The SSA conversion works under the assumption that all the memory
operations on a given symbol always refer to the same object.
So, exclude the conversion of variables where:
* memory operations do not always match in size or offset
* there is an implicit integer/float conversion.
Signed-off-by: Luc Van Oostenryck <luc.vanoostenryck@xxxxxxxxx>
---
linearize.h | 2 +-
ssa.c | 97 ++++++++++++++++++++++------
validation/mem2reg/not-same-memop0.c | 1 -
3 files changed, 80 insertions(+), 20 deletions(-)
diff --git a/linearize.h b/linearize.h
index 7909b01f29c5..86ae119c82e6 100644
--- a/linearize.h
+++ b/linearize.h
@@ -18,7 +18,7 @@ struct pseudo_user {
DECLARE_ALLOCATOR(pseudo_user);
DECLARE_PTR_LIST(pseudo_user_list, struct pseudo_user);
-DECLARE_PTRMAP(phi_map, struct symbol *, pseudo_t);
+DECLARE_PTRMAP(phi_map, struct symbol *, struct instruction *);
enum pseudo_type {
diff --git a/ssa.c b/ssa.c
index 26d46baaa16c..f61672a0b530 100644
--- a/ssa.c
+++ b/ssa.c
@@ -96,10 +96,22 @@ static void kill_store(struct instruction *insn)
insn->bb = NULL;
}
+static bool same_memop(struct instruction *a, struct instruction *b)
+{
+ if (a->size != b->size || a->offset != b->offset)
+ return false;
+ if (is_integral_type(a->type) && is_float_type(b->type))
+ return false;
+ if (is_float_type(a->type) && is_integral_type(b->type))
+ return false;
+ return true;
+}
+
static void rewrite_local_var(struct basic_block *bb, pseudo_t addr, int nbr_stores, int nbr_uses)
{
+ struct instruction *store = NULL;
struct instruction *insn;
- pseudo_t val = NULL;
+ bool remove = false;
if (!bb)
return;
@@ -110,18 +122,21 @@ static void rewrite_local_var(struct basic_block *bb, pseudo_t addr, int nbr_sto
continue;
switch (insn->opcode) {
case OP_LOAD:
- if (!val)
- val = undef_pseudo();
- replace_with_pseudo(insn, val);
+ if (!store)
+ replace_with_pseudo(insn, undef_pseudo());
+ else if (same_memop(store, insn))
+ replace_with_pseudo(insn, store->target);
+ else
+ remove = false;
break;
case OP_STORE:
- val = insn->target;
- // can't use kill_instruction() unless
- // we add a fake user to val
- kill_store(insn);
+ store = insn;
+ remove = true;
break;
}
} END_FOR_EACH_PTR(insn);
+ if (remove)
+ kill_store(store);
}
static bool rewrite_single_store(struct instruction *store)
@@ -139,6 +154,8 @@ static bool rewrite_single_store(struct instruction *store)
// by the value from the store. This is only valid
// if the store dominate the load.
+ if (!same_memop(store, insn))
+ continue;
if (insn->bb == store->bb) {
// the load and the store are in the same BB
// we can convert if the load is after the store.
