ipa/120006 - wrong code with IPA PTA

When PTA gets support for special-handling more builtins in
find_func_aliases the corresponding code in find_func_clobbers
needs updating as well since for unhandled cases it assumes
the former will populate ESCAPED accordingly.  The following
fixes a few omissions, the testcase runs into the missing strdup
handling.  I believe the more advanced handling using modref
results and fnspecs opened a larger gap, the proper fix is to
merge both functions, gating the clobber/use part on a parameter
to avoid diverging.

	PR ipa/120006
	* tree-ssa-structalias.cc (find_func_clobbers): Handle
	strdup, strndup, realloc, index, strchr, strrchr, memchr,
	strstr, strpbrk builtins like find_func_aliases does.

	* gcc.dg/torture/pr120006.c: New testcase.

(cherry picked from commit a85b89e26b1f50997701eb428c2dd71668f216ff)

2 files changed, 67 insertions, 0 deletions

diff --git a/gcc/testsuite/gcc.dg/torture/pr120006.c b/gcc/testsuite/gcc.dg/torture/pr120006.c
new file mode 100644
index 0000000..c067f0e
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/torture/pr120006.c
@@ -0,0 +1,31 @@
+/* { dg-do run } */
+/* { dg-additional-options "-fipa-pta" } */
+
+char *b;
+int f = 1;
+
+char *xstrdup(char *i) {
+  char *c = __builtin_strdup(i);
+  if (!c)
+    __builtin_exit(1);
+  return c;
+}
+
+int main() {
+  char g;
+  char h[8];
+
+  for (int i = 0; i < 2; i++) {
+    char c = *__builtin_strdup("");
+    b = &g;
+
+    if (f) {
+      h[0] = '-';
+      h[1] = 'a';
+      h[2] = '\0';
+      b = xstrdup(h);
+   }
+  }
+  if (__builtin_strcmp(b, "-a") != 0)
+    __builtin_abort();
+}
diff --git a/gcc/tree-ssa-structalias.cc b/gcc/tree-ssa-structalias.cc
index f79b542..3ad0c69 100644
--- a/gcc/tree-ssa-structalias.cc
+++ b/gcc/tree-ssa-structalias.cc
@@ -5583,6 +5583,42 @@ find_func_clobbers (struct function *fn, gimple *origt)
 	      process_ipa_clobber (fi, gimple_call_arg (t, 2));
 	      return;
 	    }
+	  /* The following functions use what their first argument
+	     points to.  */
+	  case BUILT_IN_STRDUP:
+	  case BUILT_IN_STRNDUP:
+	  case BUILT_IN_REALLOC:
+	  case BUILT_IN_INDEX:
+	  case BUILT_IN_STRCHR:
+	  case BUILT_IN_STRRCHR:
+	  case BUILT_IN_MEMCHR:
+	    {
+	      tree src = gimple_call_arg (t, 0);
+	      get_constraint_for_ptr_offset (src, NULL_TREE, &rhsc);
+	      lhs = get_function_part_constraint (fi, fi_uses);
+	      struct constraint_expr *rhsp;
+	      FOR_EACH_VEC_ELT (rhsc, i, rhsp)
+		process_constraint (new_constraint (lhs, *rhsp));
+	      return;
+	    }
+	  /* The following functions use what their first and second argument
+	     point to.  */
+	  case BUILT_IN_STRSTR:
+	  case BUILT_IN_STRPBRK:
+	    {
+	      tree src = gimple_call_arg (t, 0);
+	      get_constraint_for_ptr_offset (src, NULL_TREE, &rhsc);
+	      lhs = get_function_part_constraint (fi, fi_uses);
+	      struct constraint_expr *rhsp;
+	      FOR_EACH_VEC_ELT (rhsc, i, rhsp)
+		process_constraint (new_constraint (lhs, *rhsp));
+	      rhsc.truncate (0);
+	      src = gimple_call_arg (t, 1);
+	      get_constraint_for_ptr_offset (src, NULL_TREE, &rhsc);
+	      FOR_EACH_VEC_ELT (rhsc, i, rhsp)
+		process_constraint (new_constraint (lhs, *rhsp));
+	      return;
+	    }
 	  /* The following functions neither read nor clobber memory.  */
 	  case BUILT_IN_ASSUME_ALIGNED:
 	  case BUILT_IN_FREE: