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[WebAssembly] Add experimental multivalue calling ABI
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Summary:
For now, this ABI simply expands all possible aggregate arguments and
returns all possible aggregates directly. This ABI will change rapidly
as we prototype and benchmark a new ABI that takes advantage of
multivalue return and possibly other changes from the MVP ABI.

Reviewers: aheejin, dschuff

Subscribers: sbc100, jgravelle-google, sunfish, cfe-commits

Tags: #clang

Differential Revision: https://reviews.llvm.org/D72972
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@tlively
tlively committed Feb 5, 2020
1 parent 649aba9 commit 8c3e6af
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Showing 4 changed files with 142 additions and 49 deletions.
10 changes: 10 additions & 0 deletions clang/lib/Basic/Targets/WebAssembly.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -33,6 +33,16 @@ const Builtin::Info WebAssemblyTargetInfo::BuiltinInfo[] = {
static constexpr llvm::StringLiteral ValidCPUNames[] = {
{"mvp"}, {"bleeding-edge"}, {"generic"}};

StringRef WebAssemblyTargetInfo::getABI() const { return ABI; }

bool WebAssemblyTargetInfo::setABI(const std::string &Name) {
if (Name != "mvp" && Name != "experimental-mv")
return false;

ABI = Name;
return true;
}

bool WebAssemblyTargetInfo::hasFeature(StringRef Feature) const {
return llvm::StringSwitch<bool>(Feature)
.Case("simd128", SIMDLevel >= SIMD128)
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5 changes: 5 additions & 0 deletions clang/lib/Basic/Targets/WebAssembly.h
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Original file line number Diff line number Diff line change
Expand Up @@ -40,6 +40,8 @@ class LLVM_LIBRARY_VISIBILITY WebAssemblyTargetInfo : public TargetInfo {
bool HasTailCall = false;
bool HasReferenceTypes = false;

std::string ABI;

public:
explicit WebAssemblyTargetInfo(const llvm::Triple &T, const TargetOptions &)
: TargetInfo(T) {
Expand All @@ -59,6 +61,9 @@ class LLVM_LIBRARY_VISIBILITY WebAssemblyTargetInfo : public TargetInfo {
IntPtrType = SignedLong;
}

StringRef getABI() const override;
bool setABI(const std::string &Name) override;

protected:
void getTargetDefines(const LangOptions &Opts,
MacroBuilder &Builder) const override;
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42 changes: 36 additions & 6 deletions clang/lib/CodeGen/TargetInfo.cpp
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Expand Up @@ -726,11 +726,19 @@ ABIArgInfo DefaultABIInfo::classifyReturnType(QualType RetTy) const {
//===----------------------------------------------------------------------===//

class WebAssemblyABIInfo final : public SwiftABIInfo {
public:
enum ABIKind {
MVP = 0,
ExperimentalMV = 1,
};

private:
DefaultABIInfo defaultInfo;
ABIKind Kind;

public:
explicit WebAssemblyABIInfo(CodeGen::CodeGenTypes &CGT)
: SwiftABIInfo(CGT), defaultInfo(CGT) {}
explicit WebAssemblyABIInfo(CodeGen::CodeGenTypes &CGT, ABIKind Kind)
: SwiftABIInfo(CGT), defaultInfo(CGT), Kind(Kind) {}

private:
ABIArgInfo classifyReturnType(QualType RetTy) const;
Expand Down Expand Up @@ -761,8 +769,9 @@ class WebAssemblyABIInfo final : public SwiftABIInfo {

class WebAssemblyTargetCodeGenInfo final : public TargetCodeGenInfo {
public:
explicit WebAssemblyTargetCodeGenInfo(CodeGen::CodeGenTypes &CGT)
: TargetCodeGenInfo(new WebAssemblyABIInfo(CGT)) {}
explicit WebAssemblyTargetCodeGenInfo(CodeGen::CodeGenTypes &CGT,
WebAssemblyABIInfo::ABIKind K)
: TargetCodeGenInfo(new WebAssemblyABIInfo(CGT, K)) {}

