Set target-abi module flag for RISC-V targets

Fixes cross-language LTO on RISC-V targets (Fixes #121924)

compiler/rustc_codegen_llvm/src/back/lto.rs

@@ -608,7 +608,7 @@ pub(crate) fn run_pass_manager(
             "LTOPostLink".as_ptr().cast(),
             11,
         ) {
-            llvm::LLVMRustAddModuleFlag(
+            llvm::LLVMRustAddModuleFlagU32(
                 module.module_llvm.llmod(),
                 llvm::LLVMModFlagBehavior::Error,
                 c"LTOPostLink".as_ptr().cast(),

compiler/rustc_codegen_llvm/src/context.rs

@@ -35,6 +35,7 @@ use libc::c_uint;
 use std::borrow::Borrow;
 use std::cell::{Cell, RefCell};
 use std::ffi::CStr;
+use std::ffi::CString;
 use std::str;
 
 /// There is one `CodegenCx` per compilation unit. Each one has its own LLVM
@@ -180,13 +181,13 @@ pub unsafe fn create_module<'ll>(
     // to ensure intrinsic calls don't use it.
     if !sess.needs_plt() {
         let avoid_plt = c"RtLibUseGOT".as_ptr().cast();
-        llvm::LLVMRustAddModuleFlag(llmod, llvm::LLVMModFlagBehavior::Warning, avoid_plt, 1);
+        llvm::LLVMRustAddModuleFlagU32(llmod, llvm::LLVMModFlagBehavior::Warning, avoid_plt, 1);
     }
 
     // Enable canonical jump tables if CFI is enabled. (See https://reviews.llvm.org/D65629.)
     if sess.is_sanitizer_cfi_canonical_jump_tables_enabled() && sess.is_sanitizer_cfi_enabled() {
         let canonical_jump_tables = c"CFI Canonical Jump Tables".as_ptr().cast();
-        llvm::LLVMRustAddModuleFlag(
+        llvm::LLVMRustAddModuleFlagU32(
             llmod,
             llvm::LLVMModFlagBehavior::Override,
             canonical_jump_tables,
@@ -197,7 +198,7 @@ pub unsafe fn create_module<'ll>(
     // Enable LTO unit splitting if specified or if CFI is enabled. (See https://reviews.llvm.org/D53891.)
     if sess.is_split_lto_unit_enabled() || sess.is_sanitizer_cfi_enabled() {
         let enable_split_lto_unit = c"EnableSplitLTOUnit".as_ptr().cast();
-        llvm::LLVMRustAddModuleFlag(
+        llvm::LLVMRustAddModuleFlagU32(
             llmod,
             llvm::LLVMModFlagBehavior::Override,
             enable_split_lto_unit,
@@ -208,7 +209,7 @@ pub unsafe fn create_module<'ll>(
     // Add "kcfi" module flag if KCFI is enabled. (See https://reviews.llvm.org/D119296.)
     if sess.is_sanitizer_kcfi_enabled() {
         let kcfi = c"kcfi".as_ptr().cast();
-        llvm::LLVMRustAddModuleFlag(llmod, llvm::LLVMModFlagBehavior::Override, kcfi, 1);
+        llvm::LLVMRustAddModuleFlagU32(llmod, llvm::LLVMModFlagBehavior::Override, kcfi, 1);
     }
 
     // Control Flow Guard is currently only supported by the MSVC linker on Windows.
@@ -217,7 +218,7 @@ pub unsafe fn create_module<'ll>(
             CFGuard::Disabled => {}
             CFGuard::NoChecks => {
                 // Set `cfguard=1` module flag to emit metadata only.
-                llvm::LLVMRustAddModuleFlag(
+                llvm::LLVMRustAddModuleFlagU32(
                     llmod,
                     llvm::LLVMModFlagBehavior::Warning,
                     c"cfguard".as_ptr() as *const _,
@@ -226,7 +227,7 @@ pub unsafe fn create_module<'ll>(
             }
             CFGuard::Checks => {
                 // Set `cfguard=2` module flag to emit metadata and checks.
-                llvm::LLVMRustAddModuleFlag(
+                llvm::LLVMRustAddModuleFlagU32(
                     llmod,
                     llvm::LLVMModFlagBehavior::Warning,
                     c"cfguard".as_ptr() as *const _,
@@ -238,26 +239,26 @@ pub unsafe fn create_module<'ll>(
 
