[WebAssembly] Enable multivalue return when multivalue ABI is used

llvm/lib/Target/WebAssembly/WebAssemblyISelLowering.cpp

@@ -1288,15 +1288,15 @@ 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 WebAssembly::canLowerReturn(Outs.size(), Subtarget);
 }
 
 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(WebAssembly::canLowerReturn(Outs.size(), Subtarget) &&
          "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

@@ -17,6 +17,7 @@
 #include "Utils/WebAssemblyTypeUtilities.h"
 #include "WebAssemblyISelLowering.h"
 #include "WebAssemblySubtarget.h"
+#include "WebAssemblyUtilities.h"
 #include "llvm/CodeGen/Analysis.h"
 #include "llvm/CodeGen/WasmEHFuncInfo.h"
 #include "llvm/Target/TargetMachine.h"
@@ -70,8 +71,9 @@ void llvm::computeSignatureVTs(const FunctionType *Ty,
   computeLegalValueVTs(ContextFunc, TM, Ty->getReturnType(), Results);
 
   MVT PtrVT = MVT::getIntegerVT(TM.createDataLayout().getPointerSizeInBits());
-  if (Results.size() > 1 &&
-      !TM.getSubtarget<WebAssemblySubtarget>(ContextFunc).hasMultivalue()) {
+  if (!WebAssembly::canLowerReturn(
+          Results.size(),
+          &TM.getSubtarget<WebAssemblySubtarget>(ContextFunc))) {
     // 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

@@ -20,6 +20,7 @@
 
 #include "WebAssemblyRuntimeLibcallSignatures.h"
 #include "WebAssemblySubtarget.h"
+#include "WebAssemblyUtilities.h"
 #include "llvm/CodeGen/RuntimeLibcalls.h"
 
