[lld] [llvm] [LLD][COFF] Prefetch inputs early-on to improve link times (PR #169224)

[Alexandre Ganea via llvm-commits]

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@@ -1023,6 +1023,30 @@ void mapped_file_region::unmapImpl() {
 
 void mapped_file_region::dontNeedImpl() {}
 
+void mapped_file_region::willNeedImpl() {
+  HMODULE kernelM = llvm::sys::windows::loadSystemModuleSecure(L"kernel32.dll");
+  if (kernelM) {
+    struct MEMORY_RANGE_ENTRY {
+      PVOID VirtualAddress;
+      SIZE_T NumberOfBytes;
+    };
+
+    // PrefetchVirtualMemory is only available on Windows 8 and later. Since we
+    // still support compilation on Windows 7, we load the function dynamically.
+    typedef BOOL(WINAPI * PrefetchVirtualMemory_t)(
+        HANDLE hProcess, ULONG_PTR NumberOfEntries,
+        _In_reads_(NumberOfEntries) MEMORY_RANGE_ENTRY * VirtualAddresses,
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aganea wrote:

I dropped `_In_reads_`. For `*VirtualAddresses`, clang-format puts it back as above, not sure why.

https://github.com/llvm/llvm-project/pull/169224