re PR tree-optimization/90387 (__builtin_constant_p and -Warray-bounds warnings)

2019-09-11  Richard Biener  <rguenther@suse.de>

	PR tree-optimization/90387
	* vr-values.c (vr_values::extract_range_basic): After inlining
	simplify non-constant __builtin_constant_p to false.

	* gcc.dg/Warray-bounds-44.c: New testcase.

From-SVN: r275639

gcc/ChangeLog

+2019-09-11  Richard Biener  <rguenther@suse.de>
+
+	PR tree-optimization/90387
+	* vr-values.c (vr_values::extract_range_basic): After inlining
+	simplify non-constant __builtin_constant_p to false.
+
 2019-09-11  Eric Botcazou  <ebotcazou@adacore.com>
 
 	PR rtl-optimization/89795

gcc/testsuite/ChangeLog

+2019-09-11  Richard Biener  <rguenther@suse.de>
+
+	PR tree-optimization/90387
+	* gcc.dg/Warray-bounds-44.c: New testcase.
+
 2019-09-11  Eric Botcazou  <ebotcazou@adacore.com>
 
 	* gcc.target/sparc/20161111-1.c: XFAIL redundant zero-extension test.

gcc/testsuite/gcc.dg/Warray-bounds-44.c

+/* { dg-do compile } */
+/* { dg-options "-O2 -Warray-bounds" } */
+
+int foo(unsigned int state, unsigned char * p, unsigned int p_len)
+{
+    static char const pattern[] = "abcd";
+    static unsigned const pattern_length = sizeof(pattern) - 1;
+
+    if (p_len == 1) {
+        return state;
+    }
+
+    if (state < pattern_length &&
+        p_len == (pattern_length - state) &&
+	(!__builtin_constant_p(p_len) ?
+         __builtin_memcmp(p, pattern + state, p_len) :
+         ((unsigned char*)p)[6] == ((unsigned char*)pattern + state)[6] /* { dg-bogus "array bounds" } */
+        )) {
+
+        return 4;
+    }
+    return 1;
+}

gcc/vr-values.c

@@ -1124,15 +1124,8 @@ vr_values::extract_range_basic (value_range *vr, gimple *stmt)
       switch (cfn)
 	{
 	case CFN_BUILT_IN_CONSTANT_P:
-	  /* If the call is __builtin_constant_p and the argument is a
-	     function parameter resolve it to false.  This avoids bogus
-	     array bound warnings.
-	     ???  We could do this as early as inlining is finished.  */
-	  arg = gimple_call_arg (stmt, 0);
-	  if (TREE_CODE (arg) == SSA_NAME
-	      && SSA_NAME_IS_DEFAULT_DEF (arg)
-	      && TREE_CODE (SSA_NAME_VAR (arg)) == PARM_DECL
-	      && cfun->after_inlining)
+	  /* Resolve calls to __builtin_constant_p after inlining.  */
+	  if (cfun->after_inlining)
 	    {
 	      vr->set_zero (type);
 	      vr->equiv_clear ();