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WebAssembly: Move validation of EH flags to TargetMachine construct time #146634

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Jul 2, 2025
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WebAssembly: Move validation of EH flags to TargetMachine construct time #146634

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7 changes: 4 additions & 3 deletions clang/test/CodeGen/WebAssembly/wasm-exception-model-flag-parse-ir-input.ll
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Expand Up @@ -2,15 +2,16 @@

; Check all the options parse
; RUN: %clang_cc1 -triple wasm32 -o - -emit-llvm -exception-model=none %s | FileCheck %s
; RUN: %clang_cc1 -triple wasm32 -o - -emit-llvm -exception-model=wasm %s | FileCheck %s
; RUN: %clang_cc1 -triple wasm32 -o - -emit-llvm -exception-model=dwarf %s | FileCheck %s
; RUN: %clang_cc1 -triple wasm32 -o - -emit-llvm -exception-model=sjlj %s | FileCheck %s
; RUN: %clang_cc1 -triple wasm32 -o - -emit-llvm -exception-model=wasm -mllvm -wasm-enable-eh %s | FileCheck %s

; RUN: not %clang_cc1 -triple wasm32 -o - -emit-llvm -exception-model=invalid %s 2>&1 | FileCheck -check-prefix=ERR %s
; RUN: not %clang_cc1 -triple wasm32 -o - -emit-llvm -exception-model=dwarf %s 2>&1 | FileCheck -check-prefix=ERR-BE %s
; RUN: not %clang_cc1 -triple wasm32 -o - -emit-llvm -exception-model=sjlj %s 2>&1 | FileCheck -check-prefix=ERR-BE %s

; CHECK-LABEL: define void @test(

; ERR: error: invalid value 'invalid' in '-exception-model=invalid'
; ERR-BE: fatal error: error in backend: -exception-model should be either 'none' or 'wasm'
define void @test() {
ret void
}
2 changes: 1 addition & 1 deletion clang/test/CodeGenCXX/builtins-eh-wasm.cpp
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@@ -1,4 +1,4 @@
// RUN: %clang_cc1 -triple wasm32-unknown-unknown -fexceptions -fcxx-exceptions -target-feature +reference-types -target-feature +exception-handling -target-feature +multivalue -exception-model=wasm -emit-llvm -o - %s | FileCheck %s
// RUN: %clang_cc1 -triple wasm32-unknown-unknown -fexceptions -fcxx-exceptions -target-feature +reference-types -target-feature +exception-handling -target-feature +multivalue -mllvm -wasm-enable-eh -exception-model=wasm -emit-llvm -o - %s | FileCheck %s

// Check if __builtin_wasm_throw and __builtin_wasm_rethrow are correctly
// invoked when placed in try-catch.
Expand Down
6 changes: 3 additions & 3 deletions clang/test/CodeGenCXX/wasm-eh.cpp
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Expand Up @@ -393,9 +393,9 @@ void noexcept_throw() noexcept {
// CHECK-NEXT: call void @_ZSt9terminatev()


// RUN: %clang_cc1 %s -triple wasm32-unknown-unknown -fms-extensions -fexceptions -fcxx-exceptions -exception-model=wasm -target-feature +exception-handling -emit-llvm -o - -std=c++11 2>&1 | FileCheck %s --check-prefix=WARNING-DEFAULT
// RUN: %clang_cc1 %s -triple wasm32-unknown-unknown -fms-extensions -fexceptions -fcxx-exceptions -exception-model=wasm -target-feature +exception-handling -Wwasm-exception-spec -emit-llvm -o - -std=c++11 2>&1 | FileCheck %s --check-prefix=WARNING-ON
// RUN: %clang_cc1 %s -triple wasm32-unknown-unknown -fms-extensions -fexceptions -fcxx-exceptions -exception-model=wasm -target-feature +exception-handling -Wno-wasm-exception-spec -emit-llvm -o - -std=c++11 2>&1 | FileCheck %s --check-prefix=WARNING-OFF
// RUN: %clang_cc1 %s -triple wasm32-unknown-unknown -fms-extensions -fexceptions -fcxx-exceptions -mllvm -wasm-enable-eh -exception-model=wasm -target-feature +exception-handling -emit-llvm -o - -std=c++11 2>&1 | FileCheck %s --check-prefix=WARNING-DEFAULT
// RUN: %clang_cc1 %s -triple wasm32-unknown-unknown -fms-extensions -fexceptions -fcxx-exceptions -mllvm -wasm-enable-eh -exception-model=wasm -target-feature +exception-handling -Wwasm-exception-spec -emit-llvm -o - -std=c++11 2>&1 | FileCheck %s --check-prefix=WARNING-ON
// RUN: %clang_cc1 %s -triple wasm32-unknown-unknown -fms-extensions -fexceptions -fcxx-exceptions -mllvm -wasm-enable-eh -exception-model=wasm -target-feature +exception-handling -Wno-wasm-exception-spec -emit-llvm -o - -std=c++11 2>&1 | FileCheck %s --check-prefix=WARNING-OFF
// RUN: %clang_cc1 %s -triple wasm32-unknown-unknown -fexceptions -fcxx-exceptions -emit-llvm -o - -std=c++11 2>&1 | FileCheck %s --check-prefix=EM-EH-WARNING

