[libc-commits] [libc] 1c71603 - [libc] Add rep; movsb as an accelerator under x86

[Guillaume Chatelet via libc-commits]

Author: Guillaume Chatelet
Date: 2021-10-08T13:34:59Z
New Revision: 1c7160300db124468ef4a26ec55ad3d6e6527a69

URL: https://github.com/llvm/llvm-project/commit/1c7160300db124468ef4a26ec55ad3d6e6527a69
DIFF: https://github.com/llvm/llvm-project/commit/1c7160300db124468ef4a26ec55ad3d6e6527a69.diff

LOG: [libc] Add rep;movsb as an accelerator under x86

Added: 
    

Modified: 
    libc/src/string/memory_utils/elements_x86.h

Removed: 
    


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diff  --git a/libc/src/string/memory_utils/elements_x86.h b/libc/src/string/memory_utils/elements_x86.h
index 2873fff8b2e22..9521e0625ab85 100644
--- a/libc/src/string/memory_utils/elements_x86.h
+++ b/libc/src/string/memory_utils/elements_x86.h
@@ -160,6 +160,12 @@ using _64 = __llvm_libc::Repeated<_8, 8>;
 using _128 = __llvm_libc::Repeated<_8, 16>;
 #endif
 
+struct Accelerator {
+  static void Copy(char *dst, const char *src, size_t count) {
+    asm volatile("rep movsb" : "+D"(dst), "+S"(src), "+c"(count) : : "memory");
+  }
+};
+
 } // namespace x86
 } // namespace __llvm_libc