Hello,
this avoids folding __builtin_constant_p to 0 early when we are not forced
to do so. Clearly this has an effect, since it uncovered a bug in
wi::lshift, fixed today ;-)
I wasn't sure about using |= or just =, the first one seemed more
conservative.
Bootstrap+regtest on x86_64-pc-linux-gnu.
2019-07-11 Marc Glisse <marc.gli...@inria.fr>
gcc/cp/
* constexpr.c (cxx_eval_builtin_function_call): Only set
force_folding_builtin_constant_p if manifestly_const_eval.
gcc/testsuite/
* g++.dg/pr85746.C: New file.
--
Marc GlisseIndex: gcc/cp/constexpr.c
===================================================================
--- gcc/cp/constexpr.c (revision 273356)
+++ gcc/cp/constexpr.c (working copy)
@@ -1248,21 +1248,21 @@ cxx_eval_builtin_function_call (const co
&dummy1, &dummy2);
}
if (bi_const_p)
/* For __builtin_constant_p, fold all expressions with constant values
even if they aren't C++ constant-expressions. */
args[i] = cp_fold_rvalue (args[i]);
}
bool save_ffbcp = force_folding_builtin_constant_p;
- force_folding_builtin_constant_p = true;
+ force_folding_builtin_constant_p |= ctx->manifestly_const_eval;
tree save_cur_fn = current_function_decl;
/* Return name of ctx->call->fundef->decl for __builtin_FUNCTION (). */
if (fndecl_built_in_p (fun, BUILT_IN_FUNCTION)
&& ctx->call
&& ctx->call->fundef)
current_function_decl = ctx->call->fundef->decl;
new_call = fold_builtin_call_array (EXPR_LOCATION (t), TREE_TYPE (t),
CALL_EXPR_FN (t), nargs, args);
current_function_decl = save_cur_fn;
force_folding_builtin_constant_p = save_ffbcp;
Index: gcc/testsuite/g++.dg/pr85746.C
===================================================================
--- gcc/testsuite/g++.dg/pr85746.C (nonexistent)
+++ gcc/testsuite/g++.dg/pr85746.C (working copy)
@@ -0,0 +1,10 @@
+/* { dg-do compile } */
+/* { dg-options "-O -fdump-tree-gimple" } */
+
+int f(int a,int b){
+ // The front-end should not fold this to 0.
+ int c = __builtin_constant_p(a < b);
+ return c;
+}
+
+/* { dg-final { scan-tree-dump "__builtin_constant_p" "gimple" } } */
