From b454a26fc2228ee93ccec766a619520a599c764d Mon Sep 17 00:00:00 2001
From: Aldy Hernandez <aldyh@redhat.com>
Date: Thu, 14 May 2020 16:25:42 +0200
Subject: If argument of __builtin_constant_p resolves to a constant, return
 range of 1.

---
 gcc/gimple-range-cfg.cc | 6 ++++++
 1 file changed, 6 insertions(+)

(limited to 'gcc')

diff --git a/gcc/gimple-range-cfg.cc b/gcc/gimple-range-cfg.cc
index f7d61b8..0ed06a2 100644
--- a/gcc/gimple-range-cfg.cc
+++ b/gcc/gimple-range-cfg.cc
@@ -277,6 +277,12 @@ gimple_ranger::range_of_builtin_call (irange &r, gcall *call)
 	  // r.equiv_clear ();
 	  return true;
 	}
+      arg = gimple_call_arg (call, 0);
+      if (range_of_expr (r, arg, call) && r.singleton_p ())
+	{
+	  r.set (build_one_cst (type), build_one_cst (type));
+	  return true;
+	}
       break;
 
     CASE_CFN_FFS:
-- 
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