[lld] r332308 - [WebAssembly] Allow signautre of entry function to be flexible
Sam Clegg via llvm-commits
llvm-commits at lists.llvm.org
Mon May 14 19:00:39 PDT 2018
On Mon, May 14, 2018 at 6:15 PM, Dan Gohman <sunfish at mozilla.com> wrote:
> Hi Sam,
>
> Sorry for the late arrival here. Are there use cases that need flexible
> signatures? It seems like even if we can support it now, it's not
> immediately obvious that we're always going to want to support it in the
> future.
The common use cases that I'm looking at are emscripten, and the wasm
waterfall test
which both basically do `--entry=main`. Without this change this
means every program
would generate a linker warning about the entry point signature not
being correct.
This change is mostly to allow these use cases and suppress the
warning in this case.
If we update those two consumers I could see us reverting this change
perhaps. Is that
what you are suggesting?
>
> Dan
>
>
> On Mon, May 14, 2018 at 1:01 PM, Sam Clegg via llvm-commits
> <llvm-commits at lists.llvm.org> wrote:
>>
>> Author: sbc
>> Date: Mon May 14 16:01:16 2018
>> New Revision: 332308
>>
>> URL: http://llvm.org/viewvc/llvm-project?rev=332308&view=rev
>> Log:
>> [WebAssembly] Allow signautre of entry function to be flexible
>>
>> Since we a no longer using this function for the wasm start
>> section we don't actually care what its signature is.
>>
>> Differential Revision: https://reviews.llvm.org/D46594
>>
>> Added:
>> lld/trunk/test/wasm/entry-signature.ll
>> Modified:
>> lld/trunk/test/wasm/Inputs/comdat2.ll
>> lld/trunk/test/wasm/data-layout.ll
>> lld/trunk/test/wasm/data-segment-merging.ll
>> lld/trunk/test/wasm/entry.ll
>> lld/trunk/test/wasm/fatal-warnings.ll
>> lld/trunk/test/wasm/load-undefined.test
>> lld/trunk/test/wasm/undefined-entry.test
>> lld/trunk/wasm/Driver.cpp
>> lld/trunk/wasm/SymbolTable.cpp
>>
>> Modified: lld/trunk/test/wasm/Inputs/comdat2.ll
>> URL:
>> http://llvm.org/viewvc/llvm-project/lld/trunk/test/wasm/Inputs/comdat2.ll?rev=332308&r1=332307&r2=332308&view=diff
>>
>> ==============================================================================
>> --- lld/trunk/test/wasm/Inputs/comdat2.ll (original)
>> +++ lld/trunk/test/wasm/Inputs/comdat2.ll Mon May 14 16:01:16 2018
>> @@ -9,5 +9,5 @@ entry:
>>
>> define i32 @callInline2() {
>> entry:
>> - ret i32 ptrtoint (i32 ()* @inlineFn to i32)
>> + ret i32 ptrtoint (i32 ()* @inlineFn to i32)
>> }
>>
>> Modified: lld/trunk/test/wasm/data-layout.ll
>> URL:
>> http://llvm.org/viewvc/llvm-project/lld/trunk/test/wasm/data-layout.ll?rev=332308&r1=332307&r2=332308&view=diff
>>
>> ==============================================================================
>> --- lld/trunk/test/wasm/data-layout.ll (original)
>> +++ lld/trunk/test/wasm/data-layout.ll Mon May 14 16:01:16 2018
>> @@ -13,7 +13,7 @@ target triple = "wasm32-unknown-unknown"
>> @local_struct = hidden global %struct.s zeroinitializer, align 4
>> @local_struct_internal_ptr = hidden local_unnamed_addr global i32*
>> getelementptr inbounds (%struct.s, %struct.s* @local_struct, i32 0, i32 1),
>> align 4
>>
>> -; RUN: wasm-ld -no-gc-sections --allow-undefined -o %t.wasm %t.o
>> %t.hello.o
>> +; RUN: wasm-ld -no-gc-sections --allow-undefined --no-entry -o %t.wasm
>> %t.o %t.hello.o
>> ; RUN: obj2yaml %t.wasm | FileCheck %s
>>
>> ; CHECK: - Type: MEMORY
>> @@ -57,7 +57,7 @@ target triple = "wasm32-unknown-unknown"
>> ; CHECK-NEXT: - Type: CUSTOM
>>
>>
>> -; RUN: wasm-ld -no-gc-sections --allow-undefined \
>> +; RUN: wasm-ld -no-gc-sections --allow-undefined --no-entry \
>> ; RUN: --initial-memory=131072 --max-memory=131072 -o %t_max.wasm
>> %t.o \
>> ; RUN: %t.hello.o
