[M3devel] m3_load/m3_store/bit_field_ref lose offset??
Tony Hosking
hosking at cs.purdue.edu
Sat Nov 8 23:55:54 CET 2008
Have you checked to make sure that the pre-gcc IR makes sense? Does
it see these values as 32-bit or 64-bit? The reason I ask is that
there may be something wrong in your m3middle target specs that cause
bad IR. Once we know the IR looks right then we can try and fix the
problem.
Antony Hosking | Associate Professor | Computer Science | Purdue
University
305 N. University Street | West Lafayette | IN 47907 | USA
Office +1 765 494 6001 | Mobile +1 765 427 5484
On 8 Nov 2008, at 15:45, Jay wrote:
>
> truncated as usual...along with losing a lot of whitespace..
> Let's see...
>
>
> Tony, how about switching these #if's?
> I explain some of why below.
>
> static void
> m3_store (tree v, int o, tree src_t, m3_type src_T, tree dst_t,
> m3_type dst_T)
> {
> tree val;
> #if 0
> if (o != 0 || TREE_TYPE (v) != dst_t) {
> v = m3_build3 (BIT_FIELD_REF, dst_t, v, TYPE_SIZE (dst_t),
> bitsize_int (o));
> }
> #else
> /* failsafe, but inefficient */
> if (o != 0 || TREE_TYPE (v) != dst_t) {
> v = m3_build1 (ADDR_EXPR, t_addr, v);
> v = m3_build2 (PLUS_EXPR, t_addr, v, size_int (o / BITS_PER_UNIT));
> v = m3_build1 (INDIRECT_REF, dst_t,
> m3_cast (build_pointer_type (dst_t), v));
> }
> #endif
> TREE_THIS_VOLATILE (v) = 1; /* force this to avoid aliasing
> problems */
> val = m3_cast (src_t, EXPR_REF (-1));
> if (src_T != dst_T) {
> val = m3_build1 (CONVERT_EXPR, dst_t, val);
> }
> add_stmt (build2 (MODIFY_EXPR, dst_t, v, val));
> EXPR_POP ();
> }
> m3_load (tree v, int o, tree src_t, m3_type src_T, tree dst_t,
> m3_type dst_T)
> {
> #if 0
> if (o != 0 || TREE_TYPE (v) != src_t) {
> v = m3_build3 (BIT_FIELD_REF, src_t, v, TYPE_SIZE (src_t),
> bitsize_int (o));
> }
> #else
> /* failsafe, but inefficient */
> if (o != 0 || TREE_TYPE (v) != src_t) {
> v = m3_build1 (ADDR_EXPR, t_addr, v);
> v = m3_build2 (PLUS_EXPR, t_addr, v, size_int (o / BITS_PER_UNIT));
> v = m3_build1 (INDIRECT_REF, src_t,
> m3_cast (build_pointer_type (src_t), v));
> }
> #endif
> TREE_THIS_VOLATILE (v) = 1; /* force this to avoid aliasing
> problems */
> if (src_T != dst_T) {
> v = m3_build1 (CONVERT_EXPR, dst_t, v);
> }
> EXPR_PUSH (v);
> }
>
> I'm working on MIPS64_OPENBSD (OpenBSD on an SGI O2).
> In an early version it seems that many loads/stores of global
> variables is wrong.
> The "first" code affected is RTLinker_ExpandModuleTable.
>
> PROCEDURE ExpandModuleTable () =
> CONST InitialTableSize = 500;
> VAR new_mods: ADDRESS; n_bytes: INTEGER;
> BEGIN
> IF (modules = NIL) THEN
> (* first time... *)
> max_modules := InitialTableSize;
> modules := Cstdlib.malloc (InitialTableSize * BYTESIZE
> (RT0.ModulePtr));
> IF (modules = NIL) THEN Cstdlib.abort (); END;
> ELSE
> n_bytes := max_modules * BYTESIZE (RT0.ModulePtr);
> new_mods := Cstdlib.malloc (n_bytes + n_bytes);
> IF (new_mods = NIL) THEN Cstdlib.abort (); END;
> EVAL Cstring.memcpy (new_mods, modules, n_bytes);
> Cstdlib.free (modules);
> modules := new_mods;
> INC (max_modules, max_modules);
> END;
> END ExpandModuleTable;
>
> It should read back modules as NIL.
