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3f6c1ee0f5
ir/ir_sccp.c
Dmitry Stogov 3f6c1ee0f5 cleanup
2022-06-15 22:48:19 +03:00

668 lines
18 KiB
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#include "ir.h"
#include "ir_private.h"
/* SCCP - Sparse Conditional Constant Propagation + Copy Propagation
*
* M. N. Wegman and F. K. Zadeck. "Constant propagation with conditional branches"
* ACM Transactions on Programming Languages and Systems, 13(2):181-210, April 1991
*/
#define IR_TOP IR_UNUSED
#define IR_BOTTOM IR_LAST_OP
#define IR_MAKE_TOP(ref) do {IR_ASSERT(ref > 0); _values[ref].optx = IR_TOP;} while (0)
#define IR_MAKE_BOTTOM(ref) do {IR_ASSERT(ref > 0); _values[ref].optx = IR_BOTTOM;} while (0)
#define IR_IS_TOP(ref) (ref >= 0 && _values[ref].optx == IR_TOP)
#define IR_IS_BOTTOM(ref) (ref >= 0 && _values[ref].optx == IR_BOTTOM)
#define IR_IS_REACHABLE(ref) (ref >= 0 && _values[ref].optx != IR_TOP)
#define IR_COMBO_COPY_PROPAGATION 1
#define IR_COMBO_RESTART 1
#if IR_COMBO_COPY_PROPAGATION
IR_ALWAYS_INLINE ir_ref ir_sccp_identity(ir_insn *_values, ir_ref a)
{
if (a > 0 && _values[a].op == IR_COPY) {
a = _values[a].op1;
IR_ASSERT(a <= 0 || _values[a].op != IR_COPY);
}
return a;
}
#endif
static ir_ref ir_sccp_fold(ir_ctx *ctx, ir_insn *_values, ir_ref res, uint32_t opt, ir_ref op1, ir_ref op2, ir_ref op3)
{
ir_insn *op1_insn, *op2_insn, *op3_insn, *insn;
#if IR_COMBO_RESTART
restart:
#endif
#if IR_COMBO_COPY_PROPAGATION
op1 = ir_sccp_identity(_values, op1);
op2 = ir_sccp_identity(_values, op2);
op3 = ir_sccp_identity(_values, op3);
#endif
op1_insn = (op1 > 0 && IR_IS_CONST_OP(_values[op1].op)) ? _values + op1 : ctx->ir_base + op1;
op2_insn = (op2 > 0 && IR_IS_CONST_OP(_values[op2].op)) ? _values + op2 : ctx->ir_base + op2;
op3_insn = (op3 > 0 && IR_IS_CONST_OP(_values[op3].op)) ? _values + op3 : ctx->ir_base + op3;
switch (ir_folding(ctx, opt, op1, op2, op3, op1_insn, op2_insn, op3_insn)) {
case IR_FOLD_DO_RESTART:
#if IR_COMBO_RESTART
opt = ctx->fold_insn.optx;
op1 = ctx->fold_insn.op1;
op2 = ctx->fold_insn.op2;
op3 = ctx->fold_insn.op3;
goto restart;
#endif
case IR_FOLD_DO_CSE:
case IR_FOLD_DO_EMIT:
IR_MAKE_BOTTOM(res);
return 1;
case IR_FOLD_DO_COPY:
op1 = ctx->fold_insn.op1;
#if IR_COMBO_COPY_PROPAGATION
op1 = ir_sccp_identity(_values, op1);
#endif
insn = (op1 > 0 && IR_IS_CONST_OP(_values[op1].op)) ? _values + op1 : ctx->ir_base + op1;
if (IR_IS_CONST_OP(insn->op)) {
/* pass */
#if IR_COMBO_COPY_PROPAGATION
} else if (IR_IS_TOP(res)) {
_values[res].optx = IR_OPT(IR_COPY, insn->type);
_values[res].op1 = op1;
return 1;
} else if (_values[res].op == IR_COPY && _values[res].op1 == op1) {
return 0;
#endif
} else {
IR_MAKE_BOTTOM(res);
return 1;
}
break;
case IR_FOLD_DO_CONST:
insn = &ctx->fold_insn;
break;
default:
IR_ASSERT(0);
return 0;
}
if (IR_IS_TOP(res)) {
_values[res].optx = IR_OPT(insn->type, insn->type);
_values[res].val.u64 = insn->val.u64;
return 1;
