[WebAssembly] Disable multivalue emission temporarily

llvm/lib/Target/WebAssembly/WebAssemblyISelLowering.cpp

@@ -43,6 +43,8 @@ using namespace llvm;
 
 #define DEBUG_TYPE "wasm-lower"
 
+extern cl::opt<bool> WasmEmitMultiValue;
+
 WebAssemblyTargetLowering::WebAssemblyTargetLowering(
     const TargetMachine &TM, const WebAssemblySubtarget &STI)
     : TargetLowering(TM), Subtarget(&STI) {
@@ -1288,15 +1290,16 @@ bool WebAssemblyTargetLowering::CanLowerReturn(
     const SmallVectorImpl<ISD::OutputArg> &Outs,
     LLVMContext & /*Context*/) const {
   // WebAssembly can only handle returning tuples with multivalue enabled
-  return Subtarget->hasMultivalue() || Outs.size() <= 1;
+  return (Subtarget->hasMultivalue() && WasmEmitMultiValue) || Outs.size() <= 1;
 }
 
 SDValue WebAssemblyTargetLowering::LowerReturn(
     SDValue Chain, CallingConv::ID CallConv, bool /*IsVarArg*/,
     const SmallVectorImpl<ISD::OutputArg> &Outs,
     const SmallVectorImpl<SDValue> &OutVals, const SDLoc &DL,
     SelectionDAG &DAG) const {
-  assert((Subtarget->hasMultivalue() || Outs.size() <= 1) &&
+  assert(((Subtarget->hasMultivalue() && WasmEmitMultiValue) ||
+          Outs.size() <= 1) &&
          "MVP WebAssembly can only return up to one value");
   if (!callingConvSupported(CallConv))
     fail(DL, DAG, "WebAssembly doesn't support non-C calling conventions");

llvm/lib/Target/WebAssembly/WebAssemblyMachineFunctionInfo.cpp

@@ -22,6 +22,8 @@
 #include "llvm/Target/TargetMachine.h"
 using namespace llvm;
 
+extern cl::opt<bool> WasmEmitMultiValue;
+
 WebAssemblyFunctionInfo::~WebAssemblyFunctionInfo() = default; // anchor.
 
 MachineFunctionInfo *WebAssemblyFunctionInfo::clone(
@@ -71,7 +73,8 @@ void llvm::computeSignatureVTs(const FunctionType *Ty,
 
   MVT PtrVT = MVT::getIntegerVT(TM.createDataLayout().getPointerSizeInBits());
   if (Results.size() > 1 &&
-      !TM.getSubtarget<WebAssemblySubtarget>(ContextFunc).hasMultivalue()) {
+      (!TM.getSubtarget<WebAssemblySubtarget>(ContextFunc).hasMultivalue() ||
+       !WasmEmitMultiValue)) {
     // WebAssembly can't lower returns of multiple values without demoting to
     // sret unless multivalue is enabled (see
     // WebAssemblyTargetLowering::CanLowerReturn). So replace multiple return

llvm/lib/Target/WebAssembly/WebAssemblyRuntimeLibcallSignatures.cpp

@@ -24,6 +24,8 @@
 
 using namespace llvm;
 
