upstream rustc_codegen_llvm changes for enzyme/autodiff

compiler/rustc_codegen_llvm/src/llvm/enzyme_ffi.rs

@@ -0,0 +1,29 @@
+#![allow(non_camel_case_types)]
+
+use libc::{c_char, c_uint};
+
+use super::ffi::{BasicBlock, Metadata, Module, Type, Value};
+use crate::llvm::Bool;
+extern "C" {
+    // Enzyme
+    pub fn LLVMRustHasMetadata(I: &Value, KindID: c_uint) -> bool;
+    pub fn LLVMRustEraseInstBefore(BB: &BasicBlock, I: &Value);
+    pub fn LLVMRustGetLastInstruction<'a>(BB: &BasicBlock) -> Option<&'a Value>;
+    pub fn LLVMRustDIGetInstMetadata(I: &Value) -> Option<&Metadata>;
+    pub fn LLVMRustEraseInstFromParent(V: &Value);
+    pub fn LLVMRustGetTerminator<'a>(B: &BasicBlock) -> &'a Value;
+    pub fn LLVMRustVerifyFunction(V: &Value, action: LLVMRustVerifierFailureAction) -> Bool;
+
+    pub fn LLVMGetFunctionCallConv(F: &Value) -> c_uint;
+    pub fn LLVMGetReturnType(T: &Type) -> &Type;
+    pub fn LLVMGetParams(Fnc: &Value, parms: *mut &Value);
+    pub fn LLVMGetNamedFunction(M: &Module, Name: *const c_char) -> Option<&Value>;
+}
+
+#[repr(C)]
+#[derive(Copy, Clone, PartialEq)]
+pub enum LLVMRustVerifierFailureAction {
+    LLVMAbortProcessAction = 0,
+    LLVMPrintMessageAction = 1,
+    LLVMReturnStatusAction = 2,
+}