Jo Shields 3c1f479b9d Imported Upstream version 4.0.0~alpha1
Former-commit-id: 806294f5ded97629b74c85c09952f2a74fe182d9
2015-04-07 09:35:12 +01:00

1463 lines
38 KiB
C

/*
* ssa.c: Static single assign form support for the JIT compiler.
*
* Author:
* Dietmar Maurer (dietmar@ximian.com)
*
* (C) 2003 Ximian, Inc.
* Copyright 2011 Xamarin, Inc (http://www.xamarin.com)
*/
#include <config.h>
#include <string.h>
#include <mono/metadata/debug-helpers.h>
#include <mono/metadata/mempool.h>
#include <mono/metadata/mempool-internals.h>
#ifndef DISABLE_JIT
#include "mini.h"
#ifdef HAVE_ALLOCA_H
#include <alloca.h>
#endif
#define CREATE_PRUNED_SSA
//#define DEBUG_SSA 1
#define NEW_PHI(cfg,dest,val) do { \
MONO_INST_NEW ((cfg), (dest), OP_PHI); \
(dest)->inst_c0 = (val); \
} while (0)
typedef struct {
MonoBasicBlock *bb;
MonoInst *inst;
} MonoVarUsageInfo;
static void
unlink_target (MonoBasicBlock *bb, MonoBasicBlock *target)
{
int i;
for (i = 0; i < bb->out_count; i++) {
if (bb->out_bb [i] == target) {
bb->out_bb [i] = bb->out_bb [--bb->out_count];
break;
}
}
for (i = 0; i < target->in_count; i++) {
if (target->in_bb [i] == bb) {
target->in_bb [i] = target->in_bb [--target->in_count];
break;
}
}
}
static void
unlink_unused_bblocks (MonoCompile *cfg)
{
int i, j;
MonoBasicBlock *bb;
g_assert (cfg->comp_done & MONO_COMP_REACHABILITY);
if (G_UNLIKELY (cfg->verbose_level > 1))
printf ("\nUNLINK UNUSED BBLOCKS:\n");
for (bb = cfg->bb_entry; bb && bb->next_bb;) {
if (!(bb->next_bb->flags & BB_REACHABLE)) {
bb->next_bb = bb->next_bb->next_bb;
} else
bb = bb->next_bb;
}
for (i = 1; i < cfg->num_bblocks; i++) {
bb = cfg->bblocks [i];
if (!(bb->flags & BB_REACHABLE)) {
for (j = 0; j < bb->in_count; j++) {
unlink_target (bb->in_bb [j], bb);
}
for (j = 0; j < bb->out_count; j++) {
unlink_target (bb, bb->out_bb [j]);
}
if (G_UNLIKELY (cfg->verbose_level > 1))
printf ("\tUnlinked BB%d\n", bb->block_num);
}
}
}
/**
* remove_bb_from_phis:
*
* Remove BB from the PHI statements in TARGET.
*/
static void
remove_bb_from_phis (MonoCompile *cfg, MonoBasicBlock *bb, MonoBasicBlock *target)
{
MonoInst *ins;
int i, j;
for (i = 0; i < target->in_count; i++) {
if (target->in_bb [i] == bb) {
break;
}
}
g_assert (i < target->in_count);
for (ins = target->code; ins; ins = ins->next) {
if (MONO_IS_PHI (ins)) {
for (j = i; j < ins->inst_phi_args [0] - 1; ++j)
ins->inst_phi_args [j + 1] = ins->inst_phi_args [j + 2];
ins->inst_phi_args [0] --;
}
else
break;
}
}
static inline int
op_phi_to_move (int opcode)
{
switch (opcode) {
case OP_PHI:
return OP_MOVE;
case OP_FPHI:
return OP_FMOVE;
case OP_VPHI:
return OP_VMOVE;
case OP_XPHI:
return OP_XMOVE;
default:
g_assert_not_reached ();
}
return -1;
}
static inline void
record_use (MonoCompile *cfg, MonoInst *var, MonoBasicBlock *bb, MonoInst *ins)
{
MonoMethodVar *info;
MonoVarUsageInfo *ui = mono_mempool_alloc (cfg->mempool, sizeof (MonoVarUsageInfo));
info = MONO_VARINFO (cfg, var->inst_c0);
ui->bb = bb;
ui->inst = ins;
info->uses = g_list_prepend_mempool (cfg->mempool, info->uses, ui);
}
typedef struct {
MonoInst *var;
int idx;
} RenameInfo;
/**
* mono_ssa_rename_vars:
*
* Implement renaming of SSA variables. Also compute def-use information in parallel.
* @stack_history points to an area of memory which can be used for storing changes
* made to the stack, so they can be reverted later.
