Pass debuginfo_compression through FFI as an enum

Author: Zalathar

compiler/rustc_codegen_llvm/src/back/owned_target_machine.rs

@@ -36,7 +36,7 @@ impl OwnedTargetMachine {
         use_init_array: bool,
         split_dwarf_file: &CStr,
         output_obj_file: &CStr,
-        debug_info_compression: &CStr,
+        debug_info_compression: llvm::CompressionKind,
         use_emulated_tls: bool,
         use_wasm_eh: bool,
     ) -> Result<Self, LlvmError<'static>> {
@@ -62,7 +62,7 @@ impl OwnedTargetMachine {
                 use_init_array,
                 split_dwarf_file.as_ptr(),
                 output_obj_file.as_ptr(),
-                debug_info_compression.as_ptr(),
+                debug_info_compression,
                 use_emulated_tls,
                 use_wasm_eh,
             )

compiler/rustc_codegen_llvm/src/back/write.rs

@@ -6,9 +6,6 @@ use std::sync::Arc;
 use std::{fs, slice, str};
 
 use libc::{c_char, c_int, c_void, size_t};
-use llvm::{
-    LLVMRustLLVMHasZlibCompressionForDebugSymbols, LLVMRustLLVMHasZstdCompressionForDebugSymbols,
-};
 use rustc_codegen_ssa::back::link::ensure_removed;
 use rustc_codegen_ssa::back::versioned_llvm_target;
 use rustc_codegen_ssa::back::write::{
@@ -252,21 +249,25 @@ pub(crate) fn target_machine_factory(
 
     let use_emulated_tls = matches!(sess.tls_model(), TlsModel::Emulated);
 
-    let debuginfo_compression = sess.opts.debuginfo_compression.to_string();
-    match sess.opts.debuginfo_compression {
-        rustc_session::config::DebugInfoCompression::Zlib => {
-            if !unsafe { LLVMRustLLVMHasZlibCompressionForDebugSymbols() } {
+    let debuginfo_compression = match sess.opts.debuginfo_compression {
+        config::DebugInfoCompression::None => llvm::CompressionKind::None,
+        config::DebugInfoCompression::Zlib => {
+            if llvm::LLVMRustLLVMHasZlibCompression() {
+                llvm::CompressionKind::Zlib
+            } else {
                 sess.dcx().emit_warn(UnknownCompression { algorithm: "zlib" });
+                llvm::CompressionKind::None
             }
         }
-        rustc_session::config::DebugInfoCompression::Zstd => {
-            if !unsafe { LLVMRustLLVMHasZstdCompressionForDebugSymbols() } {
+        config::DebugInfoCompression::Zstd => {
+            if llvm::LLVMRustLLVMHasZstdCompression() {
+                llvm::CompressionKind::Zstd
+            } else {
                 sess.dcx().emit_warn(UnknownCompression { algorithm: "zstd" });
+                llvm::CompressionKind::None
             }
         }
-        rustc_session::config::DebugInfoCompression::None => {}
     };
-    let debuginfo_compression = SmallCStr::new(&debuginfo_compression);
 
     let file_name_display_preference =
         sess.filename_display_preference(RemapPathScopeComponents::DEBUGINFO);
@@ -310,7 +311,7 @@ pub(crate) fn target_machine_factory(
             use_init_array,
             &split_dwarf_file,
             &output_obj_file,
-            &debuginfo_compression,
+            debuginfo_compression,
             use_emulated_tls,
             use_wasm_eh,
         )

compiler/rustc_codegen_llvm/src/llvm/ffi.rs

@@ -677,6 +677,15 @@ pub(crate) enum Opcode {
     CatchSwitch = 65,
 }
 
+/// Must match the layout of `LLVMRustCompressionKind`.
+#[derive(Copy, Clone)]
+#[repr(C)]
+pub(crate) enum CompressionKind {
+    None = 0,
+    Zlib = 1,
+    Zstd = 2,
+}
+
 unsafe extern "C" {
     type Opaque;
 }
@@ -2328,7 +2337,7 @@ unsafe extern "C" {
         UseInitArray: bool,
         SplitDwarfFile: *const c_char,
         OutputObjFile: *const c_char,
-        DebugInfoCompression: *const c_char,
+        DebugInfoCompression: CompressionKind,
         UseEmulatedTls: bool,
         UseWasmEH: bool,
     ) -> *mut TargetMachine;
@@ -2516,9 +2525,8 @@ unsafe extern "C" {
 
     pub(crate) fn LLVMRustGetElementTypeArgIndex(CallSite: &Value) -> i32;
 
-    pub(crate) fn LLVMRustLLVMHasZlibCompressionForDebugSymbols() -> bool;
-
-    pub(crate) fn LLVMRustLLVMHasZstdCompressionForDebugSymbols() -> bool;
+    pub(crate) safe fn LLVMRustLLVMHasZlibCompression() -> bool;
+    pub(crate) safe fn LLVMRustLLVMHasZstdCompression() -> bool;
 
     pub(crate) fn LLVMRustGetSymbols(
         buf_ptr: *const u8,

compiler/rustc_llvm/llvm-wrapper/PassWrapper.cpp

@@ -224,6 +224,32 @@ static FloatABI::ABIType fromRust(LLVMRustFloatABI RustFloatAbi) {
   report_fatal_error("Bad FloatABI.");
 }
 
