From: Matthias Kretz <m.kretz@gsi.de>
Date: Fri, 13 Jan 2023 15:20:36 +0000 (+0100)
Subject: libstdc++: Ensure __builtin_constant_p isn't lost on the way
X-Git-Tag: releases/gcc-12.3.0~336
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=d1084be3151d447cffe2d36667e67939dcdf3e75;p=thirdparty%2Fgcc.git

libstdc++: Ensure __builtin_constant_p isn't lost on the way

The more expensive code path should only be taken if it can be optimized
away.

Signed-off-by: Matthias Kretz <m.kretz@gsi.de>

libstdc++-v3/ChangeLog:

	* include/experimental/bits/simd.h
	(_SimdWrapper::_M_is_constprop_none_of)
	(_SimdWrapper::_M_is_constprop_all_of): Return false unless the
	computed result still satisfies __builtin_constant_p.

(cherry picked from commit fea34ee491104f325682cc5fb75683b7d74a0a3b)
---

diff --git a/libstdc++-v3/include/experimental/bits/simd.h b/libstdc++-v3/include/experimental/bits/simd.h
index b0226fa4c530..2b1e5bcbe946 100644
--- a/libstdc++-v3/include/experimental/bits/simd.h
+++ b/libstdc++-v3/include/experimental/bits/simd.h
@@ -2673,7 +2673,8 @@ template <typename _Tp, size_t _Width>
 	  else
 	    __execute_n_times<_Width>(
 	      [&](auto __i) { __r &= _M_data[__i.value] == _Tp(); });
-	  return __r;
+	  if (__builtin_constant_p(__r))
+	    return __r;
 	}
       return false;
     }
@@ -2693,7 +2694,8 @@ template <typename _Tp, size_t _Width>
 	  else
 	    __execute_n_times<_Width>(
 	      [&](auto __i) { __r &= _M_data[__i.value] == ~_Tp(); });
-	  return __r;
+	  if (__builtin_constant_p(__r))
+	    return __r;
 	}
       return false;
     }