAME_VALUE;
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break;
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case DW_CFA_register:
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@ -460,11 +476,10 @@ static struct dwarf2_frame_cache *
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dwarf2_frame_cache (struct frame_info *next_frame, void **this_cache)
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{
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struct cleanup *old_chain;
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int num_regs = NUM_REGS + NUM_PSEUDO_REGS;
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const int num_regs = NUM_REGS + NUM_PSEUDO_REGS;
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struct dwarf2_frame_cache *cache;
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struct dwarf2_frame_state *fs;
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struct dwarf2_fde *fde;
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int reg;
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if (*this_cache)
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return *this_cache;
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@ -535,34 +550,65 @@ dwarf2_frame_cache (struct frame_info *next_frame, void **this_cache)
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internal_error (__FILE__, __LINE__, "Unknown CFA rule.");
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}
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/* Save the register info in the cache. */
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for (reg = 0; reg < fs->regs.num_regs; reg++)
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{
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int regnum;
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/* Initialize things so that all registers are marked as
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unspecified. */
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{
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int regnum;
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for (regnum = 0; regnum < num_regs; regnum++)
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cache->reg[regnum].how = REG_UNSPECIFIED;
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}
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/* Skip the return address column. */
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if (reg == fs->retaddr_column)
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/* NOTE: cagney/2003-06-07: Is this right? What if the
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RETADDR_COLUM corresponds to a real register (and, worse,
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that isn't the PC_REGNUM)? I'm guessing that the PC_REGNUM
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further down is trying to handle this. That can't be right
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though - PC_REGNUM may not be valid (it can be -ve). I
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think, instead when RETADDR_COLUM isn't a real register, it
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should map itself onto frame_pc_unwind. */
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continue;
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/* Go through the DWARF2 CFI generated table and save its register
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location information in the cache. */
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{
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int column; /* CFI speak for "register number". */
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for (column = 0; column < fs->regs.num_regs; column++)
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{
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int regnum;
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/* Skip the return address column. */
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if (column == fs->retaddr_column)
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/* NOTE: cagney/2003-06-07: Is this right? What if
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RETADDR_COLUMN corresponds to a real register (and,
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worse, that isn't the PC_REGNUM)? I'm guessing that the
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PC_REGNUM further down is trying to handle this. That
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can't be right though - PC_REGNUM may not be valid (it
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can be -ve). I think, instead when RETADDR_COLUM isn't a
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real register, it should map itself onto frame_pc_unwind. */
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continue;
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/* Use the GDB register number as index. */
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regnum = DWARF2_REG_TO_REGNUM (reg);
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/* Use the GDB register number as the destination index. */
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regnum = DWARF2_REG_TO_REGNUM (column);
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if (regnum >= 0 && regnum < num_regs)
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cache->reg[regnum] = fs->regs.reg[reg];
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}
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/* If there's no corresponding GDB register, ignore it. */
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if (regnum < 0 || regnum >= num_regs)
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continue;
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/* NOTE: cagney/2003-09-05: CFI should specify the disposition
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of all debug info registers. If it doesn't complain (but
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not too loudly). It turns out that GCC, assumes that an
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unspecified register implies "same value" when CFI (draft
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7) specifies nothing at all. Such a register could equally
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be interpreted as "undefined". Also note that this check
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isn't sufficient - it only checks that all registers in the
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range [0 .. max column] are specified - and won't detect
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problems when a debug info register falls outside of the
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table. Need a way of iterating through all the valid
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DWARF2 register numbers. */
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if (fs->regs.reg[column].how == REG_UNSPECIFIED)
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complaint (&symfile_complaints,
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"Incomplete CFI data; unspecified registers at 0x%s",
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paddr (fs->pc));
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cache->reg[regnum] = fs->regs.reg[column];
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}
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}
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/* Store the location of the return addess. If the return address
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column (adjusted) is not the same as gdb's PC_REGNUM, then this
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implies a copy from the ra column register. */
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if (fs->retaddr_column < fs->regs.num_regs
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&& fs->regs.reg[fs->retaddr_column].how != REG_UNSAVED)
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&& fs->regs.reg[fs->retaddr_column].how != REG_UNDEFINED)
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{
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/* See comment above about a possibly -ve PC_REGNUM. If this
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assertion fails, it's a problem with this code and not the