+extern cl::opt<bool> WasmEmitMultiValue;
+
 namespace {
 
 enum RuntimeLibcallSignature {
@@ -694,7 +696,7 @@ void llvm::getLibcallSignature(const WebAssemblySubtarget &Subtarget,
     Params.push_back(PtrTy);
     break;
   case i64_i64_func_f32:
-    if (Subtarget.hasMultivalue()) {
+    if (Subtarget.hasMultivalue() && WasmEmitMultiValue) {
       Rets.push_back(wasm::ValType::I64);
       Rets.push_back(wasm::ValType::I64);
     } else {
@@ -703,7 +705,7 @@ void llvm::getLibcallSignature(const WebAssemblySubtarget &Subtarget,
     Params.push_back(wasm::ValType::F32);
     break;
   case i64_i64_func_f64:
-    if (Subtarget.hasMultivalue()) {
+    if (Subtarget.hasMultivalue() && WasmEmitMultiValue) {
       Rets.push_back(wasm::ValType::I64);
       Rets.push_back(wasm::ValType::I64);
     } else {
@@ -712,7 +714,7 @@ void llvm::getLibcallSignature(const WebAssemblySubtarget &Subtarget,
     Params.push_back(wasm::ValType::F64);
     break;
   case i16_i16_func_i16_i16:
-    if (Subtarget.hasMultivalue()) {
+    if (Subtarget.hasMultivalue() && WasmEmitMultiValue) {
       Rets.push_back(wasm::ValType::I32);
       Rets.push_back(wasm::ValType::I32);
     } else {
@@ -722,7 +724,7 @@ void llvm::getLibcallSignature(const WebAssemblySubtarget &Subtarget,
     Params.push_back(wasm::ValType::I32);
     break;
   case i32_i32_func_i32_i32:
-    if (Subtarget.hasMultivalue()) {
+    if (Subtarget.hasMultivalue() && WasmEmitMultiValue) {
       Rets.push_back(wasm::ValType::I32);
       Rets.push_back(wasm::ValType::I32);
     } else {
@@ -732,7 +734,7 @@ void llvm::getLibcallSignature(const WebAssemblySubtarget &Subtarget,
     Params.push_back(wasm::ValType::I32);
     break;
   case i64_i64_func_i64_i64:
-    if (Subtarget.hasMultivalue()) {
+    if (Subtarget.hasMultivalue() && WasmEmitMultiValue) {
       Rets.push_back(wasm::ValType::I64);
       Rets.push_back(wasm::ValType::I64);
     } else {
@@ -742,7 +744,7 @@ void llvm::getLibcallSignature(const WebAssemblySubtarget &Subtarget,
     Params.push_back(wasm::ValType::I64);
     break;
   case i64_i64_func_i64_i64_i64_i64:
-    if (Subtarget.hasMultivalue()) {
+    if (Subtarget.hasMultivalue() && WasmEmitMultiValue) {
       Rets.push_back(wasm::ValType::I64);
       Rets.push_back(wasm::ValType::I64);
     } else {
@@ -754,7 +756,7 @@ void llvm::getLibcallSignature(const WebAssemblySubtarget &Subtarget,
     Params.push_back(wasm::ValType::I64);
     break;
   case i64_i64_func_i64_i64_i64_i64_iPTR:
-    if (Subtarget.hasMultivalue()) {
+    if (Subtarget.hasMultivalue() && WasmEmitMultiValue) {
       Rets.push_back(wasm::ValType::I64);
       Rets.push_back(wasm::ValType::I64);
     } else {
@@ -767,7 +769,7 @@ void llvm::getLibcallSignature(const WebAssemblySubtarget &Subtarget,
     Params.push_back(PtrTy);
     break;
   case i64_i64_i64_i64_func_i64_i64_i64_i64:
-    if (Subtarget.hasMultivalue()) {
+    if (Subtarget.hasMultivalue() && WasmEmitMultiValue) {
       Rets.push_back(wasm::ValType::I64);
       Rets.push_back(wasm::ValType::I64);
       Rets.push_back(wasm::ValType::I64);
@@ -781,7 +783,7 @@ void llvm::getLibcallSignature(const WebAssemblySubtarget &Subtarget,
     Params.push_back(wasm::ValType::I64);
     break;
   case i64_i64_func_i64_i64_i32:
-    if (Subtarget.hasMultivalue()) {
+    if (Subtarget.hasMultivalue() && WasmEmitMultiValue) {
       Rets.push_back(wasm::ValType::I64);
       Rets.push_back(wasm::ValType::I64);
     } else {
@@ -851,7 +853,7 @@ void llvm::getLibcallSignature(const WebAssemblySubtarget &Subtarget,
     Params.push_back(wasm::ValType::I64);
     break;
   case i64_i64_func_i64_i64_i64_i64_i64_i64:
-    if (Subtarget.hasMultivalue()) {
+    if (Subtarget.hasMultivalue() && WasmEmitMultiValue) {
       Rets.push_back(wasm::ValType::I64);
       Rets.push_back(wasm::ValType::I64);
     } else {
@@ -865,7 +867,7 @@ void llvm::getLibcallSignature(const WebAssemblySubtarget &Subtarget,
     Params.push_back(wasm::ValType::I64);
     break;
   case i64_i64_func_i32:
-    if (Subtarget.hasMultivalue()) {
+    if (Subtarget.hasMultivalue() && WasmEmitMultiValue) {
       Rets.push_back(wasm::ValType::I64);
       Rets.push_back(wasm::ValType::I64);
     } else {
@@ -874,7 +876,7 @@ void llvm::getLibcallSignature(const WebAssemblySubtarget &Subtarget,
     Params.push_back(wasm::ValType::I32);
     break;
   case i64_i64_func_i64:
-    if (Subtarget.hasMultivalue()) {
+    if (Subtarget.hasMultivalue() && WasmEmitMultiValue) {
       Rets.push_back(wasm::ValType::I64);
       Rets.push_back(wasm::ValType::I64);
     } else {

llvm/lib/Target/WebAssembly/WebAssemblyTargetMachine.cpp

@@ -54,6 +54,15 @@ static cl::opt<bool> WasmDisableFixIrreducibleControlFlowPass(
              " irreducible control flow optimization pass"),
     cl::init(false));
 
