4 files changed, 65 insertions, 14 deletions
diff --git a/compiler/rustc_llvm/Cargo.toml b/compiler/rustc_llvm/Cargo.toml
index 7c402310436..4f3ce77efc4 100644
--- a/compiler/rustc_llvm/Cargo.toml
+++ b/compiler/rustc_llvm/Cargo.toml
@@ -1,7 +1,7 @@
 [package]
 name = "rustc_llvm"
 version = "0.0.0"
-edition = "2021"
+edition = "2024"
 
 [dependencies]
 # tidy-alphabetical-start
@@ -12,5 +12,5 @@ libc = "0.2.73"
 # tidy-alphabetical-start
 # Pinned so `cargo update` bumps don't cause breakage. Please also update the
 # pinned `cc` in `rustc_codegen_ssa` if you update `cc` here.
-cc = "=1.2.7"
+cc = "=1.2.13"
 # tidy-alphabetical-end
diff --git a/compiler/rustc_llvm/build.rs b/compiler/rustc_llvm/build.rs
index d9d28299413..3d1f3b2cd4d 100644
--- a/compiler/rustc_llvm/build.rs
+++ b/compiler/rustc_llvm/build.rs
@@ -51,9 +51,13 @@ fn detect_llvm_link() -> (&'static str, &'static str) {
 fn restore_library_path() {
     let key = tracked_env_var_os("REAL_LIBRARY_PATH_VAR").expect("REAL_LIBRARY_PATH_VAR");
     if let Some(env) = tracked_env_var_os("REAL_LIBRARY_PATH") {
-        env::set_var(&key, env);
+        unsafe {
+            env::set_var(&key, env);
+        }
     } else {
-        env::remove_var(&key);
+        unsafe {
+            env::remove_var(&key);
+        }
     }
 }
 
@@ -193,6 +197,10 @@ fn main() {
         cfg.define(&flag, None);
     }
 
+    if tracked_env_var_os("LLVM_ENZYME").is_some() {
+        cfg.define("ENZYME", None);
+    }
+
     if tracked_env_var_os("LLVM_RUSTLLVM").is_some() {
         cfg.define("LLVM_RUSTLLVM", None);
     }
diff --git a/compiler/rustc_llvm/llvm-wrapper/PassWrapper.cpp b/compiler/rustc_llvm/llvm-wrapper/PassWrapper.cpp
index 6447a9362b3..9ce4abdb432 100644
--- a/compiler/rustc_llvm/llvm-wrapper/PassWrapper.cpp
+++ b/compiler/rustc_llvm/llvm-wrapper/PassWrapper.cpp
@@ -22,6 +22,7 @@
 #include "llvm/Passes/StandardInstrumentations.h"
 #include "llvm/Support/CBindingWrapping.h"
 #include "llvm/Support/FileSystem.h"
+#include "llvm/Support/Program.h"
 #include "llvm/Support/TimeProfiler.h"
 #include "llvm/Support/VirtualFileSystem.h"
 #include "llvm/Target/TargetMachine.h"
@@ -472,16 +473,19 @@ extern "C" LLVMTargetMachineRef LLVMRustCreateTargetMachine(
     assert(ArgsCstrBuff[ArgsCstrBuffLen - 1] == '\0');
     auto Arg0 = std::string(ArgsCstrBuff);
     buffer_offset = Arg0.size() + 1;
-    auto ArgsCppStr = std::string(ArgsCstrBuff + buffer_offset,
-                                  ArgsCstrBuffLen - buffer_offset);
-    auto i = 0;
-    while (i != std::string::npos) {
-      i = ArgsCppStr.find('\0', i + 1);
-      if (i != std::string::npos)
-        ArgsCppStr.replace(i, 1, " ");
+
+    std::string CommandlineArgs;
+    raw_string_ostream OS(CommandlineArgs);
+    ListSeparator LS(" ");
+    for (StringRef Arg : split(StringRef(ArgsCstrBuff + buffer_offset,
+                                         ArgsCstrBuffLen - buffer_offset),
+                               '\0')) {
+      OS << LS;
+      sys::printArg(OS, Arg, /*Quote=*/true);
     }
+    OS.flush();
     Options.MCOptions.Argv0 = Arg0;
-    Options.MCOptions.CommandlineArgs = ArgsCppStr;
+    Options.MCOptions.CommandlineArgs = CommandlineArgs;
 #else
     int buffer_offset = 0;
     assert(ArgsCstrBuff[ArgsCstrBuffLen - 1] == '\0');
@@ -688,14 +692,23 @@ struct LLVMRustSanitizerOptions {
   bool SanitizeKernelAddressRecover;
 };
 
