[WebAssembly] Disable multivalue emission temporarily #82714
Merged
Conversation
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
We plan to enable multivalue in the features section soon (llvm#80923) for other reasons, such as the feature having been standardized for many years and other features being developed (e.g. EH) depending on it. This is separate from enabling Clang experimental multivalue ABI (`-Xclang -target-abi -Xclang experimental-mv`), but it turned out we generate some multivalue code in the backend as well if it is enabled in the features section. Given that our backend multivalue generation still has not been much used nor tested, and enabling the feature in the features section can be a separate decision from how much multialue (including none) we decide to generate for now, I'd like to temporarily disable the actual generation of multivalue in our backend. To do that, this adds an internal flag `-wasm-emit-multivalue` that defaults to false. All our existing multivalue tests can use this to test multivalue code. This flag can be removed later when we are confident the multivalue generation is well tested.
|
@llvm/pr-subscribers-backend-webassembly Author: Heejin Ahn (aheejin) ChangesWe plan to enable multivalue in the features section soon (#80923) for other reasons, such as the feature having been standardized for many years and other features being developed (e.g. EH) depending on it. This is separate from enabling Clang experimental multivalue ABI ( Given that our backend multivalue generation still has not been much used nor tested, and enabling the feature in the features section can be a separate decision from how much multialue (including none) we decide to generate for now, I'd like to temporarily disable the actual generation of multivalue in our backend. To do that, this adds an internal flag Full diff: https://github.com/llvm/llvm-project/pull/82714.diff 9 Files Affected:
diff --git a/llvm/lib/Target/WebAssembly/WebAssemblyISelLowering.cpp b/llvm/lib/Target/WebAssembly/WebAssemblyISelLowering.cpp
index 7c47790d1e3515..36f067956e63a5 100644
--- a/llvm/lib/Target/WebAssembly/WebAssemblyISelLowering.cpp
+++ b/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) {
@@ -1288,7 +1290,7 @@ 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(
@@ -1296,7 +1298,8 @@ SDValue WebAssemblyTargetLowering::LowerReturn(
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");
diff --git a/llvm/lib/Target/WebAssembly/WebAssemblyMachineFunctionInfo.cpp b/llvm/lib/Target/WebAssembly/WebAssemblyMachineFunctionInfo.cpp
index 1e959111a4dbcb..b969b8370a3e5e 100644
--- a/llvm/lib/Target/WebAssembly/WebAssemblyMachineFunctionInfo.cpp
+++ b/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
diff --git a/llvm/lib/Target/WebAssembly/WebAssemblyRuntimeLibcallSignatures.cpp b/llvm/lib/Target/WebAssembly/WebAssemblyRuntimeLibcallSignatures.cpp
index 3e2e029695ab6f..2a84c90c89602e 100644
--- a/llvm/lib/Target/WebAssembly/WebAssemblyRuntimeLibcallSignatures.cpp
+++ b/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 {
diff --git a/llvm/lib/Target/WebAssembly/WebAssemblyTargetMachine.cpp b/llvm/lib/Target/WebAssembly/WebAssemblyTargetMachine.cpp
index 42043a7b8680a4..8814d0570dc41f 100644
--- a/llvm/lib/Target/WebAssembly/WebAssemblyTargetMachine.cpp
+++ b/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(
diff --git a/llvm/test/CodeGen/WebAssembly/lower-em-ehsjlj-multi-return.ll b/llvm/test/CodeGen/WebAssembly/lower-em-ehsjlj-multi-return.ll
index 4f33439db770dc..daf46c6eef0252 100644
--- a/llvm/test/CodeGen/WebAssembly/lower-em-ehsjlj-multi-return.ll
+++ b/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.
