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Re: [rfa:ppc] Cleanup SVR4 push dummy call
- From: Andrew Cagney <ac131313 at redhat dot com>
- To: Andrew Cagney <ac131313 at redhat dot com>
- Cc: gdb-patches at sources dot redhat dot com
- Date: Fri, 12 Sep 2003 11:01:07 -0400
- Subject: Re: [rfa:ppc] Cleanup SVR4 push dummy call
- References: <3F61DC59.5040706@redhat.com>
Hello,
This patch rewrites ppc_svr4_push_dummy_call so that it implements the two-pass push-arguments algorithm using a "for" loop.
The simplification identified and fixed the bugs:
- Altivec registers on the stack weren't being 16 byte aligned
- Floats weren't being converted to doubles before being stored in register/memory ("gdb.base/callfuncs.exp: p t_float_values2" now passes).
Ok?
Andrew
PS: I intend moving align_{up,down} to utils.c but that is separate.
Oops, try this. It's got the up-to-date changelog and uses a more
readable context diff.
Andrew
2003-09-12 Andrew Cagney <cagney@redhat.com>
* ppc-sysv-tdep.c (align_up, align_down): Replace "round2" macro.
(ppc_sysv_abi_push_dummy_call): Rewrite, use a two pass loop.
Index: ppc-sysv-tdep.c
===================================================================
RCS file: /cvs/src/src/gdb/ppc-sysv-tdep.c,v
retrieving revision 1.9
diff -c -r1.9 ppc-sysv-tdep.c
*** ppc-sysv-tdep.c 11 Sep 2003 19:27:25 -0000 1.9
--- ppc-sysv-tdep.c 12 Sep 2003 14:57:41 -0000
***************
*** 29,39 ****
#include "ppc-tdep.h"
! /* round2 rounds x up to the nearest multiple of s assuming that s is a
! power of 2 */
! #undef round2
! #define round2(x,s) ((((long) (x) - 1) & ~(long)((s)-1)) + (s))
/* Pass the arguments in either registers, or in the stack. Using the
ppc sysv ABI, the first eight words of the argument list (that might
--- 29,48 ----
#include "ppc-tdep.h"
! /* Ensure that X is aligned to an S byte boundary (assuming that S is
! a power of 2) rounding up/down where necessary. */
! static ULONGEST
! align_up (ULONGEST x, int s)
! {
! return (x + s - 1) & -s;
! }
!
! static ULONGEST
! align_down (ULONGEST x, int s)
! {
! return (x & -s);
! }
/* Pass the arguments in either registers, or in the stack. Using the
ppc sysv ABI, the first eight words of the argument list (that might
***************
*** 52,349 ****
int nargs, struct value **args, CORE_ADDR sp,
int struct_return, CORE_ADDR struct_addr)
{
- int argno;
- /* Next available general register for non-float, non-vector arguments. */
- int greg;
- /* Next available floating point register for float arguments. */
- int freg;
- /* Next available vector register for vector arguments. */
- int vreg;
- int argstkspace;
- int structstkspace;
- int argoffset;
- int structoffset;
- struct type *type;
- int len;
- char old_sp_buf[4];
- CORE_ADDR saved_sp;
struct gdbarch_tdep *tdep = gdbarch_tdep (current_gdbarch);
! greg = 3;
! freg = 1;
! vreg = 2;
! argstkspace = 0;
! structstkspace = 0;
!
! /* If the function is returning a `struct', then the first word
! (which will be passed in r3) is used for struct return address.
! In that case we should advance one word and start from r4
! register to copy parameters. */
! if (struct_return)
! {
! regcache_raw_write_signed (regcache, tdep->ppc_gp0_regnum + greg,
! struct_addr);
! greg++;
! }
! /* Figure out how much new stack space is required for arguments
! which don't fit in registers. Unlike the PowerOpen ABI, the
! SysV ABI doesn't reserve any extra space for parameters which
! are put in registers. */
! for (argno = 0; argno < nargs; argno++)
{
! struct value *arg = args[argno];
! type = check_typedef (VALUE_TYPE (arg));
! len = TYPE_LENGTH (type);
!
