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[mono][interp] Reduce max memory usage during interp compilation
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Create a new mempool for optimization iteration. For complex methods we typically do multiple optimization iterations. For each iteration we were allocating memory from the global method mempool, which was freed at the end of method compilation. We now allocate most of the memory inside a separate mempool which is freed at the end of each iteration.

Allocate some of the temporary data with malloc so we can free it earlier. As an exception we allocate also var_values with malloc. We don't allocate it to the global mempool since this table is very big and it is wasteful. We don't allocate it to the optimization mempool since it is used for better code gen outside of optimization passes, in the var offset allocator.
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@BrzVlad
BrzVlad committed Jan 20, 2024
1 parent 7ec65fa commit b09c0d2
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Showing 3 changed files with 37 additions and 15 deletions.
45 changes: 30 additions & 15 deletions src/mono/mono/mini/interp/transform-opt.c
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Original file line number Diff line number Diff line change
Expand Up @@ -532,8 +532,8 @@ dfs_visit (TransformData *td)
{
int dfs_index = 0;
int next_stack_index = 0;
td->bblocks = (InterpBasicBlock**)mono_mempool_alloc0 (td->mempool, sizeof (InterpBasicBlock*) * td->bb_count);
InterpBasicBlock **stack = (InterpBasicBlock**)mono_mempool_alloc0 (td->mempool, sizeof (InterpBasicBlock*) * td->bb_count);
td->bblocks = (InterpBasicBlock**)mono_mempool_alloc0 (td->opt_mempool, sizeof (InterpBasicBlock*) * td->bb_count);
InterpBasicBlock **stack = (InterpBasicBlock**)g_malloc0 (sizeof (InterpBasicBlock*) * td->bb_count);

g_assert (!td->entry_bb->in_count);
stack [next_stack_index++] = td->entry_bb;
Expand All @@ -558,6 +558,7 @@ dfs_visit (TransformData *td)
}
}

g_free (stack);
return dfs_index;
}

Expand Down Expand Up @@ -622,7 +623,7 @@ is_bblock_ssa_cfg (TransformData *td, InterpBasicBlock *bb)
static void
interp_compute_dominators (TransformData *td)
{
InterpBasicBlock **idoms = (InterpBasicBlock**)mono_mempool_alloc0 (td->mempool, sizeof (InterpBasicBlock*) * td->bblocks_count);
InterpBasicBlock **idoms = (InterpBasicBlock**)mono_mempool_alloc0 (td->opt_mempool, sizeof (InterpBasicBlock*) * td->bblocks_count);

idoms [0] = td->entry_bb;
gboolean changed = TRUE;
Expand Down Expand Up @@ -698,7 +699,7 @@ static void
interp_compute_dominance_frontier (TransformData *td)
{
int bitsize = mono_bitset_alloc_size (td->bblocks_count, 0);
char *mem = (char *)mono_mempool_alloc0 (td->mempool, bitsize * td->bblocks_count);
char *mem = (char *)mono_mempool_alloc0 (td->opt_mempool, bitsize * td->bblocks_count);

for (int i = 0; i < td->bblocks_count; i++) {
td->bblocks [i]->dfrontier = mono_bitset_mem_new (mem, td->bblocks_count, 0);
Expand Down Expand Up @@ -975,7 +976,7 @@ static void
compute_gen_kill_sets (TransformData *td)
{
int bitsize = mono_bitset_alloc_size (td->renamable_vars_size, 0);
char *mem = (char *)mono_mempool_alloc0 (td->mempool, bitsize * td->bblocks_count * 4);
char *mem = (char *)mono_mempool_alloc0 (td->opt_mempool, bitsize * td->bblocks_count * 4);

for (int i = 0; i < td->bblocks_count; i++) {
InterpBasicBlock *bb = td->bblocks [i];
Expand Down Expand Up @@ -1094,7 +1095,7 @@ bb_insert_phi (TransformData *td, InterpBasicBlock *bb, int var)
g_print ("BB%d NEW_PHI %d\n", bb->index, var);

