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Allow removing of partially aliased loads in iterative optimization pass
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@dstogov
dstogov committed Feb 18, 2025
1 parent 77da032 commit e534ff3
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Showing 2 changed files with 61 additions and 31 deletions.
62 changes: 34 additions & 28 deletions ir.c
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Original file line number Diff line number Diff line change
Expand Up @@ -2015,7 +2015,7 @@ ir_alias ir_check_partial_aliasing(const ir_ctx *ctx, ir_ref addr1, ir_ref addr2
return IR_MAY_ALIAS;
}

IR_ALWAYS_INLINE ir_ref ir_find_aliasing_load_i(ir_ctx *ctx, ir_ref ref, ir_type type, ir_ref addr, ir_ref limit, bool allow_casting)
IR_ALWAYS_INLINE ir_ref ir_find_aliasing_load_i(ir_ctx *ctx, ir_ref ref, ir_type type, ir_ref addr, ir_ref limit)
{
ir_insn *insn;
uint32_t modified_regset = 0;
Expand All @@ -2026,13 +2026,11 @@ IR_ALWAYS_INLINE ir_ref ir_find_aliasing_load_i(ir_ctx *ctx, ir_ref ref, ir_type
if (insn->op2 == addr) {
if (insn->type == type) {
return ref; /* load forwarding (L2L) */
} else if (!allow_casting) {
/* pass */
} else if (ir_type_size[insn->type] == ir_type_size[type]) {
return ir_fold1(ctx, IR_OPT(IR_BITCAST, type), ref); /* load forwarding with bitcast (L2L) */
return ref; /* load forwarding with bitcast (L2L) */
} else if (ir_type_size[insn->type] > ir_type_size[type]
&& IR_IS_TYPE_INT(type) && IR_IS_TYPE_INT(insn->type)) {
return ir_fold1(ctx, IR_OPT(IR_TRUNC, type), ref); /* partial load forwarding (L2L) */
return ref; /* partial load forwarding (L2L) */
}
}
} else if (insn->op == IR_STORE) {
Expand All @@ -2045,13 +2043,11 @@ IR_ALWAYS_INLINE ir_ref ir_find_aliasing_load_i(ir_ctx *ctx, ir_ref ref, ir_type
return IR_UNUSED;
} else if (type2 == type) {
return insn->op3; /* store forwarding (S2L) */
} else if (!allow_casting) {
return IR_UNUSED;
} else if (ir_type_size[type2] == ir_type_size[type]) {
return ir_fold1(ctx, IR_OPT(IR_BITCAST, type), insn->op3); /* store forwarding with bitcast (S2L) */
return insn->op3; /* store forwarding with bitcast (S2L) */
} else if (ir_type_size[type2] > ir_type_size[type]
&& IR_IS_TYPE_INT(type) && IR_IS_TYPE_INT(type2)) {
return ir_fold1(ctx, IR_OPT(IR_TRUNC, type), insn->op3); /* partial store forwarding (S2L) */
return insn->op3; /* partial store forwarding (S2L) */
} else {
return IR_UNUSED;
}
Expand All @@ -2071,10 +2067,10 @@ IR_ALWAYS_INLINE ir_ref ir_find_aliasing_load_i(ir_ctx *ctx, ir_ref ref, ir_type

ir_ref ir_find_aliasing_load(ir_ctx *ctx, ir_ref ref, ir_type type, ir_ref addr)
{
return ir_find_aliasing_load_i(ctx, ref, type, addr, (addr > 0 && addr < ref) ? addr : 1, 0);
return ir_find_aliasing_load_i(ctx, ref, type, addr, (addr > 0 && addr < ref) ? addr : 1);
}

IR_ALWAYS_INLINE ir_ref ir_find_aliasing_vload_i(ir_ctx *ctx, ir_ref ref, ir_type type, ir_ref var, bool allow_casting)
IR_ALWAYS_INLINE ir_ref ir_find_aliasing_vload_i(ir_ctx *ctx, ir_ref ref, ir_type type, ir_ref var)
{
ir_insn *insn;