! if (TYPE_CODE (type) == TYPE_CODE_FLT
! && ppc_floating_point_unit_p (current_gdbarch))
{
! if (freg <= 8)
! freg++;
! else
! {
! /* SysV ABI converts floats to doubles when placed in
! memory and requires 8 byte alignment */
! if (argstkspace & 0x4)
! argstkspace += 4;
! argstkspace += 8;
! }
}
! else if (len == 8
! && (TYPE_CODE (type) == TYPE_CODE_INT /* long long */
! || (!ppc_floating_point_unit_p (current_gdbarch)
! && TYPE_CODE (type) == TYPE_CODE_FLT))) /* double */
{
! if (greg > 9)
! {
! greg = 11;
! if (argstkspace & 0x4)
! argstkspace += 4;
! argstkspace += 8;
! }
! else
! {
! if ((greg & 1) == 0)
! greg++;
! greg += 2;
! }
! }
! else if (!TYPE_VECTOR (type))
! {
! if (len > 4
! || TYPE_CODE (type) == TYPE_CODE_STRUCT
! || TYPE_CODE (type) == TYPE_CODE_UNION)
! {
! /* Rounding to the nearest multiple of 8 may not be necessary,
! but it is safe. Particularly since we don't know the
! field types of the structure */
! structstkspace += round2 (len, 8);
! }
! if (greg <= 10)
! greg++;
! else
! argstkspace += 4;
! }
! else
! {
! if (len == 16
! && TYPE_CODE (type) == TYPE_CODE_ARRAY
! && TYPE_VECTOR (type))
! {
! if (vreg <= 13)
! vreg++;
else
{
! /* Vector arguments must be aligned to 16 bytes on
! the stack. */
! argstkspace += round2 (argstkspace, 16);
! argstkspace += 16;
}
}
! else if (len == 8
! && TYPE_CODE (type) == TYPE_CODE_ARRAY
! && TYPE_VECTOR (type))
! {
! if (greg <= 10)
! greg++;
! else
! {
! /* Vector arguments must be aligned to 8 bytes on
! the stack. */
! argstkspace += round2 (argstkspace, 8);
! argstkspace += 8;
! }
! }
! }
! }
!
! /* Get current SP location */
! saved_sp = read_sp ();
!
! sp -= argstkspace + structstkspace;
!
! /* Allocate space for backchain and callee's saved lr */
! sp -= 8;
!
! /* Make sure that we maintain 16 byte alignment */
! sp &= ~0x0f;
!
! /* Update %sp before proceeding any further. */
! regcache_raw_write_signed (regcache, SP_REGNUM, sp);
!
! /* write the backchain */
! store_unsigned_integer (old_sp_buf, 4, saved_sp);
! write_memory (sp, old_sp_buf, 4);
!
! argoffset = 8;
! structoffset = argoffset + argstkspace;
! freg = 1;
! greg = 3;
! vreg = 2;
!
! /* Fill in r3 with the return structure, if any */
! if (struct_return)
! {
! write_register (tdep->ppc_gp0_regnum + greg, struct_addr);
! greg++;
! }
!
! /* Now fill in the registers and stack... */
! for (argno = 0; argno < nargs; argno++)
! {
! struct value *arg = args[argno];
! char *val = VALUE_CONTENTS (arg);
! type = check_typedef (VALUE_TYPE (arg));
! len = TYPE_LENGTH (type);
!