*/
static void
mono_ssa_rename_vars (MonoCompile *cfg, int max_vars, MonoBasicBlock *bb, gboolean *originals_used, MonoInst **stack, guint32 *lvreg_stack, gboolean *lvreg_defined, RenameInfo *stack_history, int stack_history_size)
{
MonoInst *ins, *new_var;
int i, j, idx;
GSList *tmp;
int stack_history_len = 0;
if (cfg->verbose_level >= 4)
printf ("\nRENAME VARS BLOCK %d:\n", bb->block_num);
/* First pass: Create new vars */
for (ins = bb->code; ins; ins = ins->next) {
const char *spec = INS_INFO (ins->opcode);
int num_sregs;
int sregs [MONO_MAX_SRC_REGS];
#ifdef DEBUG_SSA
printf ("\tProcessing "); mono_print_ins (ins);
#endif
if (ins->opcode == OP_NOP)
continue;
/* SREGs */
num_sregs = mono_inst_get_src_registers (ins, sregs);
for (i = 0; i < num_sregs; ++i) {
if (spec [MONO_INST_SRC1 + i] != ' ') {
MonoInst *var = get_vreg_to_inst (cfg, sregs [i]);
if (var && !(var->flags & (MONO_INST_VOLATILE|MONO_INST_INDIRECT))) {
int idx = var->inst_c0;
if (stack [idx]) {
if (var->opcode != OP_ARG)
g_assert (stack [idx]);
sregs [i] = stack [idx]->dreg;
record_use (cfg, stack [idx], bb, ins);
}
else
record_use (cfg, var, bb, ins);
}
else if (G_UNLIKELY (!var && lvreg_stack [sregs [i]]))
sregs [i] = lvreg_stack [sregs [i]];
}
}
mono_inst_set_src_registers (ins, sregs);
if (MONO_IS_STORE_MEMBASE (ins)) {
MonoInst *var = get_vreg_to_inst (cfg, ins->dreg);
if (var && !(var->flags & (MONO_INST_VOLATILE|MONO_INST_INDIRECT))) {
int idx = var->inst_c0;
if (stack [idx]) {
if (var->opcode != OP_ARG)
g_assert (stack [idx]);
ins->dreg = stack [idx]->dreg;
record_use (cfg, stack [idx], bb, ins);
}
else
record_use (cfg, var, bb, ins);
}
else if (G_UNLIKELY (!var && lvreg_stack [ins->dreg]))
ins->dreg = lvreg_stack [ins->dreg];
}
/* DREG */
if ((spec [MONO_INST_DEST] != ' ') && !MONO_IS_STORE_MEMBASE (ins)) {
MonoInst *var = get_vreg_to_inst (cfg, ins->dreg);
MonoMethodVar *info;
if (var && !(var->flags & (MONO_INST_VOLATILE|MONO_INST_INDIRECT))) {
idx = var->inst_c0;
g_assert (idx < max_vars);
if (var->opcode == OP_ARG)
originals_used [idx] = TRUE;
/* FIXME: */
g_assert (stack_history_len < stack_history_size);
stack_history [stack_history_len].var = stack [idx];
stack_history [stack_history_len].idx = idx;
stack_history_len ++;
if (originals_used [idx]) {
new_var = mono_compile_create_var (cfg, var->inst_vtype, OP_LOCAL);
new_var->flags = var->flags;
MONO_VARINFO (cfg, new_var->inst_c0)->reg = idx;
if (cfg->verbose_level >= 4)
printf (" R%d -> R%d\n", var->dreg, new_var->dreg);
stack [idx] = new_var;
ins->dreg = new_var->dreg;
var = new_var;
}
else {
stack [idx] = var;
originals_used [idx] = TRUE;
}
info = MONO_VARINFO (cfg, var->inst_c0);
info->def = ins;
info->def_bb = bb;
}
else if (G_UNLIKELY (!var && lvreg_defined [ins->dreg] && (ins->dreg >= MONO_MAX_IREGS))) {
/* Perform renaming for local vregs */
lvreg_stack [ins->dreg] = vreg_is_ref (cfg, ins->dreg) ? mono_alloc_ireg_ref (cfg) : mono_alloc_preg (cfg);
ins->dreg = lvreg_stack [ins->dreg];
}
else
lvreg_defined [ins->dreg] = TRUE;
}
#ifdef DEBUG_SSA
printf ("\tAfter processing "); mono_print_ins (ins);
#endif
}
/* Rename PHI arguments in succeeding bblocks */
for (i = 0; i < bb->out_count; i++) {
MonoBasicBlock *n = bb->out_bb [i];
for (j = 0; j < n->in_count; j++)
if (n->in_bb [j] == bb)
break;
for (ins = n->code; ins; ins = ins->next) {
if (MONO_IS_PHI (ins)) {
idx = ins->inst_c0;
if (stack [idx])
new_var = stack [idx];
else
new_var = cfg->varinfo [idx];
#ifdef DEBUG_SSA
printf ("FOUND PHI %d (%d, %d)\n", idx, j, new_var->inst_c0);
#endif
ins->inst_phi_args [j + 1] = new_var->dreg;
record_use (cfg, new_var, n, ins);
if (G_UNLIKELY (cfg->verbose_level >= 4))
printf ("\tAdd PHI R%d <- R%d to BB%d\n", ins->dreg, new_var->dreg, n->block_num);
}
else
/* The phi nodes are at the beginning of the bblock */
break;
}
}
if (bb->dominated) {
for (tmp = bb->dominated; tmp; tmp = tmp->next) {
mono_ssa_rename_vars (cfg, max_vars, (MonoBasicBlock *)tmp->data, originals_used, stack, lvreg_stack, lvreg_defined, stack_history + stack_history_len, stack_history_size - stack_history_len);
}
}
/* Restore stack */
for (i = stack_history_len - 1; i >= 0; i--) {
stack [stack_history [i].idx] = stack_history [i].var;
}
cfg->comp_done |= MONO_COMP_SSA_DEF_USE;
}
void
mono_ssa_compute (MonoCompile *cfg)
{
int i, j, idx, bitsize;
MonoBitSet *set;
MonoMethodVar *vinfo = g_new0 (MonoMethodVar, cfg->num_varinfo);
MonoInst *ins, **stack;
guint8 *buf, *buf_start;
RenameInfo *stack_history;
int stack_history_size;
gboolean *originals;
guint32 *lvreg_stack;
gboolean *lvreg_defined;
g_assert (!(cfg->comp_done & MONO_COMP_SSA));
g_assert (!cfg->disable_ssa);
if (cfg->verbose_level >= 4)
printf ("\nCOMPUTE SSA %d (R%d-)\n\n", cfg->num_varinfo, cfg->next_vreg);
#ifdef CREATE_PRUNED_SSA
/* we need liveness for pruned SSA */
if (!(cfg->comp_done & MONO_COMP_LIVENESS))
mono_analyze_liveness (cfg);
#endif
mono_compile_dominator_info (cfg, MONO_COMP_DOM | MONO_COMP_IDOM | MONO_COMP_DFRONTIER);
bitsize = mono_bitset_alloc_size (cfg->num_bblocks, 0);