+// Must match the layout of `rustc_codegen_llvm::llvm::ffi::CompressionKind`.
+enum class LLVMRustCompressionKind {
+  None = 0,
+  Zlib = 1,
+  Zstd = 2,
+};
+
+static llvm::DebugCompressionType
+fromRust(LLVMRustCompressionKind Kind) {
+  switch (Kind) {
+  case LLVMRustCompressionKind::None:
+    return llvm::DebugCompressionType::None;
+  case LLVMRustCompressionKind::Zlib:
+    if (!llvm::compression::zlib::isAvailable()) {
+      report_fatal_error("LLVMRustCompressionKind::Zlib not available");
+    }
+    return llvm::DebugCompressionType::Zlib;
+  case LLVMRustCompressionKind::Zstd:
+    if (!llvm::compression::zstd::isAvailable()) {
+      report_fatal_error("LLVMRustCompressionKind::Zstd not available");
+    }
+    return llvm::DebugCompressionType::Zstd;
+  }
+  report_fatal_error("bad LLVMRustCompressionKind");
+}
+
 extern "C" void LLVMRustPrintTargetCPUs(LLVMTargetMachineRef TM,
                                         RustStringRef OutStr) {
   ArrayRef<SubtargetSubTypeKV> CPUTable =
@@ -271,7 +297,8 @@ extern "C" LLVMTargetMachineRef LLVMRustCreateTargetMachine(
     bool TrapUnreachable, bool Singlethread, bool VerboseAsm,
     bool EmitStackSizeSection, bool RelaxELFRelocations, bool UseInitArray,
     const char *SplitDwarfFile, const char *OutputObjFile,
-    const char *DebugInfoCompression, bool UseEmulatedTls, bool UseWasmEH) {
+    LLVMRustCompressionKind DebugInfoCompression, bool UseEmulatedTls,
+    bool UseWasmEH) {
 
   auto OptLevel = fromRust(RustOptLevel);
   auto RM = fromRust(RustReloc);
@@ -307,16 +334,10 @@ extern "C" LLVMTargetMachineRef LLVMRustCreateTargetMachine(
   if (OutputObjFile) {
     Options.ObjectFilenameForDebug = OutputObjFile;
   }
-  if (!strcmp("zlib", DebugInfoCompression) &&
-      llvm::compression::zlib::isAvailable()) {
-    Options.MCOptions.CompressDebugSections = DebugCompressionType::Zlib;
-  } else if (!strcmp("zstd", DebugInfoCompression) &&
-             llvm::compression::zstd::isAvailable()) {
-    Options.MCOptions.CompressDebugSections = DebugCompressionType::Zstd;
-  } else if (!strcmp("none", DebugInfoCompression)) {
-    Options.MCOptions.CompressDebugSections = DebugCompressionType::None;
-  }
-
+  // To avoid fatal errors, make sure the Rust-side code only passes a
+  // compression kind that is known to be supported by this build of LLVM, via
+  // `LLVMRustLLVMHasZlibCompression` and `LLVMRustLLVMHasZstdCompression`.
+  Options.MCOptions.CompressDebugSections = fromRust(DebugInfoCompression);
   Options.MCOptions.X86RelaxRelocations = RelaxELFRelocations;
   Options.UseInitArray = UseInitArray;
   Options.EmulatedTLS = UseEmulatedTls;

compiler/rustc_llvm/llvm-wrapper/RustWrapper.cpp

@@ -1640,11 +1640,11 @@ extern "C" bool LLVMRustIsNonGVFunctionPointerTy(LLVMValueRef V) {
   return false;
 }
 
-extern "C" bool LLVMRustLLVMHasZlibCompressionForDebugSymbols() {
+extern "C" bool LLVMRustLLVMHasZlibCompression() {
   return llvm::compression::zlib::isAvailable();
 }
 
-extern "C" bool LLVMRustLLVMHasZstdCompressionForDebugSymbols() {
+extern "C" bool LLVMRustLLVMHasZstdCompression() {
   return llvm::compression::zstd::isAvailable();
 }
 

compiler/rustc_session/src/config.rs

@@ -583,17 +583,6 @@ pub enum DebugInfoCompression {
     Zstd,
 }
 
-impl ToString for DebugInfoCompression {
-    fn to_string(&self) -> String {
-        match self {
-            DebugInfoCompression::None => "none",
-            DebugInfoCompression::Zlib => "zlib",
-            DebugInfoCompression::Zstd => "zstd",
-        }
-        .to_owned()
-    }
-}
-
 #[derive(Clone, Copy, Debug, PartialEq, Hash)]
 pub enum MirStripDebugInfo {
     None,