     if let Some(BranchProtection { bti, pac_ret }) = sess.opts.unstable_opts.branch_protection {
         if sess.target.arch == "aarch64" {
-            llvm::LLVMRustAddModuleFlag(
+            llvm::LLVMRustAddModuleFlagU32(
                 llmod,
                 llvm::LLVMModFlagBehavior::Min,
                 c"branch-target-enforcement".as_ptr().cast(),
                 bti.into(),
             );
-            llvm::LLVMRustAddModuleFlag(
+            llvm::LLVMRustAddModuleFlagU32(
                 llmod,
                 llvm::LLVMModFlagBehavior::Min,
                 c"sign-return-address".as_ptr().cast(),
                 pac_ret.is_some().into(),
             );
             let pac_opts = pac_ret.unwrap_or(PacRet { leaf: false, key: PAuthKey::A });
-            llvm::LLVMRustAddModuleFlag(
+            llvm::LLVMRustAddModuleFlagU32(
                 llmod,
                 llvm::LLVMModFlagBehavior::Min,
                 c"sign-return-address-all".as_ptr().cast(),
                 pac_opts.leaf.into(),
             );
-            llvm::LLVMRustAddModuleFlag(
+            llvm::LLVMRustAddModuleFlagU32(
                 llmod,
                 llvm::LLVMModFlagBehavior::Min,
                 c"sign-return-address-with-bkey".as_ptr().cast(),
@@ -273,7 +274,7 @@ pub unsafe fn create_module<'ll>(
 
     // Pass on the control-flow protection flags to LLVM (equivalent to `-fcf-protection` in Clang).
     if let CFProtection::Branch | CFProtection::Full = sess.opts.unstable_opts.cf_protection {
-        llvm::LLVMRustAddModuleFlag(
+        llvm::LLVMRustAddModuleFlagU32(
             llmod,
             llvm::LLVMModFlagBehavior::Override,
             c"cf-protection-branch".as_ptr().cast(),
@@ -281,7 +282,7 @@ pub unsafe fn create_module<'ll>(
         )
     }
     if let CFProtection::Return | CFProtection::Full = sess.opts.unstable_opts.cf_protection {
-        llvm::LLVMRustAddModuleFlag(
+        llvm::LLVMRustAddModuleFlagU32(
             llmod,
             llvm::LLVMModFlagBehavior::Override,
             c"cf-protection-return".as_ptr().cast(),
@@ -290,7 +291,7 @@ pub unsafe fn create_module<'ll>(
     }
 
     if sess.opts.unstable_opts.virtual_function_elimination {
-        llvm::LLVMRustAddModuleFlag(
+        llvm::LLVMRustAddModuleFlagU32(
             llmod,
             llvm::LLVMModFlagBehavior::Error,
             c"Virtual Function Elim".as_ptr().cast(),
@@ -300,7 +301,7 @@ pub unsafe fn create_module<'ll>(
 
     // Set module flag to enable Windows EHCont Guard (/guard:ehcont).
     if sess.opts.unstable_opts.ehcont_guard {
-        llvm::LLVMRustAddModuleFlag(
+        llvm::LLVMRustAddModuleFlagU32(
             llmod,
             llvm::LLVMModFlagBehavior::Warning,
             c"ehcontguard".as_ptr() as *const _,
@@ -326,6 +327,23 @@ pub unsafe fn create_module<'ll>(
         llvm::LLVMMDNodeInContext(llcx, &name_metadata, 1),
     );
 
