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Re: RFA/dwarf: Fix the GCC 2.95.3 store.exp regression for multi-register variables
- From: Elena Zannoni <ezannoni at redhat dot com>
- To: Daniel Jacobowitz <drow at mvista dot com>
- Cc: gdb-patches at sources dot redhat dot com
- Date: Thu, 3 Apr 2003 16:56:53 -0500
- Subject: Re: RFA/dwarf: Fix the GCC 2.95.3 store.exp regression for multi-register variables
- References: <20030312204053.GA31861@nevyn.them.org>
Daniel Jacobowitz writes:
> This kills both a hack and the regression discussed on gdb at dot Instead of
> returning the value of the register and the register number, if the
> expression evaluator only returns the register number, we can use
> value_from_register. This way we share multi-register variable handling
> with the non-LOC_COMPUTED case.
>
> This patch removes a FIXME and an interface I didn't much like (the lval
> argument to dwarf_expr_read_reg) so I'm pretty happy with it. Everything
> should go back to working that worked before.
>
> Is this OK?
>
Dan, seems good. Expecially since it simplifies some code.
No other regressions, right? :-)
elena
> --
> Daniel Jacobowitz
> MontaVista Software Debian GNU/Linux Developer
>
> 2003-03-12 Daniel Jacobowitz <drow at mvista dot com>
>
> * dwarf2expr.h (struct dwarf_expr_context): Remove extra arguments
> to read_reg and update its comment. Remove regnum member.
> * dwarf2expr.c (execute_stack_op): Remove memaddr and expr_lval.
> Don't call read_reg when setting in_reg. Call read_reg to get
> the frame base if it's in a register. Return the register number
> on the stack instead of in the context. Remove extra arguments
> to read_reg.
> * dwarf2loc.c (dwarf_expr_read_reg): Remove extra arguments.
> (dwarf2_evaluate_loc_desc): Call value_from_register. Expect
> the register number on the expression stack.
> (needs_frame_read_reg): Remove extra arguments.
>
> Index: dwarf2expr.c
> ===================================================================
> RCS file: /big/fsf/rsync/src-cvs/src/gdb/dwarf2expr.c,v
> retrieving revision 1.3
> diff -u -p -r1.3 dwarf2expr.c
> --- dwarf2expr.c 5 Mar 2003 18:00:02 -0000 1.3
> +++ dwarf2expr.c 12 Mar 2003 20:31:06 -0000
> @@ -231,11 +231,10 @@ execute_stack_op (struct dwarf_expr_cont
> while (op_ptr < op_end)
> {
> enum dwarf_location_atom op = *op_ptr++;
> - CORE_ADDR result, memaddr;
> + CORE_ADDR result;
> ULONGEST uoffset, reg;
> LONGEST offset;
> int bytes_read;
> - enum lval_type expr_lval;
>
> ctx->in_reg = 0;
>
> @@ -361,19 +360,8 @@ execute_stack_op (struct dwarf_expr_cont
> error ("DWARF-2 expression error: DW_OP_reg operations must be "
> "used alone.");
>
> - /* FIXME drow/2003-02-21: This call to read_reg could be pushed
> - into the evaluator's caller by changing the semantics for in_reg.
> - Then we wouldn't need to return an lval_type and a memaddr. */
> - result = (ctx->read_reg) (ctx->baton, op - DW_OP_reg0, &expr_lval,
> - &memaddr);
> -
> - if (expr_lval == lval_register)
> - {
> - ctx->regnum = op - DW_OP_reg0;
> - ctx->in_reg = 1;
> - }
> - else
> - result = memaddr;
> + result = op - DW_OP_reg0;
> + ctx->in_reg = 1;
>
> break;
>
> @@ -383,16 +371,8 @@ execute_stack_op (struct dwarf_expr_cont
> error ("DWARF-2 expression error: DW_OP_reg operations must be "
> "used alone.");
>
> - result = (ctx->read_reg) (ctx->baton, reg, &expr_lval, &memaddr);
> -
> - if (expr_lval == lval_register)
> - {
> - ctx->regnum = reg;
> - ctx->in_reg = 1;
> - }
> - else
> - result = memaddr;
> -
> + result = reg;
> + ctx->in_reg = 1;
> break;
>
> case DW_OP_breg0:
> @@ -429,8 +409,7 @@ execute_stack_op (struct dwarf_expr_cont
> case DW_OP_breg31:
> {
> op_ptr = read_sleb128 (op_ptr, op_end, &offset);
> - result = (ctx->read_reg) (ctx->baton, op - DW_OP_breg0,
> - &expr_lval, &memaddr);
> + result = (ctx->read_reg) (ctx->baton, op - DW_OP_breg0);
> result += offset;
> }
> break;
> @@ -438,7 +417,7 @@ execute_stack_op (struct dwarf_expr_cont
> {
> op_ptr = read_uleb128 (op_ptr, op_end, ®);
> op_ptr = read_sleb128 (op_ptr, op_end, &offset);
> - result = (ctx->read_reg) (ctx->baton, reg, &expr_lval, &memaddr);
> + result = (ctx->read_reg) (ctx->baton, reg);
> result += offset;
> }
> break;
> @@ -457,7 +436,9 @@ execute_stack_op (struct dwarf_expr_cont