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@ -572,7 +618,7 @@ dwarf2_frame_cache (struct frame_info *next_frame, void **this_cache)
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}
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else
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{
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reg = DWARF2_REG_TO_REGNUM (fs->retaddr_column);
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int reg = DWARF2_REG_TO_REGNUM (fs->retaddr_column);
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if (reg != PC_REGNUM)
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{
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/* See comment above about PC_REGNUM being -ve. If this
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@ -611,7 +657,9 @@ dwarf2_frame_prev_register (struct frame_info *next_frame, void **this_cache,
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switch (cache->reg[regnum].how)
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{
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case REG_UNSAVED:
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case REG_UNDEFINED:
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/* If CFI explicitly specified that the value isn't defined,
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mark it as optimized away - the value isn't available. */
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*optimizedp = 1;
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*lvalp = not_lval;
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*addrp = 0;
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@ -636,6 +684,13 @@ dwarf2_frame_prev_register (struct frame_info *next_frame, void **this_cache,
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very real posibility that CFA is an offset from some
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other register, having nothing to do with the unwound SP
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value. */
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/* FIXME: cagney/2003-09-05: I think I understand. GDB was
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lumping the two states "unspecified" and "undefined"
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together. Here SP_REGNUM was "unspecified", GCC assuming
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that in such a case CFA would be used. This branch of
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the if statement should be deleted - the problem of
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SP_REGNUM is now handed by the case REG_UNSPECIFIED
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below. */
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*optimizedp = 0;
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if (valuep)
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{
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@ -687,7 +742,59 @@ dwarf2_frame_prev_register (struct frame_info *next_frame, void **this_cache,
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}
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break;
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case REG_UNMODIFIED:
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case REG_UNSPECIFIED:
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/* GCC, in its infinite wisdom decided to not provide unwind
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information for registers that are "same value". Since
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DWARF2 (3 draft 7) doesn't define such behavior, said
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registers are actually undefined (which is different to CFI
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"undefined"). Code above issues a complaint about this.
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Here just fudge the books, assume GCC, and that the value is
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more inner on the stack. */
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if (SP_REGNUM >= 0 && regnum == SP_REGNUM)
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{
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/* Can things get worse? Yep! One of the registers GCC
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forgot to provide unwind information for was the stack
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pointer. Outch! GCC appears to assumes that the CFA
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address can be used - after all it points to the inner
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most address of the previous frame before the function
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call and that's always the same as the stack pointer on
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return, right? Wrong. See GCC's i386 STDCALL option for
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an ABI that has a different entry and return stack
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pointer. */
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/* DWARF V3 Draft 7 p102: Typically, the CFA is defined to
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be the value of the stack pointer at the call site in the
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previous frame (which may be different from its value on
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entry to the current frame). */
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/* DWARF V3 Draft 7 p103: The first column of the rules
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defines the rule which computes the CFA value; it may be
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either a register and a signed offset that are added
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together or a DWARF expression that is evaluated. */
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/* NOTE: cagney/2003-09-05: Should issue a complain.
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Unfortunatly it turns out that DWARF2 CFI has a problem.
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Since CFI specifies the location at which a register was
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saved (not its value) it isn't possible to specify
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something like "unwound(REG) == REG + constant" using CFI
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as will almost always occure with the stack pointer. I
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guess CFI should be point SP at CFA. Ref: danielj,
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"Describing unsaved stack pointers", posted to dwarf2
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list 2003-08-15. */
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*optimizedp = 0;
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*lvalp = not_lval;
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*addrp = 0;
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*realnump = -1;
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if (valuep)
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/* Store the value. */
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store_typed_address (valuep, builtin_type_void_data_ptr,
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cache->cfa);
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}
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else
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/* Assume that the register can be found in the next inner
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most frame. */
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frame_register_unwind (next_frame, regnum,
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optimizedp, lvalp, addrp, realnump, valuep);
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break;
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case REG_SAME_VALUE:
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frame_register_unwind (next_frame, regnum,
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optimizedp, lvalp, addrp, realnump, valuep);
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break;
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