} else if (_values[res].opt != IR_OPT(insn->type, insn->type) || _values[res].val.u64 != insn->val.u64) {
IR_MAKE_BOTTOM(res);
return 1;
}
return 0;
}
static bool ir_sccp_join_values(ir_ctx *ctx, ir_insn *_values, ir_ref a, ir_ref b)
{
ir_insn *v;
if (!IR_IS_BOTTOM(a) && !IR_IS_TOP(b)) {
b = ir_sccp_identity(_values, b);
v = IR_IS_CONST_REF(b) ? &ctx->ir_base[b] : &_values[b];
if (IR_IS_TOP(a)) {
#if IR_COMBO_COPY_PROPAGATION
if (v->op == IR_BOTTOM) {
_values[a].optx = IR_OPT(IR_COPY, ctx->ir_base[b].type);
_values[a].op1 = b;
return 1;
}
#endif
_values[a].optx = v->opt;
_values[a].val.u64 = v->val.u64;
return 1;
} else if (_values[a].opt == v->opt && _values[a].val.u64 == v->val.u64) {
/* pass */
#if IR_COMBO_COPY_PROPAGATION
} else if (_values[a].op == IR_COPY && _values[a].op1 == b) {
/* pass */
#endif
} else {
IR_MAKE_BOTTOM(a);
return 1;
}
}
return 0;
}
static bool ir_sccp_is_true(ir_ctx *ctx, ir_insn *_values, ir_ref a)
{
ir_insn *v = IR_IS_CONST_REF(a) ? &ctx->ir_base[a] : &_values[a];
if (v->type == IR_BOOL) {
return v->val.b;
}
IR_ASSERT(0 && "NYI");
return 0;
}
static bool ir_sccp_is_equal(ir_ctx *ctx, ir_insn *_values, ir_ref a, ir_ref b)
{
ir_insn *v1 = IR_IS_CONST_REF(a) ? &ctx->ir_base[a] : &_values[a];
ir_insn *v2 = IR_IS_CONST_REF(b) ? &ctx->ir_base[b] : &_values[b];
return v1->val.u64 == v2->val.u64;
}
static void ir_sccp_remove_from_use_list(ir_ctx *ctx, ir_ref from, ir_ref ref)
{
ir_ref j, n, *p, *q, use;
ir_use_list *use_list = &ctx->use_lists[from];
ir_ref skip = 0;
n = use_list->count;
for (j = 0, p = q = &ctx->use_edges[use_list->refs]; j < n; j++, p++) {
use = *p;
if (use == ref) {
skip++;
} else {
if (p != q) {
*q = use;
}
q++;
}
}
use_list->count -= skip;
#if IR_COMBO_COPY_PROPAGATION
if (skip) {
do {
*q = IR_UNUSED;
q++;
} while (--skip);
}
#endif
}
#if IR_COMBO_COPY_PROPAGATION
static void ir_sccp_add_to_use_list(ir_ctx *ctx, ir_ref to, ir_ref ref)
{
ir_use_list *use_list = &ctx->use_lists[to];
ir_ref n = use_list->refs + use_list->count;
if (ctx->use_edges[n] == IR_UNUSED) {
ctx->use_edges[n] = ref;
use_list->count++;
} else {
IR_ASSERT(0 && "NIY: insert def->use edges"); // TODO:
}
}
#endif
static void ir_sccp_replace_insn(ir_ctx *ctx, ir_insn *_values, ir_ref ref, ir_ref new_ref)
{
ir_ref j, n, *p, use, k, l;
ir_insn *insn;
ir_use_list *use_list;
IR_ASSERT(ref != new_ref);
insn = &ctx->ir_base[ref];
n = ir_input_edges_count(ctx, insn);
for (j = 1, p = insn->ops + 1; j <= n; j++, p++) {
ir_ref input = *p;
if (input > 0) {
ir_sccp_remove_from_use_list(ctx, input, ref);
}
}
use_list = &ctx->use_lists[ref];
n = use_list->count;
for (j = 0, p = &ctx->use_edges[use_list->refs]; j < n; j++, p++) {
use = *p;
if (IR_IS_REACHABLE(use)) {
insn = &ctx->ir_base[use];
l = ir_input_edges_count(ctx, insn);
for (k = 1; k <= l; k++) {
if (insn->ops[k] == ref) {
insn->ops[k] = new_ref;
}
}
#if IR_COMBO_COPY_PROPAGATION
if (new_ref > 0 && IR_IS_BOTTOM(use)) {
ir_sccp_add_to_use_list(ctx, new_ref, use);
}
#endif
// TODO: Folding ???
