[WebAssembly] Do not emit tail calls with return type mismatch
Summary:
return_call and return_call_indirect are only valid if the return
types of the callee and caller match. We were previously not enforcing
that, which was producing invalid modules.
Reviewers: aheejin
Subscribers: dschuff, sbc100, jgravelle-google, hiraditya, sunfish, llvm-commits
Tags: #llvm
Differential Revision: https://reviews.llvm.org/D65246
llvm-svn: 367339
diff --git a/llvm/lib/Target/WebAssembly/WebAssemblyISelLowering.cpp b/llvm/lib/Target/WebAssembly/WebAssemblyISelLowering.cpp
index 4064a98..065a1a7 100644
--- a/llvm/lib/Target/WebAssembly/WebAssemblyISelLowering.cpp
+++ b/llvm/lib/Target/WebAssembly/WebAssemblyISelLowering.cpp
@@ -644,13 +644,36 @@
if (CLI.IsPatchPoint)
fail(DL, DAG, "WebAssembly doesn't support patch point yet");
- // Fail if tail calls are required but not enabled
- if (!Subtarget->hasTailCall()) {
- if ((CallConv == CallingConv::Fast && CLI.IsTailCall &&
- MF.getTarget().Options.GuaranteedTailCallOpt) ||
- (CLI.CS && CLI.CS.isMustTailCall()))
- fail(DL, DAG, "WebAssembly 'tail-call' feature not enabled");
- CLI.IsTailCall = false;
+ if (CLI.IsTailCall) {
+ bool MustTail = CLI.CS && CLI.CS.isMustTailCall();
+ if (Subtarget->hasTailCall() && !CLI.IsVarArg) {
+ // Do not tail call unless caller and callee return types match
+ const Function &F = MF.getFunction();
+ const TargetMachine &TM = getTargetMachine();
+ Type *RetTy = F.getReturnType();
+ SmallVector<MVT, 4> CallerRetTys;
+ SmallVector<MVT, 4> CalleeRetTys;
+ computeLegalValueVTs(F, TM, RetTy, CallerRetTys);
+ computeLegalValueVTs(F, TM, CLI.RetTy, CalleeRetTys);
+ bool TypesMatch = CallerRetTys.size() == CalleeRetTys.size() &&
+ std::equal(CallerRetTys.begin(), CallerRetTys.end(),
+ CalleeRetTys.begin());
+ if (!TypesMatch) {
+ // musttail in this case would be an LLVM IR validation failure
+ assert(!MustTail);
+ CLI.IsTailCall = false;
+ }
+ } else {
+ CLI.IsTailCall = false;
+ if (MustTail) {
+ if (CLI.IsVarArg) {
+ // The return would pop the argument buffer
+ fail(DL, DAG, "WebAssembly does not support varargs tail calls");
+ } else {
+ fail(DL, DAG, "WebAssembly 'tail-call' feature not enabled");
+ }
+ }
+ }
}
SmallVectorImpl<ISD::InputArg> &Ins = CLI.Ins;
diff --git a/llvm/lib/Target/WebAssembly/WebAssemblyMCInstLower.cpp b/llvm/lib/Target/WebAssembly/WebAssemblyMCInstLower.cpp
index d9089de..26baac3 100644
--- a/llvm/lib/Target/WebAssembly/WebAssemblyMCInstLower.cpp
+++ b/llvm/lib/Target/WebAssembly/WebAssemblyMCInstLower.cpp
@@ -226,6 +226,17 @@
if (WebAssembly::isCallIndirect(MI->getOpcode()))
Params.pop_back();
+ // return_call_indirect instructions have the return type of the
+ // caller
+ if (MI->getOpcode() == WebAssembly::RET_CALL_INDIRECT) {
+ const Function &F = MI->getMF()->getFunction();
+ const TargetMachine &TM = MI->getMF()->getTarget();
+ Type *RetTy = F.getReturnType();
+ SmallVector<MVT, 4> CallerRetTys;
+ computeLegalValueVTs(F, TM, RetTy, CallerRetTys);
+ valTypesFromMVTs(CallerRetTys, Returns);
+ }
+
auto *WasmSym = cast<MCSymbolWasm>(Sym);
auto Signature = make_unique<wasm::WasmSignature>(std::move(Returns),
std::move(Params));