void setTargetAttributes(const Decl *D, llvm::GlobalValue *GV,
CodeGen::CodeGenModule &CGM) const override {
Expand Down Expand Up @@ -813,6 +822,20 @@ ABIArgInfo WebAssemblyABIInfo::classifyArgumentType(QualType Ty) const {
// though watch out for things like bitfields.
if (const Type *SeltTy = isSingleElementStruct(Ty, getContext()))
return ABIArgInfo::getDirect(CGT.ConvertType(QualType(SeltTy, 0)));
// For the experimental multivalue ABI, fully expand all other aggregates
if (Kind == ABIKind::ExperimentalMV) {
const RecordType *RT = Ty->getAs<RecordType>();
assert(RT);
bool HasBitField = false;
for (auto *Field : RT->getDecl()->fields()) {
if (Field->isBitField()) {
HasBitField = true;
break;
}
}
if (!HasBitField)
return ABIArgInfo::getExpand();
}
}

// Otherwise just do the default thing.
Expand All @@ -832,6 +855,9 @@ ABIArgInfo WebAssemblyABIInfo::classifyReturnType(QualType RetTy) const {
// ABIArgInfo::getDirect().
if (const Type *SeltTy = isSingleElementStruct(RetTy, getContext()))
return ABIArgInfo::getDirect(CGT.ConvertType(QualType(SeltTy, 0)));
// For the experimental multivalue ABI, return all other aggregates
if (Kind == ABIKind::ExperimentalMV)
return ABIArgInfo::getDirect();
}
}

Expand Down Expand Up @@ -9828,8 +9854,12 @@ const TargetCodeGenInfo &CodeGenModule::getTargetCodeGenInfo() {
}

case llvm::Triple::wasm32:
case llvm::Triple::wasm64:
return SetCGInfo(new WebAssemblyTargetCodeGenInfo(Types));
case llvm::Triple::wasm64: {
WebAssemblyABIInfo::ABIKind Kind = WebAssemblyABIInfo::MVP;
if (getTarget().getABI() == "experimental-mv")
Kind = WebAssemblyABIInfo::ExperimentalMV;
return SetCGInfo(new WebAssemblyTargetCodeGenInfo(Types, Kind));
}

case llvm::Triple::arm:
case llvm::Triple::armeb:
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134 changes: 91 additions & 43 deletions clang/test/CodeGen/wasm-arguments.c
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Original file line number Diff line number Diff line change
Expand Up @@ -2,91 +2,139 @@
// RUN: | FileCheck %s -check-prefix=WEBASSEMBLY32
// RUN: %clang_cc1 -triple wasm64-unknown-unknown %s -emit-llvm -o - \
// RUN: | FileCheck %s -check-prefix=WEBASSEMBLY64
// RUN: %clang_cc1 -triple wasm32-unknown-unknown %s -target-abi experimental-mv -emit-llvm -o - \
// RUN: | FileCheck %s -check-prefix=EXPERIMENTAL-MV

// Basic argument/attribute tests for WebAssembly
// Basic argument/attribute and return tests for WebAssembly

// WEBASSEMBLY32: define void @f0(i32 %i, i32 %j, i64 %k, double %l, fp128 %m)
// WEBASSEMBLY64: define void @f0(i32 %i, i64 %j, i64 %k, double %l, fp128 %m)
void f0(int i, long j, long long k, double l, long double m) {}
// WEBASSEMBLY32: define void @misc_args(i32 %i, i32 %j, i64 %k, double %l, fp128 %m)
// WEBASSEMBLY64: define void @misc_args(i32 %i, i64 %j, i64 %k, double %l, fp128 %m)
void misc_args(int i, long j, long long k, double l, long double m) {}

typedef struct {
int aa;
int bb;
} s1;