diff --git a/llvm/test/CodeGen/WebAssembly/multivalue-dont-move-def-past-use.mir b/llvm/test/CodeGen/WebAssembly/multivalue-dont-move-def-past-use.mir
index 4b4661b144667f..4fadbd5f07e6df 100644
--- a/llvm/test/CodeGen/WebAssembly/multivalue-dont-move-def-past-use.mir
+++ b/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"
diff --git a/llvm/test/CodeGen/WebAssembly/multivalue-stackify.ll b/llvm/test/CodeGen/WebAssembly/multivalue-stackify.ll
index 52a8c686824d33..f4f93ac2f30ce3 100644
--- a/llvm/test/CodeGen/WebAssembly/multivalue-stackify.ll
+++ b/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
diff --git a/llvm/test/CodeGen/WebAssembly/multivalue.ll b/llvm/test/CodeGen/WebAssembly/multivalue.ll
index 675009c8f3e548..846691e5ff0cda 100644
--- a/llvm/test/CodeGen/WebAssembly/multivalue.ll
+++ b/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 }
}
diff --git a/llvm/test/CodeGen/WebAssembly/multivalue_libcall.ll b/llvm/test/CodeGen/WebAssembly/multivalue_libcall.ll
index 47c5ae7b457dde..7bf37b59353ad6 100644
--- a/llvm/test/CodeGen/WebAssembly/multivalue_libcall.ll
+++ b/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
|
|
✅ With the latest revision this PR passed the C/C++ code formatter. |
tlively
approved these changes
Feb 23, 2024
|
Correct. |
|
Sounds good! |
|
one small input from downstream user: the ghc wasm backend distributes its own wasi-sdk fork based on llvm trunk and we do enable multi-value by default, including the experimental mv abi in c, in the hope of uncovering more bugs for the sake of upstream as well as rest of the wasm ecosystem. other than #71124, multi value as well as the new abi hasn't caused us other trouble so far. this patch looks easy enough to workaround in our downstream builds so we can continue to test against the mv abi without needing to figure out how to pass that flag all the way up from the clang driver, etc. still, i'm rather surprised such a significant change was proposed and merged in such a short timeline, with absolutely no community notice or grace period :/ |
|
@aheejin, if we revert this commit to avoid disrupting downstream users, do we have a backup plan that would allow us to make progress on new EH? |
|
@TerrorJack Oh, I wasn't aware this feature had active users, and thought this as mainly an internal issue. But good to know that you use it, and sorry for the inconvenience. @tlively It is a little unclear to me how we define disruptions. What we caused in users like @TerrorJack's workflow can count as disruptions, but if we enable multivalue (either by default or at least when Wasm EH is used) and that reveals some untested parts in the toolchain, that might count as potential disruptions as well. If I run Emscripten tests with multivalue enabled, currently all Emscripten EH tests (or anything that use I'll then revert this patch for now and investigate a little more on the failures. |
|
@TerrorJack, is the multivalue-enabled wasi-sdk you distribute used in production or is it only meant for finding toolchain bugs? |
|
@tlively it's used in production and we ship it to ghc wasm backend's end users. |
|
For this use case we could make the experimental MV ABI flag also enable |
aheejin
added a commit
that referenced
this pull request
Feb 28, 2024
This reverts commit 6e6bf9f. It turned out the multivalue feature had active outside users and it could cause some disruptions to them, so I'd like to investigate more about the workarounds before doing this.
