Hi,
The attached patch adds special-casing for strcpy/strncpy to dse pass.
Bootstrapped+tested on x86_64-unknown-linux-gnu.
OK for GCC 8 ?
Thanks,
Prathamesh
diff --git a/gcc/testsuite/gcc.dg/tree-ssa/pr79715.c
b/gcc/testsuite/gcc.dg/tree-ssa/pr79715.c
new file mode 100644
index 0000000..1a832ca
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/tree-ssa/pr79715.c
@@ -0,0 +1,12 @@
+/* { dg-do compile } */
+/* { dg-options "-O2 -fdump-tree-dse-details" } */
+
+void f(const char *s)
+{
+ unsigned n = __builtin_strlen (s) + 1;
+ char *p = __builtin_malloc (n);
+ __builtin_strcpy (p, s);
+ __builtin_free (p);
+}
+
+/* { dg-final { scan-tree-dump "Deleted dead call: __builtin_strcpy" "dse1" }
} */
diff --git a/gcc/tree-ssa-dse.c b/gcc/tree-ssa-dse.c
index 53feaf3..6d3c3c3 100644
--- a/gcc/tree-ssa-dse.c
+++ b/gcc/tree-ssa-dse.c
@@ -97,6 +97,8 @@ initialize_ao_ref_for_dse (gimple *stmt, ao_ref *write)
case BUILT_IN_MEMCPY:
case BUILT_IN_MEMMOVE:
case BUILT_IN_MEMSET:
+ case BUILT_IN_STRNCPY:
+ case BUILT_IN_STRCPY:
{
tree size = NULL_TREE;
if (gimple_call_num_args (stmt) == 3)
@@ -395,6 +397,8 @@ maybe_trim_memstar_call (ao_ref *ref, sbitmap live, gimple
*stmt)
{
case BUILT_IN_MEMCPY:
case BUILT_IN_MEMMOVE:
+ case BUILT_IN_STRNCPY:
+ case BUILT_IN_STRCPY:
{
int head_trim, tail_trim;
compute_trims (ref, live, &head_trim, &tail_trim, stmt);
@@ -713,6 +717,7 @@ dse_dom_walker::dse_optimize_stmt (gimple_stmt_iterator
*gsi)
case BUILT_IN_MEMCPY:
case BUILT_IN_MEMMOVE:
case BUILT_IN_MEMSET:
+ case BUILT_IN_STRNCPY:
{
/* Occasionally calls with an explicit length of zero
show up in the IL. It's pointless to do analysis
@@ -723,7 +728,10 @@ dse_dom_walker::dse_optimize_stmt (gimple_stmt_iterator
*gsi)
delete_dead_call (gsi);
return;
}
-
+ }
+ /* fallthru */
+ case BUILT_IN_STRCPY:
+ {
gimple *use_stmt;
enum dse_store_status store_status;
m_byte_tracking_enabled