buf = buf_start = g_malloc0 (mono_bitset_alloc_size (cfg->num_bblocks, 0) * cfg->num_varinfo);
for (i = 0; i < cfg->num_varinfo; ++i) {
vinfo [i].def_in = mono_bitset_mem_new (buf, cfg->num_bblocks, 0);
buf += bitsize;
vinfo [i].idx = i;
/* implicit reference at start */
if (cfg->varinfo [i]->opcode == OP_ARG)
mono_bitset_set_fast (vinfo [i].def_in, 0);
}
for (i = 0; i < cfg->num_bblocks; ++i) {
MONO_BB_FOR_EACH_INS (cfg->bblocks [i], ins) {
if (ins->opcode == OP_NOP)
continue;
if (!MONO_IS_STORE_MEMBASE (ins) && get_vreg_to_inst (cfg, ins->dreg)) {
mono_bitset_set_fast (vinfo [get_vreg_to_inst (cfg, ins->dreg)->inst_c0].def_in, i);
}
}
}
/* insert phi functions */
for (i = 0; i < cfg->num_varinfo; ++i) {
MonoInst *var = cfg->varinfo [i];
#if SIZEOF_REGISTER == 4
if (var->type == STACK_I8 && !COMPILE_LLVM (cfg))
continue;
#endif
if (var->flags & (MONO_INST_VOLATILE|MONO_INST_INDIRECT))
continue;
/* Most variables have only one definition */
if (mono_bitset_count (vinfo [i].def_in) <= 1)
continue;
set = mono_compile_iterated_dfrontier (cfg, vinfo [i].def_in);
if (cfg->verbose_level >= 4) {
if (mono_bitset_count (set) > 0) {
printf ("\tR%d needs PHI functions in ", var->dreg);
mono_blockset_print (cfg, set, "", -1);
}
}
mono_bitset_foreach_bit (set, idx, cfg->num_bblocks) {
MonoBasicBlock *bb = cfg->bblocks [idx];
/* fixme: create pruned SSA? we would need liveness information for that */
if (bb == cfg->bb_exit && !COMPILE_LLVM (cfg))
continue;
if ((cfg->comp_done & MONO_COMP_LIVENESS) && !mono_bitset_test_fast (bb->live_in_set, i)) {
//printf ("%d is not live in BB%d %s\n", i, bb->block_num, mono_method_full_name (cfg->method, TRUE));
continue;
}
NEW_PHI (cfg, ins, i);
switch (var->type) {
case STACK_I4:
case STACK_I8:
case STACK_PTR:
case STACK_MP:
case STACK_OBJ:
ins->opcode = OP_PHI;
break;
case STACK_R8:
ins->opcode = OP_FPHI;
break;
case STACK_VTYPE:
ins->opcode = MONO_CLASS_IS_SIMD (cfg, var->klass) ? OP_XPHI : OP_VPHI;
break;
}
if (var->inst_vtype->byref)
ins->klass = mono_defaults.int_class;
else
ins->klass = var->klass;
ins->inst_phi_args = mono_mempool_alloc0 (cfg->mempool, sizeof (int) * (cfg->bblocks [idx]->in_count + 1));
ins->inst_phi_args [0] = cfg->bblocks [idx]->in_count;
/* For debugging */
for (j = 0; j < cfg->bblocks [idx]->in_count; ++j)
ins->inst_phi_args [j + 1] = -1;
ins->dreg = cfg->varinfo [i]->dreg;
mono_bblock_insert_before_ins (bb, bb->code, ins);
#ifdef DEBUG_SSA
printf ("ADD PHI BB%d %s\n", cfg->bblocks [idx]->block_num, mono_method_full_name (cfg->method, TRUE));
#endif
}
}
/* free the stuff */
g_free (vinfo);
g_free (buf_start);
/* Renaming phase */
stack = alloca (sizeof (MonoInst *) * cfg->num_varinfo);
memset (stack, 0, sizeof (MonoInst *) * cfg->num_varinfo);
lvreg_stack = g_new0 (guint32, cfg->next_vreg);
lvreg_defined = g_new0 (gboolean, cfg->next_vreg);
stack_history_size = 10240;
stack_history = g_new (RenameInfo, stack_history_size);
originals = g_new0 (gboolean, cfg->num_varinfo);
mono_ssa_rename_vars (cfg, cfg->num_varinfo, cfg->bb_entry, originals, stack, lvreg_stack, lvreg_defined, stack_history, stack_history_size);
g_free (stack_history);
g_free (originals);
g_free (lvreg_stack);
g_free (lvreg_defined);
if (cfg->verbose_level >= 4)
printf ("\nEND COMPUTE SSA.\n\n");
cfg->comp_done |= MONO_COMP_SSA;
}
void
mono_ssa_remove (MonoCompile *cfg)
{
MonoInst *ins, *var, *move;
int bbindex, i, j, first;
g_assert (cfg->comp_done & MONO_COMP_SSA);
for (i = 0; i < cfg->num_bblocks; ++i) {
MonoBasicBlock *bb = cfg->bblocks [i];
if (cfg->verbose_level >= 4)
printf ("\nREMOVE SSA %d:\n", bb->block_num);
for (ins = bb->code; ins; ins = ins->next) {
if (MONO_IS_PHI (ins)) {
g_assert (ins->inst_phi_args [0] == bb->in_count);
var = get_vreg_to_inst (cfg, ins->dreg);
/* Check for PHI nodes where all the inputs are the same */
first = ins->inst_phi_args [1];
for (j = 1; j < bb->in_count; ++j)
if (first != ins->inst_phi_args [j + 1])
break;
if ((bb->in_count > 1) && (j == bb->in_count)) {
ins->opcode = op_phi_to_move (ins->opcode);
if (ins->opcode == OP_VMOVE)
g_assert (ins->klass);
ins->sreg1 = first;
} else {
for (j = 0; j < bb->in_count; j++) {
MonoBasicBlock *pred = bb->in_bb [j];
int sreg = ins->inst_phi_args [j + 1];
if (cfg->verbose_level >= 4)
printf ("\tADD R%d <- R%d in BB%d\n", var->dreg, sreg, pred->block_num);
if (var->dreg != sreg) {
MONO_INST_NEW (cfg, move, op_phi_to_move (ins->opcode));
if (move->opcode == OP_VMOVE) {
g_assert (ins->klass);
move->klass = ins->klass;
}
move->dreg = var->dreg;
move->sreg1 = sreg;
mono_add_ins_to_end (pred, move);
}
}
NULLIFY_INS (ins);
}
}
}
}
if (cfg->verbose_level >= 4) {
for (i = 0; i < cfg->num_bblocks; ++i) {
MonoBasicBlock *bb = cfg->bblocks [i];
mono_print_bb (bb, "AFTER REMOVE SSA:");
}
}
/*
* Removal of SSA form introduces many copies. To avoid this, we tyry to coalesce
* the variables if possible. Since the newly introduced SSA variables don't
* have overlapping live ranges (because we don't do agressive optimization), we
* can coalesce them into the original variable.
