[SSCP] dynamic functions: Handle multiple undefined dynamic functions in the same TU

illuhad · illuhad · commit 9a9afcc8bd45 · 2025-05-16T20:17:47.000+02:00
diff --git a/src/compiler/sscp/DynamicFunctionSupport.cpp b/src/compiler/sscp/DynamicFunctionSupport.cpp
@@ -82,7 +82,14 @@ llvm::PreservedAnalyses HostSideDynamicFunctionHandlerPass::run(llvm::Module &M,
       if (F->isDeclaration()) {
         F->setLinkage(llvm::GlobalValue::LinkOnceODRLinkage);
         auto BB = llvm::BasicBlock::Create(M.getContext(), "entry", F);
-        new llvm::UnreachableInst(M.getContext(), BB);
+        // It seems that LLVM handles functions that only have unreachable inst differently
+        // if there address is taken - we can no longer get unique function pointer
+        // addresses for those, which breaks reflection. So try to generate a trivial function
+        // instead.
+        if(F->getReturnType()->isVoidTy())
+          llvm::ReturnInst::Create(M.getContext(), BB);
+        else
+          llvm::ReturnInst::Create(M.getContext(), llvm::UndefValue::get(F->getReturnType()), BB);
       }
     }
   }
diff --git a/tests/compiler/sscp/dynamic_function.cpp b/tests/compiler/sscp/dynamic_function.cpp
@@ -26,6 +26,10 @@ void execute_operations_with_definition(int* data, sycl::item<1> idx) {
 
 void execute_operations_without_definition(int* data, sycl::item<1> idx);
 
+// Checks that we can distinguish two undefined dynamic functions in the same
+// TU
+void execute_operations_without_definition2(int* data, sycl::item<1> idx);
+
 
 int main() {
   sycl::queue q = get_queue();
@@ -59,6 +63,20 @@ int main() {
     std::cout << *data << std::endl;
   }
 
+  {
+    *data = 0;
+  
+    sycl::AdaptiveCpp_jit::dynamic_function_config dyn_function_config;
+    dyn_function_config.define(&execute_operations_without_definition2, &myfunction1);
+    q.parallel_for(sycl::range{1}, dyn_function_config.apply([=](sycl::item<1> idx){
+      execute_operations_without_definition2(data, idx);
+    }));
+
+    q.wait();
+    // CHECK: 1
+    std::cout << *data << std::endl;
+  }
+
   {
     *data = 0;
   

Original file line number	Diff line number	Diff line change
`@@ -82,7 +82,14 @@ llvm::PreservedAnalyses HostSideDynamicFunctionHandlerPass::run(llvm::Module &M,`
`82`	`82`	`if (F->isDeclaration()) {`
`83`	`83`	`F->setLinkage(llvm::GlobalValue::LinkOnceODRLinkage);`
`84`	`84`	`auto BB = llvm::BasicBlock::Create(M.getContext(), "entry", F);`
`85`		`- new llvm::UnreachableInst(M.getContext(), BB);`
	`85`	`+ // It seems that LLVM handles functions that only have unreachable inst differently`
	`86`	`+ // if there address is taken - we can no longer get unique function pointer`
	`87`	`+ // addresses for those, which breaks reflection. So try to generate a trivial function`
	`88`	`+ // instead.`
	`89`	`+ if(F->getReturnType()->isVoidTy())`
	`90`	`+ llvm::ReturnInst::Create(M.getContext(), BB);`
	`91`	`+ else`
	`92`	`+ llvm::ReturnInst::Create(M.getContext(), llvm::UndefValue::get(F->getReturnType()), BB);`
`86`	`93`	`}`
`87`	`94`	`}`
`88`	`95`	`}`