! if (TYPE_CODE (type) == TYPE_CODE_FLT
! && ppc_floating_point_unit_p (current_gdbarch))
! {
! if (freg <= 8)
! {
! ULONGEST regval;
! if (len > 8)
! printf_unfiltered (
! "Fatal Error: a floating point parameter #%d with a size > 8 is found!\n", argno);
! regval = extract_unsigned_integer (val, len);
! write_register (FP0_REGNUM + freg, regval);
! freg++;
! }
! else
! {
! /* SysV ABI converts floats to doubles when placed in
! memory and requires 8 byte alignment */
! /* FIXME: Convert floats to doubles */
! if (argoffset & 0x4)
! argoffset += 4;
! write_memory (sp + argoffset, val, len);
! argoffset += 8;
! }
! }
! else if (len == 8
! && (TYPE_CODE (type) == TYPE_CODE_INT /* long long */
! || (!ppc_floating_point_unit_p (current_gdbarch)
! && TYPE_CODE (type) == TYPE_CODE_FLT))) /* double */
! {
! if (greg > 9)
! {
! greg = 11;
! if (argoffset & 0x4)
! argoffset += 4;
! write_memory (sp + argoffset, val, len);
! argoffset += 8;
! }
! else
! {
! ULONGEST regval;
! if ((greg & 1) == 0)
! greg++;
! regval = extract_unsigned_integer (val, 4);
! write_register (tdep->ppc_gp0_regnum + greg, regval);
! regval = extract_unsigned_integer (val + 4, 4);
! write_register (tdep->ppc_gp0_regnum + greg + 1, regval);
! greg += 2;
! }
! }
! else if (!TYPE_VECTOR (type))
! {
! char val_buf[4];
! if (len > 4
! || TYPE_CODE (type) == TYPE_CODE_STRUCT
! || TYPE_CODE (type) == TYPE_CODE_UNION)
! {
! write_memory (sp + structoffset, val, len);
! store_unsigned_integer (val_buf, 4, sp + structoffset);
! structoffset += round2 (len, 8);
! }
! else
! {
! memset (val_buf, 0, 4);
! memcpy (val_buf, val, len);
! }
! if (greg <= 10)
! {
! ULONGEST regval = extract_unsigned_integer (val_buf, 4);
! write_register (tdep->ppc_gp0_regnum + greg, regval);
! greg++;
! }
! else
! {
! write_memory (sp + argoffset, val_buf, 4);
! argoffset += 4;
}
! }
! else
! {
! if (len == 16
! && TYPE_CODE (type) == TYPE_CODE_ARRAY
! && TYPE_VECTOR (type))
{
! char *v_val_buf = alloca (16);
! memset (v_val_buf, 0, 16);
! memcpy (v_val_buf, val, len);
if (vreg <= 13)
{
! regcache_cooked_write (current_regcache,
! tdep->ppc_vr0_regnum + vreg,
! v_val_buf);
vreg++;
}
else
{
! write_memory (sp + argoffset, v_val_buf, 16);
argoffset += 16;
}
}
else if (len == 8
&& TYPE_CODE (type) == TYPE_CODE_ARRAY
! && TYPE_VECTOR (type))
{
! char *v_val_buf = alloca (8);
! memset (v_val_buf, 0, 8);
! memcpy (v_val_buf, val, len);
if (greg <= 10)
{
! regcache_cooked_write (current_regcache,
! tdep->ppc_ev0_regnum + greg,
! v_val_buf);
greg++;
}
else
{
! write_memory (sp + argoffset, v_val_buf, 8);
argoffset += 8;
}
}
! }
}
/* Point the inferior function call's return address at the dummy's
breakpoint. */
! regcache_raw_write_signed (regcache, tdep->ppc_lr_regnum, bp_addr);
- target_store_registers (-1);
return sp;
}
--- 61,330 ----
int nargs, struct value **args, CORE_ADDR sp,
int struct_return, CORE_ADDR struct_addr)
{
struct gdbarch_tdep *tdep = gdbarch_tdep (current_gdbarch);
+ const CORE_ADDR saved_sp = read_sp ();
+ int argspace = 0; /* 0 is an initial wrong guess. */
+ int write_pass;
+
+ /* Go through the argument list twice.
+
+ Pass 1: Figure out how much new stack space is required for
+ arguments and pushed values. Unlike the PowerOpen ABI, the SysV
+ ABI doesn't reserve any extra space for parameters which are put
+ in registers, but does always push structures and then pass their
+ address.