 using namespace llvm;
@@ -694,7 +695,7 @@ void WebAssembly::getLibcallSignature(const WebAssemblySubtarget &Subtarget,
     Params.push_back(PtrTy);
     break;
   case i64_i64_func_f32:
-    if (Subtarget.hasMultivalue()) {
+    if (WebAssembly::canLowerMultivalueReturn(&Subtarget)) {
       Rets.push_back(wasm::ValType::I64);
       Rets.push_back(wasm::ValType::I64);
     } else {
@@ -703,7 +704,7 @@ void WebAssembly::getLibcallSignature(const WebAssemblySubtarget &Subtarget,
     Params.push_back(wasm::ValType::F32);
     break;
   case i64_i64_func_f64:
-    if (Subtarget.hasMultivalue()) {
+    if (WebAssembly::canLowerMultivalueReturn(&Subtarget)) {
       Rets.push_back(wasm::ValType::I64);
       Rets.push_back(wasm::ValType::I64);
     } else {
@@ -712,7 +713,7 @@ void WebAssembly::getLibcallSignature(const WebAssemblySubtarget &Subtarget,
     Params.push_back(wasm::ValType::F64);
     break;
   case i16_i16_func_i16_i16:
-    if (Subtarget.hasMultivalue()) {
+    if (WebAssembly::canLowerMultivalueReturn(&Subtarget)) {
       Rets.push_back(wasm::ValType::I32);
       Rets.push_back(wasm::ValType::I32);
     } else {
@@ -722,7 +723,7 @@ void WebAssembly::getLibcallSignature(const WebAssemblySubtarget &Subtarget,
     Params.push_back(wasm::ValType::I32);
     break;
   case i32_i32_func_i32_i32:
-    if (Subtarget.hasMultivalue()) {
+    if (WebAssembly::canLowerMultivalueReturn(&Subtarget)) {
       Rets.push_back(wasm::ValType::I32);
       Rets.push_back(wasm::ValType::I32);
     } else {
@@ -732,7 +733,7 @@ void WebAssembly::getLibcallSignature(const WebAssemblySubtarget &Subtarget,
     Params.push_back(wasm::ValType::I32);
     break;
   case i64_i64_func_i64_i64:
-    if (Subtarget.hasMultivalue()) {
+    if (WebAssembly::canLowerMultivalueReturn(&Subtarget)) {
       Rets.push_back(wasm::ValType::I64);
       Rets.push_back(wasm::ValType::I64);
     } else {
@@ -742,7 +743,7 @@ void WebAssembly::getLibcallSignature(const WebAssemblySubtarget &Subtarget,
     Params.push_back(wasm::ValType::I64);
     break;
   case i64_i64_func_i64_i64_i64_i64:
-    if (Subtarget.hasMultivalue()) {
+    if (WebAssembly::canLowerMultivalueReturn(&Subtarget)) {
       Rets.push_back(wasm::ValType::I64);
       Rets.push_back(wasm::ValType::I64);
     } else {
@@ -754,7 +755,7 @@ void WebAssembly::getLibcallSignature(const WebAssemblySubtarget &Subtarget,
     Params.push_back(wasm::ValType::I64);
     break;
   case i64_i64_func_i64_i64_i64_i64_iPTR:
-    if (Subtarget.hasMultivalue()) {
+    if (WebAssembly::canLowerMultivalueReturn(&Subtarget)) {
       Rets.push_back(wasm::ValType::I64);
       Rets.push_back(wasm::ValType::I64);
     } else {
@@ -767,7 +768,7 @@ void WebAssembly::getLibcallSignature(const WebAssemblySubtarget &Subtarget,
     Params.push_back(PtrTy);
     break;
   case i64_i64_i64_i64_func_i64_i64_i64_i64:
-    if (Subtarget.hasMultivalue()) {
+    if (WebAssembly::canLowerMultivalueReturn(&Subtarget)) {
       Rets.push_back(wasm::ValType::I64);
       Rets.push_back(wasm::ValType::I64);
       Rets.push_back(wasm::ValType::I64);
@@ -781,7 +782,7 @@ void WebAssembly::getLibcallSignature(const WebAssemblySubtarget &Subtarget,
     Params.push_back(wasm::ValType::I64);
     break;
   case i64_i64_func_i64_i64_i32:
-    if (Subtarget.hasMultivalue()) {
+    if (WebAssembly::canLowerMultivalueReturn(&Subtarget)) {
       Rets.push_back(wasm::ValType::I64);
       Rets.push_back(wasm::ValType::I64);
     } else {
@@ -851,7 +852,7 @@ void WebAssembly::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 (WebAssembly::canLowerMultivalueReturn(&Subtarget)) {
       Rets.push_back(wasm::ValType::I64);
       Rets.push_back(wasm::ValType::I64);
     } else {
@@ -865,7 +866,7 @@ void WebAssembly::getLibcallSignature(const WebAssemblySubtarget &Subtarget,
     Params.push_back(wasm::ValType::I64);
     break;
   case i64_i64_func_i32:
-    if (Subtarget.hasMultivalue()) {
+    if (WebAssembly::canLowerMultivalueReturn(&Subtarget)) {
       Rets.push_back(wasm::ValType::I64);
       Rets.push_back(wasm::ValType::I64);
     } else {
@@ -874,7 +875,7 @@ void WebAssembly::getLibcallSignature(const WebAssemblySubtarget &Subtarget,
     Params.push_back(wasm::ValType::I32);
     break;
   case i64_i64_func_i64:
-    if (Subtarget.hasMultivalue()) {
+    if (WebAssembly::canLowerMultivalueReturn(&Subtarget)) {
       Rets.push_back(wasm::ValType::I64);
       Rets.push_back(wasm::ValType::I64);
     } else {

llvm/lib/Target/WebAssembly/WebAssemblyTargetMachine.cpp

@@ -128,7 +128,8 @@ WebAssemblyTargetMachine::WebAssemblyTargetMachine(
                                        "n32:64-S128-ni:1:10:20"),
           TT, CPU, FS, Options, getEffectiveRelocModel(RM, TT),
           getEffectiveCodeModel(CM, CodeModel::Large), OL),
-      TLOF(new WebAssemblyTargetObjectFile()) {
+      TLOF(new WebAssemblyTargetObjectFile()),
+      UsesMultivalueABI(Options.MCOptions.getABIName() == "experimental-mv") {
   // WebAssembly type-checks instructions, but a noreturn function with a return
   // type that doesn't match the context will cause a check failure. So we lower
   // LLVM 'unreachable' to ISD::TRAP and then lower that to WebAssembly's

