This patch tries to track the debug location of memory variables
that have a target_for_debug_bind (and thus have a type that
satisfies is_gimple_reg_type). For each such variable V:
* "# DEBUG V s=> V" marks the start of V's lifetime
* during V's lifetime, "# DEBUG V => X" records that the value of V is
given by X instead of DECL_RTL (V).
* each assignment to V implicitly reestablishes the link between V
and DECL_RTL (V).
* as before, "V = {CLOBBER}" marks the end of V's lifetime.
When removing "V = X", gsi_remove tries to insert the equivalent of
"# DEBUG V => X" at the place of the original assignment, falling back
on a "# DEBUG V => NULL" reset if that fails.
The change to insert_debug_temp_for_var_def is mostly reindentation.
The patch only handles VAR_DECLs, but we might want to extend it
to PARM_DECLs too.
2019-06-01 Richard Sandiford <richard.sandif...@arm.com>
gcc/
* tree-core.h (tree_decl_with_vis): Group bitfields into bytes.
(tree_decl_with_vis::track_direct_refs_for_debug_p): New field.
* tree-streamer-in.c (unpack_ts_decl_with_vis_value_fields): Handle it.
* tree-streamer-out.c (pack_ts_decl_with_vis_value_fields): Likewise.
* tree.h (DECL_TRACK_DIRECT_REFS_FOR_DEBUG_P): New macro.
(track_direct_refs_for_debug_p): New function.
* cfgexpand.c (expand_debug_locations): Use DECL_RTL_REF to
handle VAR s=> VAR.
(expand_gimple_basic_block): Insert the initialized equivalent
of VAR s=> VAR after each direct assignment to VAR.
* gimplify.c (scoped_possible_mem_var_p): New function, split out
from...
(gimplify_bind_expr): ...here. Decide whether it would be worth
tracking the location of a non-gimple-reg VAR_DECL using debug
stmts and insns. Mark them with DECL_TRACK_DIRECT_REFS_FOR_DEBUG_P
if so and use gimple_debug_source_binds to mark the start of their
lifetime.
* gimple-low.c (lower_stmt): Allow gimple_debug_source_binds
before lowering.
* tree-cfg.c (make_blocks): Handle gimple_debug_source_binds.
* tree-ssa.c (insert_debug_temp_for_var_def): Handle VAR_DECLs
as well as SSA_NAMEs.
(insert_debug_temps_for_defs): Insert gimple_debug_binds for
VAR_DECLs for which DECL_TRACK_DIRECT_REFS_FOR_DEBUG_P is set.
gcc/testsuite/
* gcc.dg/guality/addr-taken-1.c: New test.
* gcc.dg/guality/addr-taken-2.c: Likewise.
Index: gcc/tree-core.h
===================================================================
--- gcc/tree-core.h 2019-05-29 10:49:39.896700883 +0100
+++ gcc/tree-core.h 2019-06-01 16:38:35.421667415 +0100
@@ -1761,13 +1761,12 @@ struct GTY(()) tree_decl_with_vis {
unsigned dllimport_flag : 1;
/* Don't belong to VAR_DECL exclusively. */
unsigned weak_flag : 1;
-
unsigned seen_in_bind_expr : 1;
+
unsigned comdat_flag : 1;
/* Used for FUNCTION_DECL, VAR_DECL and in C++ for TYPE_DECL. */
ENUM_BITFIELD(symbol_visibility) visibility : 2;
unsigned visibility_specified : 1;
-
/* Belong to FUNCTION_DECL exclusively. */
unsigned init_priority_p : 1;
/* Used by C++ only. Might become a generic decl flag. */
@@ -1776,11 +1775,16 @@ struct GTY(()) tree_decl_with_vis {