@@ -257,21 +274,40 @@ external_visibility:
kill_dead_stores(ep, addr, !mod);
}
-static pseudo_t lookup_var(struct basic_block *bb, struct symbol *var)
+static struct instruction *lookup_var(struct basic_block *bb, struct symbol *var)
{
do {
- pseudo_t val = phi_map_lookup(bb->phi_map, var);
- if (val)
- return val;
+ struct instruction *insn = phi_map_lookup(bb->phi_map, var);
+ if (insn)
+ return insn;
} while ((bb = bb->idom));
- return undef_pseudo();
+ return NULL;
}
static struct instruction_list *phis_all;
static struct instruction_list *phis_used;
+static struct instruction_list *stores;
+
+static bool matching_load(struct instruction *def, struct instruction *insn)
+{
+ if (insn->size != def->size)
+ return false;
+ switch (def->opcode) {
+ case OP_STORE:
+ case OP_LOAD:
+ if (insn->offset != def->offset)
+ return false;
+ case OP_PHI:
+ break;
+ default:
+ return false;
+ }
+ return true;
+}
static void ssa_rename_insn(struct basic_block *bb, struct instruction *insn)
{
+ struct instruction *def;
struct symbol *var;
pseudo_t addr;
pseudo_t val;
@@ -284,8 +320,8 @@ static void ssa_rename_insn(struct basic_block *bb, struct instruction *insn)
var = addr->sym;
if (!var || !var->torename)
break;
- phi_map_update(&bb->phi_map, var, insn->target);
- kill_store(insn);
+ phi_map_update(&bb->phi_map, var, insn);
+ add_instruction(&stores, insn);
break;
case OP_LOAD:
addr = insn->src;
@@ -294,14 +330,22 @@ static void ssa_rename_insn(struct basic_block *bb, struct instruction *insn)
var = addr->sym;
if (!var || !var->torename)
break;
- val = lookup_var(bb, var);
+ def = lookup_var(bb, var);
+ if (!def) {
+ val = undef_pseudo();
+ } else if (!matching_load(def, insn)) {
+ var->torename = false;
+ break;
+ } else {
+ val = def->target;
+ }
replace_with_pseudo(insn, val);
break;
case OP_PHI:
var = insn->type;
if (!var || !var->torename)
break;
- phi_map_update(&bb->phi_map, var, insn->target);
+ phi_map_update(&bb->phi_map, var, insn);
add_instruction(&phis_all, insn);
break;
}
@@ -348,7 +392,8 @@ static void ssa_rename_phi(struct instruction *insn)
return;
FOR_EACH_PTR(insn->bb->parents, par) {
struct instruction *term = delete_last_instruction(&par->insns);
- pseudo_t val = lookup_var(par, var);
+ struct instruction *def = lookup_var(par, var);
+ pseudo_t val = def ? def->target : undef_pseudo();
pseudo_t phi = alloc_phi(par, val, var);
phi->ident = var->ident;
add_instruction(&par->insns, term);
@@ -376,6 +421,18 @@ static void ssa_rename_phis(struct entrypoint *ep)
} END_FOR_EACH_PTR(phi);
}
+static void remove_dead_stores(struct instruction_list *stores)
+{
+ struct instruction *store;
+
+ FOR_EACH_PTR(stores, store) {
+ struct symbol *var = store->addr->sym;
+
+ if (var->torename)
+ kill_store(store);
+ } END_FOR_EACH_PTR(store);
+}
+
void ssa_convert(struct entrypoint *ep)
{
struct basic_block *bb;
@@ -393,6 +450,7 @@ void ssa_convert(struct entrypoint *ep)
} END_FOR_EACH_PTR(bb);
// try to promote memory accesses to pseudos
+ stores = NULL;
FOR_EACH_PTR(ep->accesses, pseudo) {
ssa_convert_one_var(ep, pseudo->sym);
} END_FOR_EACH_PTR(pseudo);
@@ -401,4 +459,7 @@ void ssa_convert(struct entrypoint *ep)
phis_all = phis_used = NULL;
ssa_rename_insns(ep);
ssa_rename_phis(ep);
+
+ // remove now dead stores
+ remove_dead_stores(stores);
}
diff --git a/validation/mem2reg/not-same-memop0.c b/validation/mem2reg/not-same-memop0.c
index 7a84ddce4efc..4de981956b74 100644
--- a/validation/mem2reg/not-same-memop0.c
+++ b/validation/mem2reg/not-same-memop0.c
@@ -16,7 +16,6 @@ static void foo(struct s s)
/*
* check-name: not-same-memop0
* check-command: test-linearize -Wno-decl -fdump-ir=mem2reg $file
- * check-known-to-fail
*
* check-output-start
local:
--
2.30.0