> What happens is it reads back modules as not NIL,
> and then max_modules should also be zero, but is "large", leading to
> malloc to fail,
> and abort called.
>
> The output of cm3cg -y is reasonable.
> It indicates offset loads.
>
> What is incorrect is that in many loads and stores, but not all, the
> offsets are lost.
>
> (923) begin_procedure
> procedure RTLinker__ExpandModuleTable
> RTLinker__ExpandModuleTable(924) set_source_line
> source line 208
> (925) load_nil
> (926) store
> store (M3_AJWxb1_new_mods) offset 0x0 src_t 0xb dst_t 0xb
> (927) set_source_line
> source line 207
> (928) set_source_line
> source line 210
> (929) load_nil
> (930) load
> m3cg_load (MM_RTLinker): offset 0x440, convert 0xb -> 0xb
>
> Here is the incorrect code:
>
> .globl RTLinker__ExpandModuleTable
> .stabd 46,0,0
> .stabn 68,0,206,.LM108
> .LM108:
> .LFBB8:
> .set nomips16
> .ent RTLinker__ExpandModuleTable
> RTLinker__ExpandModuleTable:
> .frame $fp,64,$31 # vars= 32, regs= 3/0, args= 0, gp= 0
> .mask 0xd0000000,-8
> .fmask 0x00000000,0
> daddiu $sp,$sp,-64
> sd $31,56($sp)
> sd $fp,48($sp)
> sd $28,40($sp)
> move $fp,$sp
> lui $28,%hi(%neg(%gp_rel(RTLinker__ExpandModuleTable)))
> daddu $28,$28,$25
> daddiu $28,$28,%lo(%neg(%gp_rel(RTLinker__ExpandModuleTable)))
> .LBB9:
> .stabn 68,0,208,.LM109
> .LM109:
> sd $0,16($fp)
> .stabn 68,0,210,.LM110
> .LM110:
> dla $2,MM_RTLinker
> ld $2,0($2) << WRONG
> bne $2,$0,.L61
> .stabn 68,0,212,.LM111
> .LM111:
> dla $3,MM_RTLinker
> ld $2,128($3)
> andi $2,$2,0x0
> ori $2,$2,0x1f4
> sd $2,128($3)
> .stabn 68,0,213,.LM112
> .LM112:
> li $4,4000 # 0xfa0
> jal malloc
> sd $2,0($fp)
> ld $4,0($fp)
> dla $3,MM_RTLinker
> ld $2,136($3)
> andi $2,$2,0x0
> or $2,$4,$2
> sd $2,136($3) << OK, offset seems low, but it agrees with
> elsewhere
> .stabn 68,0,214,.LM113
> .LM113:
> dla $2,MM_RTLinker
> ld $2,0($2) << WRONG
> bne $2,$0,.L65
> jal abort
> b .L65
> .L61:
> .stabn 68,0,216,.LM114
> .LM114:
> dla $2,MM_RTLinker
> ld $2,0($2) << WRONG
> dsll $2,$2,3
> sd $2,8($fp)
> .stabn 68,0,217,.LM115
> .LM115:
> ld $3,8($fp)
> ld $2,8($fp)
> daddu $2,$3,$2
> move $4,$2
> jal malloc
> sd $2,0($fp)
> ld $2,0($fp)
> sd $2,16($fp)
> .stabn 68,0,218,.LM116
> .LM116:
> ld $2,16($fp)
> bne $2,$0,.L64
> jal abort
> .L64:
> .stabn 68,0,219,.LM117
> .LM117:
> ld $4,16($fp)
> dla $2,MM_RTLinker
> ld $2,0($2) << WRONG
> ld $3,8($fp)
> move $5,$2
> move $6,$3
> jal memcpy
> sd $2,0($fp)
> .stabn 68,0,220,.LM118
> .LM118:
> dla $2,MM_RTLinker