llvm/lib/Target/WebAssembly/WebAssemblyTargetMachine.h

@@ -24,6 +24,7 @@ namespace llvm {
 class WebAssemblyTargetMachine final : public LLVMTargetMachine {
   std::unique_ptr<TargetLoweringObjectFile> TLOF;
   mutable StringMap<std::unique_ptr<WebAssemblySubtarget>> SubtargetMap;
+  bool UsesMultivalueABI = false;
 
 public:
   WebAssemblyTargetMachine(const Target &T, const Triple &TT, StringRef CPU,
@@ -62,6 +63,8 @@ class WebAssemblyTargetMachine final : public LLVMTargetMachine {
                                 PerFunctionMIParsingState &PFS,
                                 SMDiagnostic &Error,
                                 SMRange &SourceRange) const override;
+
+  bool usesMultivalueABI() const { return UsesMultivalueABI; }
 };
 
 } // end namespace llvm

llvm/lib/Target/WebAssembly/WebAssemblyUtilities.cpp

@@ -13,7 +13,7 @@
 
 #include "WebAssemblyUtilities.h"
 #include "WebAssemblyMachineFunctionInfo.h"
-#include "WebAssemblySubtarget.h"
+#include "WebAssemblyTargetMachine.h"
 #include "llvm/CodeGen/MachineInstr.h"
 #include "llvm/CodeGen/MachineLoopInfo.h"
 #include "llvm/IR/Function.h"
@@ -179,3 +179,15 @@ unsigned WebAssembly::getCopyOpcodeForRegClass(const TargetRegisterClass *RC) {
     llvm_unreachable("Unexpected register class");
   }
 }
+
+bool WebAssembly::canLowerMultivalueReturn(
+    const WebAssemblySubtarget *Subtarget) {
+  const auto &TM = static_cast<const WebAssemblyTargetMachine &>(
+      Subtarget->getTargetLowering()->getTargetMachine());
+  return Subtarget->hasMultivalue() && TM.usesMultivalueABI();
+}
+
+bool WebAssembly::canLowerReturn(size_t ResultSize,
+                                 const WebAssemblySubtarget *Subtarget) {
+  return ResultSize <= 1 || canLowerMultivalueReturn(Subtarget);
+}

llvm/lib/Target/WebAssembly/WebAssemblyUtilities.h

@@ -63,6 +63,16 @@ MachineInstr *findCatch(MachineBasicBlock *EHPad);
 /// Returns the appropriate copy opcode for the given register class.
 unsigned getCopyOpcodeForRegClass(const TargetRegisterClass *RC);
 
+/// Returns true if multivalue returns of a function can be lowered directly,
+/// i.e., not indirectly via a pointer parameter that points to the value in
+/// memory.
+bool canLowerMultivalueReturn(const WebAssemblySubtarget *Subtarget);
+
+/// Returns true if the function's return value(s) can be lowered directly,
+/// i.e., not indirectly via a pointer parameter that points to the value in
+/// memory.
+bool canLowerReturn(size_t ResultSize, const WebAssemblySubtarget *Subtarget);
+
 } // end namespace WebAssembly
 
 } // end namespace llvm

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 -target-abi=experimental-mv 2>&1 | FileCheck %s --check-prefix=EH
+; RUN: not --crash llc < %s -enable-emscripten-sjlj -mattr=+multivalue -target-abi=experimental-mv 2>&1 | 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 -target-abi=experimental-mv -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 -target-abi=experimental-mv | 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 -target-abi=experimental-mv | FileCheck %s
+; RUN: llc < %s -asm-verbose=false -verify-machineinstrs -mcpu=mvp -mattr=+reference-types,+multivalue,+tail-call -target-abi=experimental-mv | 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 -target-abi=experimental-mv | FileCheck %s --check-prefix REGS
+; RUN: llc < %s --filetype=obj -mcpu=mvp -mattr=+multivalue,+tail-call -target-abi=experimental-mv | 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 -target-abi=experimental-mv | 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