[WebAssembly] Error on Wasm SjLj if +exception-handling is missing (#181070)HEADmain

This checks every user function of `setjmp` or `longjmp` and if any of
them does not have `+exception-handling` target feature, errors out.

Hopefully this gives a clearer error message to the users in case they
do not provide consistent SjLj flags at compile time vs. link time.

Closes #178135 and closes
https://github.com/emscripten-core/emscripten/issues/26165.

1 files changed, 25 insertions, 0 deletions

diff --git a/llvm/lib/Target/WebAssembly/WebAssemblyLowerEmscriptenEHSjLj.cpp b/llvm/lib/Target/WebAssembly/WebAssemblyLowerEmscriptenEHSjLj.cpp
index c3990d1..ba81537 100644
--- a/llvm/lib/Target/WebAssembly/WebAssemblyLowerEmscriptenEHSjLj.cpp
+++ b/llvm/lib/Target/WebAssembly/WebAssemblyLowerEmscriptenEHSjLj.cpp
@@ -482,6 +482,14 @@ static Value *getAddrSizeInt(Module *M, uint64_t C) {
   return IRB.getIntN(M->getDataLayout().getPointerSizeInBits(), C);
 }
 
+// Returns true if the function has "target-features"="+exception-handling"
+// attribute.
+static bool hasEHTargetFeatureAttr(const Function &F) {
+  Attribute FeaturesAttr = F.getFnAttribute("target-features");
+  return FeaturesAttr.isValid() &&
+         FeaturesAttr.getValueAsString().contains("+exception-handling");
+}
+
 // Returns __cxa_find_matching_catch_N function, where N = NumClauses + 2.
 // This is because a landingpad instruction contains two more arguments, a
 // personality function and a cleanup bit, and __cxa_find_matching_catch_N
@@ -1004,6 +1012,7 @@ bool WebAssemblyLowerEmscriptenEHSjLj::runOnModule(Module &M) {
   // Function registration and data pre-gathering for setjmp/longjmp handling
   if (DoSjLj) {
     assert(EnableEmSjLj || EnableWasmSjLj);
+
     if (EnableEmSjLj) {
       // Register emscripten_longjmp function
       FunctionType *FTy = FunctionType::get(
@@ -1019,6 +1028,22 @@ bool WebAssemblyLowerEmscriptenEHSjLj::runOnModule(Module &M) {
       WasmLongjmpF->addFnAttr(Attribute::NoReturn);
     }
 
+    if (EnableWasmSjLj) {
+      for (auto *SjLjF : {SetjmpF, LongjmpF}) {
+        if (SjLjF) {
+          for (User *U : SjLjF->users()) {
+            if (auto *CI = dyn_cast<CallInst>(U)) {
+              auto &F = *CI->getFunction();
+              if (!hasEHTargetFeatureAttr(F))
+                report_fatal_error("Function " + F.getName() +
+                                   " is using setjmp/longjmp but does not have "
+                                   "+exception-handling target feature");
+            }
+          }
+        }
+      }
+    }
+
     if (SetjmpF) {
       Type *Int8PtrTy = IRB.getPtrTy();
       Type *Int32PtrTy = IRB.getPtrTy();