// Wasm EH ignores dynamic exception specifications with types at the moment.
Expand Down
110 changes: 52 additions & 58 deletions llvm/lib/Target/WebAssembly/WebAssemblyTargetMachine.cpp
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Expand Up @@ -111,6 +111,57 @@ static Reloc::Model getEffectiveRelocModel(std::optional<Reloc::Model> RM,
return *RM;
}

using WebAssembly::WasmEnableEH;
using WebAssembly::WasmEnableEmEH;
using WebAssembly::WasmEnableEmSjLj;
using WebAssembly::WasmEnableSjLj;

static void basicCheckForEHAndSjLj(TargetMachine *TM) {

// You can't enable two modes of EH at the same time
if (WasmEnableEmEH && WasmEnableEH)
report_fatal_error(
"-enable-emscripten-cxx-exceptions not allowed with -wasm-enable-eh");
// You can't enable two modes of SjLj at the same time
if (WasmEnableEmSjLj && WasmEnableSjLj)
report_fatal_error(
"-enable-emscripten-sjlj not allowed with -wasm-enable-sjlj");
// You can't mix Emscripten EH with Wasm SjLj.
if (WasmEnableEmEH && WasmEnableSjLj)
report_fatal_error(
"-enable-emscripten-cxx-exceptions not allowed with -wasm-enable-sjlj");

if (TM->Options.ExceptionModel == ExceptionHandling::None) {
// FIXME: These flags should be removed in favor of directly using the
// generically configured ExceptionsType
if (WebAssembly::WasmEnableEH || WebAssembly::WasmEnableSjLj)
TM->Options.ExceptionModel = ExceptionHandling::Wasm;
}

// Basic Correctness checking related to -exception-model
if (TM->Options.ExceptionModel != ExceptionHandling::None &&
TM->Options.ExceptionModel != ExceptionHandling::Wasm)
report_fatal_error("-exception-model should be either 'none' or 'wasm'");
if (WasmEnableEmEH && TM->Options.ExceptionModel == ExceptionHandling::Wasm)
report_fatal_error("-exception-model=wasm not allowed with "
"-enable-emscripten-cxx-exceptions");
if (WasmEnableEH && TM->Options.ExceptionModel != ExceptionHandling::Wasm)
report_fatal_error(
"-wasm-enable-eh only allowed with -exception-model=wasm");
if (WasmEnableSjLj && TM->Options.ExceptionModel != ExceptionHandling::Wasm)
report_fatal_error(
"-wasm-enable-sjlj only allowed with -exception-model=wasm");
if ((!WasmEnableEH && !WasmEnableSjLj) &&
TM->Options.ExceptionModel == ExceptionHandling::Wasm)
report_fatal_error(
"-exception-model=wasm only allowed with at least one of "
"-wasm-enable-eh or -wasm-enable-sjlj");

// Currently it is allowed to mix Wasm EH with Emscripten SjLj as an interim
// measure, but some code will error out at compile time in this combination.
// See WebAssemblyLowerEmscriptenEHSjLj pass for details.
}

/// Create an WebAssembly architecture model.
///
WebAssemblyTargetMachine::WebAssemblyTargetMachine(
Expand Down Expand Up @@ -149,7 +200,7 @@ WebAssemblyTargetMachine::WebAssemblyTargetMachine(
this->Options.UniqueSectionNames = true;

initAsmInfo();

basicCheckForEHAndSjLj(this);
// Note that we don't use setRequiresStructuredCFG(true). It disables
// optimizations than we're ok with, and want, such as critical edge
// splitting and tail merging.
Expand Down Expand Up @@ -400,61 +451,6 @@ FunctionPass *WebAssemblyPassConfig::createTargetRegisterAllocator(bool) {
return nullptr; // No reg alloc
}

using WebAssembly::WasmEnableEH;
using WebAssembly::WasmEnableEmEH;
using WebAssembly::WasmEnableEmSjLj;
using WebAssembly::WasmEnableSjLj;

static void basicCheckForEHAndSjLj(TargetMachine *TM) {

// You can't enable two modes of EH at the same time
if (WasmEnableEmEH && WasmEnableEH)
report_fatal_error(
"-enable-emscripten-cxx-exceptions not allowed with -wasm-enable-eh");
// You can't enable two modes of SjLj at the same time
if (WasmEnableEmSjLj && WasmEnableSjLj)
report_fatal_error(
"-enable-emscripten-sjlj not allowed with -wasm-enable-sjlj");
// You can't mix Emscripten EH with Wasm SjLj.
if (WasmEnableEmEH && WasmEnableSjLj)
report_fatal_error(
"-enable-emscripten-cxx-exceptions not allowed with -wasm-enable-sjlj");

