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The register allocator now makes a spirited attempt to honour register

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attributes when allocating. Unfortunately, backward edges don't work (because
the limited def-use chain stuff doesn't work across basic blocks). Needs more
thought.
This commit is contained in:
David Given 2016-10-09 15:09:34 +02:00
parent 38de688c5a
commit 23c3575f0f
7 changed files with 75 additions and 20 deletions
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7
mach/proto/mcg/hop.h
View file

@ -21,6 +21,11 @@ struct insel
u;
};
struct constraint
{
uint32_t attrs;
};
struct hop
{
int id;
@ -29,6 +34,8 @@ struct hop
ARRAYOF(struct insel) insels;
struct vreg* output;
PMAPOF(struct vreg, struct constraint) constraints;
ARRAYOF(struct vreg) ins;
ARRAYOF(struct vreg) outs;
ARRAYOF(struct vreg) throughs;

20
mach/proto/mcg/pass_instructionselection.c
View file

@ -78,15 +78,29 @@ static void emit_eoi(void)
hop_add_eoi_insel(current_hop);
}
static void constrain_input_reg(int child, int attr)
static struct constraint* get_constraint(struct vreg* vreg)
{
struct constraint* c = pmap_findleft(&current_hop->constraints, vreg);
if (!c)
{
c = calloc(1, sizeof(*c));
pmap_put(&current_hop->constraints, vreg, c);
}
return c;
}
static void constrain_input_reg(int child, uint32_t attr)
{
struct vreg* vreg = find_vreg_of_child(child);
struct constraint* c;
if (vreg)
array_appendu(&current_hop->ins, vreg);
get_constraint(vreg)->attrs = attr;
}
static void constrain_output_reg(int attr)
static void constrain_output_reg(uint32_t attr)
{
struct vreg* vreg = current_hop->output;
@ -95,6 +109,8 @@ static void constrain_output_reg(int attr)
array_appendu(&current_hop->outs, vreg);
vreg->defined = current_hop;
get_constraint(vreg)->attrs = attr;
}
static const struct burm_emitter_data emitter_data =

37
mach/proto/mcg/pass_registerallocator.c
View file

@ -28,7 +28,7 @@ static void wire_up_blocks_ins_outs(void)
}
}
static struct hreg* allocate_hreg(register_assignment_t* regs, struct vreg* vreg)
static struct hreg* allocate_hreg(register_assignment_t* regs, struct vreg* vreg, uint32_t attr)
{
int i;
@ -36,11 +36,14 @@ static struct hreg* allocate_hreg(register_assignment_t* regs, struct vreg* vreg
{
struct hreg* hreg = hregs.item[i];
if (!pmap_findleft(regs, hreg))
{
if (hreg->attrs & attr)
{
pmap_put(regs, hreg, vreg);
return hreg;
}
}
}
fatal("ran out of registers");
}
@ -81,7 +84,8 @@ static void select_registers(struct hop* hop,
for (i=0; i<hop->outs.count; i++)
{
struct vreg* vreg = hop->outs.item[i];
allocate_hreg(out, vreg);
struct constraint* c = pmap_findleft(&hop->constraints, vreg);
allocate_hreg(out, vreg, c->attrs);
}
}
@ -97,7 +101,7 @@ void pass_register_allocator(void)
struct basicblock* bb = dominance.preorder.item[i];
register_assignment_t* old = bb->regsin;
tracef('R', "R: allocating block %s\n", bb->name);
tracef('R', "R: considering block %s\n", bb->name);
/* Attempt to import any block input registers from a predecessor. At
* least one predecessor should export it; our graph traversal order
@ -151,21 +155,42 @@ void pass_register_allocator(void)
/* It's possible for the previous stage to fail because in in has
* clobbered the physical register we were wanting. So we need to
* allocate a new register for that phi value. */
* allocate a new register for that phi value.
*
* We don't bother allocating anything if the vreg is never used.
* */
for (j=0; j<bb->phis.count; j++)
{
struct vreg* vreg = bb->phis.item[j].left;
if (!pmap_findright(old, vreg))
allocate_hreg(old, vreg);
struct phi* phi = bb->phis.item[j].right;
if (!pmap_findright(old, vreg) && (vreg->used.count > 0))
{
struct hop* used = vreg->used.item[0];
struct constraint* c = pmap_findleft(&used->constraints, vreg);
struct hreg* hreg = allocate_hreg(old, vreg, c->attrs);
tracef('R', "R: import fallback hreg %s for phi input %%%d from %s\n",
hreg->name, vreg->id, phi->prev->name);
}
}
for (j=0; j<bb->hops.count; j++)
{
int k;
struct hop* hop = bb->hops.item[j];
register_assignment_t* in = &hop->regsin;
register_assignment_t* out = &hop->regsout;;
tracef('R', "R: %d from $%d:", hop->id, hop->ir->id);
for (k=0; k<hop->ins.count; k++)
tracef('R', " r%%%d", hop->ins.item[k]->id);
for (k=0; k<hop->throughs.count; k++)
tracef('R', " =%%%d", hop->throughs.item[k]->id);
for (k=0; k<hop->outs.count; k++)
tracef('R', " w%%%d", hop->outs.item[k]->id);
tracef('R', "\n");
select_registers(hop, old, in, out);
old = out;