Turned out I only reverted this on my fork.. Reverted it in upstream now. |
aheejin
added a commit
to aheejin/llvm-project
that referenced
this pull request
Apr 12, 2024
Multivalue feature of WebAssembly has been standardized for several years now. I think it makes sense to be able to enable it in the feature section by default for our clang/llvm-produced binaries so that the multivalue feature can be used as necessary when necessary within our toolchain and also when running other optimizers (e.g. wasm-opt) after the LLVM code generation. But some WebAssembly toolchains, such as Emscripten, do not provide both mulvalue-returning and not-multivalue-returning versions of libraries. Also allowing the uses of multivalue in the features section does not necessarily mean we generate them whenever we can to the fullest, which is a different code generation / optimization option. So this makes the lowering of multivalue returns conditional on the use of 'experimental-mv' target ABI. This ABI is turned off by default and turned on by passing `-Xclang -target-abi -Xclang experimental-mv` to `clang`, or `-target-abi experimental-mv` to `clang -cc1` or `llc`. But the purpose of this PR is not tying the multivalue lowering to this specific 'experimental-mv'. 'experimental-mv' is just one multivalue ABI we currently have, and it is still experimental, meaning it is not very well optimized or tuned for performance. (e.g. it does not have the limitation of the max number of multivalue-lowered values, which can be detrimental to performance.) We may change the name of this ABI, or improve it, or add a new multivalue ABI in the future. Also I heard that WASI is planning to add their multivalue ABI soon. So the plan is, whenever any one of multivalue ABIs is enabled, we enable the lowering of multivalue returns in the backend. We currently have only 'experimental-mv' in the repo so we only check for that in this PR. Related past discussions: llvm#82714 WebAssembly/tool-conventions#223 (comment)
aheejin
added a commit
that referenced
this pull request
Apr 23, 2024
…88492) Multivalue feature of WebAssembly has been standardized for several years now. I think it makes sense to be able to enable it in the feature section by default for our clang/llvm-produced binaries so that the multivalue feature can be used as necessary when necessary within our toolchain and also when running other optimizers (e.g. wasm-opt) after the LLVM code generation. But some WebAssembly toolchains, such as Emscripten, do not provide both mulvalue-returning and not-multivalue-returning versions of libraries. Also allowing the uses of multivalue in the features section does not necessarily mean we generate them whenever we can to the fullest, which is a different code generation / optimization option. So this makes the lowering of multivalue returns conditional on the use of 'experimental-mv' target ABI. This ABI is turned off by default and turned on by passing `-Xclang -target-abi -Xclang experimental-mv` to `clang`, or `-target-abi experimental-mv` to `clang -cc1` or `llc`. But the purpose of this PR is not tying the multivalue lowering to this specific 'experimental-mv'. 'experimental-mv' is just one multivalue ABI we currently have, and it is still experimental, meaning it is not very well optimized or tuned for performance. (e.g. it does not have the limitation of the max number of multivalue-lowered values, which can be detrimental to performance.) We may change the name of this ABI, or improve it, or add a new multivalue ABI in the future. Also I heard that WASI is planning to add their multivalue ABI soon. So the plan is, whenever any one of multivalue ABIs is enabled, we enable the lowering of multivalue returns in the backend. We currently have only 'experimental-mv' in the repo so we only check for that in this PR. Related past discussions: #82714 WebAssembly/tool-conventions#223 (comment)
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment
Add this suggestion to a batch that can be applied as a single commit.
This suggestion is invalid because no changes were made to the code.
Suggestions cannot be applied while the pull request is closed.
Suggestions cannot be applied while viewing a subset of changes.
Only one suggestion per line can be applied in a batch.
Add this suggestion to a batch that can be applied as a single commit.
Applying suggestions on deleted lines is not supported.
You must change the existing code in this line in order to create a valid suggestion.
Outdated suggestions cannot be applied.
This suggestion has been applied or marked resolved.
Suggestions cannot be applied from pending reviews.
Suggestions cannot be applied on multi-line comments.
Suggestions cannot be applied while the pull request is queued to merge.
Suggestion cannot be applied right now. Please check back later.
We plan to enable multivalue in the features section soon (#80923) for other reasons, such as the feature having been standardized for many years and other features being developed (e.g. EH) depending on it. This is separate from enabling Clang experimental multivalue ABI (
-Xclang -target-abi -Xclang experimental-mv), but it turned out we generate some multivalue code in the backend as well if it is enabled in the features section.Given that our backend multivalue generation still has not been much used nor tested, and enabling the feature in the features section can be a separate decision from how much multialue (including none) we decide to generate for now, I'd like to temporarily disable the actual generation of multivalue in our backend. To do that, this adds an internal flag
-wasm-emit-multivaluethat defaults to false. All our existing multivalue tests can use this to test multivalue code. This flag can be removed later when we are confident the multivalue generation is well tested.