*/
for (bbindex = 0; bbindex < cfg->num_bblocks; ++bbindex) {
MonoBasicBlock *bb = cfg->bblocks [bbindex];
for (ins = bb->code; ins; ins = ins->next) {
const char *spec = INS_INFO (ins->opcode);
int num_sregs;
int sregs [MONO_MAX_SRC_REGS];
if (ins->opcode == OP_NOP)
continue;
if (spec [MONO_INST_DEST] != ' ') {
MonoInst *var = get_vreg_to_inst (cfg, ins->dreg);
if (var) {
MonoMethodVar *vmv = MONO_VARINFO (cfg, var->inst_c0);
/*
* The third condition avoids coalescing with variables eliminated
* during deadce.
*/
if ((vmv->reg != -1) && (vmv->idx != vmv->reg) && (MONO_VARINFO (cfg, vmv->reg)->reg != -1)) {
printf ("COALESCE: R%d -> R%d\n", ins->dreg, cfg->varinfo [vmv->reg]->dreg);
ins->dreg = cfg->varinfo [vmv->reg]->dreg;
}
}
}
num_sregs = mono_inst_get_src_registers (ins, sregs);
for (i = 0; i < num_sregs; ++i) {
MonoInst *var = get_vreg_to_inst (cfg, sregs [i]);
if (var) {
MonoMethodVar *vmv = MONO_VARINFO (cfg, var->inst_c0);
if ((vmv->reg != -1) && (vmv->idx != vmv->reg) && (MONO_VARINFO (cfg, vmv->reg)->reg != -1)) {
printf ("COALESCE: R%d -> R%d\n", sregs [i], cfg->varinfo [vmv->reg]->dreg);
sregs [i] = cfg->varinfo [vmv->reg]->dreg;
}
}
}
mono_inst_set_src_registers (ins, sregs);
}
}
for (i = 0; i < cfg->num_varinfo; ++i) {
MONO_VARINFO (cfg, i)->reg = -1;
}
if (cfg->comp_done & MONO_COMP_REACHABILITY)
unlink_unused_bblocks (cfg);
cfg->comp_done &= ~MONO_COMP_LIVENESS;
cfg->comp_done &= ~MONO_COMP_SSA;
}
static void
mono_ssa_create_def_use (MonoCompile *cfg)
{
MonoBasicBlock *bb;
MonoInst *ins;
int i;
g_assert (!(cfg->comp_done & MONO_COMP_SSA_DEF_USE));
for (bb = cfg->bb_entry; bb; bb = bb->next_bb) {
for (ins = bb->code; ins; ins = ins->next) {
const char *spec = INS_INFO (ins->opcode);
MonoMethodVar *info;
int num_sregs;
int sregs [MONO_MAX_SRC_REGS];
if (ins->opcode == OP_NOP)
continue;
/* SREGs */
num_sregs = mono_inst_get_src_registers (ins, sregs);
for (i = 0; i < num_sregs; ++i) {
MonoInst *var = get_vreg_to_inst (cfg, sregs [i]);
if (var && !(var->flags & (MONO_INST_VOLATILE|MONO_INST_INDIRECT)))
record_use (cfg, var, bb, ins);
}
if (MONO_IS_STORE_MEMBASE (ins)) {
MonoInst *var = get_vreg_to_inst (cfg, ins->dreg);
if (var && !(var->flags & (MONO_INST_VOLATILE|MONO_INST_INDIRECT)))
record_use (cfg, var, bb, ins);
}
if (MONO_IS_PHI (ins)) {
for (i = ins->inst_phi_args [0]; i > 0; i--) {
g_assert (ins->inst_phi_args [i] != -1);
record_use (cfg, get_vreg_to_inst (cfg, ins->inst_phi_args [i]), bb, ins);
}
}
/* DREG */
if ((spec [MONO_INST_DEST] != ' ') && !MONO_IS_STORE_MEMBASE (ins)) {
MonoInst *var = get_vreg_to_inst (cfg, ins->dreg);
if (var && !(var->flags & (MONO_INST_VOLATILE|MONO_INST_INDIRECT))) {
info = MONO_VARINFO (cfg, var->inst_c0);
info->def = ins;
info->def_bb = bb;
}
}
}
}
cfg->comp_done |= MONO_COMP_SSA_DEF_USE;
}
static void
mono_ssa_copyprop (MonoCompile *cfg)
{
int i, index;
GList *l;
g_assert ((cfg->comp_done & MONO_COMP_SSA_DEF_USE));
for (index = 0; index < cfg->num_varinfo; ++index) {
MonoInst *var = cfg->varinfo [index];
MonoMethodVar *info = MONO_VARINFO (cfg, index);
if (info->def && (MONO_IS_MOVE (info->def))) {
MonoInst *var2 = get_vreg_to_inst (cfg, info->def->sreg1);
if (var2 && !(var2->flags & (MONO_INST_VOLATILE|MONO_INST_INDIRECT)) && MONO_VARINFO (cfg, var2->inst_c0)->def && (!MONO_IS_PHI (MONO_VARINFO (cfg, var2->inst_c0)->def))) {
/* Rewrite all uses of var to be uses of var2 */
int dreg = var->dreg;
int sreg1 = var2->dreg;
l = info->uses;
while (l) {
MonoVarUsageInfo *u = (MonoVarUsageInfo*)l->data;
MonoInst *ins = u->inst;
GList *next = l->next;
int num_sregs;
int sregs [MONO_MAX_SRC_REGS];
num_sregs = mono_inst_get_src_registers (ins, sregs);
for (i = 0; i < num_sregs; ++i) {
if (sregs [i] == dreg)
break;
}
if (i < num_sregs) {
g_assert (sregs [i] == dreg);
sregs [i] = sreg1;
mono_inst_set_src_registers (ins, sregs);
} else if (MONO_IS_STORE_MEMBASE (ins) && ins->dreg == dreg) {
ins->dreg = sreg1;
} else if (MONO_IS_PHI (ins)) {
for (i = ins->inst_phi_args [0]; i > 0; i--) {
int sreg = ins->inst_phi_args [i];
if (sreg == var->dreg)
break;
}
g_assert (i > 0);
ins->inst_phi_args [i] = sreg1;
}
else
g_assert_not_reached ();
record_use (cfg, var2, u->bb, ins);
l = next;
}
info->uses = NULL;
}
}
}
if (cfg->verbose_level >= 4) {
MonoBasicBlock *bb;
for (bb = cfg->bb_entry; bb; bb = bb->next_bb)
mono_print_bb (bb, "AFTER SSA COPYPROP");
}
}
static int
evaluate_ins (MonoCompile *cfg, MonoInst *ins, MonoInst **res, MonoInst **carray)
