[Webassembly][multivalue] update libcall signature when multivalue feature enabled

[HerrCai0907]

Summary

fixed: #59095
Update libcall signatures to use multivalue return rather than returning via a pointer
when the multivalue features is enabled in the WebAssembly backend.

[tlively]

For the description, here's some possible clearer wording:

Update libcall signatures to use multivalue return rather than returning via a pointer when the multivalue features is enabled in the WebAssembly backend.

We also still don't have a stable C calling convention that uses multivalue, so this doesn't seem entirely future-proof, but maybe that's ok.

llvm/docs/ReleaseNotes.rst

145 ↗

(On Diff #505976)

We don't typically add release notes for bug fixes like this (although maybe we should?)

llvm/test/CodeGen/WebAssembly/multivalue_libcall.ll

2

It would be good to use the utils/update_llc_test_checks.py script to automatically produce the test output.

5

Incomplete sentence?

22–25

I don't think the CHECK lines are actually being checked because FileCheck is only run with MULTIVALUE and NO_MULTIVALUE prefixes.

[HerrCai0907]

update test, remove description in release note

[HerrCai0907]

update comment in testcase

[tlively]

LGTM besides using the test update script.

llvm/test/CodeGen/WebAssembly/multivalue_libcall.ll

5

[HerrCai0907]

update testcase using utils/update_llc_test_checks.py

[tlively]

Code LGTM, although it looks like there may be some missing cases reported in https://github.com/llvm/llvm-project/issues/59095. Testing the end-to-end integration here might be a good thing to do in cross-project-tests.