> ld $2,0($2) << WRONG
> move $4,$2
> jal free
> .stabn 68,0,221,.LM119
> .LM119:
> ld $4,16($fp)
> dla $3,MM_RTLinker
> ld $2,136($3) << OK
> andi $2,$2,0x0
> or $2,$4,$2
> sd $2,136($3) << OK
> .stabn 68,0,222,.LM120
> .LM120:
> dla $2,MM_RTLinker
> ld $3,0($2) << WRONG
> dla $2,MM_RTLinker
> ld $2,0($2) << WRONG
> daddu $4,$3,$2
> dla $3,MM_RTLinker
> ld $2,128($3) << OK
> andi $2,$2,0x0
> or $2,$2,$4
> sd $2,128($3) << OK
> .L65:
> .LBE9:
> .stabn 68,0,224,.LM121
> .LM121:
> move $sp,$fp
> ld $31,56($sp)
> ld $fp,48($sp)
> ld $28,40($sp)
> daddiu $sp,$sp,64
> j $31
> .end RTLinker__ExpandModuleTable
>
> Here is corrected code:
>
> RTLinker__ExpandModuleTable:
> .frame $fp,64,$31 # vars= 32, regs= 3/0, args= 0, gp= 0
> .mask 0xd0000000,-8
> .fmask 0x00000000,0
> daddiu $sp,$sp,-64
> sd $31,56($sp)
> sd $fp,48($sp)
> sd $28,40($sp)
> move $fp,$sp
> lui $28,%hi(%neg(%gp_rel(RTLinker__ExpandModuleTable)))
> daddu $28,$28,$25
> daddiu $28,$28,%lo(%neg(%gp_rel(RTLinker__ExpandModuleTable)))
> .LBB9:
> .stabn 68,0,208,.LM109
> .LM109:
> sd $0,16($fp)
> .stabn 68,0,210,.LM110
> .LM110:
> dla $2,MM_RTLinker
> daddiu $2,$2,136 << CORRECT (offset seems low, but at least it
> isn't zero)
> ld $2,0($2)
> bne $2,$0,.L61
> .stabn 68,0,212,.LM111
> .LM111:
> dla $2,MM_RTLinker
> daddiu $3,$2,128 << CORRECT
> li $2,500 # 0x1f4
> sd $2,0($3)
> .stabn 68,0,213,.LM112
> .LM112:
> li $4,4000 # 0xfa0
> jal malloc
> sd $2,0($fp)
> dla $2,MM_RTLinker
> daddiu $3,$2,136 << CORRECT
> ld $2,0($fp)
> sd $2,0($3)
> .stabn 68,0,214,.LM113
> .LM113:
> dla $2,MM_RTLinker
> daddiu $2,$2,136 << CORRECT
> ld $2,0($2)
> bne $2,$0,.L65
> jal abort
> b .L65
> .L61:
>
> I still dump core with this change, but I get much further.
> I have not tested this change at all otherwise -- i.e. on working
> platforms.
>
> I have not debugged through the gcc/m3cg code to see why
> the offsets are only sometimes lost, or why other platforms
> have no problem. Is MIPS's "global pointer" unusual these days?
> I know SPARC has similar, and all the non-x86, non-AMD64 NT platforms
> had similar, but that's essentially nothing now (I'm not counting
> IA64).
> I know Linux has PLT (procedure linkage table) and GOT (global
> offset table).
> Same thing?
> I haven't looked much at other MIPS ports yet.
>
> http://modula3.elegosoft.com/cgi-bin/cvsweb.cgi/cm3/m3-sys/m3cc/gcc/gcc/m3cg/parse.c.diff?r1=1.7;r2=1.8
>
> is what made it look about like it does -- in particularing using
> BIT_FIELD_REF.
