[llvm] [WebAssemblyLowerEmscriptenEHSjLj] Don't assign import names to generated function declarations (PR #71599)

[via llvm-commits]

llvmbot wrote:


<!--LLVM PR SUMMARY COMMENT-->

@llvm/pr-subscribers-backend-webassembly

Author: Sam Clegg (sbc100)

<details>
<summary>Changes</summary>

These days we would prefer that the linker report errors when these symbols are not defined.  Assigning import names like this tells the linker not to report errors when these symbols are missing and simply import them.  However, this leads to much less useful undefined symbol errors after the linker is done.

Note that keep the old behavior for the `invoke_xxx` functions since its not possible for is to declare all possible permutations ahead of time in a library.

See https://github.com/emscripten-core/emscripten/pull/20536

---
Full diff: https://github.com/llvm/llvm-project/pull/71599.diff


4 Files Affected:

- (modified) llvm/lib/Target/WebAssembly/WebAssemblyLowerEmscriptenEHSjLj.cpp (+7-2) 
- (modified) llvm/test/CodeGen/WebAssembly/lower-em-ehsjlj-options.ll (-8) 
- (modified) llvm/test/CodeGen/WebAssembly/lower-em-sjlj.ll (-7) 
- (modified) llvm/test/CodeGen/WebAssembly/lower-wasm-ehsjlj.ll (+1-1) 


``````````diff
diff --git a/llvm/lib/Target/WebAssembly/WebAssemblyLowerEmscriptenEHSjLj.cpp b/llvm/lib/Target/WebAssembly/WebAssemblyLowerEmscriptenEHSjLj.cpp
index 5e84fff351b23d1..4c64c50974538f3 100644
--- a/llvm/lib/Target/WebAssembly/WebAssemblyLowerEmscriptenEHSjLj.cpp
+++ b/llvm/lib/Target/WebAssembly/WebAssemblyLowerEmscriptenEHSjLj.cpp
@@ -448,7 +448,12 @@ static std::string getSignature(FunctionType *FTy) {
 
 static Function *getEmscriptenFunction(FunctionType *Ty, const Twine &Name,
                                        Module *M) {
-  Function* F = Function::Create(Ty, GlobalValue::ExternalLinkage, Name, M);
+  return Function::Create(Ty, GlobalValue::ExternalLinkage, Name, M);
+}
+
+static Function *getInvokeFunction(FunctionType *Ty, const Twine &Name,
+                                   Module *M) {
+  Function* F = getEmscriptenFunction(Ty, Name, M);
   // Tell the linker that this function is expected to be imported from the
   // 'env' module.
   if (!F->hasFnAttribute("wasm-import-module")) {
@@ -591,7 +596,7 @@ Function *WebAssemblyLowerEmscriptenEHSjLj::getInvokeWrapper(CallBase *CI) {
 
   FunctionType *FTy = FunctionType::get(CalleeFTy->getReturnType(), ArgTys,
                                         CalleeFTy->isVarArg());
-  Function *F = getEmscriptenFunction(FTy, "__invoke_" + Sig, M);
+  Function *F = getInvokeFunction(FTy, "__invoke_" + Sig, M);
   InvokeWrappers[Sig] = F;
   return F;
 }
diff --git a/llvm/test/CodeGen/WebAssembly/lower-em-ehsjlj-options.ll b/llvm/test/CodeGen/WebAssembly/lower-em-ehsjlj-options.ll
index aa4d87756c87d0a..9694e1c5b442ee3 100644
--- a/llvm/test/CodeGen/WebAssembly/lower-em-ehsjlj-options.ll
+++ b/llvm/test/CodeGen/WebAssembly/lower-em-ehsjlj-options.ll