phi->dreg = var;
phi->info.args = (int*)mono_mempool_alloc (td->mempool, (bb->in_count + 1) * sizeof (int));
phi->info.args = (int*)mono_mempool_alloc (td->opt_mempool, (bb->in_count + 1) * sizeof (int));
int i;
for (i = 0; i < bb->in_count; i++)
phi->info.args [i] = var;
Expand All @@ -1109,7 +1110,7 @@ bb_insert_dead_phi (TransformData *td, InterpBasicBlock *bb, int var)
bitset = bb->first_ins->info.dead_phi_vars;
} else {
InterpInst *phi = interp_insert_ins_bb (td, bb, NULL, MINT_DEAD_PHI);
gpointer mem = mono_mempool_alloc0 (td->mempool, mono_bitset_alloc_size (td->renamable_vars_size, 0));
gpointer mem = mono_mempool_alloc0 (td->opt_mempool, mono_bitset_alloc_size (td->renamable_vars_size, 0));
phi->info.dead_phi_vars = bitset = mono_bitset_mem_new (mem, td->renamable_vars_size, 0);
}
int ext_index = td->vars [var].ext_index;
Expand Down Expand Up @@ -1322,7 +1323,7 @@ rename_vars_in_bb_start (TransformData *td, InterpBasicBlock *bb)
if (renamed_var != -1) {
g_assert (td->vars [renamed_var].renamed_ssa_fixed);
int renamed_var_ext = td->vars [renamed_var].ext_index;
InterpLivenessPosition *liveness_ptr = (InterpLivenessPosition*)mono_mempool_alloc (td->mempool, sizeof (InterpLivenessPosition));
InterpLivenessPosition *liveness_ptr = (InterpLivenessPosition*)mono_mempool_alloc (td->opt_mempool, sizeof (InterpLivenessPosition));
*liveness_ptr = current_liveness;
td->renamed_fixed_vars [renamed_var_ext].live_limit_bblocks = g_slist_prepend (td->renamed_fixed_vars [renamed_var_ext].live_limit_bblocks, liveness_ptr);
}
Expand All @@ -1347,7 +1348,7 @@ rename_vars_in_bb_end (TransformData *td, InterpBasicBlock *bb)
g_assert (td->vars [renamed_var].renamed_ssa_fixed);
int renamed_var_ext = td->vars [renamed_var].ext_index;
if (!td->renamed_fixed_vars [renamed_var_ext].live_out_bblocks) {
gpointer mem = mono_mempool_alloc0 (td->mempool, mono_bitset_alloc_size (td->bblocks_count, 0));
gpointer mem = mono_mempool_alloc0 (td->opt_mempool, mono_bitset_alloc_size (td->bblocks_count, 0));
td->renamed_fixed_vars [renamed_var_ext].live_out_bblocks = mono_bitset_mem_new (mem, td->bblocks_count, 0);
}

Expand Down Expand Up @@ -1386,8 +1387,8 @@ static void
rename_vars (TransformData *td)
{
int next_stack_index = 0;
InterpBasicBlock **stack = (InterpBasicBlock**)mono_mempool_alloc0 (td->mempool, sizeof (InterpBasicBlock*) * td->bblocks_count);
gboolean *bb_status = (gboolean*)mono_mempool_alloc0 (td->mempool, sizeof (InterpBasicBlock*) * td->bblocks_count);
InterpBasicBlock **stack = (InterpBasicBlock**)g_malloc0 (sizeof (InterpBasicBlock*) * td->bblocks_count);
gboolean *bb_status = (gboolean*)g_malloc0 (sizeof (InterpBasicBlock*) * td->bblocks_count);

stack [next_stack_index++] = td->entry_bb;

