make Enzyme build optional

Author: ZuseZ4

src/bootstrap/configure.py

@@ -72,6 +72,7 @@ def v(*args):
 o("optimize-llvm", "llvm.optimize", "build optimized LLVM")
 o("llvm-assertions", "llvm.assertions", "build LLVM with assertions")
 o("llvm-plugins", "llvm.plugins", "build LLVM with plugin interface")
+o("llvm-enzyme", "llvm.enzyme", "build LLVM with enzyme")
 o("debug-assertions", "rust.debug-assertions", "build with debugging assertions")
 o("debug-assertions-std", "rust.debug-assertions-std", "build the standard library with debugging assertions")
 o("overflow-checks", "rust.overflow-checks", "build with overflow checks")

src/bootstrap/src/core/build_steps/compile.rs

@@ -1638,12 +1638,11 @@ impl Step for Assemble {
         }
 
         // Build enzyme
-        let enzyme_install = Some(builder.ensure(llvm::Enzyme { target: build_compiler.host }));
-        //let enzyme_install = if builder.config.llvm_enzyme {
-        //    Some(builder.ensure(llvm::Enzyme { target: build_compiler.host }))
-        //} else {
-        //    None
-        //};
+        let enzyme_install = if builder.config.llvm_enzyme {
+            Some(builder.ensure(llvm::Enzyme { target: build_compiler.host }))
+        } else {
+            None
+        };
 
         if let Some(enzyme_install) = enzyme_install {
             let src_lib = enzyme_install.join("build/Enzyme/LLVMEnzyme-17.so");

src/bootstrap/src/core/builder.rs

@@ -1417,8 +1417,10 @@ impl<'a> Builder<'a> {
         }
 
         // https://rust-lang.zulipchat.com/#narrow/stream/182449-t-compiler.2Fhelp/topic/.E2.9C.94.20link.20new.20library.20into.20stage1.2Frustc
-        rustflags.arg("-l");
-        rustflags.arg("LLVMEnzyme-17");
+        if self.config.llvm_enzyme {
+            rustflags.arg("-l");
+            rustflags.arg("LLVMEnzyme-17");
+        }
 
         let use_new_symbol_mangling = match self.config.rust_new_symbol_mangling {
             Some(setting) => {

src/bootstrap/src/core/config/config.rs

@@ -211,6 +211,7 @@ pub struct Config {
     pub llvm_assertions: bool,
     pub llvm_tests: bool,
     pub llvm_plugins: bool,
+    pub llvm_enzyme: bool,
     pub llvm_optimize: bool,
     pub llvm_thin_lto: bool,
     pub llvm_release_debuginfo: bool,
@@ -872,6 +873,7 @@ define_config! {
         release_debuginfo: Option<bool> = "release-debuginfo",
         assertions: Option<bool> = "assertions",
         tests: Option<bool> = "tests",
+        enzyme: Option<bool> = "enzyme",
         plugins: Option<bool> = "plugins",
         ccache: Option<StringOrBool> = "ccache",
         static_libstdcpp: Option<bool> = "static-libstdcpp",
@@ -1494,6 +1496,7 @@ impl Config {
         // we'll infer default values for them later
         let mut llvm_assertions = None;
         let mut llvm_tests = None;
+        let mut llvm_enzyme = None;
         let mut llvm_plugins = None;
         let mut debug = None;
         let mut debug_assertions = None;
@@ -1697,6 +1700,7 @@ impl Config {
                 release_debuginfo,
                 assertions,
                 tests,
+                enzyme,
                 plugins,
                 ccache,
                 static_libstdcpp,
@@ -1729,6 +1733,7 @@ impl Config {
             set(&mut config.ninja_in_file, ninja);
             llvm_assertions = assertions;
             llvm_tests = tests;
+            llvm_enzyme = enzyme;
             llvm_plugins = plugins;
             set(&mut config.llvm_optimize, optimize_toml);
             set(&mut config.llvm_thin_lto, thin_lto);
@@ -1885,6 +1890,7 @@ impl Config {
 
         config.llvm_assertions = llvm_assertions.unwrap_or(false);
         config.llvm_tests = llvm_tests.unwrap_or(false);
+        config.llvm_enzyme = llvm_enzyme.unwrap_or(true);
         config.llvm_plugins = llvm_plugins.unwrap_or(false);
         config.rust_optimize = optimize.unwrap_or(RustOptimize::Bool(true));