First working version of LLVM in Windows

lib/llvm-backend/src/platform/win.rs

@@ -0,0 +1,80 @@
+use super::common::round_up_to_page_size;
+use crate::structs::{LLVMResult, MemProtect};
+use std::ptr;
+
+use winapi::um::memoryapi::{VirtualAlloc, VirtualFree};
+use winapi::um::winnt::{
+    MEM_COMMIT, MEM_DECOMMIT, MEM_RESERVE, PAGE_EXECUTE_READ, PAGE_NOACCESS, PAGE_READONLY,
+    PAGE_READWRITE,
+};
+
+pub unsafe fn visit_fde(_addr: *mut u8, _size: usize, _visitor: extern "C" fn(*mut u8)) {
+    // Do nothing on Windows
+}
+
+pub unsafe fn install_signal_handler() {
+    // Do nothing on Windows
+}
+
+pub unsafe fn alloc_memory(
+    size: usize,
+    protect: MemProtect,
+    ptr_out: &mut *mut u8,
+    size_out: &mut usize,
+) -> LLVMResult {
+    let size = round_up_to_page_size(size);
+    let flags = if protect == MemProtect::NONE {
+        MEM_RESERVE
+    } else {
+        MEM_RESERVE | MEM_COMMIT
+    };
+    let ptr = VirtualAlloc(
+        ptr::null_mut(),
+        size,
+        flags,
+        memprotect_to_protect_const(protect),
+    );
+
+    if ptr.is_null() {
+        return LLVMResult::ALLOCATE_FAILURE;
+    }
+
+    *ptr_out = ptr as _;
+    *size_out = size;
+    LLVMResult::OK
+}
+
+pub unsafe fn protect_memory(ptr: *mut u8, size: usize, protect: MemProtect) -> LLVMResult {
+    let size = round_up_to_page_size(size);
+    let ptr = VirtualAlloc(
+        ptr as _,
+        size,
+        MEM_COMMIT,
+        memprotect_to_protect_const(protect),
+    );
+
+    if ptr.is_null() {
+        LLVMResult::PROTECT_FAILURE
+    } else {
+        LLVMResult::OK
+    }
+}
+
+pub unsafe fn dealloc_memory(ptr: *mut u8, size: usize) -> LLVMResult {
+    let success = VirtualFree(ptr as _, size, MEM_DECOMMIT);
+    // If the function succeeds, the return value is nonzero.
+    if success == 1 {
+        LLVMResult::OK
+    } else {
+        LLVMResult::DEALLOC_FAILURE
+    }
+}
+
+fn memprotect_to_protect_const(protect: MemProtect) -> u32 {
+    match protect {
+        MemProtect::NONE => PAGE_NOACCESS,
+        MemProtect::READ => PAGE_READONLY,
+        MemProtect::READ_WRITE => PAGE_READWRITE,
+        MemProtect::READ_EXECUTE => PAGE_EXECUTE_READ,
+    }
+}