{
MonoInst *args [MONO_MAX_SRC_REGS];
int rs [MONO_MAX_SRC_REGS];
MonoInst *c0;
gboolean const_args = TRUE;
const char *spec = INS_INFO (ins->opcode);
int num_sregs, i;
int sregs [MONO_MAX_SRC_REGS];
/* Short-circuit this */
if (ins->opcode == OP_ICONST) {
*res = ins;
return 1;
}
if (ins->opcode == OP_NOP)
return 2;
num_sregs = mono_inst_get_src_registers (ins, sregs);
for (i = 0; i < MONO_MAX_SRC_REGS; ++i)
args [i] = NULL;
for (i = 0; i < num_sregs; ++i) {
MonoInst *var = get_vreg_to_inst (cfg, sregs [i]);
rs [i] = 2;
args [i] = carray [sregs [i]];
if (args [i])
rs [i] = 1;
else if (var && !(var->flags & (MONO_INST_VOLATILE|MONO_INST_INDIRECT)))
rs [i] = MONO_VARINFO (cfg, var->inst_c0)->cpstate;
if (rs [i] != 1)
const_args = FALSE;
}
c0 = NULL;
if (num_sregs > 0 && const_args) {
g_assert (num_sregs <= 2);
if ((spec [MONO_INST_DEST] != ' ') && carray [ins->dreg]) {
// Cached value
*res = carray [ins->dreg];
return 1;
}
c0 = mono_constant_fold_ins (cfg, ins, args [0], args [1], FALSE);
if (c0) {
if (G_UNLIKELY (cfg->verbose_level > 1)) {
printf ("\t cfold -> ");
mono_print_ins (c0);
}
*res = c0;
return 1;
}
else
/* Can't cfold this ins */
return 2;
}
if (num_sregs == 0)
return 2;
for (i = 0; i < num_sregs; ++i) {
if (rs [i] == 2)
return 2;
}
return 0;
}
static inline void
change_varstate (MonoCompile *cfg, GList **cvars, MonoMethodVar *info, int state, MonoInst *c0, MonoInst **carray)
{
if (info->cpstate >= state)
return;
info->cpstate = state;
if (G_UNLIKELY (cfg->verbose_level > 1))
printf ("\tState of R%d set to %d\n", cfg->varinfo [info->idx]->dreg, info->cpstate);
if (state == 1)
g_assert (c0);
carray [cfg->varinfo [info->idx]->dreg] = c0;
if (!g_list_find (*cvars, info)) {
*cvars = g_list_prepend (*cvars, info);
}
}
static inline void
add_cprop_bb (MonoCompile *cfg, MonoBasicBlock *bb, GList **bblist)
{
if (G_UNLIKELY (cfg->verbose_level > 1))
printf ("\tAdd BB%d to worklist\n", bb->block_num);
if (!(bb->flags & BB_REACHABLE)) {
bb->flags |= BB_REACHABLE;
*bblist = g_list_prepend (*bblist, bb);
}
}
static void
visit_inst (MonoCompile *cfg, MonoBasicBlock *bb, MonoInst *ins, GList **cvars, GList **bblist, MonoInst **carray)
{
const char *spec = INS_INFO (ins->opcode);
if (ins->opcode == OP_NOP)
return;
if (cfg->verbose_level > 1)
mono_print_ins (ins);
/* FIXME: Support longs/floats */
/* FIXME: Work on vregs as well */
if (MONO_IS_PHI (ins)) {
MonoMethodVar *info = MONO_VARINFO (cfg, get_vreg_to_inst (cfg, ins->dreg)->inst_c0);
MonoInst *c0 = NULL;
int j;
for (j = 1; j <= ins->inst_phi_args [0]; j++) {
MonoInst *var = get_vreg_to_inst (cfg, ins->inst_phi_args [j]);
MonoMethodVar *mv = MONO_VARINFO (cfg, var->inst_c0);
MonoInst *src = mv->def;
if (mv->def_bb && !(mv->def_bb->flags & BB_REACHABLE))
continue;
if (!mv->def || !src || mv->cpstate == 2) {
change_varstate (cfg, cvars, info, 2, NULL, carray);
break;
}
if (mv->cpstate == 0)
continue;
g_assert (carray [var->dreg]);
if (!c0)
c0 = carray [var->dreg];
/* FIXME: */
if (c0->opcode != OP_ICONST) {
change_varstate (cfg, cvars, info, 2, NULL, carray);
break;
}
if (carray [var->dreg]->inst_c0 != c0->inst_c0) {
change_varstate (cfg, cvars, info, 2, NULL, carray);
break;
}
}
if (c0 && info->cpstate < 1) {
change_varstate (cfg, cvars, info, 1, c0, carray);
g_assert (c0->opcode == OP_ICONST);
}
}
else if (!MONO_IS_STORE_MEMBASE (ins) && ((spec [MONO_INST_SRC1] != ' ') || (spec [MONO_INST_SRC2] != ' ') || (spec [MONO_INST_DEST] != ' '))) {
MonoInst *var, *c0;
int state;
if (spec [MONO_INST_DEST] != ' ')
var = get_vreg_to_inst (cfg, ins->dreg);
else
var = NULL;
c0 = NULL;
state = evaluate_ins (cfg, ins, &c0, carray);
if (var && !(var->flags & (MONO_INST_VOLATILE|MONO_INST_INDIRECT))) {
MonoMethodVar *info = MONO_VARINFO (cfg, var->inst_c0);
if (info->cpstate < 2) {
if (state == 1)
change_varstate (cfg, cvars, info, 1, c0, carray);
else if (state == 2)
change_varstate (cfg, cvars, info, 2, NULL, carray);
}
}
else if (!var && (ins->dreg != -1)) {
/*
* We don't record def-use information for local vregs since it would be
* expensive. Instead, we depend on the fact that all uses of the vreg are in
* the same bblock, so they will be examined after the definition.
* FIXME: This isn't true if the ins is visited through an SSA edge.
*/
if (c0) {
carray [ins->dreg] = c0;
} else {
if (carray [ins->dreg]) {
/*
* The state of the vreg changed from constant to non-constant
* -> need to rescan the whole bblock.