unsigned cxx_constructor : 1;
/* Belong to FUNCTION_DECL exclusively. */
unsigned cxx_destructor : 1;
+
/* Belong to FUNCTION_DECL exclusively. */
unsigned final : 1;
/* Belong to FUNCTION_DECL exclusively. */
unsigned regdecl_flag : 1;
- /* 14 unused bits. */
+ /* Records whether direct references to VAR_DECLs should be tracked via
+ debug stmts. */
+ unsigned track_direct_refs_for_debug_p : 1;
+
+ /* 13 unused bits. */
};
struct GTY(()) tree_var_decl {
Index: gcc/tree-streamer-in.c
===================================================================
--- gcc/tree-streamer-in.c 2019-05-29 10:49:39.896700883 +0100
+++ gcc/tree-streamer-in.c 2019-06-01 16:38:35.421667415 +0100
@@ -307,6 +307,8 @@ unpack_ts_decl_with_vis_value_fields (st
{
DECL_HARD_REGISTER (expr) = (unsigned) bp_unpack_value (bp, 1);
DECL_IN_CONSTANT_POOL (expr) = (unsigned) bp_unpack_value (bp, 1);
+ DECL_TRACK_DIRECT_REFS_FOR_DEBUG_P (expr)
+ = (unsigned) bp_unpack_value (bp, 1);
}
if (TREE_CODE (expr) == FUNCTION_DECL)
Index: gcc/tree-streamer-out.c
===================================================================
--- gcc/tree-streamer-out.c 2019-05-29 10:49:39.620701683 +0100
+++ gcc/tree-streamer-out.c 2019-06-01 16:38:35.421667415 +0100
@@ -269,6 +269,7 @@ pack_ts_decl_with_vis_value_fields (stru
bp_pack_value (bp, DECL_HARD_REGISTER (expr), 1);
/* DECL_IN_TEXT_SECTION is set during final asm output only. */
bp_pack_value (bp, DECL_IN_CONSTANT_POOL (expr), 1);
+ bp_pack_value (bp, DECL_TRACK_DIRECT_REFS_FOR_DEBUG_P (expr), 1);
}
if (TREE_CODE (expr) == FUNCTION_DECL)
Index: gcc/tree.h
===================================================================
--- gcc/tree.h 2019-05-29 10:49:37.876706747 +0100
+++ gcc/tree.h 2019-06-01 16:38:35.421667415 +0100
@@ -2888,6 +2888,12 @@ #define DECL_DEBUG_EXPR(NODE) \
#define SET_DECL_DEBUG_EXPR(NODE, VAL) \
(decl_debug_expr_insert (VAR_DECL_CHECK (NODE), VAL))
+/* For a VAR_DECL, true if accesses to the variable can't be rewritten
+ into SSA form but if we nevertheless want to use debug stmts
+ (and later debug insns) to track its location. */
+#define DECL_TRACK_DIRECT_REFS_FOR_DEBUG_P(NODE) \
+ (VAR_DECL_CHECK (NODE)->decl_with_vis.track_direct_refs_for_debug_p)
+
extern priority_type decl_init_priority_lookup (tree);
extern priority_type decl_fini_priority_lookup (tree);
extern void decl_init_priority_insert (tree, priority_type);
@@ -4733,6 +4739,15 @@ extern tree get_unwidened (tree, tree);
extern tree get_narrower (tree, int *);
+/* Return true if T is a DECL for which DECL_TRACK_DIRECT_REFS_FOR_DEBUG_P
+ applies. */
+
+inline bool
+track_direct_refs_for_debug_p (const_tree t)
+{
+ return VAR_P (t) && DECL_TRACK_DIRECT_REFS_FOR_DEBUG_P (t);
+}
+
/* Return true if T is an expression that get_inner_reference handles. */
static inline bool
Index: gcc/cfgexpand.c
===================================================================
--- gcc/cfgexpand.c 2019-05-29 10:49:39.524701962 +0100
+++ gcc/cfgexpand.c 2019-06-01 16:38:35.413667438 +0100