! Pass 2: Replay the same computation but this time also write the
! values out to the target. */
! for (write_pass = 0; write_pass < 2; write_pass++)
{
! int argno;
! /* Next available floating point register for float and double
! arguments. */
! int freg = 1;
! /* Next available general register for non-float, non-vector
! arguments. */
! int greg = 3;
! /* Next available vector register for vector arguments. */
! int vreg = 2;
! /* Arguments start above the "LR save word" and "Back chain". */
! int argoffset = 2 * tdep->wordsize;
! /* Structures start after the arguments. */
! int structoffset = argoffset + argspace;
!
! /* If the function is returning a `struct', then the first word
! (which will be passed in r3) is used for struct return
! address. In that case we should advance one word and start
! from r4 register to copy parameters. */
! if (struct_return)
{
! if (write_pass)
! regcache_cooked_write_signed (regcache,
! tdep->ppc_gp0_regnum + greg,
! struct_addr);
! greg++;
}
!
! for (argno = 0; argno < nargs; argno++)
{
! struct value *arg = args[argno];
! struct type *type = check_typedef (VALUE_TYPE (arg));
! int len = TYPE_LENGTH (type);
! char *val = VALUE_CONTENTS (arg);
!
! if (TYPE_CODE (type) == TYPE_CODE_FLT
! && ppc_floating_point_unit_p (current_gdbarch)
! && len <= 8)
! {
! /* Floating point value converted to "double" then
! passed in an FP register, when the registers run out,
! 8 byte aligned stack is used. */
! if (freg <= 8)
! {
! if (write_pass)
! {
! /* Always store the floating point value using
! the register's floating-point format. */
! char regval[MAX_REGISTER_SIZE];
! struct type *regtype
! = register_type (gdbarch, FP0_REGNUM + freg);
! convert_typed_floating (val, type, regval, regtype);
! regcache_cooked_write (regcache, FP0_REGNUM + freg,
! regval);
! }
! freg++;
! }
else
{
! /* SysV ABI converts floats to doubles before
! writing them to an 8 byte aligned stack location. */
! argoffset = align_up (argoffset, 8);
! if (write_pass)
! {
! char memval[8];
! struct type *memtype;
! switch (TARGET_BYTE_ORDER)
! {
! case BFD_ENDIAN_BIG:
! memtype = builtin_type_ieee_double_big;
! break;
! case BFD_ENDIAN_LITTLE:
! memtype = builtin_type_ieee_double_little;
! break;
! default:
! internal_error (__FILE__, __LINE__, "bad switch");
! }
! convert_typed_floating (val, type, memval, memtype);
! write_memory (sp + argoffset, val, len);
! }
! argoffset += 8;
}
}
! else if (len == 8
! && (TYPE_CODE (type) == TYPE_CODE_INT /* long long */
! || (!ppc_floating_point_unit_p (current_gdbarch)
! && TYPE_CODE (type) == TYPE_CODE_FLT))) /* double */
! {
! /* "long long" or "double" passed in an odd/even
! register pair with the low addressed word in the odd
! register and the high addressed word in the even
! register, or when the registers run out an 8 byte
! aligned stack location. */
! if (greg > 9)
! {
! /* Just in case GREG was 10. */
! greg = 11;
! argoffset = align_up (argoffset, 8);
! write_memory (sp + argoffset, val, len);
! argoffset += 8;
! }
! else if (tdep->wordsize == 8)
! {
! if (write_pass)
! regcache_cooked_write (regcache,
! tdep->ppc_gp0_regnum + greg,
! val);
! greg += 1;
! }
! else
! {
! /* Must start on an odd register - r3/r4 etc. */
! if ((greg & 1) == 0)
! greg++;
! if (write_pass)
! {
! regcache_cooked_write (regcache,
! tdep->ppc_gp0_regnum + greg + 0,
