Auto merge of #136428 - EnzymeAD:enable-autodiff, r=oli-obk

test building enzyme in CI

1) This PR fixes a significant compile-time regression, by only running the expensive autodiff pipeline, if the users pass the newly introduced Enable value to the `-Zautodiff=` flag. It updates the test(s) accordingly. It gives a nice error if users forget that.
2) It fixes macos support by explicitly linking against the Enzyme build folder. This doesn't cover CI macos yet.
3) It fixes the issue that setting ENZYME_RUNPASS was ignored by enzyme and in fact did not schedule enzyme's opt pass.
4) It also re-enables support for various other values for the autodiff flag, which were ignored since the refactor.
5) I merged some improvements to Enzyme core, which means we do not longer depend on LLVM being build with the Plugin Interface enabled.
6) Unrelated to other fixes, this changes `rustc_autodiff` to `EncodeCrossCrate::Yes`. It is not enough on it's own to enable usage of Enzyme in libraries, but it is for sure a piece of the fixes needed to get this to work.

try-job: x86_64-gnu

r? `@oli-obk`

Tracking:

- https://github.com/rust-lang/rust/issues/124509

1 files changed, 94 insertions, 0 deletions

diff --git a/compiler/rustc_codegen_llvm/src/llvm/enzyme_ffi.rs b/compiler/rustc_codegen_llvm/src/llvm/enzyme_ffi.rs
index 39bac13a968..daa6696e963 100644
--- a/compiler/rustc_codegen_llvm/src/llvm/enzyme_ffi.rs
+++ b/compiler/rustc_codegen_llvm/src/llvm/enzyme_ffi.rs
@@ -35,3 +35,97 @@ pub enum LLVMRustVerifierFailureAction {
     LLVMPrintMessageAction = 1,
     LLVMReturnStatusAction = 2,
 }
+
+#[cfg(llvm_enzyme)]
+pub use self::Enzyme_AD::*;
+
+#[cfg(llvm_enzyme)]
+pub mod Enzyme_AD {
+    use libc::c_void;
+    extern "C" {
+        pub fn EnzymeSetCLBool(arg1: *mut ::std::os::raw::c_void, arg2: u8);
+    }
+    extern "C" {
+        static mut EnzymePrintPerf: c_void;
+        static mut EnzymePrintActivity: c_void;
+        static mut EnzymePrintType: c_void;
+        static mut EnzymePrint: c_void;
+        static mut EnzymeStrictAliasing: c_void;
+        static mut looseTypeAnalysis: c_void;
+        static mut EnzymeInline: c_void;
+        static mut RustTypeRules: c_void;
+    }
+    pub fn set_print_perf(print: bool) {
+        unsafe {
+            EnzymeSetCLBool(std::ptr::addr_of_mut!(EnzymePrintPerf), print as u8);
+        }
+    }
+    pub fn set_print_activity(print: bool) {
+        unsafe {
+            EnzymeSetCLBool(std::ptr::addr_of_mut!(EnzymePrintActivity), print as u8);
+        }
+    }
+    pub fn set_print_type(print: bool) {
+        unsafe {
+            EnzymeSetCLBool(std::ptr::addr_of_mut!(EnzymePrintType), print as u8);
+        }
+    }
+    pub fn set_print(print: bool) {
+        unsafe {
+            EnzymeSetCLBool(std::ptr::addr_of_mut!(EnzymePrint), print as u8);
+        }
+    }
+    pub fn set_strict_aliasing(strict: bool) {
+        unsafe {
+            EnzymeSetCLBool(std::ptr::addr_of_mut!(EnzymeStrictAliasing), strict as u8);
+        }
+    }
+    pub fn set_loose_types(loose: bool) {
+        unsafe {
+            EnzymeSetCLBool(std::ptr::addr_of_mut!(looseTypeAnalysis), loose as u8);
+        }
+    }
+    pub fn set_inline(val: bool) {
+        unsafe {
+            EnzymeSetCLBool(std::ptr::addr_of_mut!(EnzymeInline), val as u8);
+        }
+    }
+    pub fn set_rust_rules(val: bool) {
+        unsafe {
+            EnzymeSetCLBool(std::ptr::addr_of_mut!(RustTypeRules), val as u8);
+        }
+    }
+}
+
+#[cfg(not(llvm_enzyme))]
+pub use self::Fallback_AD::*;
+
+#[cfg(not(llvm_enzyme))]
+pub mod Fallback_AD {
+    #![allow(unused_variables)]
+
+    pub fn set_inline(val: bool) {
+        unimplemented!()
+    }
+    pub fn set_print_perf(print: bool) {
+        unimplemented!()
+    }
+    pub fn set_print_activity(print: bool) {
+        unimplemented!()
+    }
+    pub fn set_print_type(print: bool) {
+        unimplemented!()
+    }
+    pub fn set_print(print: bool) {
+        unimplemented!()
+    }
+    pub fn set_strict_aliasing(strict: bool) {
+        unimplemented!()
+    }
+    pub fn set_loose_types(loose: bool) {
+        unimplemented!()
+    }
+    pub fn set_rust_rules(val: bool) {
+        unimplemented!()
+    }
+}