From 87f2bcefb3ee4890081d693556ab5d36504c7b00 Mon Sep 17 00:00:00 2001
From: Cyrill Leutwiler <cyrill@parity.io>
Date: Thu, 21 Nov 2024 21:48:42 +0100
Subject: [PATCH] dump the elf shared object into the debug output directory
 (#119)

Signed-off-by: Cyrill Leutwiler <bigcyrill@hotmail.com>
---
 crates/common/src/extension.rs                  |  3 +++
 crates/linker/src/lib.rs                        |  9 ++-------
 crates/llvm-context/src/debug_config/ir_type.rs |  3 +++
 crates/llvm-context/src/debug_config/mod.rs     | 10 ++++++++++
 crates/llvm-context/src/polkavm/context/mod.rs  | 10 ++++++++--
 5 files changed, 26 insertions(+), 9 deletions(-)

diff --git a/crates/common/src/extension.rs b/crates/common/src/extension.rs
index 64e23853..d37fe4c0 100644
--- a/crates/common/src/extension.rs
+++ b/crates/common/src/extension.rs
@@ -41,3 +41,6 @@ pub static EXTENSION_POLKAVM_ASSEMBLY: &str = "pvmasm";
 
 /// The PolkaVM bytecode file extension.
 pub static EXTENSION_POLKAVM_BINARY: &str = "pvm";
+
+/// The ELF shared object file extension.
+pub static EXTENSION_SHARED_OBJECT: &str = "so";
diff --git a/crates/linker/src/lib.rs b/crates/linker/src/lib.rs
index b5c81cb5..e49bb378 100644
--- a/crates/linker/src/lib.rs
+++ b/crates/linker/src/lib.rs
@@ -29,7 +29,7 @@ fn invoke_lld(cmd_args: &[&str]) -> bool {
     unsafe { LLDELFLink(args.as_ptr(), args.len()) == 0 }
 }
 
-fn polkavm_linker<T: AsRef<[u8]>>(code: T) -> anyhow::Result<Vec<u8>> {
+pub fn polkavm_linker<T: AsRef<[u8]>>(code: T) -> anyhow::Result<Vec<u8>> {
     let mut config = polkavm_linker::Config::default();
     config.set_strip(true);
     config.set_optimize(true);
@@ -79,10 +79,5 @@ pub fn link<T: AsRef<[u8]>>(input: T) -> anyhow::Result<Vec<u8>> {
         return Err(anyhow::anyhow!("ld.lld failed"));
     }
 
-    if env::var("PVM_LINKER_DUMP_SO").is_ok() {
-        fs::copy(&output_path, "/tmp/out.so")?;
-    };
-
-    let blob = fs::read(&output_path)?;
-    polkavm_linker(blob)
+    Ok(fs::read(&output_path)?)
 }
diff --git a/crates/llvm-context/src/debug_config/ir_type.rs b/crates/llvm-context/src/debug_config/ir_type.rs
index 2ea88f96..43a44487 100644
--- a/crates/llvm-context/src/debug_config/ir_type.rs
+++ b/crates/llvm-context/src/debug_config/ir_type.rs
@@ -15,6 +15,8 @@ pub enum IRType {
     LLVM,
     /// Whether to dump the assembly code.
     Assembly,
+    /// Whether to dump the ELF shared object
+    SO,
     /// Whether to jump JSON
     #[cfg(debug_assertions)]
     JSON,
@@ -31,6 +33,7 @@ impl IRType {
             Self::Assembly => revive_common::EXTENSION_POLKAVM_ASSEMBLY,
             #[cfg(debug_assertions)]
             Self::JSON => revive_common::EXTENSION_JSON,
+            Self::SO => revive_common::EXTENSION_SHARED_OBJECT,
         }
     }
 }
diff --git a/crates/llvm-context/src/debug_config/mod.rs b/crates/llvm-context/src/debug_config/mod.rs
index 49c31ac0..f44cb194 100644
--- a/crates/llvm-context/src/debug_config/mod.rs
+++ b/crates/llvm-context/src/debug_config/mod.rs
@@ -94,6 +94,16 @@ impl DebugConfig {
         Ok(())
     }
 
+    /// Dumps the code object.
+    pub fn dump_object(&self, contract_path: &str, code: &[u8]) -> anyhow::Result<()> {
+        let mut file_path = self.output_directory.to_owned();
+        let full_file_name = Self::full_file_name(contract_path, None, IRType::SO);
+        file_path.push(full_file_name);
+        std::fs::write(file_path, code)?;
+
+        Ok(())
+    }
+
     /// Dumps the stage output as a json file suitable for use with --recursive-process
     #[cfg(debug_assertions)]
     pub fn dump_stage_output(
diff --git a/crates/llvm-context/src/polkavm/context/mod.rs b/crates/llvm-context/src/polkavm/context/mod.rs
index bf39ded9..9feb9254 100644
--- a/crates/llvm-context/src/polkavm/context/mod.rs
+++ b/crates/llvm-context/src/polkavm/context/mod.rs
@@ -296,11 +296,17 @@ where
                 )
             })?;
 
-        let bytecode = revive_linker::link(buffer.as_slice())?;
+        let shared_object = revive_linker::link(buffer.as_slice())?;
+
+        if let Some(ref debug_config) = self.debug_config {
+            debug_config.dump_object(contract_path, &shared_object)?;
+        }
+
+        let polkavm_bytecode = revive_linker::polkavm_linker(shared_object)?;
 
         let build = match crate::polkavm::build_assembly_text(
             contract_path,
-            &bytecode,
+            &polkavm_bytecode,
             metadata_hash,
             self.debug_config(),
         ) {