! val + 0);
! regcache_cooked_write (regcache,
! tdep->ppc_gp0_regnum + greg + 1,
! val + 4);
! }
! greg += 2;
! }
}
! else if (len == 16
! && TYPE_CODE (type) == TYPE_CODE_ARRAY
! && TYPE_VECTOR (type)
! && tdep->ppc_vr0_regnum >= 0)
{
! /* Vector parameter passed in an Altivec register, or
! when that runs out, 16 byte aligned stack location. */
if (vreg <= 13)
{
! if (write_pass)
! regcache_cooked_write (current_regcache,
! tdep->ppc_vr0_regnum + vreg,
! val);
vreg++;
}
else
{
! argoffset = align_up (argoffset, 16);
! if (write_pass)
! write_memory (sp + argoffset, val, 16);
argoffset += 16;
}
}
else if (len == 8
&& TYPE_CODE (type) == TYPE_CODE_ARRAY
! && TYPE_VECTOR (type)
! && tdep->ppc_ev0_regnum >= 0)
{
! /* Vector parameter passed in an e500 register, or when
! that runs out, 8 byte aligned stack location. Note
! that since e500 vector and general purpose registers
! both map onto the same underlying register set, a
! "greg" and not a "vreg" is consumed here. A cooked
! write stores the value in the correct locations
! within the raw register cache. */
if (greg <= 10)
{
! if (write_pass)
! regcache_cooked_write (current_regcache,
! tdep->ppc_ev0_regnum + greg,
! val);
greg++;
}
else
{
! argoffset = align_up (argoffset, 8);
! if (write_pass)
! write_memory (sp + argoffset, val, 8);
argoffset += 8;
}
}
! else
! {
! /* Reduce the parameter down to something that fits in a
! "word". */
! char word[MAX_REGISTER_SIZE];
! memset (word, 0, MAX_REGISTER_SIZE);
! if (len > tdep->wordsize
! || TYPE_CODE (type) == TYPE_CODE_STRUCT
! || TYPE_CODE (type) == TYPE_CODE_UNION)
! {
! /* Structs and large values are put on an 8 byte
! aligned stack ... */
! structoffset = align_up (structoffset, 8);
! if (write_pass)
! write_memory (sp + structoffset, val, len);
! /* ... and then a "word" pointing to that address is
! passed as the parameter. */
! store_unsigned_integer (word, tdep->wordsize,
! sp + structoffset);
! structoffset += len;
! }
! else if (TYPE_CODE (type) == TYPE_CODE_INT)
! /* Sign or zero extend the "int" into a "word". */
! store_unsigned_integer (word, tdep->wordsize,
! unpack_long (type, val));
! else
! /* Always goes in the low address. */
! memcpy (word, val, len);
! /* Store that "word" in a register, or on the stack.
! The words have "4" byte alignment. */
! if (greg <= 10)
! {
! if (write_pass)
! regcache_cooked_write (regcache,
! tdep->ppc_gp0_regnum + greg,
! word);
! greg++;
! }
! else
! {
! argoffset = align_up (argoffset, tdep->wordsize);
! if (write_pass)
! write_memory (sp + argoffset, word, tdep->wordsize);
! argoffset += tdep->wordsize;
! }
! }
! }
!
! /* Compute the actual stack space requirements. */
! if (!write_pass)
! {
! /* Remember the amount of space needed by the arguments. */
! argspace = argoffset;
! /* Allocate space for both the arguments and the structures. */
! sp -= (argoffset + structoffset);
! /* Ensure that the stack is still 16 byte aligned. */
! sp = align_down (sp, 16);
! }
}
+ /* Update %sp. */
+ regcache_cooked_write_signed (regcache, SP_REGNUM, sp);
+
+ /* Write the backchain (it occupies WORDSIZED bytes). */
+ write_memory_signed_integer (sp, tdep->wordsize, saved_sp);
+
/* Point the inferior function call's return address at the dummy's
breakpoint. */
! regcache_cooked_write_signed (regcache, tdep->ppc_lr_regnum, bp_addr);
return sp;
}