Expand All @@ -1414,6 +1415,9 @@ rename_vars (TransformData *td)
}
}

g_free (stack);
g_free (bb_status);

if (td->verbose_level) {
g_print ("\nFIXED SSA VARS LIVENESS LIMIT:\n");
for (unsigned int i = 0; i < td->renamed_fixed_vars_size; i++) {
Expand Down Expand Up @@ -1718,7 +1722,7 @@ interp_link_bblocks (TransformData *td, InterpBasicBlock *from, InterpBasicBlock
static void
interp_mark_reachable_bblocks (TransformData *td)
{
InterpBasicBlock **queue = mono_mempool_alloc0 (td->mempool, td->bb_count * sizeof (InterpBasicBlock*));
InterpBasicBlock **queue = g_malloc0 (td->bb_count * sizeof (InterpBasicBlock*));
InterpBasicBlock *current;
int cur_index = 0;
int next_position = 0;
Expand Down Expand Up @@ -1761,6 +1765,8 @@ interp_mark_reachable_bblocks (TransformData *td)
if (needs_retry)
goto retry;
}

g_free (queue);
}

/**
Expand Down Expand Up @@ -2714,7 +2720,7 @@ interp_cprop (TransformData *td)
// FIXME
// There is no need to zero, if we pay attention to phi args vars. They
// can be used before the definition.
td->var_values = (InterpVarValue*) mono_mempool_alloc0 (td->mempool, td->vars_size * sizeof (InterpVarValue));
td->var_values = (InterpVarValue*) g_malloc0 (td->vars_size * sizeof (InterpVarValue));

// Traverse in dfs order. This guarantees that we always reach the definition first before the
// use of the var. Exception is only for phi nodes, where we don't care about the definition
Expand Down Expand Up @@ -3790,8 +3796,7 @@ interp_prepare_no_ssa_opt (TransformData *td)
td->vars [i].has_indirects = (td->vars [i].indirects > 0) ? TRUE : FALSE;
}

if (!td->bblocks)
td->bblocks = (InterpBasicBlock**)mono_mempool_alloc0 (td->mempool, sizeof (InterpBasicBlock*) * td->bb_count);
td->bblocks = (InterpBasicBlock**)mono_mempool_alloc0 (td->opt_mempool, sizeof (InterpBasicBlock*) * td->bb_count);

int i = 0;
for (InterpBasicBlock *bb = td->entry_bb; bb != NULL; bb = bb->next_bb) {
Expand Down Expand Up @@ -3861,6 +3866,14 @@ interp_optimize_code (TransformData *td)
g_print ("Huge method. SSA disabled for first iteration\n");
}
optimization_retry:
if (td->opt_mempool != NULL)
mono_mempool_destroy (td->opt_mempool);
if (td->var_values != NULL) {
g_free (td->var_values);
td->var_values = NULL;
}
td->opt_mempool = mono_mempool_new ();

td->need_optimization_retry = FALSE;

if (td->disable_ssa)
Expand Down Expand Up @@ -3897,6 +3910,8 @@ interp_optimize_code (TransformData *td)
goto optimization_retry;
}

mono_mempool_destroy (td->opt_mempool);

if (td->verbose_level) {
g_print ("\nOptimized IR:\n");
mono_interp_print_td_code (td);
Expand Down
6 changes: 6 additions & 0 deletions src/mono/mono/mini/interp/transform.c
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Original file line number Diff line number Diff line change
Expand Up @@ -8875,6 +8875,12 @@ generate (MonoMethod *method, MonoMethodHeader *header, InterpMethod *rtm, MonoG
if (td->optimized) {
MONO_TIME_TRACK (mono_interp_stats.optimize_time, interp_optimize_code (td));
interp_alloc_offsets (td);
// Offset allocator uses computed ref counts from var values. We have to free this
// table later here.
if (td->var_values != NULL) {
g_free (td->var_values);
td->var_values = NULL;
}
#if HOST_BROWSER
if (mono_interp_opt & INTERP_OPT_JITERPRETER)
jiterp_insert_entry_points (rtm, td);
Expand Down
1 change: 1 addition & 0 deletions src/mono/mono/mini/interp/transform.h
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Original file line number Diff line number Diff line change
Expand Up @@ -324,6 +324,7 @@ typedef struct
InterpBasicBlock **idoms; // immediate dominator for each bblock, index from reverse postorder dfs
int bb_count;
MonoMemPool *mempool;
MonoMemPool *opt_mempool;
MonoMemoryManager *mem_manager;
GList *basic_blocks;
GPtrArray *relocs;
Expand Down

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