*/
carray [ins->dreg] = NULL;
/* FIXME: Speed this up */
if (!g_list_find (*bblist, bb))
*bblist = g_list_prepend (*bblist, bb);
}
}
}
if (MONO_IS_JUMP_TABLE (ins)) {
int i;
MonoJumpInfoBBTable *table = MONO_JUMP_TABLE_FROM_INS (ins);
if (!ins->next || ins->next->opcode != OP_PADD) {
/* The PADD was optimized away */
/* FIXME: handle this as well */
for (i = 0; i < table->table_size; i++)
if (table->table [i])
add_cprop_bb (cfg, table->table [i], bblist);
return;
}
g_assert (ins->next->opcode == OP_PADD);
g_assert (ins->next->sreg1 == ins->dreg);
if (carray [ins->next->sreg2]) {
#if SIZEOF_REGISTER == 8
int idx = carray [ins->next->sreg2]->inst_c0 >> 3;
#else
int idx = carray [ins->next->sreg2]->inst_c0 >> 2;
#endif
if ((idx < 0) || (idx >= table->table_size))
/* Out-of-range, no branch is executed */
return;
else
if (table->table [idx])
add_cprop_bb (cfg, table->table [idx], bblist);
}
else {
for (i = 0; i < table->table_size; i++)
if (table->table [i])
add_cprop_bb (cfg, table->table [i], bblist);
}
}
if (ins->opcode == OP_SWITCH) {
int i;
MonoJumpInfoBBTable *table = ins->inst_p0;
for (i = 0; i < table->table_size; i++)
if (table->table [i])
add_cprop_bb (cfg, table->table [i], bblist);
}
/* Handle COMPARE+BRCOND pairs */
if (ins->next && MONO_IS_COND_BRANCH_OP (ins->next)) {
if (c0) {
g_assert (c0->opcode == OP_ICONST);
if (c0->inst_c0)
ins->next->flags |= MONO_INST_CFOLD_TAKEN;
else
ins->next->flags |= MONO_INST_CFOLD_NOT_TAKEN;
}
else {
ins->next->flags &= ~(MONO_INST_CFOLD_TAKEN | MONO_INST_CFOLD_NOT_TAKEN);
}
visit_inst (cfg, bb, ins->next, cvars, bblist, carray);
}
} else if (ins->opcode == OP_BR) {
add_cprop_bb (cfg, ins->inst_target_bb, bblist);
} else if (MONO_IS_COND_BRANCH_OP (ins)) {
if (ins->flags & MONO_INST_CFOLD_TAKEN) {
add_cprop_bb (cfg, ins->inst_true_bb, bblist);
} else if (ins->flags & MONO_INST_CFOLD_NOT_TAKEN) {
if (ins->inst_false_bb)
add_cprop_bb (cfg, ins->inst_false_bb, bblist);
} else {
add_cprop_bb (cfg, ins->inst_true_bb, bblist);
if (ins->inst_false_bb)
add_cprop_bb (cfg, ins->inst_false_bb, bblist);
}
}
}
/**
* fold_ins:
*
* Replace INS with its constant value, if it exists
*/
static void
fold_ins (MonoCompile *cfg, MonoBasicBlock *bb, MonoInst *ins, MonoInst **carray)
{
const char *spec = INS_INFO (ins->opcode);
int opcode2;
int num_sregs = mono_inst_get_num_src_registers (ins);
if ((ins->opcode != OP_NOP) && (ins->dreg != -1) && !MONO_IS_STORE_MEMBASE (ins)) {
if (carray [ins->dreg] && (spec [MONO_INST_DEST] == 'i') && (ins->dreg >= MONO_MAX_IREGS)) {
/* Perform constant folding */
/* FIXME: */
g_assert (carray [ins->dreg]->opcode == OP_ICONST);
ins->opcode = OP_ICONST;
ins->inst_c0 = carray [ins->dreg]->inst_c0;
MONO_INST_NULLIFY_SREGS (ins);
} else if (num_sregs == 2 && carray [ins->sreg2]) {
/* Perform op->op_imm conversion */
opcode2 = mono_op_to_op_imm (ins->opcode);
if (opcode2 != -1) {
ins->opcode = opcode2;
ins->inst_imm = carray [ins->sreg2]->inst_c0;
ins->sreg2 = -1;
if ((opcode2 == OP_VOIDCALL) || (opcode2 == OP_CALL) || (opcode2 == OP_LCALL) || (opcode2 == OP_FCALL))
((MonoCallInst*)ins)->fptr = (gpointer)ins->inst_imm;
}
} else {
/* FIXME: Handle 3 op insns */
}
if (MONO_IS_JUMP_TABLE (ins)) {
int i;
MonoJumpInfoBBTable *table = MONO_JUMP_TABLE_FROM_INS (ins);
if (!ins->next || ins->next->opcode != OP_PADD) {
/* The PADD was optimized away */
/* FIXME: handle this as well */
return;
}
g_assert (ins->next->opcode == OP_PADD);
g_assert (ins->next->sreg1 == ins->dreg);
g_assert (ins->next->next->opcode == OP_LOAD_MEMBASE);
if (carray [ins->next->sreg2]) {
/* Convert to a simple branch */
#if SIZEOF_REGISTER == 8
int idx = carray [ins->next->sreg2]->inst_c0 >> 3;
#else
int idx = carray [ins->next->sreg2]->inst_c0 >> 2;
#endif
if (!((idx >= 0) && (idx < table->table_size))) {
/* Out of range, eliminate the whole switch */
for (i = 0; i < table->table_size; ++i) {
remove_bb_from_phis (cfg, bb, table->table [i]);
mono_unlink_bblock (cfg, bb, table->table [i]);
}
NULLIFY_INS (ins);
NULLIFY_INS (ins->next);
NULLIFY_INS (ins->next->next);
if (ins->next->next->next)
NULLIFY_INS (ins->next->next->next);
return;
}
if (!ins->next->next->next || ins->next->next->next->opcode != OP_BR_REG) {
/* A one-way switch which got optimized away */
if (G_UNLIKELY (cfg->verbose_level > 1)) {
printf ("\tNo cfold on ");
mono_print_ins (ins);
}
return;
}
if (G_UNLIKELY (cfg->verbose_level > 1)) {
printf ("\tcfold on ");