+// This symbol won't be available or used when Enzyme is not enabled.
+// Always set AugmentPassBuilder to true, since it registers optimizations which
+// will improve the performance for Enzyme.
+#ifdef ENZYME
+extern "C" void registerEnzymeAndPassPipeline(llvm::PassBuilder &PB,
+                                              /* augmentPassBuilder */ bool);
+#endif
+
 extern "C" LLVMRustResult LLVMRustOptimize(
     LLVMModuleRef ModuleRef, LLVMTargetMachineRef TMRef,
     LLVMRustPassBuilderOptLevel OptLevelRust, LLVMRustOptStage OptStage,
     bool IsLinkerPluginLTO, bool NoPrepopulatePasses, bool VerifyIR,
     bool LintIR, bool UseThinLTOBuffers, bool MergeFunctions, bool UnrollLoops,
     bool SLPVectorize, bool LoopVectorize, bool DisableSimplifyLibCalls,
-    bool EmitLifetimeMarkers, LLVMRustSanitizerOptions *SanitizerOptions,
-    const char *PGOGenPath, const char *PGOUsePath, bool InstrumentCoverage,
+    bool EmitLifetimeMarkers, bool RunEnzyme,
+    LLVMRustSanitizerOptions *SanitizerOptions, const char *PGOGenPath,
+    const char *PGOUsePath, bool InstrumentCoverage,
     const char *InstrProfileOutput, const char *PGOSampleUsePath,
     bool DebugInfoForProfiling, void *LlvmSelfProfiler,
     LLVMRustSelfProfileBeforePassCallback BeforePassCallback,
@@ -1010,6 +1023,18 @@ extern "C" LLVMRustResult LLVMRustOptimize(
     MPM.addPass(NameAnonGlobalPass());
   }
 
+  // now load "-enzyme" pass:
+#ifdef ENZYME
+  if (RunEnzyme) {
+    registerEnzymeAndPassPipeline(PB, true);
+    if (auto Err = PB.parsePassPipeline(MPM, "enzyme")) {
+      std::string ErrMsg = toString(std::move(Err));
+      LLVMRustSetLastError(ErrMsg.c_str());
+      return LLVMRustResult::Failure;
+    }
+  }
+#endif
+
   // Upgrade all calls to old intrinsics first.
   for (Module::iterator I = TheModule->begin(), E = TheModule->end(); I != E;)
     UpgradeCallsToIntrinsic(&*I++); // must be post-increment, as we remove
diff --git a/compiler/rustc_llvm/llvm-wrapper/RustWrapper.cpp b/compiler/rustc_llvm/llvm-wrapper/RustWrapper.cpp
index b8cef6a7e25..aea2a8dd097 100644
--- a/compiler/rustc_llvm/llvm-wrapper/RustWrapper.cpp
+++ b/compiler/rustc_llvm/llvm-wrapper/RustWrapper.cpp
@@ -1767,6 +1767,24 @@ extern "C" LLVMValueRef LLVMRustBuildMaxNum(LLVMBuilderRef B, LLVMValueRef LHS,
   return wrap(unwrap(B)->CreateMaxNum(unwrap(LHS), unwrap(RHS)));
 }
 
+#if LLVM_VERSION_LT(19, 0)
+enum {
+  LLVMGEPFlagInBounds = (1 << 0),
+  LLVMGEPFlagNUSW = (1 << 1),
+  LLVMGEPFlagNUW = (1 << 2),
+};
+extern "C" LLVMValueRef
+LLVMBuildGEPWithNoWrapFlags(LLVMBuilderRef B, LLVMTypeRef Ty,
+                            LLVMValueRef Pointer, LLVMValueRef *Indices,
+                            unsigned NumIndices, const char *Name,
+                            unsigned NoWrapFlags) {
+  if (NoWrapFlags & LLVMGEPFlagInBounds)
+    return LLVMBuildInBoundsGEP2(B, Ty, Pointer, Indices, NumIndices, Name);
+  else
+    return LLVMBuildGEP2(B, Ty, Pointer, Indices, NumIndices, Name);
+}
+#endif
+
 // Transfers ownership of DiagnosticHandler unique_ptr to the caller.
 extern "C" DiagnosticHandler *
 LLVMRustContextGetDiagnosticHandler(LLVMContextRef C) {