// Structs should be passed byval and not split up.
// WEBASSEMBLY32: define void @f1(%struct.s1* byval(%struct.s1) align 4 %i)
// WEBASSEMBLY64: define void @f1(%struct.s1* byval(%struct.s1) align 4 %i)
void f1(s1 i) {}
// WEBASSEMBLY32: define void @struct_arg(%struct.s1* byval(%struct.s1) align 4 %i)
// WEBASSEMBLY64: define void @struct_arg(%struct.s1* byval(%struct.s1) align 4 %i)

typedef struct {
int cc;
} s2;
// Single-element structs should be returned as the one element.
// WEBASSEMBLY32: define i32 @f2()
// WEBASSEMBLY64: define i32 @f2()
s2 f2(void) {
s2 foo;
// Except in the experimental multivalue ABI, where structs are passed in args
// EXPERIMENTAL-MV: define void @struct_arg(i32 %i.0, i32 %i.1)
void struct_arg(s1 i) {}

// Structs should be returned sret and not simplified by the frontend.
// WEBASSEMBLY32: define void @struct_ret(%struct.s1* noalias sret %agg.result)
// WEBASSEMBLY32: ret void
// WEBASSEMBLY64: define void @struct_ret(%struct.s1* noalias sret %agg.result)
// WEBASSEMBLY64: ret void

// Except with the experimental multivalue ABI, which returns structs by value
// EXPERIMENTAL-MV: define %struct.s1 @struct_ret()
// EXPERIMENTAL-MV: ret %struct.s1 %0
s1 struct_ret() {
s1 foo;
return foo;
}

typedef struct {
int cc;
int dd;
} s3;
// Structs should be returned sret and not simplified by the frontend.
// WEBASSEMBLY32: define void @f3(%struct.s3* noalias sret %agg.result)
// WEBASSEMBLY64: define void @f3(%struct.s3* noalias sret %agg.result)
s3 f3(void) {
s3 foo;
} s2;

// Single-element structs should be passed as the one element.
// WEBASSEMBLY32: define void @single_elem_arg(i32 %i.coerce)
// WEBASSEMBLY64: define void @single_elem_arg(i32 %i.coerce)
// EXPERIMENTAL-MV: define void @single_elem_arg(i32 %i.coerce)
void single_elem_arg(s2 i) {}

// Single-element structs should be passed as the one element.
// WEBASSEMBLY32: define i32 @single_elem_ret()
// WEBASSEMBLY32: ret i32
// WEBASSEMBLY64: define i32 @single_elem_ret()
// EXPERIMENTAL-MV: define i32 @single_elem_ret()
s2 single_elem_ret() {
s2 foo;
return foo;
}

// WEBASSEMBLY32: define void @f4(i64 %i)
// WEBASSEMBLY64: define void @f4(i64 %i)
void f4(long long i) {}
// WEBASSEMBLY32: define void @long_long_arg(i64 %i)
// WEBASSEMBLY64: define void @long_long_arg(i64 %i)
void long_long_arg(long long i) {}

// i8/i16 should be signext, i32 and higher should not.
// WEBASSEMBLY32: define void @f5(i8 signext %a, i16 signext %b)
// WEBASSEMBLY64: define void @f5(i8 signext %a, i16 signext %b)
void f5(char a, short b) {}
// WEBASSEMBLY32: define void @char_short_arg(i8 signext %a, i16 signext %b)
// WEBASSEMBLY64: define void @char_short_arg(i8 signext %a, i16 signext %b)
void char_short_arg(char a, short b) {}

// WEBASSEMBLY32: define void @f6(i8 zeroext %a, i16 zeroext %b)
// WEBASSEMBLY64: define void @f6(i8 zeroext %a, i16 zeroext %b)
void f6(unsigned char a, unsigned short b) {}
// WEBASSEMBLY32: define void @uchar_ushort_arg(i8 zeroext %a, i16 zeroext %b)
// WEBASSEMBLY64: define void @uchar_ushort_arg(i8 zeroext %a, i16 zeroext %b)
void uchar_ushort_arg(unsigned char a, unsigned short b) {}

enum my_enum {
ENUM1,
ENUM2,
ENUM3,
};