> (ctx->get_frame_base) (ctx->baton, &datastart, &datalen);
> dwarf_expr_eval (ctx, datastart, datalen);
> result = dwarf_expr_fetch (ctx, 0);
> - if (! ctx->in_reg)
> + if (ctx->in_reg)
> + result = (ctx->read_reg) (ctx->baton, result);
> + else
> {
> char *buf = alloca (TARGET_ADDR_BIT / TARGET_CHAR_BIT);
> int bytes_read;
> Index: dwarf2expr.h
> ===================================================================
> RCS file: /big/fsf/rsync/src-cvs/src/gdb/dwarf2expr.h,v
> retrieving revision 1.2
> diff -u -p -r1.2 dwarf2expr.h
> --- dwarf2expr.h 28 Feb 2003 20:03:18 -0000 1.2
> +++ dwarf2expr.h 12 Mar 2003 20:31:38 -0000
> @@ -36,13 +36,8 @@ struct dwarf_expr_context
> to all of the callback functions. */
> void *baton;
>
> - /* Return the value of register number REGNUM. LVALP will be set
> - to the kind of lval this register is (generally lval_register
> - for the current frame's registers or lval_memory for a register
> - saved to the stack). For lval_memory ADDRP will be set to the
> - saved location of the register. */
> - CORE_ADDR (*read_reg) (void *baton, int regnum, enum lval_type *lvalp,
> - CORE_ADDR *addrp);
> + /* Return the value of register number REGNUM. */
> + CORE_ADDR (*read_reg) (void *baton, int regnum);
>
> /* Read LENGTH bytes at ADDR into BUF. */
> void (*read_mem) (void *baton, char *buf, CORE_ADDR addr,
> @@ -77,12 +72,8 @@ struct dwarf_expr_context
> int recursion_depth, max_recursion_depth;
>
> /* Non-zero if the result is in a register. The register number
> - will be in REGNUM, and the result will be the contents of the
> - register. */
> + will be on the expression stack. */
> int in_reg;
> -
> - /* If the result is in a register, the register number. */
> - int regnum;
> };
>
> struct dwarf_expr_context *new_dwarf_expr_context ();
> Index: dwarf2loc.c
> ===================================================================
> RCS file: /big/fsf/rsync/src-cvs/src/gdb/dwarf2loc.c,v
> retrieving revision 1.3
> diff -u -p -r1.3 dwarf2loc.c
> --- dwarf2loc.c 5 Mar 2003 18:00:02 -0000 1.3
> +++ dwarf2loc.c 12 Mar 2003 20:33:59 -0000
> @@ -54,11 +54,11 @@ struct dwarf_expr_baton
> type will be returned in LVALP, and for lval_memory the register
> save address will be returned in ADDRP. */
> static CORE_ADDR
> -dwarf_expr_read_reg (void *baton, int dwarf_regnum, enum lval_type *lvalp,
> - CORE_ADDR *addrp)
> +dwarf_expr_read_reg (void *baton, int dwarf_regnum)
> {
> struct dwarf_expr_baton *debaton = (struct dwarf_expr_baton *) baton;
> - CORE_ADDR result;
> + CORE_ADDR result, save_addr;
> + enum lval_type lval_type;
> char *buf;
> int optimized, regnum, realnum, regsize;
>
> @@ -66,8 +66,8 @@ dwarf_expr_read_reg (void *baton, int dw
> regsize = register_size (current_gdbarch, regnum);
> buf = (char *) alloca (regsize);
>
> - frame_register (debaton->frame, regnum, &optimized, lvalp, addrp, &realnum,
> - buf);
> + frame_register (debaton->frame, regnum, &optimized, &lval_type, &save_addr,
> + &realnum, buf);
> result = extract_address (buf, regsize);
>
> return result;
> @@ -138,21 +138,15 @@ dwarf2_evaluate_loc_desc (struct symbol
> ctx->get_tls_address = dwarf_expr_tls_address;
>
> dwarf_expr_eval (ctx, data, size);
> -
> - retval = allocate_value (SYMBOL_TYPE (var));
> - VALUE_BFD_SECTION (retval) = SYMBOL_BFD_SECTION (var);
> + result = dwarf_expr_fetch (ctx, 0);
>
> if (ctx->in_reg)
> - {
> - store_unsigned_integer (VALUE_CONTENTS_RAW (retval),
> - TYPE_LENGTH (SYMBOL_TYPE (var)),
> - dwarf_expr_fetch (ctx, 0));
> - VALUE_LVAL (retval) = lval_register;
> - VALUE_REGNO (retval) = ctx->regnum;
> - }
> + retval = value_from_register (SYMBOL_TYPE (var), result, frame);
> else
> {
> - result = dwarf_expr_fetch (ctx, 0);
> + retval = allocate_value (SYMBOL_TYPE (var));
> + VALUE_BFD_SECTION (retval) = SYMBOL_BFD_SECTION (var);
> +
> VALUE_LVAL (retval) = lval_memory;
> VALUE_LAZY (retval) = 1;
> VALUE_ADDRESS (retval) = result;
> @@ -176,8 +170,7 @@ struct needs_frame_baton
>
> /* Reads from registers do require a frame. */
> static CORE_ADDR
> -needs_frame_read_reg (void *baton, int regnum, enum lval_type *lvalp,
> - CORE_ADDR *addrp)
> +needs_frame_read_reg (void *baton, int regnum)
> {
> struct needs_frame_baton *nf_baton = baton;
> nf_baton->needs_frame = 1;