}
}
use_list->refs = 0;
use_list->count = 0;
insn = &ctx->ir_base[ref];
n = ir_input_edges_count(ctx, insn);
for (j = 1; j <= n; j++) {
insn->ops[j] = IR_UNUSED;
}
insn->optx = IR_NOP;
}
static void ir_sccp_replace_use(ir_ctx *ctx, ir_ref ref, ir_ref use, ir_ref new_use)
{
ir_use_list *use_list = &ctx->use_lists[ref];
ir_ref i, n, *p;
n = use_list->count;
for (i = 0, p = &ctx->use_edges[use_list->refs]; i < n; i++, p++) {
if (*p == use) {
*p = new_use;
}
}
}
static void ir_sccp_remove_if(ir_ctx *ctx, ir_insn *_values, ir_ref ref, ir_ref dst)
{
ir_ref j, n, *p, use, next;
ir_insn *insn, *next_insn;
ir_use_list *use_list = &ctx->use_lists[ref];
insn = &ctx->ir_base[ref];
n = use_list->count;
for (j = 0, p = &ctx->use_edges[use_list->refs]; j < n; j++, p++) {
use = *p;
if (use == dst) {
next = ctx->use_edges[ctx->use_lists[use].refs];
next_insn = &ctx->ir_base[next];
/* remove IF and IF_TRUE/FALSE from double linked control list */
next_insn->op1 = insn->op1;
ir_sccp_replace_use(ctx, insn->op1, ref, next);
/* remove IF and IF_TRUE/FALSE instructions */
ir_sccp_replace_insn(ctx, _values, ref, IR_UNUSED);
ir_sccp_replace_insn(ctx, _values, use, IR_UNUSED);
break;
}
}
}
static void ir_sccp_remove_unreachable_merge_inputs(ir_ctx *ctx, ir_insn *_values, ir_ref ref, ir_ref unreachable_inputs)
{
ir_ref i, j, n, k, *p, use;
ir_insn *insn, *use_insn;
ir_use_list *use_list;
ir_bitset life_inputs;
insn = &ctx->ir_base[ref];
n = insn->inputs_count;
if (n == 0) {
n = 2;
}
if (n - unreachable_inputs == 1) {
/* remove MERGE completely */
for (j = 1; j <= n; j++) {
if (insn->ops[j] && IR_IS_REACHABLE(insn->ops[j])) {
ir_ref prev, next = IR_UNUSED, input = insn->ops[j];
ir_insn *next_insn = NULL, *input_insn = &ctx->ir_base[input];
IR_ASSERT(input_insn->op == IR_END);
prev = input_insn->op1;
use_list = &ctx->use_lists[ref];
for (k = 0, p = &ctx->use_edges[use_list->refs]; k < use_list->count; k++, p++) {
use = *p;
use_insn = &ctx->ir_base[use];
if (use_insn->op == IR_PHI) {
IR_ASSERT(0 && "NIY: ???"); // TODO:
} else {
next = use;
next_insn = use_insn;
}
}
IR_ASSERT(prev && next);
/* remove MERGE and input END from double linked control list */
next_insn->op1 = prev;
ir_sccp_replace_use(ctx, prev, input, next);
/* remove MERGE and input END instructions */
ir_sccp_replace_insn(ctx, _values, ref, IR_UNUSED);
ir_sccp_replace_insn(ctx, _values, input, IR_UNUSED);
break;
}
}
} else {
IR_ASSERT(insn->op == IR_MERGE);
n = insn->inputs_count;
if (n == 0) {
n = 3;
}
i = 1;
life_inputs = ir_bitset_malloc(n + 1);
for (j = 1; j <= n; j++) {
if (insn->ops[j]) {
if (i != j) {
insn->ops[i] = insn->ops[j];
}
ir_bitset_incl(life_inputs, j);
i++;
}
}
i--;
if (i == 2) {
i = 0;
}