mono_print_ins (ins);
}
/* Unlink target bblocks */
for (i = 0; i < table->table_size; ++i) {
if (table->table [i] != table->table [idx]) {
remove_bb_from_phis (cfg, bb, table->table [i]);
mono_unlink_bblock (cfg, bb, table->table [i]);
}
}
/* Change the OP_BR_REG to a simple branch */
ins->next->next->next->opcode = OP_BR;
ins->next->next->next->inst_target_bb = table->table [idx];
ins->next->next->next->sreg1 = -1;
/* Nullify the other instructions */
NULLIFY_INS (ins);
NULLIFY_INS (ins->next);
NULLIFY_INS (ins->next->next);
}
}
}
else if (MONO_IS_COND_BRANCH_OP (ins)) {
if (ins->flags & MONO_INST_CFOLD_TAKEN) {
remove_bb_from_phis (cfg, bb, ins->inst_false_bb);
mono_unlink_bblock (cfg, bb, ins->inst_false_bb);
ins->opcode = OP_BR;
ins->inst_target_bb = ins->inst_true_bb;
} else if (ins->flags & MONO_INST_CFOLD_NOT_TAKEN) {
remove_bb_from_phis (cfg, bb, ins->inst_true_bb);
mono_unlink_bblock (cfg, bb, ins->inst_true_bb);
ins->opcode = OP_BR;
ins->inst_target_bb = ins->inst_false_bb;
}
}
}
void
mono_ssa_cprop (MonoCompile *cfg)
{
MonoInst **carray;
MonoBasicBlock *bb;
GList *bblock_list, *cvars;
GList *tmp;
int i;
//printf ("SIMPLE OPTS BB%d %s\n", bb->block_num, mono_method_full_name (cfg->method, TRUE));
carray = g_new0 (MonoInst*, cfg->next_vreg);
if (!(cfg->comp_done & MONO_COMP_SSA_DEF_USE))
mono_ssa_create_def_use (cfg);
bblock_list = g_list_prepend (NULL, cfg->bb_entry);
cfg->bb_entry->flags |= BB_REACHABLE;
memset (carray, 0, sizeof (MonoInst *) * cfg->num_varinfo);
for (i = 0; i < cfg->num_varinfo; i++) {
MonoMethodVar *info = MONO_VARINFO (cfg, i);
if (!info->def)
info->cpstate = 2;
}
for (bb = cfg->bb_entry->next_bb; bb; bb = bb->next_bb) {
/*
* FIXME: This should be bb->flags & BB_FLAG_EXCEPTION_HANDLER, but
* that would still allow unreachable try's to be removed.
*/
if (bb->region)
add_cprop_bb (cfg, bb, &bblock_list);
}
cvars = NULL;
while (bblock_list) {
MonoInst *inst;
bb = (MonoBasicBlock *)bblock_list->data;
bblock_list = g_list_delete_link (bblock_list, bblock_list);
g_assert (bb->flags & BB_REACHABLE);
/*
* Some bblocks are linked to 2 others even through they fall through to the
* next bblock.
*/
if (!(bb->last_ins && MONO_IS_BRANCH_OP (bb->last_ins))) {
for (i = 0; i < bb->out_count; ++i)
add_cprop_bb (cfg, bb->out_bb [i], &bblock_list);
}
if (cfg->verbose_level > 1)
printf ("\nSSA CONSPROP BB%d:\n", bb->block_num);
for (inst = bb->code; inst; inst = inst->next) {
visit_inst (cfg, bb, inst, &cvars, &bblock_list, carray);
}
while (cvars) {
MonoMethodVar *info = (MonoMethodVar *)cvars->data;
cvars = g_list_delete_link (cvars, cvars);
for (tmp = info->uses; tmp; tmp = tmp->next) {
MonoVarUsageInfo *ui = (MonoVarUsageInfo *)tmp->data;
if (!(ui->bb->flags & BB_REACHABLE))
continue;
visit_inst (cfg, ui->bb, ui->inst, &cvars, &bblock_list, carray);
}
}
}
for (bb = cfg->bb_entry->next_bb; bb; bb = bb->next_bb) {
MonoInst *inst;
for (inst = bb->code; inst; inst = inst->next) {
fold_ins (cfg, bb, inst, carray);
}
}
g_free (carray);
cfg->comp_done |= MONO_COMP_REACHABILITY;
/* fixme: we should update usage infos during cprop, instead of computing it again */
cfg->comp_done &= ~MONO_COMP_SSA_DEF_USE;
for (i = 0; i < cfg->num_varinfo; i++) {
MonoMethodVar *info = MONO_VARINFO (cfg, i);
info->def = NULL;
info->uses = NULL;
}
}
static inline void
add_to_dce_worklist (MonoCompile *cfg, MonoMethodVar *var, MonoMethodVar *use, GList **wl)
{
GList *tmp;
*wl = g_list_prepend_mempool (cfg->mempool, *wl, use);
for (tmp = use->uses; tmp; tmp = tmp->next) {
MonoVarUsageInfo *ui = (MonoVarUsageInfo *)tmp->data;
if (ui->inst == var->def) {
/* from the mempool */
use->uses = g_list_remove_link (use->uses, tmp);
break;
}
}
}
void
mono_ssa_deadce (MonoCompile *cfg)
{
int i;
GList *work_list;
g_assert (cfg->comp_done & MONO_COMP_SSA);
//printf ("DEADCE %s\n", mono_method_full_name (cfg->method, TRUE));
if (!(cfg->comp_done & MONO_COMP_SSA_DEF_USE))
mono_ssa_create_def_use (cfg);
mono_ssa_copyprop (cfg);
work_list = NULL;
for (i = 0; i < cfg->num_varinfo; i++) {
MonoMethodVar *info = MONO_VARINFO (cfg, i);
work_list = g_list_prepend_mempool (cfg->mempool, work_list, info);
}
while (work_list) {
MonoMethodVar *info = (MonoMethodVar *)work_list->data;
work_list = g_list_remove_link (work_list, work_list);
/*
* The second part of the condition happens often when PHI nodes have their dreg
* as one of their arguments due to the fact that we use the original vars.