// Here we make sure TargetOptions.ExceptionModel is the same as
// MCAsmInfo.ExceptionsType. Normally these have to be the same, because clang
// stores the exception model info in LangOptions, which is later transferred
// to TargetOptions and MCAsmInfo. But when clang compiles bitcode directly,
// clang's LangOptions is not used and thus the exception model info is not
// correctly transferred to TargetOptions and MCAsmInfo, so we make sure we
// have the correct exception model in WebAssemblyMCAsmInfo constructor. But
// in this case TargetOptions is still not updated, so we make sure they are
// the same.
TM->Options.ExceptionModel = TM->getMCAsmInfo()->getExceptionHandlingType();

// Basic Correctness checking related to -exception-model
if (TM->Options.ExceptionModel != ExceptionHandling::None &&
TM->Options.ExceptionModel != ExceptionHandling::Wasm)
report_fatal_error("-exception-model should be either 'none' or 'wasm'");
if (WasmEnableEmEH && TM->Options.ExceptionModel == ExceptionHandling::Wasm)
report_fatal_error("-exception-model=wasm not allowed with "
"-enable-emscripten-cxx-exceptions");
if (WasmEnableEH && TM->Options.ExceptionModel != ExceptionHandling::Wasm)
report_fatal_error(
"-wasm-enable-eh only allowed with -exception-model=wasm");
if (WasmEnableSjLj && TM->Options.ExceptionModel != ExceptionHandling::Wasm)
report_fatal_error(
"-wasm-enable-sjlj only allowed with -exception-model=wasm");
if ((!WasmEnableEH && !WasmEnableSjLj) &&
TM->Options.ExceptionModel == ExceptionHandling::Wasm)
report_fatal_error(
"-exception-model=wasm only allowed with at least one of "
"-wasm-enable-eh or -wasm-enable-sjlj");

// Currently it is allowed to mix Wasm EH with Emscripten SjLj as an interim
// measure, but some code will error out at compile time in this combination.
// See WebAssemblyLowerEmscriptenEHSjLj pass for details.
}

//===----------------------------------------------------------------------===//
// The following functions are called from lib/CodeGen/Passes.cpp to modify
// the CodeGen pass sequence.
Expand All @@ -475,8 +471,6 @@ void WebAssemblyPassConfig::addIRPasses() {
if (getOptLevel() != CodeGenOptLevel::None)
addPass(createWebAssemblyOptimizeReturned());

basicCheckForEHAndSjLj(TM);

// If exception handling is not enabled and setjmp/longjmp handling is
// enabled, we lower invokes into calls and delete unreachable landingpad
// blocks. Lowering invokes when there is no EH support is done in
Expand Down
2 changes: 1 addition & 1 deletion llvm/test/CodeGen/WebAssembly/cfg-stackify-eh-legacy.mir
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# RUN: llc -mtriple=wasm32-unknown-unknown -wasm-use-legacy-eh -exception-model=wasm -mattr=+exception-handling -run-pass wasm-cfg-stackify %s -o - | FileCheck %s
# RUN: llc -mtriple=wasm32-unknown-unknown -wasm-use-legacy-eh -wasm-enable-eh -exception-model=wasm -mattr=+exception-handling -run-pass wasm-cfg-stackify %s -o - | FileCheck %s

--- |
target triple = "wasm32-unknown-unknown"
Expand Down
2 changes: 1 addition & 1 deletion llvm/test/CodeGen/WebAssembly/exception-legacy.mir
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@@ -1,4 +1,4 @@
# RUN: llc -mtriple=wasm32-unknown-unknown -wasm-use-legacy-eh -exception-model=wasm -mattr=+exception-handling -run-pass wasm-late-eh-prepare -run-pass wasm-cfg-stackify %s -o - | FileCheck %s
# RUN: llc -mtriple=wasm32-unknown-unknown -wasm-use-legacy-eh -wasm-enable-eh -exception-model=wasm -mattr=+exception-handling -run-pass wasm-late-eh-prepare -run-pass wasm-cfg-stackify %s -o - | FileCheck %s

--- |
target triple = "wasm32-unknown-unknown"
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2 changes: 1 addition & 1 deletion llvm/test/CodeGen/WebAssembly/function-info.mir
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@@ -1,4 +1,4 @@
# RUN: llc -mtriple=wasm32-unknown-unknown -exception-model=wasm -mattr=+exception-handling,+multivalue,+simd128 -run-pass wasm-cfg-sort -run-pass wasm-cfg-stackify %s -o - | FileCheck %s
# RUN: llc -mtriple=wasm32-unknown-unknown -exception-model=wasm -wasm-enable-sjlj -mattr=+exception-handling,+multivalue,+simd128 -run-pass wasm-cfg-sort -run-pass wasm-cfg-stackify %s -o - | FileCheck %s

--- |
target triple = "wasm32-unknown-unknown"
Expand Down
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