insn->inputs_count = i;
n++;
use_list = &ctx->use_lists[ref];
for (k = 0, p = &ctx->use_edges[use_list->refs]; k < use_list->count; k++, p++) {
use = *p;
use_insn = &ctx->ir_base[use];
if (use_insn->op == IR_PHI) {
i = 2;
for (j = 2; j <= n; j++) {
if (ir_bitset_in(life_inputs, j - 1)) {
if (i != j) {
use_insn->ops[i] = use_insn->ops[j];
}
i++;
}
}
}
}
}
}
static void ir_sccp_mark_reachable_data(ir_ctx *ctx, ir_bitset worklist, ir_insn *_values, ir_insn *insn)
{
int j, n, use;
uint32_t flags = ir_op_flags[insn->op];
n = ir_input_edges_count(ctx, insn);
for (j = 1; j <= n; j++) {
if (IR_OPND_KIND(flags, j) == IR_OPND_DATA || IR_OPND_KIND(flags, j) == IR_OPND_VAR) {
use = insn->ops[j];
if (use > 0 && IR_IS_TOP(use) && !ir_bitset_in(worklist, use)) {
ir_bitset_incl(worklist, use);
ir_sccp_mark_reachable_data(ctx, worklist, _values, &ctx->ir_base[use]);
}
}
}
}
int ir_sccp(ir_ctx *ctx)
{
ir_ref i, j, n, *p, use;
ir_use_list *use_list;
ir_insn *insn, *use_insn;
uint32_t flags;
uint32_t len = ir_bitset_len(ctx->insns_count);
ir_bitset worklist = ir_bitset_malloc(ctx->insns_count);
ir_insn *_values = ir_mem_calloc(ctx->insns_count, sizeof(ir_insn));
ctx->flags |= IR_OPT_IN_SCCP;
/* A bit modified SCCP algorith of M. N. Wegman and F. K. Zadeck */
ir_bitset_incl(worklist, 1);
while ((i = ir_bitset_pop_first(worklist, len)) >= 0) {
insn = &ctx->ir_base[i];
flags = ir_op_flags[insn->op];
if (flags & IR_OP_FLAG_DATA) {
if (insn->op == IR_PHI) {
ir_insn *merge_insn = &ctx->ir_base[insn->op1];
bool changed = 0;
n = ir_input_edges_count(ctx, insn);
if (IR_IS_TOP(i)) {
for (j = 0; j < (n>>2); j++) {
_values[i+j+1].optx = IR_BOTTOM; /* keep the tail of a long multislot instruction */
}
}
for (j = 1; j <= n; j++) {
if (merge_insn->ops[j] && IR_IS_REACHABLE(merge_insn->ops[j])) {
if (ir_sccp_join_values(ctx, _values, i, insn->ops[j + 1])) {
changed = 1;
}
}
}
if (!changed) {
continue;
}
} else if (IR_IS_FOLDABLE_OP(insn->op)) {
// bool has_bottom = 0;
bool has_top = 0;
n = ir_input_edges_count(ctx, insn);
for (j = 1; j <= n; j++) {
// if (IR_IS_BOTTOM(insn->ops[j])) {
// has_bottom = 1;
// } else
if (IR_IS_TOP(insn->ops[j])) {
has_top = 1;
}
}
if (has_top) {
continue;
}
if (!ir_sccp_fold(ctx, _values, i, insn->opt, insn->op1, insn->op2, insn->op3)) {
continue;
}
} else {
IR_MAKE_BOTTOM(i);
}
} else {
if (insn->op == IR_IF) {
if (IR_IS_TOP(insn->op2)) {
continue;
}
if (!IR_IS_BOTTOM(insn->op2)) {
bool b = ir_sccp_is_true(ctx, _values, insn->op2);
use_list = &ctx->use_lists[i];
n = use_list->count;
for (j = 0, p = &ctx->use_edges[use_list->refs]; j < n; j++, p++) {
use = *p;
IR_ASSERT(use > 0);
use_insn = &ctx->ir_base[use];
IR_ASSERT(use_insn->op == IR_IF_TRUE || use_insn->op == IR_IF_FALSE);