// Enums should be treated as the underlying i32.
// WEBASSEMBLY32: define void @f7(i32 %a)
// WEBASSEMBLY64: define void @f7(i32 %a)
void f7(enum my_enum a) {}
// WEBASSEMBLY32: define void @enum_arg(i32 %a)
// WEBASSEMBLY64: define void @enum_arg(i32 %a)
void enum_arg(enum my_enum a) {}

enum my_big_enum {
ENUM4 = 0xFFFFFFFFFFFFFFFF,
};

// Big enums should be treated as the underlying i64.
// WEBASSEMBLY32: define void @f8(i64 %a)
// WEBASSEMBLY64: define void @f8(i64 %a)
void f8(enum my_big_enum a) {}
// WEBASSEMBLY32: define void @big_enum_arg(i64 %a)
// WEBASSEMBLY64: define void @big_enum_arg(i64 %a)
void big_enum_arg(enum my_big_enum a) {}

union simple_union {
int a;
char b;
};

// Unions should be passed as byval structs.
// WEBASSEMBLY32: define void @f9(%union.simple_union* byval(%union.simple_union) align 4 %s)
// WEBASSEMBLY64: define void @f9(%union.simple_union* byval(%union.simple_union) align 4 %s)
void f9(union simple_union s) {}
// WEBASSEMBLY32: define void @union_arg(%union.simple_union* byval(%union.simple_union) align 4 %s)
// WEBASSEMBLY64: define void @union_arg(%union.simple_union* byval(%union.simple_union) align 4 %s)
// EXPERIMENTAL-MV: define void @union_arg(i32 %s.0)
void union_arg(union simple_union s) {}

// Unions should be returned sret and not simplified by the frontend.
// WEBASSEMBLY32: define void @union_ret(%union.simple_union* noalias sret %agg.result)
// WEBASSEMBLY32: ret void
// WEBASSEMBLY64: define void @union_ret(%union.simple_union* noalias sret %agg.result)
// WEBASSEMBLY64: ret void

// The experimental multivalue ABI returns them by value, though.
// EXPERIMENTAL-MV: define %union.simple_union @union_ret()
// EXPERIMENTAL-MV: ret %union.simple_union %0
union simple_union union_ret() {
union simple_union bar;
return bar;
}

typedef struct {
int b4 : 4;
int b3 : 3;
int b8 : 8;
} bitfield1;

// Bitfields should be passed as byval structs.
// WEBASSEMBLY32: define void @f10(%struct.bitfield1* byval(%struct.bitfield1) align 4 %bf1)
// WEBASSEMBLY64: define void @f10(%struct.bitfield1* byval(%struct.bitfield1) align 4 %bf1)
void f10(bitfield1 bf1) {}
// WEBASSEMBLY32: define void @bitfield_arg(%struct.bitfield1* byval(%struct.bitfield1) align 4 %bf1)
// WEBASSEMBLY64: define void @bitfield_arg(%struct.bitfield1* byval(%struct.bitfield1) align 4 %bf1)
// EXPERIMENTAL-MV: define void @bitfield_arg(%struct.bitfield1* byval(%struct.bitfield1) align 4 %bf1)
void bitfield_arg(bitfield1 bf1) {}

// And returned via sret pointers.
// WEBASSEMBLY32: define void @bitfield_ret(%struct.bitfield1* noalias sret %agg.result)
// WEBASSEMBLY64: define void @bitfield_ret(%struct.bitfield1* noalias sret %agg.result)

// Except, of course, in the experimental multivalue ABI
// EXPERIMENTAL-MV: define %struct.bitfield1 @bitfield_ret()
bitfield1 bitfield_ret() {
bitfield1 baz;
return baz;
}

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