llvm/lib/Target/WebAssembly/WebAssemblyRuntimeLibcallSignatures.cpp

case i64_func_i64_i64:
     break;
   case i64_func_i64_i64_iPTR:
     Rets.push_back(wasm::ValType::I64);
     Params.push_back(wasm::ValType::I64);
     Params.push_back(wasm::ValType::I64);
     Params.push_back(PtrTy);
     break;
   case i64_i64_func_f32:
-#if 0 // TODO: Enable this when wasm gets multiple-return-value support.
+    if (Subtarget.hasMultivalue()) {
       Rets.push_back(wasm::ValType::I64);
       Rets.push_back(wasm::ValType::I64);
-#else
+    } else {
       Params.push_back(PtrTy);
-#endif
+    }
     Params.push_back(wasm::ValType::F32);
     break;
   case i64_i64_func_f64:
-#if 0 // TODO: Enable this when wasm gets multiple-return-value support.
+    if (Subtarget.hasMultivalue()) {
       Rets.push_back(wasm::ValType::I64);
       Rets.push_back(wasm::ValType::I64);
-#else
+    } else {
       Params.push_back(PtrTy);
-#endif
+    }
     Params.push_back(wasm::ValType::F64);
     break;
   case i16_i16_func_i16_i16:
-#if 0 // TODO: Enable this when wasm gets multiple-return-value support.
+    if (Subtarget.hasMultivalue()) {
       Rets.push_back(wasm::ValType::I32);
       Rets.push_back(wasm::ValType::I32);
-#else
+    } else {
       Params.push_back(PtrTy);
-#endif
+    }
     Params.push_back(wasm::ValType::I32);
     Params.push_back(wasm::ValType::I32);
     break;
   case i32_i32_func_i32_i32:
-#if 0 // TODO: Enable this when wasm gets multiple-return-value support.
+    if (Subtarget.hasMultivalue()) {
       Rets.push_back(wasm::ValType::I32);
       Rets.push_back(wasm::ValType::I32);
-#else
+    } else {
       Params.push_back(PtrTy);
-#endif
+    }
     Params.push_back(wasm::ValType::I32);
     Params.push_back(wasm::ValType::I32);
     break;
   case i64_i64_func_i64_i64:
-#if 0 // TODO: Enable this when wasm gets multiple-return-value support.
+    if (Subtarget.hasMultivalue()) {
       Rets.push_back(wasm::ValType::I64);
       Rets.push_back(wasm::ValType::I64);
-#else
+    } else {
       Params.push_back(PtrTy);
-#endif
+    }
     Params.push_back(wasm::ValType::I64);
     Params.push_back(wasm::ValType::I64);
     break;
   case i64_i64_func_i64_i64_i64_i64:
-#if 0 // TODO: Enable this when wasm gets multiple-return-value support.
+    if (Subtarget.hasMultivalue()) {
       Rets.push_back(wasm::ValType::I64);
       Rets.push_back(wasm::ValType::I64);
-#else
+    } else {
       Params.push_back(PtrTy);
-#endif
+    }
     Params.push_back(wasm::ValType::I64);
     Params.push_back(wasm::ValType::I64);
     Params.push_back(wasm::ValType::I64);
     Params.push_back(wasm::ValType::I64);
     break;
   case i64_i64_func_i64_i64_i64_i64_iPTR:
-#if 0 // TODO: Enable this when wasm gets multiple-return-value support.
+    if (Subtarget.hasMultivalue()) {
       Rets.push_back(wasm::ValType::I64);
       Rets.push_back(wasm::ValType::I64);
-#else
+    } else {
       Params.push_back(PtrTy);
-#endif
+    }
     Params.push_back(wasm::ValType::I64);
     Params.push_back(wasm::ValType::I64);
     Params.push_back(wasm::ValType::I64);
     Params.push_back(wasm::ValType::I64);
     Params.push_back(PtrTy);
     break;
   case i64_i64_i64_i64_func_i64_i64_i64_i64:
-#if 0 // TODO: Enable this when wasm gets multiple-return-value support.
+    if (Subtarget.hasMultivalue()) {
       Rets.push_back(wasm::ValType::I64);
       Rets.push_back(wasm::ValType::I64);
       Rets.push_back(wasm::ValType::I64);
       Rets.push_back(wasm::ValType::I64);
-#else
+    } else {
       Params.push_back(PtrTy);
-#endif
+    }
     Params.push_back(wasm::ValType::I64);
     Params.push_back(wasm::ValType::I64);
     Params.push_back(wasm::ValType::I64);
     Params.push_back(wasm::ValType::I64);
     break;
   case i64_i64_func_i64_i64_i32:
-#if 0 // TODO: Enable this when wasm gets multiple-return-value support.
+    if (Subtarget.hasMultivalue()) {
       Rets.push_back(wasm::ValType::I64);
       Rets.push_back(wasm::ValType::I64);
       Rets.push_back(wasm::ValType::I64);
       Rets.push_back(wasm::ValType::I64);
-#else
+    } else {
       Params.push_back(PtrTy);
-#endif
+    }
     Params.push_back(wasm::ValType::I64);
     Params.push_back(wasm::ValType::I64);
     Params.push_back(wasm::ValType::I32);
     break;
   case iPTR_func_i32:
     Rets.push_back(PtrTy);
     Params.push_back(wasm::ValType::I32);
     break;
void llvm::getLibcallSignature(const WebAssemblySubtarget &Subtarget,
                                StringRef Name,
                                SmallVectorImpl<wasm::ValType> &Rets,
                                SmallVectorImpl<wasm::ValType> &Params) {
   static StaticLibcallNameMap LibcallNameMap;
   auto &Map = LibcallNameMap.Map;
   auto Val = Map.find(Name);
 #ifndef NDEBUG
   if (Val == Map.end()) {
-    auto message = std::string("unexpected runtime library name: ") +
-                   std::string(Name);
+    auto message =
+        std::string("unexpected runtime library name: ") + std::string(Name);
     llvm_unreachable(message.c_str());
   }
 #endif
   return getLibcallSignature(Subtarget, Val->second, Rets, Params);
 }