if ((use_insn->op == IR_IF_TRUE) == b) {
if (IR_IS_TOP(i)) {
_values[i].optx = IR_IF;
_values[i].op1 = use;
} else if (_values[i].optx != IR_IF || _values[i].op1 != use) {
IR_MAKE_BOTTOM(i);
}
if (!IR_IS_BOTTOM(use)) {
ir_bitset_incl(worklist, use);
}
break;
}
}
continue;
}
IR_MAKE_BOTTOM(i);
} else if (insn->op == IR_SWITCH) {
if (IR_IS_TOP(insn->op2)) {
continue;
}
if (!IR_IS_BOTTOM(insn->op2)) {
ir_ref default_case = IR_UNUSED;
use_list = &ctx->use_lists[i];
n = use_list->count;
for (j = 0, p = &ctx->use_edges[use_list->refs]; j < n; j++, p++) {
use = *p;
IR_ASSERT(use > 0);
use_insn = &ctx->ir_base[use];
if (use_insn->op == IR_CASE_VAL) {
if (ir_sccp_is_equal(ctx, _values, insn->op2, use_insn->op2)) {
if (IR_IS_TOP(i)) {
_values[i].optx = IR_IF;
_values[i].op1 = use;
} else if (_values[i].optx != IR_IF || _values[i].op1 != use) {
IR_MAKE_BOTTOM(i);
}
if (!IR_IS_BOTTOM(use)) {
ir_bitset_incl(worklist, use);
}
default_case = IR_UNUSED;
break;
}
} else if (use_insn->op == IR_CASE_DEFAULT) {
default_case = use;
}
}
if (default_case) {
use_insn = &ctx->ir_base[default_case];
if (IR_IS_TOP(i)) {
_values[i].optx = IR_IF;
_values[i].op1 = default_case;
} else if (_values[i].optx != IR_IF || _values[i].op1 != default_case) {
IR_MAKE_BOTTOM(i);
}
if (!IR_IS_BOTTOM(default_case)) {
ir_bitset_incl(worklist, default_case);
}
}
if (!IR_IS_BOTTOM(i)) {
continue;
}
}
IR_MAKE_BOTTOM(i);
} else if (insn->op == IR_MERGE || insn->op == IR_LOOP_BEGIN) {
ir_ref unreachable_inputs = 0;
n = ir_input_edges_count(ctx, insn);
if (IR_IS_TOP(i)) {
for (j = 0; j < (n>>2); j++) {
_values[i+j+1].optx = IR_BOTTOM; /* keep the tail of a long multislot instruction */
}
}
for (j = 1; j <= n; j++) {
if (insn->ops[j]) {
if (!IR_IS_REACHABLE(insn->ops[j])) {
unreachable_inputs++;
}
}
}
if (unreachable_inputs == 0) {
IR_MAKE_BOTTOM(i);
} else if (_values[i].op1 != unreachable_inputs) {
_values[i].optx = insn->op;
_values[i].op1 = unreachable_inputs;
} else {
continue;
}
} else {
IR_MAKE_BOTTOM(i);
if (insn->op == IR_CALL || insn->op == IR_TAILCALL) {
n = ir_input_edges_count(ctx, insn);
for (j = 0; j < (n>>2); j++) {
_values[i+j+1].optx = IR_BOTTOM; /* keep the tail of a long multislot instruction */
}
}
flags = ir_op_flags[insn->op];
n = ir_input_edges_count(ctx, insn);
for (j = 1; j <= n; j++) {
if (IR_OPND_KIND(flags, j) == IR_OPND_DATA || IR_OPND_KIND(flags, j) == IR_OPND_VAR) {
use = insn->ops[j];
if (use > 0 && IR_IS_TOP(use) && !ir_bitset_in(worklist, use)) {
ir_bitset_incl(worklist, use);
ir_sccp_mark_reachable_data(ctx, worklist, _values, &ctx->ir_base[use]);
}
}
}
// ir_sccp_mark_reachable_data(ctx, worklist, _values, insn);
}
}
use_list = &ctx->use_lists[i];