@@ -5429,8 +5429,15 @@ expand_debug_locations (void)
val = NULL_RTX;
else
{
- if (INSN_VAR_LOCATION_STATUS (insn)
- == VAR_INIT_STATUS_UNINITIALIZED)
+ if (INSN_VAR_LOCATION_DECL (insn) == value)
+ {
+ if (DECL_RTL_SET_P (value))
+ val = gen_rtx_DECL_RTL_REF (DECL_MODE (value), value);
+ else
+ val = NULL_RTX;
+ }
+ else if (INSN_VAR_LOCATION_STATUS (insn)
+ == VAR_INIT_STATUS_UNINITIALIZED)
val = expand_debug_source_expr (value);
/* The avoid_deep_ter_for_debug function inserts
debug bind stmts after SSA_NAME definition, with the
@@ -5900,6 +5907,19 @@ expand_gimple_basic_block (basic_block b
maybe_dump_rtl_for_gimple_stmt (stmt, last);
}
}
+ if (MAY_HAVE_DEBUG_BIND_INSNS)
+ {
+ /* If the statement is assigning to a memory variable whose
+ location we're tracking for debug purposes, emit a note
+ to say that the variable now lives in memory. */
+ tree lhs = gimple_get_lhs (stmt);
+ if (lhs && track_direct_refs_for_debug_p (lhs))
+ {
+ rtx val = gen_rtx_VAR_LOCATION (DECL_MODE (lhs), lhs, (rtx) lhs,
+ VAR_INIT_STATUS_INITIALIZED);
+ emit_debug_insn (val);
+ }
+ }
}
currently_expanding_gimple_stmt = NULL;
Index: gcc/gimplify.c
===================================================================
--- gcc/gimplify.c 2019-05-31 17:26:54.647201231 +0100
+++ gcc/gimplify.c 2019-06-01 16:38:35.417667427 +0100
@@ -1295,6 +1295,21 @@ asan_poison_variables (hash_set<tree> *v
}
}
+/* Return true if variable VAR is local to its BIND_EXPR and might need
+ to live in memory. */
+
+static bool
+scoped_possible_mem_var_p (tree var)
+{
+ return (!DECL_HARD_REGISTER (var)
+ && !TREE_THIS_VOLATILE (var)
+ && !DECL_HAS_VALUE_EXPR_P (var)
+ /* Only care about variables that have to be in memory. Others
+ will be rewritten into SSA names, hence moved to the
+ top-level. */
+ && !is_gimple_reg (var));
+}
+
/* Gimplify a BIND_EXPR. Just voidify and recurse. */
static enum gimplify_status
@@ -1313,6 +1328,7 @@ gimplify_bind_expr (tree *expr_p, gimple
tree temp = voidify_wrapper_expr (bind_expr, NULL);
/* Mark variables seen in this bind expr. */
+ body = NULL;
for (t = BIND_EXPR_VARS (bind_expr); t ; t = DECL_CHAIN (t))
{
if (VAR_P (t))
@@ -1348,6 +1364,18 @@ gimplify_bind_expr (tree *expr_p, gimple
&& (VAR_P (t) && !DECL_HARD_REGISTER (t))
&& !needs_to_live_in_memory (t))
DECL_GIMPLE_REG_P (t) = 1;
+
+ if (MAY_HAVE_DEBUG_BIND_INSNS
+ && VAR_P (t)
+ && !is_global_var (t)
+ && DECL_CONTEXT (t) == current_function_decl
+ && scoped_possible_mem_var_p (t)
+ && target_for_debug_bind (t) == t)
+ {
+ gdebug *sb = gimple_build_debug_source_bind (t, t, NULL);
+ gimple_seq_add_stmt (&body, sb);
+ DECL_TRACK_DIRECT_REFS_FOR_DEBUG_P (t) = 1;
+ }
}
bind_stmt = gimple_build_bind (BIND_EXPR_VARS (bind_expr), NULL,
@@ -1358,7 +1386,6 @@ gimplify_bind_expr (tree *expr_p, gimple
gimplify_ctxp->save_stack = false;
/* Gimplify the body into the GIMPLE_BIND tuple's body. */
- body = NULL;
gimplify_stmt (&BIND_EXPR_BODY (bind_expr), &body);
gimple_bind_set_body (bind_stmt, body);
@@ -1401,13 +1428,7 @@ gimplify_bind_expr (tree *expr_p, gimple