llvm/test/CodeGen/WebAssembly/multivalue_libcall.ll

+; NOTE: Assertions have been autogenerated by utils/update_llc_test_checks.py UTC_ARGS: --version 2
+; RUN: llc < %s -verify-machineinstrs -mcpu=mvp -mattr=+multivalue | FileCheck %s --check-prefix=MULTIVALUE
+; RUN: llc < %s -verify-machineinstrs -mcpu=mvp | FileCheck %s --check-prefix=NO_MULTIVALUE
+
+; Test libcall signatures when multivalue is enabled and disabled
+
+target triple = "wasm32-unknown-unknown"
+
+@c = global i128 0, align 16
+
+define void @multivalue_sdiv(i128 noundef %a, i128 noundef %b) #0 {
+; MULTIVALUE-LABEL: multivalue_sdiv:
+; MULTIVALUE:         .functype multivalue_sdiv (i64, i64, i64, i64) -> ()
+; MULTIVALUE-NEXT:  # %bb.0:
+; MULTIVALUE-NEXT:    local.get 0
+; MULTIVALUE-NEXT:    local.get 1
+; MULTIVALUE-NEXT:    local.get 2
+; MULTIVALUE-NEXT:    local.get 3
+; MULTIVALUE-NEXT:    call __divti3
+; MULTIVALUE-NEXT:    local.set 2
+; MULTIVALUE-NEXT:    local.set 3
+; MULTIVALUE-NEXT:    i32.const c
+; MULTIVALUE-NEXT:    local.get 2
+; MULTIVALUE-NEXT:    i64.store 8
+; MULTIVALUE-NEXT:    i32.const 0
+; MULTIVALUE-NEXT:    local.get 3
+; MULTIVALUE-NEXT:    i64.store c
+; MULTIVALUE-NEXT:    # fallthrough-return
+;
+; NO_MULTIVALUE-LABEL: multivalue_sdiv:
+; NO_MULTIVALUE:         .functype multivalue_sdiv (i64, i64, i64, i64) -> ()
+; NO_MULTIVALUE-NEXT:    .local i32
+; NO_MULTIVALUE-NEXT:  # %bb.0:
+; NO_MULTIVALUE-NEXT:    global.get __stack_pointer
+; NO_MULTIVALUE-NEXT:    i32.const 16
+; NO_MULTIVALUE-NEXT:    i32.sub
+; NO_MULTIVALUE-NEXT:    local.tee 4
+; NO_MULTIVALUE-NEXT:    global.set __stack_pointer
+; NO_MULTIVALUE-NEXT:    local.get 4
+; NO_MULTIVALUE-NEXT:    local.get 0
+; NO_MULTIVALUE-NEXT:    local.get 1
+; NO_MULTIVALUE-NEXT:    local.get 2
+; NO_MULTIVALUE-NEXT:    local.get 3
+; NO_MULTIVALUE-NEXT:    call __divti3
+; NO_MULTIVALUE-NEXT:    i32.const c
+; NO_MULTIVALUE-NEXT:    local.get 4
+; NO_MULTIVALUE-NEXT:    i32.const 8
+; NO_MULTIVALUE-NEXT:    i32.add
+; NO_MULTIVALUE-NEXT:    i64.load 0
+; NO_MULTIVALUE-NEXT:    i64.store 8
+; NO_MULTIVALUE-NEXT:    i32.const 0
+; NO_MULTIVALUE-NEXT:    local.get 4
+; NO_MULTIVALUE-NEXT:    i64.load 0
+; NO_MULTIVALUE-NEXT:    i64.store c
+; NO_MULTIVALUE-NEXT:    local.get 4
+; NO_MULTIVALUE-NEXT:    i32.const 16
+; NO_MULTIVALUE-NEXT:    i32.add
+; NO_MULTIVALUE-NEXT:    global.set __stack_pointer
+; NO_MULTIVALUE-NEXT:    # fallthrough-return
+  %div = sdiv i128 %a, %b
+  store i128 %div, ptr @c, align 16
+  ret void
+}