*/
if (info->def && (!info->uses || ((info->uses->next == NULL) && (((MonoVarUsageInfo*)info->uses->data)->inst == info->def)))) {
MonoInst *def = info->def;
/* Eliminating FMOVE could screw up the fp stack */
if (MONO_IS_MOVE (def) && (!MONO_ARCH_USE_FPSTACK || (def->opcode != OP_FMOVE))) {
MonoInst *src_var = get_vreg_to_inst (cfg, def->sreg1);
if (src_var && !(src_var->flags & (MONO_INST_VOLATILE|MONO_INST_INDIRECT)))
add_to_dce_worklist (cfg, info, MONO_VARINFO (cfg, src_var->inst_c0), &work_list);
NULLIFY_INS (def);
info->reg = -1;
} else if ((def->opcode == OP_ICONST) || (def->opcode == OP_I8CONST) || MONO_IS_ZERO (def)) {
NULLIFY_INS (def);
info->reg = -1;
} else if (MONO_IS_PHI (def)) {
int j;
for (j = def->inst_phi_args [0]; j > 0; j--) {
MonoMethodVar *u = MONO_VARINFO (cfg, get_vreg_to_inst (cfg, def->inst_phi_args [j])->inst_c0);
add_to_dce_worklist (cfg, info, u, &work_list);
}
NULLIFY_INS (def);
info->reg = -1;
}
else if (def->opcode == OP_NOP) {
}
//else
//mono_print_ins (def);
}
}
}
#if 0
void
mono_ssa_strength_reduction (MonoCompile *cfg)
{
MonoBasicBlock *bb;
int i;
g_assert (cfg->comp_done & MONO_COMP_SSA);
g_assert (cfg->comp_done & MONO_COMP_LOOPS);
g_assert (cfg->comp_done & MONO_COMP_SSA_DEF_USE);
for (bb = cfg->bb_entry->next_bb; bb; bb = bb->next_bb) {
GList *lp = bb->loop_blocks;
if (lp) {
MonoBasicBlock *h = (MonoBasicBlock *)lp->data;
/* we only consider loops with 2 in bblocks */
if (!h->in_count == 2)
continue;
for (i = 0; i < cfg->num_varinfo; i++) {
MonoMethodVar *info = MONO_VARINFO (cfg, i);
if (info->def && info->def->ssa_op == MONO_SSA_STORE &&
info->def->inst_i0->opcode == OP_LOCAL && g_list_find (lp, info->def_bb)) {
MonoInst *v = info->def->inst_i1;
printf ("FOUND %d in %s\n", info->idx, mono_method_full_name (cfg->method, TRUE));
}
}
}
}
}
#endif
void
mono_ssa_loop_invariant_code_motion (MonoCompile *cfg)
{
MonoBasicBlock *bb, *h, *idom;
MonoInst *ins, *n, *tins;
int i;
g_assert (cfg->comp_done & MONO_COMP_SSA);
if (!(cfg->comp_done & MONO_COMP_LOOPS) || !(cfg->comp_done & MONO_COMP_SSA_DEF_USE))
return;
for (bb = cfg->bb_entry->next_bb; bb; bb = bb->next_bb) {
GList *lp = bb->loop_blocks;
if (!lp)
continue;
h = (MonoBasicBlock *)lp->data;
if (bb != h)
continue;
MONO_BB_FOR_EACH_INS_SAFE (bb, n, ins) {
gboolean is_class_init = FALSE;
/*
* Try to move instructions out of loop headers into the preceeding bblock.
*/
if (ins->opcode == OP_VOIDCALL) {
MonoCallInst *call = (MonoCallInst*)ins;
if (call->fptr_is_patch) {
MonoJumpInfo *ji = (MonoJumpInfo*)call->fptr;
if (ji->type == MONO_PATCH_INFO_CLASS_INIT)
is_class_init = TRUE;
}
}
if (ins->opcode == OP_LDLEN || ins->opcode == OP_STRLEN || ins->opcode == OP_CHECK_THIS || ins->opcode == OP_AOTCONST || is_class_init) {
gboolean skip;
int sreg;
idom = h->idom;
/*
* h->nesting is needed to work around:
* http://llvm.org/bugs/show_bug.cgi?id=17868
*/
if (!(idom && idom->last_ins && idom->last_ins->opcode == OP_BR && idom->last_ins->inst_target_bb == h && h->nesting == 1)) {
continue;
}
/*
* Make sure there are no instructions with side effects before ins.
*/
skip = FALSE;
MONO_BB_FOR_EACH_INS (bb, tins) {
if (tins == ins)
break;
if (!MONO_INS_HAS_NO_SIDE_EFFECT (tins)) {
skip = TRUE;
break;
}
}
if (skip) {
/*
printf ("%s\n", mono_method_full_name (cfg->method, TRUE));
mono_print_ins (tins);
*/
continue;
}
/* Make sure we don't move the instruction before the def of its sreg */
if (ins->opcode == OP_LDLEN || ins->opcode == OP_STRLEN || ins->opcode == OP_CHECK_THIS)
sreg = ins->sreg1;
else
sreg = -1;
if (sreg != -1) {
MonoInst *tins, *var;
skip = FALSE;
for (tins = ins->prev; tins; tins = tins->prev) {
const char *spec = INS_INFO (tins->opcode);
if (tins->opcode == OP_MOVE && tins->dreg == sreg) {
sreg = tins->sreg1;
} if (spec [MONO_INST_DEST] != ' ' && tins->dreg == sreg) {
skip = TRUE;
break;
}
}
if (skip)
continue;
var = get_vreg_to_inst (cfg, sreg);
if (var && (var->flags & (MONO_INST_VOLATILE|MONO_INST_INDIRECT)))
continue;
ins->sreg1 = sreg;
}
if (cfg->verbose_level > 1) {
printf ("licm in BB%d on ", bb->block_num);
mono_print_ins (ins);
}
//{ static int count = 0; count ++; printf ("%d\n", count); }
MONO_REMOVE_INS (bb, ins);
mono_bblock_insert_before_ins (idom, idom->last_ins, ins);
if (ins->opcode == OP_LDLEN || ins->opcode == OP_STRLEN)
idom->has_array_access = TRUE;
}
}
}
cfg->comp_done &= ~MONO_COMP_SSA_DEF_USE;
for (i = 0; i < cfg->num_varinfo; i++) {
MonoMethodVar *info = MONO_VARINFO (cfg, i);
info->def = NULL;
info->uses = NULL;
}
}
#endif /* DISABLE_JIT */