&& !is_global_var (t)
&& DECL_CONTEXT (t) == current_function_decl)
{
- if (!DECL_HARD_REGISTER (t)
- && !TREE_THIS_VOLATILE (t)
- && !DECL_HAS_VALUE_EXPR_P (t)
- /* Only care for variables that have to be in memory. Others
- will be rewritten into SSA names, hence moved to the
- top-level. */
- && !is_gimple_reg (t)
+ if (scoped_possible_mem_var_p (t)
&& flag_stack_reuse != SR_NONE)
{
tree clobber = build_clobber (TREE_TYPE (t));
Index: gcc/gimple-low.c
===================================================================
--- gcc/gimple-low.c 2019-04-04 08:34:52.221937259 +0100
+++ gcc/gimple-low.c 2019-06-01 16:38:35.417667427 +0100
@@ -309,10 +309,12 @@ lower_stmt (gimple_stmt_iterator *gsi, s
break;
case GIMPLE_DEBUG:
- gcc_checking_assert (cfun->debug_nonbind_markers);
- /* We can't possibly have debug bind stmts before lowering, we
- first emit them when entering SSA. */
- gcc_checking_assert (gimple_debug_nonbind_marker_p (stmt));
+ /* The only debug bind stmts we create before lowering are
+ source binds of the form "x s=> x", to mark the start of
+ a variable's lifetime. */
+ gcc_checking_assert ((cfun->debug_nonbind_markers
+ && gimple_debug_nonbind_marker_p (stmt))
+ || gimple_debug_source_bind_p (stmt));
/* Propagate fallthruness. */
/* If the function (e.g. from PCH) had debug stmts, but they're
disabled for this compilation, remove them. */
Index: gcc/tree-cfg.c
===================================================================
--- gcc/tree-cfg.c 2019-05-29 10:49:39.900700870 +0100
+++ gcc/tree-cfg.c 2019-06-01 16:38:35.421667415 +0100
@@ -593,8 +593,8 @@ make_blocks_1 (gimple_seq seq, basic_blo
static void
make_blocks (gimple_seq seq)
{
- /* Look for debug markers right before labels, and move the debug
- stmts after the labels. Accepting labels among debug markers
+ /* Look for debug stmts right before labels, and move the debug
+ stmts after the labels. Accepting labels among debug stmts
adds no value, just complexity; if we wanted to annotate labels
with view numbers (so sequencing among markers would matter) or
somesuch, we're probably better off still moving the labels, but
@@ -635,7 +635,11 @@ make_blocks (gimple_seq seq)
/* Move the debug stmt at I after LABEL. */
if (is_gimple_debug (stmt))
{
- gcc_assert (gimple_debug_nonbind_marker_p (stmt));
+ /* Handle both debug markers and source binds of the form
+ VAR s=> VAR (which denote the beginning of VAR's
+ lifetime). */
+ gcc_assert (gimple_debug_nonbind_marker_p (stmt)
+ || gimple_debug_source_bind_p (stmt));
/* As STMT is removed, I advances to the stmt after
STMT, so the gsi_prev in the for "increment"
expression gets us to the stmt we're to visit after
Index: gcc/tree-ssa.c
===================================================================
--- gcc/tree-ssa.c 2019-05-29 10:49:39.892700893 +0100
+++ gcc/tree-ssa.c 2019-06-01 16:38:35.421667415 +0100
@@ -293,9 +293,13 @@ find_released_ssa_name (tree *tp, int *w
return NULL_TREE;
}
-/* Insert a DEBUG BIND stmt before the DEF of VAR if VAR is referenced