Expand All @@ -2084,8 +2080,6 @@ IR_ALWAYS_INLINE ir_ref ir_find_aliasing_vload_i(ir_ctx *ctx, ir_ref ref, ir_typ
if (insn->op2 == var) {
if (insn->type == type) {
return ref; /* load forwarding (L2L) */
} else if (!allow_casting) {
/* pass */;
} else if (ir_type_size[insn->type] == ir_type_size[type]) {
return ir_fold1(ctx, IR_OPT(IR_BITCAST, type), ref); /* load forwarding with bitcast (L2L) */
} else if (ir_type_size[insn->type] > ir_type_size[type]
Expand All @@ -2099,8 +2093,6 @@ IR_ALWAYS_INLINE ir_ref ir_find_aliasing_vload_i(ir_ctx *ctx, ir_ref ref, ir_typ
if (insn->op2 == var) {
if (type2 == type) {
return insn->op3; /* store forwarding (S2L) */
} else if (!allow_casting) {
break;
} else if (ir_type_size[type2] == ir_type_size[type]) {
return ir_fold1(ctx, IR_OPT(IR_BITCAST, type), insn->op3); /* store forwarding with bitcast (S2L) */
} else if (ir_type_size[type2] > ir_type_size[type]
Expand All @@ -2121,7 +2113,7 @@ IR_ALWAYS_INLINE ir_ref ir_find_aliasing_vload_i(ir_ctx *ctx, ir_ref ref, ir_typ

ir_ref ir_find_aliasing_vload(ir_ctx *ctx, ir_ref ref, ir_type type, ir_ref var)
{
return ir_find_aliasing_vload_i(ctx, ref, type, var, 0);
return ir_find_aliasing_vload_i(ctx, ref, type, var);
}

IR_ALWAYS_INLINE ir_ref ir_find_aliasing_store_i(ir_ctx *ctx, ir_ref ref, ir_ref addr, ir_ref val, ir_ref limit)
Expand Down Expand Up @@ -3120,16 +3112,23 @@ void _ir_AFREE(ir_ctx *ctx, ir_ref size)

ir_ref _ir_VLOAD(ir_ctx *ctx, ir_type type, ir_ref var)
{
ir_ref ref = IR_UNUSED;
ir_ref ref;

IR_ASSERT(ctx->control);
if (EXPECTED(ctx->flags & IR_OPT_FOLDING)) {
ref = ir_find_aliasing_vload_i(ctx, ctx->control, type, var, 1);
}
if (!ref) {
ctx->control = ref = ir_emit2(ctx, IR_OPT(IR_VLOAD, type), ctx->control, var);
ref = ir_find_aliasing_vload_i(ctx, ctx->control, type, var);
if (ref) {
ir_insn *insn = &ctx->ir_base[ref];
if (insn->type == type) {
return ref;
} else if (ir_type_size[insn->type] == ir_type_size[type]) {
return ir_fold1(ctx, IR_OPT(IR_BITCAST, type), ref); /* load forwarding with bitcast (L2L) */
} else {
return ir_fold1(ctx, IR_OPT(IR_TRUNC, type), ref); /* partial load forwarding (L2L) */
}
}
}
return ref;
return ctx->control = ir_emit2(ctx, IR_OPT(IR_VLOAD, type), ctx->control, var);
}

void _ir_VSTORE(ir_ctx *ctx, ir_ref var, ir_ref val)
Expand Down Expand Up @@ -3164,19 +3163,26 @@ void _ir_RSTORE(ir_ctx *ctx, ir_ref reg, ir_ref val)

ir_ref _ir_LOAD(ir_ctx *ctx, ir_type type, ir_ref addr)
{
ir_ref ref = IR_UNUSED;
ir_ref ref;

