add new debug helper to print module

README.md

@@ -35,13 +35,16 @@ cargo +enzyme test --examples
 ```
 
 ## Enzyme Config
-To help with debugging, Enzyme can be configured using three environment variables.
+To help with debugging, Enzyme can be configured using four environment variables.
 ```bash
 export ENZYME_PRINT_TA=1
 export ENZYME_PRINT_AA=1
 export ENZYME_PRINT=1
+export ENZYME_PRINT_MOD=1
 ```
-These will print TypeAnalysis, ActivityAnalysis and the primal + generated function respectively.
+The first three will print TypeAnalysis, ActivityAnalysis and the llvm-ir on a function basis, respectively.
+The last variable can be used to print the whole module directly before Enzyme starts
+differentiating functions. 
 
 We want to make sure that we have EnzymeStrictAliasing=0 all the time to make sure
 that Enzyme handles enums correctly. Other flags might be enabled for debug purpose.

compiler/rustc_codegen_llvm/src/back/write.rs

@@ -26,7 +26,7 @@ use llvm::{
     LLVMVoidTypeInContext, LLVMGlobalGetValueType, LLVMGetStringAttributeAtIndex,
     LLVMIsStringAttribute, LLVMRemoveStringAttributeAtIndex, LLVMRemoveEnumAttributeAtIndex, AttributeKind,
     LLVMGetFirstFunction, LLVMGetNextFunction, LLVMGetEnumAttributeAtIndex, LLVMIsEnumAttribute,
-    LLVMCreateStringAttribute, LLVMRustAddFunctionAttributes, LLVMCreateEnumAttribute
+    LLVMCreateStringAttribute, LLVMRustAddFunctionAttributes, LLVMCreateEnumAttribute, LLVMDumpModule
 };
 //use llvm::LLVMRustGetNamedValue;
 use rustc_codegen_ssa::back::link::ensure_removed;
@@ -746,6 +746,10 @@ pub(crate) unsafe fn differentiate(
 
     llvm::EnzymeSetCLBool(std::ptr::addr_of_mut!(llvm::EnzymeStrictAliasing), 0);
 
+    if std::env::var("ENZYME_PRINT_MOD").is_ok() {
+        unsafe {LLVMDumpModule(llmod);}
+
+    }
     for item in diff_items {
         let res = enzyme_ad(llmod, llcx, item);
         assert!(res.is_ok());