- by other DEBUG stmts, and replace uses of the DEF with the
- newly-created debug temp. */
+/* Insert a DEBUG BIND stmt before the DEF of VAR in cases where either:
+
+ - VAR is a decl that satisfies track_direct_refs_for_debug_p
+ - VAR is an SSA_NAME that is referenced by other DEBUG stmts
+
+ In the latter case, replace uses of the DEF with the newly-created
+ debug temp. */
void
insert_debug_temp_for_var_def (gimple_stmt_iterator *gsi, tree var)
@@ -310,35 +314,38 @@ insert_debug_temp_for_var_def (gimple_st
if (!MAY_HAVE_DEBUG_BIND_STMTS)
return;
- /* If this name has already been registered for replacement, do nothing
- as anything that uses this name isn't in SSA form. */
- if (name_registered_for_update_p (var))
- return;
-
- /* Check whether there are debug stmts that reference this variable and,
- if there are, decide whether we should use a debug temp. */
- FOR_EACH_IMM_USE_FAST (use_p, imm_iter, var)
+ if (TREE_CODE (var) == SSA_NAME)
{
- stmt = USE_STMT (use_p);
+ /* If this name has already been registered for replacement, do nothing
+ as anything that uses this name isn't in SSA form. */
+ if (name_registered_for_update_p (var))
+ return;
+
+ /* Check whether there are debug stmts that reference this variable and,
+ if there are, decide whether we should use a debug temp. */
+ FOR_EACH_IMM_USE_FAST (use_p, imm_iter, var)
+ {
+ stmt = USE_STMT (use_p);
- if (!gimple_debug_bind_p (stmt))
- continue;
+ if (!gimple_debug_bind_p (stmt))
+ continue;
- if (usecount++)
- break;
+ if (usecount++)
+ break;
- if (gimple_debug_bind_get_value (stmt) != var)
- {
- /* Count this as an additional use, so as to make sure we
- use a temp unless VAR's definition has a SINGLE_RHS that
- can be shared. */
- usecount++;
- break;
+ if (gimple_debug_bind_get_value (stmt) != var)
+ {
+ /* Count this as an additional use, so as to make sure we
+ use a temp unless VAR's definition has a SINGLE_RHS that
+ can be shared. */
+ usecount++;
+ break;
+ }
}
- }
- if (!usecount)
- return;
+ if (!usecount)
+ return;
+ }
if (gsi)
def_stmt = gsi_stmt (*gsi);
@@ -459,32 +466,38 @@ insert_debug_temp_for_var_def (gimple_st
}
}
- FOR_EACH_IMM_USE_STMT (stmt, imm_iter, var)
- {
- if (!gimple_debug_bind_p (stmt))
- continue;
-
- if (value)
- {
- FOR_EACH_IMM_USE_ON_STMT (use_p, imm_iter)
- /* unshare_expr is not needed here. vexpr is either a
- SINGLE_RHS, that can be safely shared, some other RHS
- that was unshared when we found it had a single debug
- use, or a DEBUG_EXPR_DECL, that can be safely
- shared. */
- SET_USE (use_p, unshare_expr (value));
- /* If we didn't replace uses with a debug decl fold the
- resulting expression. Otherwise we end up with invalid IL. */
- if (TREE_CODE (value) != DEBUG_EXPR_DECL)
- {
- gimple_stmt_iterator gsi = gsi_for_stmt (stmt);
- fold_stmt_inplace (&gsi);
- }
- }
- else
- gimple_debug_bind_reset_value (stmt);
+ if (TREE_CODE (var) == SSA_NAME)
+ FOR_EACH_IMM_USE_STMT (stmt, imm_iter, var)
+ {
+ if (!gimple_debug_bind_p (stmt))