@@ -6,18 +6,10 @@
 target triple = "wasm32-unknown-unknown"
 
 ; EH: .functype  invoke_vi (i32, i32) -> ()
-; EH: .import_module  invoke_vi, env
-; EH: .import_name  invoke_vi, invoke_vi
 ; EH-NOT: .functype  __invoke_void_i32
-; EH-NOT: .import_module  __invoke_void_i32
-; EH-NOT: .import_name  __invoke_void_i32
 
 ; SJLJ: .functype  emscripten_longjmp (i32, i32) -> ()
-; SJLJ: .import_module  emscripten_longjmp, env
-; SJLJ: .import_name  emscripten_longjmp, emscripten_longjmp
 ; SJLJ-NOT: .functype  emscripten_longjmp_jmpbuf
-; SJLJ-NOT: .import_module  emscripten_longjmp_jmpbuf
-; SJLJ-NOT: .import_name  emscripten_longjmp_jmpbuf
 
 %struct.__jmp_buf_tag = type { [6 x i32], i32, [32 x i32] }
 
diff --git a/llvm/test/CodeGen/WebAssembly/lower-em-sjlj.ll b/llvm/test/CodeGen/WebAssembly/lower-em-sjlj.ll
index 7115b01ed1618e9..5bb052b65a8d3ae 100644
--- a/llvm/test/CodeGen/WebAssembly/lower-em-sjlj.ll
+++ b/llvm/test/CodeGen/WebAssembly/lower-em-sjlj.ll
@@ -305,13 +305,6 @@ attributes #0 = { returns_twice }
 attributes #1 = { noreturn }
 attributes #2 = { nounwind }
 attributes #3 = { allocsize(0) }
-; CHECK-DAG: attributes #{{[0-9]+}} = { nounwind "wasm-import-module"="env" "wasm-import-name"="getTempRet0" }
-; CHECK-DAG: attributes #{{[0-9]+}} = { nounwind "wasm-import-module"="env" "wasm-import-name"="setTempRet0" }
-; CHECK-DAG: attributes #{{[0-9]+}} = { "wasm-import-module"="env" "wasm-import-name"="__invoke_void" }
-; CHECK-DAG: attributes #{{[0-9]+}} = { "wasm-import-module"="env" "wasm-import-name"="saveSetjmp" }
-; CHECK-DAG: attributes #{{[0-9]+}} = { "wasm-import-module"="env" "wasm-import-name"="testSetjmp" }
-; CHECK-DAG: attributes #{{[0-9]+}} = { noreturn "wasm-import-module"="env" "wasm-import-name"="emscripten_longjmp" }
-; CHECK-DAG: attributes #{{[0-9]+}} = { "wasm-import-module"="env" "wasm-import-name"="__invoke_ptr_i32_ptr" }
 ; CHECK-DAG: attributes #[[ALLOCSIZE_ATTR]] = { allocsize(1) }
 
 !llvm.dbg.cu = !{!2}
diff --git a/llvm/test/CodeGen/WebAssembly/lower-wasm-ehsjlj.ll b/llvm/test/CodeGen/WebAssembly/lower-wasm-ehsjlj.ll
index 25471eb50081b39..ce417a5db26308b 100644
--- a/llvm/test/CodeGen/WebAssembly/lower-wasm-ehsjlj.ll
+++ b/llvm/test/CodeGen/WebAssembly/lower-wasm-ehsjlj.ll
@@ -109,7 +109,7 @@ catch:                                            ; preds = %catch.start
   catchret from %2 to label %catchret.dest
 ; CHECK: catch:                                            ; preds = %catch.start
 ; CHECK-NEXT:   %exn = load ptr, ptr %exn.slot15, align 4
-; CHECK-NEXT:   %5 = call ptr @__cxa_begin_catch(ptr %exn) #7 [ "funclet"(token %2) ]
+; CHECK-NEXT:   %5 = call ptr @__cxa_begin_catch(ptr %exn) #3 [ "funclet"(token %2) ]
 ; CHECK-NEXT:   invoke void @__cxa_end_catch() [ "funclet"(token %2) ]
 ; CHECK-NEXT:           to label %.noexc unwind label %catch.dispatch.longjmp
 

``````````

</details>


https://github.com/llvm/llvm-project/pull/71599