IR_ASSERT(ctx->control);
if (EXPECTED(ctx->flags & IR_OPT_FOLDING)) {
if (ctx->ir_base[addr].op == IR_VADDR) {
return _ir_VLOAD(ctx, type, ctx->ir_base[addr].op1);
}
ref = ir_find_aliasing_load_i(ctx, ctx->control, type, addr, (addr > 0) ? addr : 1, 1);
}
if (!ref) {
ctx->control = ref = ir_emit2(ctx, IR_OPT(IR_LOAD, type), ctx->control, addr);
ref = ir_find_aliasing_load_i(ctx, ctx->control, type, addr, (addr > 0) ? addr : 1);
if (ref) {
ir_insn *insn = &ctx->ir_base[ref];
if (insn->type == type) {
return ref;
} else if (ir_type_size[insn->type] == ir_type_size[type]) {
return ir_fold1(ctx, IR_OPT(IR_BITCAST, type), ref); /* load forwarding with bitcast (L2L) */
} else {
return ir_fold1(ctx, IR_OPT(IR_TRUNC, type), ref); /* partial load forwarding (L2L) */
}
}
}
return ref;
return ctx->control = ir_emit2(ctx, IR_OPT(IR_LOAD, type), ctx->control, addr);
}

void _ir_STORE(ir_ctx *ctx, ir_ref addr, ir_ref val)
Expand Down
30 changes: 27 additions & 3 deletions ir_sccp.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -3009,17 +3009,41 @@ void ir_iter_opt(ir_ctx *ctx, ir_bitqueue *worklist)
} else if (insn->op == IR_LOAD) {
val = ir_find_aliasing_load(ctx, insn->op1, insn->type, insn->op2);
if (val) {
ir_insn *val_insn;
ir_ref prev, next;

remove_load:
remove_aliased_load:
prev = insn->op1;
next = ir_next_control(ctx, i);
ctx->ir_base[next].op1 = prev;
ir_use_list_remove_one(ctx, i, next);
ir_use_list_replace_one(ctx, prev, i, next);
insn->op1 = IR_UNUSED;

ir_iter_replace_insn(ctx, i, val, worklist);
val_insn = &ctx->ir_base[val];
if (val_insn->type == insn->type) {
ir_iter_replace_insn(ctx, i, val, worklist);
} else {
IR_ASSERT(!IR_IS_CONST_REF(insn->op2));
ir_use_list_remove_one(ctx, insn->op2, i);
if (ir_is_dead(ctx, insn->op2)) {
/* schedule DCE */
ir_bitqueue_add(worklist, insn->op2);
}
if (!IR_IS_CONST_REF(val)) {
ir_use_list_add(ctx, val, i);
}
if (ir_type_size[val_insn->type] == ir_type_size[insn->type]) {
/* load forwarding with bitcast (L2L) */
insn->optx = IR_OPTX(IR_BITCAST, insn->type, 1);
} else {
/* partial load forwarding (L2L) */
insn->optx = IR_OPTX(IR_TRUNC, insn->type, 1);
}
insn->op1 = val;
insn->op2 = IR_UNUSED;
ir_bitqueue_add(worklist, i);
}
}
} else if (insn->op == IR_STORE) {
if (ir_find_aliasing_store(ctx, insn->op1, insn->op2, insn->op3)) {
Expand Down Expand Up @@ -3049,7 +3073,7 @@ void ir_iter_opt(ir_ctx *ctx, ir_bitqueue *worklist)
} else if (insn->op == IR_VLOAD) {
val = ir_find_aliasing_vload(ctx, insn->op1, insn->type, insn->op2);
if (val) {
goto remove_load;
goto remove_aliased_load;
}
} else if (insn->op == IR_VSTORE) {
if (ir_find_aliasing_vstore(ctx, insn->op1, insn->op2, insn->op3)) {
Expand Down

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