+ continue;
+
+ if (value)
+ {
+ FOR_EACH_IMM_USE_ON_STMT (use_p, imm_iter)
+ /* unshare_expr is not needed here. vexpr is either a
+ SINGLE_RHS, that can be safely shared, some other RHS
+ that was unshared when we found it had a single debug
+ use, or a DEBUG_EXPR_DECL, that can be safely
+ shared. */
+ SET_USE (use_p, unshare_expr (value));
+ /* If we didn't replace uses with a debug decl fold the
+ resulting expression. Otherwise we end up with invalid IL. */
+ if (TREE_CODE (value) != DEBUG_EXPR_DECL)
+ {
+ gimple_stmt_iterator gsi = gsi_for_stmt (stmt);
+ fold_stmt_inplace (&gsi);
+ }
+ }
+ else
+ gimple_debug_bind_reset_value (stmt);
- update_stmt (stmt);
+ update_stmt (stmt);
+ }
+ else
+ {
+ gdebug *bind = gimple_build_debug_bind (var, value, def_stmt);
+ gsi_insert_before (gsi, bind, GSI_SAME_STMT);
}
}
@@ -514,6 +527,10 @@ insert_debug_temps_for_defs (gimple_stmt
insert_debug_temp_for_var_def (gsi, var);
}
+
+ tree lhs = gimple_get_lhs (stmt);
+ if (lhs && track_direct_refs_for_debug_p (lhs))
+ insert_debug_temp_for_var_def (gsi, lhs);
}
/* Reset all debug stmts that use SSA_NAME(s) defined in STMT. */
Index: gcc/testsuite/gcc.dg/guality/addr-taken-1.c
===================================================================
--- /dev/null 2019-03-08 11:40:14.606883727 +0000
+++ gcc/testsuite/gcc.dg/guality/addr-taken-1.c 2019-06-01 16:38:35.417667427
+0100
@@ -0,0 +1,36 @@
+/* { dg-do run } */
+/* { dg-options "-g" } */
+
+void __attribute__((noipa))
+get_start (int *x)
+{
+ *x = 42;
+}
+
+void __attribute__((noipa))
+consume (int *x)
+{
+ *x += 1;
+}
+
+void __attribute__((noipa))
+test (int *x, int i1, int i2, int i3, int i4)
+{
+ int base;
+ get_start (&base);
+ x[i1] = base; /* { dg-final { gdb-test . "base" "42" } } */
+ base = 100;
+ x[i2] = base; /* { dg-final { gdb-test . "base" "100" } } */
+ base += 1;
+ x[i3] = base; /* { dg-final { gdb-test . "base" "101" } } */
+ base += 1;
+ consume (&base); /* { dg-final { gdb-test . "base" "102" } } */
+ x[i4] = base; /* { dg-final { gdb-test . "base" "103" } } */
+}
+
+int
+main (void)
+{
+ int x[4];
+ test (x, 0, 1, 2, 3);
+}
Index: gcc/testsuite/gcc.dg/guality/addr-taken-2.c
===================================================================
--- /dev/null 2019-03-08 11:40:14.606883727 +0000
+++ gcc/testsuite/gcc.dg/guality/addr-taken-2.c 2019-06-01 16:38:35.417667427
+0100
@@ -0,0 +1,34 @@
+/* { dg-do run } */
+/* { dg-options "-g" } */
+
+void __attribute__((noipa))
+get_start (int *x)
+{
+ *x = 42;
+}
+
+void __attribute__((noipa))
+consume (int *x)
+{
+ *x += 1;
+}
+
+void __attribute__((noipa))
+test (int *x, int i1, int i2, int i3)
+{
+ int base;
+ get_start (&base);
+ x[i1] = base; /* { dg-final { gdb-test . "base" "42" } } */
+ base += 1;
+ x[i2] = base; /* { dg-final { gdb-test . "base" "43" } } */
+ base += 1;
+ consume (&base); /* { dg-final { gdb-test . "base" "44" } } */
+ x[i3] = base; /* { dg-final { gdb-test . "base" "45" } } */
+}
+
+int
+main (void)
+{
+ int x[3];
+ test (x, 0, 1, 2);
+}
