Hi,
This patch adjusts alloc-free removal algorithm in DCE to take into account
BUILT_IN_CHKP_BNDRET call returning bounds of allocated memory.
Bootstrapped and tested on linux-x86_64.
Thanks,
Ilya
--
gcc/
2014-06-03 Ilya Enkovich <ilya.enkov...@intel.com>
* tree-ssa-dce.c: Include target.h.
(propagate_necessity): For free call fed by alloc check
bounds are also provided by the same alloc.
(eliminate_unnecessary_stmts): Handle BUILT_IN_CHKP_BNDRET
used by free calls.
diff --git a/gcc/tree-ssa-dce.c b/gcc/tree-ssa-dce.c
index 13a71ce..59a0b71 100644
--- a/gcc/tree-ssa-dce.c
+++ b/gcc/tree-ssa-dce.c
@@ -73,6 +73,7 @@ along with GCC; see the file COPYING3. If not see
#include "flags.h"
#include "cfgloop.h"
#include "tree-scalar-evolution.h"
+#include "target.h"
static struct stmt_stats
{
@@ -778,7 +779,23 @@ propagate_necessity (bool aggressive)
&& DECL_BUILT_IN_CLASS (def_callee) == BUILT_IN_NORMAL
&& (DECL_FUNCTION_CODE (def_callee) == BUILT_IN_MALLOC
|| DECL_FUNCTION_CODE (def_callee) == BUILT_IN_CALLOC))
- continue;
+ {
+ tree retfndecl
+ = targetm.builtin_chkp_function (BUILT_IN_CHKP_BNDRET);
+ gimple bounds_def_stmt;
+ tree bounds;
+
+ /* For instrumented calls we should also check used
+ bounds are returned by the same allocation call. */
+ if (!gimple_call_with_bounds_p (stmt)
+ || ((bounds = gimple_call_arg (stmt, 1))
+ && TREE_CODE (bounds) == SSA_NAME
+ && (bounds_def_stmt = SSA_NAME_DEF_STMT (bounds))
+ && is_gimple_call (bounds_def_stmt)
+ && gimple_call_fndecl (bounds_def_stmt) == retfndecl
+ && gimple_call_arg (bounds_def_stmt, 0) == ptr))
+ continue;
+ }
}
FOR_EACH_SSA_TREE_OPERAND (use, stmt, iter, SSA_OP_USE)
@@ -1204,6 +1221,23 @@ eliminate_unnecessary_stmts (void)
&& !gimple_plf (def_stmt, STMT_NECESSARY))
gimple_set_plf (stmt, STMT_NECESSARY, false);
}
+ /* We did not propagate necessity for free calls fed
+ by allocation function to allow unnecessary
+ alloc-free sequence elimination. For instrumented
+ calls it also means we did not mark bounds producer
+ as necessary and it is time to do it in case free
+ call is not removed. */
+ if (gimple_call_with_bounds_p (stmt))
+ {
+ gimple bounds_def_stmt;
+ tree bounds = gimple_call_arg (stmt, 1);
+ gcc_assert (TREE_CODE (bounds) == SSA_NAME);
+ bounds_def_stmt = SSA_NAME_DEF_STMT (bounds);
+ if (bounds_def_stmt
+ && !gimple_plf (bounds_def_stmt, STMT_NECESSARY))
+ gimple_set_plf (bounds_def_stmt, STMT_NECESSARY,
+ gimple_plf (stmt, STMT_NECESSARY));
+ }
}
/* If GSI is not necessary then remove it. */
@@ -1216,6 +1250,7 @@ eliminate_unnecessary_stmts (void)
else if (is_gimple_call (stmt))
{
tree name = gimple_call_lhs (stmt);
+ tree retfn = targetm.builtin_chkp_function (BUILT_IN_CHKP_BNDRET);
notice_special_calls (stmt);
@@ -1233,7 +1268,9 @@ eliminate_unnecessary_stmts (void)
&& DECL_FUNCTION_CODE (call) != BUILT_IN_CALLOC
&& DECL_FUNCTION_CODE (call) != BUILT_IN_ALLOCA
&& (DECL_FUNCTION_CODE (call)
- != BUILT_IN_ALLOCA_WITH_ALIGN))))
+ != BUILT_IN_ALLOCA_WITH_ALIGN)))
+ /* Avoid doing so for bndret calls for the same reason. */
+ && (!retfn || gimple_call_fndecl (stmt) != retfn))
{
something_changed = true;
if (dump_file && (dump_flags & TDF_DETAILS))
