[PATCH] libstdc++: Resolve integer type mismatches in stdx::simd [PR122981]

Tested on x86_64, powerpc64 (le and be), aarch64, arm-none-eabi, and arm-
linux-gnueabi. OK for trunk and backports?

This supersedes Torbjörn SVENSSON's patch. Thanks Torbjörn for the important 
hint that int32_t is not an alias for int on arm-none-eabi!

---------------- 8< ---------------

From: Matthias Kretz <[email protected]>

Conversions from generic vector to ARM vector are rejected when the
value type is not equal. Since arm-none-eabi defines int32_t as long
rather than int, a generic int vector passed as int32x2_t argument is
ill-formed.

With this patch, use the intN_t aliases in general: for the central
__int_for_sizeof meta function and when bitcasting vectors in the NEON
popcount implementation.

This solution avoids unnecessary reinterpretation of generic vectors as
ARM vectors, keeping it a tiny bit more type safe.

libstdc++-v3/ChangeLog:

	* include/experimental/bits/simd.h (__int_for_sizeof): Return
	int32_t, int8_t, int16_t, and int64_t, rather than int, signed
	char, short, long, and long long.
	* include/experimental/bits/simd_neon.h (_S_popcount): Cast
	elements to int8_t, int16_t, int32_t, or int64_t, rather than
	signed char, short, int, or long.

Signed-off-by: Matthias Kretz <[email protected]>
---
 libstdc++-v3/include/experimental/bits/simd.h  | 18 ++++++++----------
 .../include/experimental/bits/simd_neon.h      |  8 ++++----
 2 files changed, 12 insertions(+), 14 deletions(-)

diff --git a/libstdc++-v3/include/experimental/bits/simd.h b/libstdc++-v3/
include/experimental/bits/simd.h
index 5b3f622c6ea..69085859819 100644
--- a/libstdc++-v3/include/experimental/bits/simd.h
+++ b/libstdc++-v3/include/experimental/bits/simd.h
@@ -608,16 +608,14 @@ struct __is_bitmask
   __int_for_sizeof()
   {
     static_assert(_Bytes > 0);
-    if constexpr (_Bytes == sizeof(int))
-      return int();
-    else if constexpr (_Bytes == sizeof(_SChar))
-      return _SChar();
-    else if constexpr (_Bytes == sizeof(short))
-      return short();
-    else if constexpr (_Bytes == sizeof(long))
-      return long();
-    else if constexpr (_Bytes == sizeof(_LLong))
-      return _LLong();
+    if constexpr (_Bytes == sizeof(int32_t))
+      return int32_t();
+    else if constexpr (_Bytes == sizeof(int8_t))
+      return int8_t();
+    else if constexpr (_Bytes == sizeof(int16_t))
+      return int16_t();
+    else if constexpr (_Bytes == sizeof(int64_t))
+      return int64_t();
   #ifdef __SIZEOF_INT128__
     else if constexpr (_Bytes == sizeof(__int128))
       return __int128();
diff --git a/libstdc++-v3/include/experimental/bits/simd_neon.h b/libstdc++-
v3/include/experimental/bits/simd_neon.h
index 8fabee7f328..e032a1ea535 100644
--- a/libstdc++-v3/include/experimental/bits/simd_neon.h
+++ b/libstdc++-v3/include/experimental/bits/simd_neon.h
@@ -480,27 +480,27 @@ _S_popcount(simd_mask<_Tp, _Abi> __k)
       {
 	if constexpr (sizeof(_Tp) == 1)
 	  {
-	    const auto __s8 = __vector_bitcast<_SChar>(__k._M_data);
+	    const auto __s8 = __vector_bitcast<int8_t>(__k._M_data);
 	    int8x8_t __tmp = __lo64(__s8) + __hi64z(__s8);
 	    return -vpadd_s8(vpadd_s8(vpadd_s8(__tmp, int8x8_t()), 
int8x8_t()),
 			     int8x8_t())[0];
 	  }
 	else if constexpr (sizeof(_Tp) == 2)
 	  {
-	    const auto __s16 = __vector_bitcast<short>(__k._M_data);
+	    const auto __s16 = __vector_bitcast<int16_t>(__k._M_data);
 	    int16x4_t __tmp = __lo64(__s16) + __hi64z(__s16);
 	    return -vpadd_s16(vpadd_s16(__tmp, int16x4_t()), int16x4_t())[0];
 	  }
 	else if constexpr (sizeof(_Tp) == 4)
 	  {
-	    const auto __s32 = __vector_bitcast<int>(__k._M_data);
+	    const auto __s32 = __vector_bitcast<int32_t>(__k._M_data);
 	    int32x2_t __tmp = __lo64(__s32) + __hi64z(__s32);
 	    return -vpadd_s32(__tmp, int32x2_t())[0];
 	  }
 	else if constexpr (sizeof(_Tp) == 8)
 	  {
 	    static_assert(sizeof(__k) == 16);
-	    const auto __s64 = __vector_bitcast<long>(__k._M_data);
+	    const auto __s64 = __vector_bitcast<int64_t>(__k._M_data);
 	    return -(__s64[0] + __s64[1]);
 	  }
       }
-- 
──────────────────────────────────────────────────────────────────────────
 Dr. Matthias Kretz                           https://mattkretz.github.io
 GSI Helmholtz Center for Heavy Ion Research               https://gsi.de
 std::simd
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