17
util/mcgg/iburg.c
View file

@ -400,8 +400,8 @@ Tree tree(const struct terminfo* ti, Tree left, Tree right)
if (ti->attr && ti->attr[0])
{
nt->attr = smap_get(&registerattrs, ti->attr);
if (!nt->attr)
t->attr = smap_get(&registerattrs, ti->attr);
if (!t->attr)
yyerror("'%s' doesn't seem to be a known register attribute", ti->attr);
}
}
@ -1077,10 +1077,12 @@ static void emit_input_regs(Tree node, int* index)
Nonterm nt = node->op;
if ((nt->kind == NONTERM) && !nt->is_fragment && !node->left && !node->right)
{
uint32_t attr = 0;
if (nt->attr->number)
attr = 1<<nt->attr->number;
print("%1data->constrain_input_reg(%d, 0x%x);\n", *index, attr);
if (node->attr)
{
uint32_t attr = 1<<node->attr->number;
print("%1data->constrain_input_reg(%d, 0x%x /* %s */);\n",
*index, attr, node->attr->name);
}
}
if (!node->left && !node->right)
@ -1118,7 +1120,8 @@ static void emitinsndata(Rule rules)
print("static void %Pemitter_%d(const struct %Pemitter_data* data) {\n", r->ern);
if (r->attr)
print("%1data->constrain_output_reg(0x%x);\n", 1<<r->attr->number);
print("%1data->constrain_output_reg(0x%x /* %s */);\n",
1<<r->attr->number, r->attr->name);
{
int index = 0;

2
util/mcgg/iburg.h
View file

@ -96,7 +96,6 @@ struct nonterm
Rule chain; /* chain rules w/non-terminal on rhs */
Nonterm link; /* next terminal in number order */
bool is_fragment; /* these instructions are all fragments */
struct regattr* attr; /* input register attribute */
};
extern void* lookup(const char* name);
extern Nonterm nonterm(const char* id, bool allocate);
@ -109,6 +108,7 @@ struct tree
const char* label; /* user label for this node */
Tree left, right; /* operands */
int nterms; /* number of terminal nodes in this tree */
struct regattr* attr; /* input register attribute */
};
extern Tree tree(const struct terminfo* ti, Tree left, Tree right);

4
util/mcgg/ir.dat
View file

@ -42,6 +42,10 @@ S AND
S OR
S EOR
S NOT
S ASL
S ASR
S LSL
S LSR
# Conversions
S CII1

4
util/mcgg/mcgg.h
View file

@ -44,8 +44,8 @@ struct burm_emitter_data
void (*emit_reg)(int child);
void (*emit_value)(int child);
void (*emit_eoi)(void);
void (*constrain_input_reg)(int child, int attr);
void (*constrain_output_reg)(int attr);
void (*constrain_input_reg)(int child, uint32_t attr);
void (*constrain_output_reg)(uint32_t attr);
};
typedef void burm_emitter_t(const struct burm_emitter_data* data);