>
> 1.7:
>
> static void m3_load (v, o, src_t, src_T, dest_t, dest_T) /* GCC32OK */
> tree v;
> int o;
> tree src_t, dest_t;
> m3_type src_T, dest_T;
> {
> if (o == 0 && TREE_TYPE (v) == src_t) {
> EXPR_PUSH (v);
> } else {
> tree adr = m3_build1 (ADDR_EXPR, t_addr, v);
> if (o != 0) {
> adr = m3_build2 (PLUS_EXPR, t_addr, adr, size_int (o /
> BITS_PER_UNIT));
> }
> EXPR_PUSH (m3_build1 (INDIRECT_REF, src_t,
> m3_cast (build_pointer_type (src_t), adr)));
> }
> #if 1
> if (src_T != dest_T) {
> EXPR_REF (-1) = m3_build1 (CONVERT_EXPR, dest_t, EXPR_REF (-1));
> }
> if (debug_vars) {
> const char *name = "noname";
> if (v != 0 && DECL_NAME(v) != 0) {
> name = IDENTIFIER_POINTER(DECL_NAME(v));
> }
> fprintf(stderr, " m3_load (%s): offset %d, convert %d -> %d\n",
> name,
> o, src_T, dest_T);
> }
> #else
> if (src_T != dest_T) {
> if (IS_INTEGER_TYPE(dest_T) && dest_t != t_int) {
> EXPR_REF (-1) = m3_build1 (CONVERT_EXPR, t_int, EXPR_REF (-1));
> } else if (IS_WORD_TYPE(dest_T) && dest_t != t_word) {
> EXPR_REF (-1) = m3_build1 (CONVERT_EXPR, t_word, EXPR_REF (-1));
> } else if (IS_INTEGER_TYPE(dest_T) || IS_WORD_TYPE(dest_T)) {
> /* okay */
> } else {
> fatal_error("m3load: cannot convert types: src_t %d dest_t %d\n",
> src_T, dest_T);
> }
> }
> #endif
> }
> static void
> m3_store (v, o, src_t, dest_t) /* GCC32OK */
> tree v;
> int o;
> tree src_t, dest_t;
> {
> tree lhs, rhs;
> if (TREE_TYPE (EXPR_REF (-1)) == src_t) {
> rhs = EXPR_REF (-1);
> } else {
> rhs = m3_cast (src_t, EXPR_REF (-1));
> }
> if (o == 0 && TREE_TYPE (v) == dest_t) {
> lhs = v;
> } else {
> tree f = make_node (FIELD_DECL);
> TREE_TYPE (f) = dest_t;
> DECL_ALIGN (f) = TYPE_ALIGN (dest_t);
> DECL_SIZE (f) = TYPE_SIZE (dest_t);
> DECL_MODE (f) = TYPE_MODE (dest_t);
> DECL_FIELD_OFFSET (f) = size_int (o / BITS_PER_UNIT);
> DECL_FIELD_BIT_OFFSET (f) = bitsize_int (o % BITS_PER_UNIT);
> DECL_FIELD_CONTEXT (f) = TREE_TYPE (v);
> lhs = m3_build2 (COMPONENT_REF, dest_t, v, f);
> }
> #if 1
> expand_assignment (lhs, m3_build1 (CONVERT_EXPR, dest_t, rhs), 0,
> 0);
> #else
> if (dest_t == NULL) {
> expand_assignment (lhs, rhs, 0, 0);
> } else {
> expand_assignment (lhs, m3_build1 (CONVERT_EXPR, dest_t, rhs), 0,
> 0);
> }
> #endif
> EXPR_POP ();
> }
>
> 1.8:
> static void
> m3_load (tree v, int o,
> tree src_t, m3_type src_T,
> tree dst_t, m3_type dst_T) /* GCC32OK */
> {
> if (o == 0 && TREE_TYPE (v) == src_t) {
> EXPR_PUSH (v);
> } else {
> EXPR_PUSH (m3_build3 (BIT_FIELD_REF, src_t, v, TYPE_SIZE (src_t),
> bitsize_int (o)));
> }
> if (src_T != dst_T) {
> EXPR_REF (-1) = m3_build1 (CONVERT_EXPR, dst_t, EXPR_REF (-1));
> }
> if (option_vars_trace) {
> const char *name = "noname";
> if (v != 0 && DECL_NAME(v) != 0) {
> name = IDENTIFIER_POINTER(DECL_NAME(v));
> }
> fprintf(stderr, " m3_load (%s): offset %d, convert %d -> %d\n",
> name,
> o, src_T, dst_T);
> }
> }
> static void
> m3_store (tree v, int o, tree src_t, tree dst_t) /* GCC32OK */
> {
> tree lhs, rhs;
> if (TREE_TYPE (EXPR_REF (-1)) == src_t) {
> rhs = EXPR_REF (-1);
> } else {
> rhs = m3_cast (src_t, EXPR_REF (-1));
> }
> if (o == 0 && TREE_TYPE (v) == dst_t) {
> lhs = v;
> } else {
> lhs = m3_build3 (BIT_FIELD_REF, dst_t, v, TYPE_SIZE (dst_t),
> bitsize_int (o));
> }
> if (src_t != dst_t) {
> rhs = m3_build1 (CONVERT_EXPR, dst_t, rhs);
> }
> expand_assignment (lhs, rhs, 0, 0);
> EXPR_POP ();
> }
>
> - Jay
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