This fixes a missed optimization regarding to coverage counters.
In the past we failed to apply proper may-alias analysis and
disregarded those counters as being possibly aliased by pointers
by accident. The following patch adds a flag so we can mark
VAR_DECLs as to be not considered as aliased by pointers so we
can make that an informed decision in this case (even though
strictly wrong - the address to those counters escapes into
the gcov info struct we build and pass to __gcov_init).
Profiledbootstrapped and tested on x86_64-unknown-linux-gnu, ok for trunk?
Do we eventually want sth like this for the branch(es)?
Thanks,
Richard.
2014-03-21 Richard Biener <rguent...@suse.de>
PR tree-optimization/60577
* tree-core.h (struct tree_base): Document nothrow_flag use
in VAR_DECL_NONALIASED.
* tree.h (VAR_DECL_NONALIASED): New.
(may_be_aliased): Adjust.
* coverage.c (build_var): Set VAR_DECL_NONALIASED.
* gcc.dg/tree-ssa/ssa-lim-11.c: New testcase.
Index: gcc/tree-core.h
===================================================================
*** gcc/tree-core.h (revision 208693)
--- gcc/tree-core.h (working copy)
*************** struct GTY(()) tree_base {
*** 987,992 ****
--- 987,995 ----
SSA_NAME_IN_FREELIST in
SSA_NAME
+ VAR_DECL_NONALIASED in
+ VAR_DECL
+
deprecated_flag:
TREE_DEPRECATED in
Index: gcc/tree.h
===================================================================
*** gcc/tree.h (revision 208693)
--- gcc/tree.h (working copy)
*************** extern void decl_fini_priority_insert (t
*** 2441,2446 ****
--- 2441,2450 ----
#define DECL_NONLOCAL_FRAME(NODE) \
(VAR_DECL_CHECK (NODE)->base.default_def_flag)
+ /* In a VAR_DECL, nonzero if this variable is not aliased by any pointer. */
+ #define DECL_NONALIASED(NODE) \
+ (VAR_DECL_CHECK (NODE)->base.nothrow_flag)
+
/* This field is used to reference anything in decl.result and is meant only
for use by the garbage collector. */
#define DECL_RESULT_FLD(NODE) \
*************** static inline bool
*** 4462,4473 ****
may_be_aliased (const_tree var)
{
return (TREE_CODE (var) != CONST_DECL
- && !((TREE_STATIC (var) || TREE_PUBLIC (var) || DECL_EXTERNAL (var))
- && TREE_READONLY (var)
- && !TYPE_NEEDS_CONSTRUCTING (TREE_TYPE (var)))
&& (TREE_PUBLIC (var)
|| DECL_EXTERNAL (var)
! || TREE_ADDRESSABLE (var)));
}
/* Return pointer to optimization flags of FNDECL. */
--- 4466,4479 ----
may_be_aliased (const_tree var)
{
return (TREE_CODE (var) != CONST_DECL
&& (TREE_PUBLIC (var)
|| DECL_EXTERNAL (var)
! || TREE_ADDRESSABLE (var))
! && !((TREE_STATIC (var) || TREE_PUBLIC (var) || DECL_EXTERNAL (var))
! && ((TREE_READONLY (var)
! && !TYPE_NEEDS_CONSTRUCTING (TREE_TYPE (var)))
! || (TREE_CODE (var) == VAR_DECL
! && DECL_NONALIASED (var)))));
}
/* Return pointer to optimization flags of FNDECL. */
Index: gcc/coverage.c
===================================================================
*** gcc/coverage.c (revision 208693)
--- gcc/coverage.c (working copy)
*************** build_var (tree fn_decl, tree type, int
*** 721,726 ****
--- 721,727 ----
DECL_NAME (var) = get_identifier (buf);
TREE_STATIC (var) = 1;
TREE_ADDRESSABLE (var) = 1;
+ DECL_NONALIASED (var) = 1;
DECL_ALIGN (var) = TYPE_ALIGN (type);
return var;
Index: gcc/testsuite/gcc.dg/tree-ssa/ssa-lim-11.c
===================================================================
*** gcc/testsuite/gcc.dg/tree-ssa/ssa-lim-11.c (revision 0)
--- gcc/testsuite/gcc.dg/tree-ssa/ssa-lim-11.c (working copy)
***************
*** 0 ****
--- 1,25 ----
+ /* { dg-do compile } */
+ /* { dg-options "-O -fprofile-arcs -fdump-tree-lim1-details" } */
+
+ struct thread_param
+ {
+ long* buf;
+ long iterations;
+ long accesses;
+ } param;
+
+ void access_buf(struct thread_param* p)
+ {
+ long i,j;
+ long iterations = p->iterations;
+ long accesses = p->accesses;
+ for (i=0; i<iterations; i++)
+ {
+ long* pbuf = p->buf;
+ for (j=0; j<accesses; j++)
+ pbuf[j] += 1;
+ }
+ }
+
+ /* { dg-final { scan-tree-dump-times "Executing store motion of
__gcov0.access_buf\\\[\[01\]\\\] from loop 1" 2 "lim1" } } */
+ /* { dg-final { cleanup-tree-dump "lim1" } } */
