I noticed that the code we generate for a simple gimple_assign_rhs1 (stmt)
is quite bad as we have two checking pieces. The implementation is now
static inline tree
gimple_assign_rhs1 (const_gimple gs)
{
GIMPLE_CHECK (gs, GIMPLE_ASSIGN);
return gimple_op (gs, 1);
}
and the hidden checking is due to gimple_op being
static inline tree *
gimple_ops (gimple gs)
{
size_t off;
/* All the tuples have their operand vector at the very bottom
of the structure. Note that those structures that do not
have an operand vector have a zero offset. */
off = gimple_ops_offset_[gimple_statement_structure (gs)];
gcc_gimple_checking_assert (off != 0);
return (tree *) ((char *) gs + off);
(ugly in itself considering that we just verified we have a gassign
which has an operand vector as member...). gimple_op incurs two
additional memory reference to compute gimple_statement_structure
and gimple_ops_offset_ plus the checking bits.
The simplest thing would be to use
GIMPLE_CHECK (gs, GIMPLE_ASSIGN);
return as_a <const gassign *> (gs)->op[1];
but that's not optimal either because we check we have a gassign
again (not optimized in stage1). So I decided to invent a fancy
as_a which reports errors similar to GIMPLE_CHECK and makes the
code look like
const gassign *ass = GIMPLE_CHECK2<const gassign *> (gs);
return ass->op[1];
for some reason I needed to overload is_a_helper for const_gimple
(I thought the is_a machinery would transparently support qualified
types?).
I'm missing a fallback for !ENABLE_GIMPLE_CHECKING as well
as an overload for 'gimple' I guess. I just changed
gimple_assign_rhs1 for now.
So this is a RFC.
I understand in the end the whole GCC may use gassign everywhere
we access gimple_assign_rhs1 but I don't see this happening soon
and this simple proof-of-concept patch already reduces unoptimized
text size of gimple-match.c from 836080 to 836359 (too bad) and
optimized from 585731 to 193190 bytes (yay!) on x86_64 using trunk.
Some inlining must go very differently - we just have 544 calls to
gimple_assign_rhs1 in gimple-match.c. .optimizes shows all calls
remaining as
<bb 89>:
_ZL18gimple_assign_rhs1PK21gimple_statement_base.part.32 (def_stmt_47);
which is
tree_node* gimple_assign_rhs1(const_gimple) (const struct
gimple_statement_base * gs)
{
<bb 2>:
gimple_check_failed (gs_1(D),
&"/space/rguenther/tramp3d/trunk/gcc/gimple.h"[0], 2381,
&"gimple_assign_rhs1"[0], 6, 0);
}
so eventually we just do a better job with profile estimation.
I think inliner-wise we are even as we get rid of the gimple_op ()
inline but instead get the GIMPLE_CHECK2 inline.
So - any comments?
Thanks,
Richard.
2015-07-27 Richard Biener <rguent...@suse.de>
* gimple.h (GIMPLE_CHECK2): New inline template function.
(gassign::code_): New constant static member.
(is_a_helper<const gassign *>): Add.
(gimple_assign_rhs1): Use GIMPLE_CHECK2 and a cheaper way
to access operand 1.
* gimple.c (gassign::code_): Define.
Index: gcc/gimple.h
===================================================================
--- gcc/gimple.h (revision 226240)
+++ gcc/gimple.h (working copy)
@@ -51,6 +51,16 @@ extern void gimple_check_failed (const_g
gimple_check_failed (__gs, __FILE__, __LINE__, __FUNCTION__, \
(CODE), ERROR_MARK); \
} while (0)
+template <typename T>
+static inline T
+GIMPLE_CHECK2(const_gimple gs, const char *file = __builtin_FILE (),
+ int line = __builtin_LINE (), const char *fun =
__builtin_FUNCTION ())
+{
+ T ret = dyn_cast <T> (gs);
+ if (ret)
+ gimple_check_failed (gs, file, line, fun, T()->code_, ERROR_MARK);
+ return ret;
+}
#else /* not ENABLE_GIMPLE_CHECKING */
#define gcc_gimple_checking_assert(EXPR) ((void)(0 && (EXPR)))
#define GIMPLE_CHECK(GS, CODE) (void)0
@@ -832,6 +842,7 @@ struct GTY((tag("GSS_WITH_OPS")))
struct GTY((tag("GSS_WITH_MEM_OPS")))
gassign : public gimple_statement_with_memory_ops
{
+ static const enum gimple_code code_ = GIMPLE_ASSIGN;
/* no additional fields; this uses the layout for GSS_WITH_MEM_OPS. */
};
@@ -864,6 +875,14 @@ is_a_helper <gassign *>::test (gimple gs
template <>
template <>
inline bool
+is_a_helper <const gassign *>::test (const_gimple gs)
+{
+ return gs->code == GIMPLE_ASSIGN;
+}
+
+template <>
+template <>
+inline bool
is_a_helper <gbind *>::test (gimple gs)
{
return gs->code == GIMPLE_BIND;
@@ -2359,8 +2378,8 @@ gimple_assign_set_lhs (gimple gs, tree l
static inline tree
gimple_assign_rhs1 (const_gimple gs)
{
- GIMPLE_CHECK (gs, GIMPLE_ASSIGN);
- return gimple_op (gs, 1);
+ const gassign *ass = GIMPLE_CHECK2<const gassign *> (gs);
+ return ass->op[1];
}
Index: gcc/gimple.c
===================================================================
--- gcc/gimple.c (revision 226240)
+++ gcc/gimple.c (working copy)
@@ -89,6 +89,10 @@ static const char * const gimple_alloc_k
"everything else"
};
+/* Static gimple tuple members. */
+const enum gimple_code gassign::code_;
+
+
/* Gimple tuple constructors.
Note: Any constructor taking a ``gimple_seq'' as a parameter, can
be passed a NULL to start with an empty sequence. */
