[llvm] [Support] Fix xxh3_128bits for Win32 builds (PR #96931)

[Fangrui Song via llvm-commits]

https://github.com/MaskRay created https://github.com/llvm/llvm-project/pull/96931

`__emulu` is used without including `intrin.h`. Actually, it's better to
rely on compiler optimizations. In this LLVM copy, we try to eliminate
unneceeded workarounds for old compilers.


>From bacc254478240f6157a202879b3dd3bd33049122 Mon Sep 17 00:00:00 2001
From: Fangrui Song <i at maskray.me>
Date: Thu, 27 Jun 2024 09:52:48 -0700
Subject: [PATCH] =?UTF-8?q?[=F0=9D=98=80=F0=9D=97=BD=F0=9D=97=BF]=20initia?=
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Created using spr 1.3.5-bogner
---
 llvm/lib/Support/xxhash.cpp | 11 -----------
 1 file changed, 11 deletions(-)

diff --git a/llvm/lib/Support/xxhash.cpp b/llvm/lib/Support/xxhash.cpp
index a0803297555ce..607789b391381 100644
--- a/llvm/lib/Support/xxhash.cpp
+++ b/llvm/lib/Support/xxhash.cpp
@@ -453,18 +453,7 @@ uint64_t llvm::xxh3_64bits(ArrayRef<uint8_t> data) {
 #define XXH_rotl64(x, r) (((x) << (r)) | ((x) >> (64 - (r))))
 #endif
 
-#if defined(_MSC_VER) && defined(_M_IX86)
-#define XXH_mult32to64(x, y) __emulu((unsigned)(x), (unsigned)(y))
-#else
-/*
- * Downcast + upcast is usually better than masking on older compilers like
- * GCC 4.2 (especially 32-bit ones), all without affecting newer compilers.
- *
- * The other method, (x & 0xFFFFFFFF) * (y & 0xFFFFFFFF), will AND both operands
- * and perform a full 64x64 multiply -- entirely redundant on 32-bit.
- */
 #define XXH_mult32to64(x, y) ((uint64_t)(uint32_t)(x) * (uint64_t)(uint32_t)(y))
-#endif
 
 /*!
  * @brief Calculates a 64->128-bit long multiply.