+    // Emit RISC-V specific target-abi metadata
+    // to workaround lld as the LTO plugin not
+    // correctly setting target-abi for the LTO object
+    // FIXME: https://github.com/llvm/llvm-project/issues/50591
+    // If llvm_abiname is empty, emit nothing.
+    if matches!(sess.target.arch.as_ref(), "riscv32" | "riscv64")
+        && !sess.target.options.llvm_abiname.is_empty()
+    {
+        let llvm_abiname = CString::new(sess.target.options.llvm_abiname.as_ref()).unwrap();
+        llvm::LLVMRustAddModuleFlagString(
+            llmod,
+            llvm::LLVMModFlagBehavior::Error,
+            c"target-abi".as_ptr() as *const _,
+            llvm_abiname.as_ptr() as *const _,
+        );
+    }
+
     // Add module flags specified via -Z llvm_module_flag
     for (key, value, behavior) in &sess.opts.unstable_opts.llvm_module_flag {
         let key = format!("{key}\0");
@@ -341,7 +359,7 @@ pub unsafe fn create_module<'ll>(
             // We already checked this during option parsing
             _ => unreachable!(),
         };
-        llvm::LLVMRustAddModuleFlag(llmod, behavior, key.as_ptr().cast(), *value)
+        llvm::LLVMRustAddModuleFlagU32(llmod, behavior, key.as_ptr().cast(), *value)
     }
 
     llmod

compiler/rustc_codegen_llvm/src/debuginfo/mod.rs

@@ -110,7 +110,7 @@ impl<'ll, 'tcx> CodegenUnitDebugContext<'ll, 'tcx> {
                     .unstable_opts
                     .dwarf_version
                     .unwrap_or(sess.target.default_dwarf_version);
-                llvm::LLVMRustAddModuleFlag(
+                llvm::LLVMRustAddModuleFlagU32(
                     self.llmod,
                     llvm::LLVMModFlagBehavior::Warning,
                     c"Dwarf Version".as_ptr().cast(),
@@ -118,7 +118,7 @@ impl<'ll, 'tcx> CodegenUnitDebugContext<'ll, 'tcx> {
                 );
             } else {
                 // Indicate that we want CodeView debug information on MSVC
-                llvm::LLVMRustAddModuleFlag(
+                llvm::LLVMRustAddModuleFlagU32(
                     self.llmod,
                     llvm::LLVMModFlagBehavior::Warning,
                     c"CodeView".as_ptr().cast(),
@@ -127,7 +127,7 @@ impl<'ll, 'tcx> CodegenUnitDebugContext<'ll, 'tcx> {
             }
 
             // Prevent bitcode readers from deleting the debug info.
-            llvm::LLVMRustAddModuleFlag(
+            llvm::LLVMRustAddModuleFlagU32(
                 self.llmod,
                 llvm::LLVMModFlagBehavior::Warning,
                 c"Debug Info Version".as_ptr().cast(),

compiler/rustc_codegen_llvm/src/llvm/ffi.rs

@@ -1801,12 +1801,20 @@ extern "C" {
     ///
     /// In order for Rust-C LTO to work, module flags must be compatible with Clang. What
     /// "compatible" means depends on the merge behaviors involved.
-    pub fn LLVMRustAddModuleFlag(
+    pub fn LLVMRustAddModuleFlagU32(
         M: &Module,
         merge_behavior: LLVMModFlagBehavior,
         name: *const c_char,
         value: u32,
     );
+
+    pub fn LLVMRustAddModuleFlagString(
+        M: &Module,
+        merge_behavior: LLVMModFlagBehavior,
+        name: *const c_char,
+        value: *const c_char,
+    );
+
     pub fn LLVMRustHasModuleFlag(M: &Module, name: *const c_char, len: size_t) -> bool;
 
     pub fn LLVMRustDIBuilderCreate(M: &Module) -> &mut DIBuilder<'_>;

compiler/rustc_llvm/llvm-wrapper/RustWrapper.cpp

@@ -817,7 +817,7 @@ extern "C" uint32_t LLVMRustVersionMinor() { return LLVM_VERSION_MINOR; }
 
 extern "C" uint32_t LLVMRustVersionMajor() { return LLVM_VERSION_MAJOR; }
 
-extern "C" void LLVMRustAddModuleFlag(
+extern "C" void LLVMRustAddModuleFlagU32(
     LLVMModuleRef M,
     Module::ModFlagBehavior MergeBehavior,
     const char *Name,
@@ -825,6 +825,15 @@ extern "C" void LLVMRustAddModuleFlag(
   unwrap(M)->addModuleFlag(MergeBehavior, Name, Value);
 }
 
