[clang] [llvm] Clang: convert `__m64` intrinsics to unconditionally use SSE2 instead of MMX. (PR #96540)

[Phoebe Wang via cfe-commits]

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@@ -337,10 +363,10 @@ _mm_unpacklo_pi32(__m64 __m1, __m64 __m2)
 ///    A 64-bit integer vector of [8 x i8].
 /// \returns A 64-bit integer vector of [8 x i8] containing the sums of both
 ///    parameters.
-static __inline__ __m64 __DEFAULT_FN_ATTRS
+static __inline__ __m64 __DEFAULT_FN_ATTRS_SSE2
 _mm_add_pi8(__m64 __m1, __m64 __m2)
 {
-    return (__m64)__builtin_ia32_paddb((__v8qi)__m1, (__v8qi)__m2);
+    return (__m64)(((__v8qu)__m1) + ((__v8qu)__m2));
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phoebewang wrote:

`__v8qi`? Same for below.

https://github.com/llvm/llvm-project/pull/96540