The following gets rid of __builtin_constant_p earlier to avoid
array-bound diagnostics on dead code. There's been enough optimization
on the fully inlined bodies so we can do that at the time of
array-bound diagnostics.
Bootstrapped and tested on x86_64-unknown-linux-gnu, applied to trunk.
Richard.
2019-09-11 Richard Biener <rguent...@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.
Index: gcc/vr-values.c
===================================================================
--- gcc/vr-values.c (revision 275638)
+++ gcc/vr-values.c (working copy)
@@ -1124,15 +1124,8 @@ vr_values::extract_range_basic (value_ra
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 ();
Index: gcc/testsuite/gcc.dg/Warray-bounds-44.c
===================================================================
--- gcc/testsuite/gcc.dg/Warray-bounds-44.c (nonexistent)
+++ gcc/testsuite/gcc.dg/Warray-bounds-44.c (working copy)
@@ -0,0 +1,23 @@
+/* { 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;
+}