+extern "C" void LLVMRustAddModuleFlagString(
+    LLVMModuleRef M,
+    Module::ModFlagBehavior MergeBehavior,
+    const char *Name,
+    const char *Value) {
+  llvm::LLVMContext &Ctx = unwrap(M)->getContext();
+  unwrap(M)->addModuleFlag(MergeBehavior, Name, llvm::MDString::get(Ctx, Value));
+}
+
 extern "C" bool LLVMRustHasModuleFlag(LLVMModuleRef M, const char *Name,
                                       size_t Len) {
   return unwrap(M)->getModuleFlag(StringRef(Name, Len)) != nullptr;

src/tools/tidy/src/allowed_run_make_makefiles.txt

@@ -36,6 +36,7 @@ run-make/crate-hash-rustc-version/Makefile
 run-make/crate-name-priority/Makefile
 run-make/cross-lang-lto-clang/Makefile
 run-make/cross-lang-lto-pgo-smoketest/Makefile
+run-make/cross-lang-lto-riscv-abi/Makefile
 run-make/cross-lang-lto-upstream-rlibs/Makefile
 run-make/cross-lang-lto/Makefile
 run-make/debug-assertions/Makefile

tests/codegen/riscv-target-abi.rs

@@ -0,0 +1,20 @@
+//@ revisions:riscv64gc riscv32gc riscv32imac
+
+//@[riscv64gc] compile-flags: --target=riscv64gc-unknown-linux-gnu
+//@[riscv64gc] needs-llvm-components: riscv
+// riscv64gc: !{i32 1, !"target-abi", !"lp64d"}
+
+//@[riscv32gc] compile-flags: --target=riscv32gc-unknown-linux-musl
+//@[riscv32gc] needs-llvm-components: riscv
+// riscv32gc: !{i32 1, !"target-abi", !"ilp32d"}
+
+//@[riscv32imac] compile-flags: --target=riscv32imac-unknown-none-elf
+//@[riscv32imac] needs-llvm-components: riscv
+// riscv32imac-NOT: !"target-abi"
+
+#![feature(no_core, lang_items)]
+#![crate_type = "lib"]
+#![no_core]
+
+#[lang = "sized"]
+trait Sized {}

tests/run-make/cross-lang-lto-riscv-abi/Makefile

@@ -0,0 +1,24 @@
+# needs-matching-clang
+
+# This test makes sure that cross-language LTO works on riscv targets
+
+include ../tools.mk
+
+all: riscv64gc-unknown-linux-gnu riscv32imac-unknown-none-elf riscv32gc-unknown-linux-gnu
+
+define check-target =
+@echo "Testing target $(1)"
+$(RUSTC) --target $(1) -Clinker-plugin-lto=on -Cpanic=abort --crate-type=rlib -o $(TMPDIR)/libriscv-xlto.a ./riscv-xlto.rs
+$(CLANG) -target $(2) -march=$(3) -mabi=$(4) -flto=thin -fuse-ld=lld -L $(TMPDIR) -lriscv-xlto -nostdlib -o $(TMPDIR)/riscv-xlto ./cstart.c
+file $(TMPDIR)/riscv-xlto | $(CGREP) "$(5)"
+endef
+
+
+riscv64gc-unknown-linux-gnu:
+	@$(call check-target,$@,riscv64-linux-gnu,rv64gc,lp64d,double-float ABI)
+
+riscv32imac-unknown-none-elf:
+	@$(call check-target,$@,riscv32-unknown-elf,rv32imac,ilp32,soft-float ABI)
+
+riscv32gc-unknown-linux-gnu:
+	@$(call check-target,$@,riscv32-linux-gnu,rv32gc,ilp32d,double-float ABI)

tests/run-make/cross-lang-lto-riscv-abi/cstart.c

@@ -0,0 +1,5 @@
+extern void hello();
+
+void _start() {
+    hello();
+}

tests/run-make/cross-lang-lto-riscv-abi/riscv-xlto.rs

@@ -0,0 +1,9 @@
+#![allow(internal_features)]
+#![feature(no_core, lang_items)]
+#![no_core]
+
+#[lang = "sized"]
+trait Sized {}
+
+#[no_mangle]
+pub fn hello() {}