This fixes PR44061 by computing a false range for __builtin_constant_p
of parameters in VRP.
Bootstrapped and tested on x86_64-unknown-linux-gnu, applied to trunk.
Richard.
2012-01-11 Richard Guenther <rguent...@suse.de>
PR tree-optimization/44061
* tree-vrp.c (extract_range_basic): Compute zero as
value-range for __builtin_constant_p of function parameters.
* gcc.dg/pr44061.c: New testcase.
Index: gcc/tree-vrp.c
===================================================================
*** gcc/tree-vrp.c (revision 195085)
--- gcc/tree-vrp.c (working copy)
*************** extract_range_basic (value_range_t *vr,
*** 3566,3573 ****
bool sop = false;
tree type = gimple_expr_type (stmt);
! if (INTEGRAL_TYPE_P (type)
! && gimple_stmt_nonnegative_warnv_p (stmt, &sop))
set_value_range_to_nonnegative (vr, type,
sop || stmt_overflow_infinity (stmt));
else if (vrp_stmt_computes_nonzero (stmt, &sop)
--- 3566,3585 ----
bool sop = false;
tree type = gimple_expr_type (stmt);
! /* 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. */
! if (gimple_call_builtin_p (stmt, BUILT_IN_CONSTANT_P))
! {
! tree 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)
! set_value_range_to_null (vr, type);
! }
! else if (INTEGRAL_TYPE_P (type)
! && gimple_stmt_nonnegative_warnv_p (stmt, &sop))
set_value_range_to_nonnegative (vr, type,
sop || stmt_overflow_infinity (stmt));
else if (vrp_stmt_computes_nonzero (stmt, &sop)
Index: gcc/testsuite/gcc.dg/pr44061.c
===================================================================
*** gcc/testsuite/gcc.dg/pr44061.c (revision 0)
--- gcc/testsuite/gcc.dg/pr44061.c (working copy)
***************
*** 0 ****
--- 1,16 ----
+ /* { dg-do compile } */
+ /* { dg-options "-O2 -Wall" } */
+
+ int a[2];
+ int foo (int q)
+ {
+ if (__builtin_constant_p (q))
+ {
+ if (q == 4)
+ return a[4]; /* { dg-bogus "array subscript is above array bounds" } */
+ else
+ return a[0];
+ }
+ else
+ return a[q];
+ }
