From 698f8c2f01ea549d77d7dc3338a12e04c11057b9 Mon Sep 17 00:00:00 2001
From: Daniel Baumann <daniel.baumann@progress-linux.org>
Date: Wed, 17 Apr 2024 14:02:58 +0200
Subject: Adding upstream version 1.64.0+dfsg1.

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>
---
 compiler/rustc_codegen_ssa/src/back/lto.rs | 104 +++++++++++++++++++++++++++++
 1 file changed, 104 insertions(+)
 create mode 100644 compiler/rustc_codegen_ssa/src/back/lto.rs

(limited to 'compiler/rustc_codegen_ssa/src/back/lto.rs')

diff --git a/compiler/rustc_codegen_ssa/src/back/lto.rs b/compiler/rustc_codegen_ssa/src/back/lto.rs
new file mode 100644
index 000000000..cb6244050
--- /dev/null
+++ b/compiler/rustc_codegen_ssa/src/back/lto.rs
@@ -0,0 +1,104 @@
+use super::write::CodegenContext;
+use crate::traits::*;
+use crate::ModuleCodegen;
+
+use rustc_data_structures::memmap::Mmap;
+use rustc_errors::FatalError;
+
+use std::ffi::CString;
+use std::sync::Arc;
+
+pub struct ThinModule<B: WriteBackendMethods> {
+    pub shared: Arc<ThinShared<B>>,
+    pub idx: usize,
+}
+
+impl<B: WriteBackendMethods> ThinModule<B> {
+    pub fn name(&self) -> &str {
+        self.shared.module_names[self.idx].to_str().unwrap()
+    }
+
+    pub fn cost(&self) -> u64 {
+        // Yes, that's correct, we're using the size of the bytecode as an
+        // indicator for how costly this codegen unit is.
+        self.data().len() as u64
+    }
+
+    pub fn data(&self) -> &[u8] {
+        let a = self.shared.thin_buffers.get(self.idx).map(|b| b.data());
+        a.unwrap_or_else(|| {
+            let len = self.shared.thin_buffers.len();
+            self.shared.serialized_modules[self.idx - len].data()
+        })
+    }
+}
+
+pub struct ThinShared<B: WriteBackendMethods> {
+    pub data: B::ThinData,
+    pub thin_buffers: Vec<B::ThinBuffer>,
+    pub serialized_modules: Vec<SerializedModule<B::ModuleBuffer>>,
+    pub module_names: Vec<CString>,
+}
+
+pub enum LtoModuleCodegen<B: WriteBackendMethods> {
+    Fat {
+        module: ModuleCodegen<B::Module>,
+        _serialized_bitcode: Vec<SerializedModule<B::ModuleBuffer>>,
+    },
+
+    Thin(ThinModule<B>),
+}
+
+impl<B: WriteBackendMethods> LtoModuleCodegen<B> {
+    pub fn name(&self) -> &str {
+        match *self {
+            LtoModuleCodegen::Fat { .. } => "everything",
+            LtoModuleCodegen::Thin(ref m) => m.name(),
+        }
+    }
+
+    /// Optimize this module within the given codegen context.
+    ///
+    /// This function is unsafe as it'll return a `ModuleCodegen` still
+    /// points to LLVM data structures owned by this `LtoModuleCodegen`.
+    /// It's intended that the module returned is immediately code generated and
+    /// dropped, and then this LTO module is dropped.
+    pub unsafe fn optimize(
+        self,
+        cgcx: &CodegenContext<B>,
+    ) -> Result<ModuleCodegen<B::Module>, FatalError> {
+        match self {
+            LtoModuleCodegen::Fat { mut module, .. } => {
+                B::optimize_fat(cgcx, &mut module)?;
+                Ok(module)
+            }
+            LtoModuleCodegen::Thin(thin) => B::optimize_thin(cgcx, thin),
+        }
+    }
+
+    /// A "gauge" of how costly it is to optimize this module, used to sort
+    /// biggest modules first.
+    pub fn cost(&self) -> u64 {
+        match *self {
+            // Only one module with fat LTO, so the cost doesn't matter.
+            LtoModuleCodegen::Fat { .. } => 0,
+            LtoModuleCodegen::Thin(ref m) => m.cost(),
+        }
+    }
+}
+
+pub enum SerializedModule<M: ModuleBufferMethods> {
+    Local(M),
+    FromRlib(Vec<u8>),
+    FromUncompressedFile(Mmap),
+}
+
+impl<M: ModuleBufferMethods> SerializedModule<M> {
+    pub fn data(&self) -> &[u8] {
+        match *self {
+            SerializedModule::Local(ref m) => m.data(),
+            SerializedModule::FromRlib(ref m) => m,
+            SerializedModule::FromUncompressedFile(ref m) => m,
+        }
+    }
+}
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