n = use_list->count;
for (j = 0, p = &ctx->use_edges[use_list->refs]; j < n; j++, p++) {
use = *p;
insn = &ctx->ir_base[use];
if ((ir_op_flags[insn->op] & IR_OP_FLAG_DATA)) {
if (insn->op != IR_PHI || IR_IS_REACHABLE(insn->op1)) {
if (!IR_IS_BOTTOM(use)) {
ir_bitset_incl(worklist, use);
}
}
} else if (insn->op == IR_MERGE || insn->op == IR_LOOP_BEGIN || IR_IS_REACHABLE(insn->op1)) {
if (!IR_IS_BOTTOM(use)) {
ir_bitset_incl(worklist, use);
}
}
}
}
#ifdef IR_DEBUG
if (ctx->flags & IR_DEBUG_SCCP) {
for (i = 1; i < ctx->insns_count; i++) {
if (IR_IS_CONST_OP(_values[i].op)) {
fprintf(stderr, "%d. CONST(", i);
ir_print_const(ctx, &_values[i], stderr);
fprintf(stderr, ")\n");
#if IR_COMBO_COPY_PROPAGATION
} else if (_values[i].op == IR_COPY) {
fprintf(stderr, "%d. COPY(%d)\n", i, _values[i].op1);
#endif
} else if (IR_IS_TOP(i)) {
fprintf(stderr, "%d. TOP\n", i);
} else if (_values[i].op == IR_IF) {
fprintf(stderr, "%d. IF(%d)\n", i, _values[i].op1);
} else if (_values[i].op == IR_MERGE || _values[i].op == IR_LOOP_BEGIN) {
fprintf(stderr, "%d. MERGE(%d)\n", i, _values[i].op1);
} else if (!IR_IS_BOTTOM(i)) {
fprintf(stderr, "%d. %d\n", i, _values[i].op);
}
}
}
#endif
for (i = 1; i < ctx->insns_count; i++) {
if (IR_IS_CONST_OP(_values[i].op)) {
/* replace instruction by constant */
j = ir_const(ctx, _values[i].val, _values[i].type);
ir_sccp_replace_insn(ctx, _values, i, j);
#if IR_COMBO_COPY_PROPAGATION
} else if (_values[i].op == IR_COPY) {
ir_sccp_replace_insn(ctx, _values, i, _values[i].op1);
#endif
} else if (IR_IS_TOP(i)) {
/* remove unreachable instruction */
insn = &ctx->ir_base[i];
if (ir_op_flags[insn->op] & IR_OP_FLAG_DATA) {
if (insn->op != IR_PARAM && insn->op != IR_VAR) {
ir_sccp_replace_insn(ctx, _values, i, IR_UNUSED);
}
} else {
if (ir_op_flags[insn->op] & IR_OP_FLAG_TERMINATOR) {
ir_ref ref = ctx->ir_base[1].op1;
if (ref == i) {
ctx->ir_base[1].op1 = insn->op3;
} else {
do {
if (ctx->ir_base[ref].op3 == i) {
ctx->ir_base[ref].op3 = insn->op3;
break;
}
ref = ctx->ir_base[ref].op3;
} while (ref);
}
}
ir_sccp_replace_insn(ctx, _values, i, IR_UNUSED);
}
} else if (_values[i].op == IR_IF) {
/* remove one way IF/SWITCH */
ir_sccp_remove_if(ctx, _values, i, _values[i].op1);
} else if (_values[i].op == IR_MERGE || _values[i].op == IR_LOOP_BEGIN) {
/* schedule merge to remove unreachable MERGE inputs */
ir_bitset_incl(worklist, i);
}
}
while ((i = ir_bitset_pop_first(worklist, len)) >= 0) {
/* remove unreachable MERGE inputs */
ir_sccp_remove_unreachable_merge_inputs(ctx, _values, i, _values[i].op1);
}
ir_mem_free(_values);
ir_mem_free(worklist);
ctx->flags &= ~IR_OPT_IN_SCCP;
return 1;
}
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