+// A temporary option to control emission of multivalue until multivalue
+// implementation is stable enough. We currently don't emit multivalue by
+// default even if the feature section allows it.
+// TODO Stabilize multivalue and delete this option
+cl::opt<bool>
+    WasmEmitMultiValue("wasm-emit-multivalue", cl::Hidden,
+                       cl::desc("WebAssembly: Emit multivalue in the backend"),
+                       cl::init(false));
+
 extern "C" LLVM_EXTERNAL_VISIBILITY void LLVMInitializeWebAssemblyTarget() {
   // Register the target.
   RegisterTargetMachine<WebAssemblyTargetMachine> X(

llvm/test/CodeGen/WebAssembly/lower-em-ehsjlj-multi-return.ll

@@ -1,5 +1,5 @@
-; RUN: not --crash llc < %s -enable-emscripten-cxx-exceptions -mattr=+multivalue 2>&1 | FileCheck %s --check-prefix=EH
-; RUN: not --crash llc < %s -enable-emscripten-sjlj -mattr=+multivalue 2>&1 | FileCheck %s --check-prefix=SJLJ
+; RUN: not --crash llc < %s -enable-emscripten-cxx-exceptions -mattr=+multivalue -wasm-emit-multivalue 2>&1 | FileCheck %s --check-prefix=EH
+; RUN: not --crash llc < %s -enable-emscripten-sjlj -mattr=+multivalue 2>&1 -wasm-emit-multivalue | FileCheck %s --check-prefix=SJLJ
 
 ; Currently multivalue returning functions are not supported in Emscripten EH /
 ; SjLj. Make sure they error out.

llvm/test/CodeGen/WebAssembly/multivalue-dont-move-def-past-use.mir

@@ -1,5 +1,5 @@
 # NOTE: Assertions have been autogenerated by utils/update_mir_test_checks.py
-# RUN: llc -mtriple=wasm32-unknown-unknown -mattr=+multivalue -run-pass=wasm-reg-stackify -verify-machineinstrs %s -o - | FileCheck %s
+# RUN: llc -mtriple=wasm32-unknown-unknown -mattr=+multivalue -wasm-emit-multivalue -run-pass=wasm-reg-stackify -verify-machineinstrs %s -o - | FileCheck %s
 
 --- |
   target datalayout = "e-m:e-p:32:32-p10:8:8-p20:8:8-i64:64-n32:64-S128-ni:1:10:20"

llvm/test/CodeGen/WebAssembly/multivalue-stackify.ll

@@ -1,7 +1,7 @@
 ; NOTE: Assertions have been autogenerated by utils/update_llc_test_checks.py
 ; NOTE: Test functions have been generated by multivalue-stackify.py.
 
-; RUN: llc < %s -verify-machineinstrs -mattr=+multivalue | FileCheck %s
+; RUN: llc < %s -verify-machineinstrs -mattr=+multivalue -wasm-emit-multivalue | FileCheck %s
 
 ; Test that the multivalue stackification works
 

llvm/test/CodeGen/WebAssembly/multivalue.ll

@@ -1,7 +1,8 @@
-; RUN: llc < %s -asm-verbose=false -verify-machineinstrs -mcpu=mvp -mattr=+multivalue,+tail-call | FileCheck %s
-; RUN: llc < %s -asm-verbose=false -verify-machineinstrs -mcpu=mvp -mattr=+reference-types,+multivalue,+tail-call | FileCheck --check-prefix REF %s
-; RUN: llc < %s -asm-verbose=false -verify-machineinstrs -disable-wasm-fallthrough-return-opt -wasm-disable-explicit-locals -wasm-keep-registers -mcpu=mvp -mattr=+multivalue,+tail-call | FileCheck %s --check-prefix REGS
-; RUN: llc < %s --filetype=obj -mcpu=mvp -mattr=+multivalue,+tail-call | obj2yaml | FileCheck %s --check-prefix OBJ
+; RUN: llc < %s -asm-verbose=false -verify-machineinstrs -mcpu=mvp -mattr=+multivalue,+tail-call -wasm-emit-multivalue | FileCheck %s
+; RUN: llc < %s -asm-verbose=false -verify-machineinstrs -mcpu=mvp -mattr=+reference-types,+multivalue,+tail-call -wasm-emit-multivalue | FileCheck --check-prefix REF %s
+; RUN: llc < %s -asm-verbose=false -verify-machineinstrs -disable-wasm-fallthrough-return-opt -wasm-disable-explicit-locals -wasm-keep-registers -mcpu=mvp -mattr=+multivalue,+tail-call -wasm-emit-multivalue | FileCheck %s --check-prefix REGS
+; RUN: llc < %s --filetype=obj -mcpu=mvp -mattr=+multivalue,+tail-call -wasm-emit-multivalue | obj2yaml | FileCheck %s --check-prefix OBJ
+; RUN: llc < %s -asm-verbose=false -verify-machineinstrs -mcpu=mvp -mattr=+multivalue,+tail-call | FileCheck %s --check-prefix NO-MULTIVALUE
 
 ; Test that the multivalue calls, returns, function types, and block
 ; types work as expected.
@@ -19,6 +20,7 @@ declare void @use_i64(i64)
 ; CHECK-NEXT: i32.const 42{{$}}
 ; CHECK-NEXT: i64.const 42{{$}}
 ; CHECK-NEXT: end_function{{$}}
+; NO-MULTIVALUE-NOT: .functype pair_const () -> (i32, i64)
 define %pair @pair_const() {
   ret %pair { i32 42, i64 42 }
 }

llvm/test/CodeGen/WebAssembly/multivalue_libcall.ll

@@ -1,5 +1,5 @@
 ; 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 -mattr=+multivalue -wasm-emit-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