[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

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

llvm/test/CodeGen/WebAssembly/multivalue_libcall.ll

1

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

4

Incomplete sentence?

21–24

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/docs/ReleaseNotes.rst

 * Support for the now-ratified Zawrs extension is no longer experimental.
 * Adds support for the vendor-defined XTHeadCmo (cache management operations) extension.
 * Adds support for the vendor-defined XTHeadSync (multi-core synchronization instructions) extension.
 * Added support for the vendor-defined XTHeadFMemIdx (indexed memory operations for floating point) extension.
 
 Changes to the WebAssembly Backend
 ----------------------------------
 
-* ...
+* Select correct libcall signature when multivalue feature enabled.
 
 Changes to the Windows Target
 -----------------------------
 
 Changes to the X86 Backend
 --------------------------
 
 Changes to the OCaml bindings

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

+; RUN: llc < %s -asm-verbose=false -verify-machineinstrs -mcpu=mvp -mattr=+multivalue | FileCheck %s --check-prefix=MULTIVALUE
+; RUN: llc < %s -asm-verbose=false -verify-machineinstrs -mcpu=mvp | FileCheck %s --check-prefix=NO_MULTIVALUE
+
+; Test that the multivalue for libcall
+
+target triple = "wasm32-unknown-unknown"
+
+@c = global i128 0, align 16
+
+; CHECK-LABEL: multivalue_sdiv:
+; CHECK: .functype  multivalue_sdiv (i64, i64, i64, i64) -> ()
+define void @multivalue_sdiv(i128 noundef %a, i128 noundef %b) #0 {
+; NO_MULTIVALUE:  .local    i32
+; NO_MULTIVALUE:  global.get  __stack_pointer
+; NO_MULTIVALUE:  i32.const 16
+; NO_MULTIVALUE:  i32.sub 
+; NO_MULTIVALUE:  local.tee 4
+; NO_MULTIVALUE:  global.set  __stack_pointer
+
+; NO_MULTIVALUE:  local.get 4
+; CHECK:  local.get 0
+; CHECK:  local.get 1
+; CHECK:  local.get 2
+; CHECK:  local.get 3
+; CHECK:  call  __divti3
+  %div = sdiv i128 %a, %b
+
+
+; NO_MULTIVALUE:  i32.const c
+; NO_MULTIVALUE:  local.get 4
+; NO_MULTIVALUE:  i32.const 8
+; NO_MULTIVALUE:  i32.add 
+; NO_MULTIVALUE:  i64.load  0
+; NO_MULTIVALUE:  i64.store 8
+; NO_MULTIVALUE:  i32.const 0
+; NO_MULTIVALUE:  local.get 4
+; NO_MULTIVALUE:  i64.load  0
+
+; MULTIVALUE:   local.set 2
+; MULTIVALUE:   local.set 3
+; MULTIVALUE:   i32.const c
+; MULTIVALUE:   local.get 2
+; MULTIVALUE:   i64.store 8
+; MULTIVALUE:   i32.const 0
+; MULTIVALUE:   local.get 3
+; CHECK:  i64.store c
+  store i128 %div, ptr @c, align 16
+
+; NO_MULTIVALUE:  local.get 4
+; NO_MULTIVALUE:  i32.const 16
+; NO_MULTIVALUE:  i32.add 
+; NO_MULTIVALUE:  global.set  __stack_pointer
+
+; CHECK:  end_function
+  ret void
+}