>> ; RUN: obj2yaml %t_max.wasm | FileCheck %s -check-prefix=CHECK-MAX
>>
>> Modified: lld/trunk/test/wasm/data-segment-merging.ll
>> URL:
>> http://llvm.org/viewvc/llvm-project/lld/trunk/test/wasm/data-segment-merging.ll?rev=332308&r1=332307&r2=332308&view=diff
>>
>> ==============================================================================
>> --- lld/trunk/test/wasm/data-segment-merging.ll (original)
>> +++ lld/trunk/test/wasm/data-segment-merging.ll Mon May 14 16:01:16 2018
>> @@ -7,7 +7,7 @@ target triple = "wasm32-unknown-unknown"
>>
>> ; RUN: llc -filetype=obj %s -o %t.data-segment-merging.o
>>
>> -; RUN: wasm-ld -no-gc-sections --allow-undefined -o %t.merged.wasm
>> %t.data-segment-merging.o
>> +; RUN: wasm-ld -no-gc-sections --no-entry -o %t.merged.wasm
>> %t.data-segment-merging.o
>> ; RUN: obj2yaml %t.merged.wasm | FileCheck %s --check-prefix=MERGE
>> ; MERGE: - Type: DATA
>> ; MERGE-NEXT: Segments:
>> @@ -18,7 +18,7 @@ target triple = "wasm32-unknown-unknown"
>> ; MERGE-NEXT: Value: 1024
>> ; MERGE-NEXT: Content:
>> 68656C6C6F00676F6F6462796500776861746576657200002A000000
>>
>> -; RUN: wasm-ld -no-gc-sections --allow-undefined --no-merge-data-segments
>> -o %t.separate.wasm %t.data-segment-merging.o
>> +; RUN: wasm-ld -no-gc-sections --no-entry --no-merge-data-segments -o
>> %t.separate.wasm %t.data-segment-merging.o
>> ; RUN: obj2yaml %t.separate.wasm | FileCheck %s --check-prefix=SEPARATE
>> ; SEPARATE: - Type: DATA
>> ; SEPARATE-NEXT: Segments:
>>
>> Added: lld/trunk/test/wasm/entry-signature.ll
>> URL:
>> http://llvm.org/viewvc/llvm-project/lld/trunk/test/wasm/entry-signature.ll?rev=332308&view=auto
>>
>> ==============================================================================
>> --- lld/trunk/test/wasm/entry-signature.ll (added)
>> +++ lld/trunk/test/wasm/entry-signature.ll Mon May 14 16:01:16 2018
>> @@ -0,0 +1,10 @@
>> +; Verify that the entry point signauture can be flexible.
>> +; RUN: llc -filetype=obj %s -o %t.o
>> +; RUN: wasm-ld -o %t1.wasm %t.o
>> +
>> +target triple = "wasm32-unknown-unknown-wasm"
>> +
>> +define hidden i32 @_start(i32, i64) local_unnamed_addr #0 {
>> +entry:
>> + ret i32 0
>> +}
>>
>> Modified: lld/trunk/test/wasm/entry.ll
>> URL:
>> http://llvm.org/viewvc/llvm-project/lld/trunk/test/wasm/entry.ll?rev=332308&r1=332307&r2=332308&view=diff
>>
>> ==============================================================================
>> --- lld/trunk/test/wasm/entry.ll (original)
>> +++ lld/trunk/test/wasm/entry.ll Mon May 14 16:01:16 2018
>> @@ -28,8 +28,8 @@ entry:
>> ; CHECK-NEXT: Index: 1
>> ; CHECK-NEXT: - Type:
>>
>> -; The __wasm_call_ctors is somewhat special. Make sure we can use it
>> -; as the entry point if we choose
>> +; The __wasm_call_ctors is somewhat special since its created by the
>> linker.
>> +; Make sure we can use it as the entry point if we choose
>> ; RUN: wasm-ld --entry=__wasm_call_ctors -o %t3.wasm %t.o
>> ; RUN: obj2yaml %t3.wasm | FileCheck %s -check-prefix=CHECK-CTOR
>>
>>
>> Modified: lld/trunk/test/wasm/fatal-warnings.ll
>> URL:
>> http://llvm.org/viewvc/llvm-project/lld/trunk/test/wasm/fatal-warnings.ll?rev=332308&r1=332307&r2=332308&view=diff
>>
>> ==============================================================================
>> --- lld/trunk/test/wasm/fatal-warnings.ll (original)
>> +++ lld/trunk/test/wasm/fatal-warnings.ll Mon May 14 16:01:16 2018
>> @@ -1,14 +1,17 @@
>> ; RUN: llc -filetype=obj %s -o %t.main.o
>> -; RUN: lld -flavor wasm -o %t.wasm %t.main.o 2>&1 | FileCheck %s
>> -check-prefix=CHECK-WARN
>> -; RUN: not lld -flavor wasm --fatal-warnings -o %t.wasm %t.main.o 2>&1 |
>> FileCheck %s -check-prefix=CHECK-FATAL
>> +; RUN: llc -filetype=obj %p/Inputs/ret32.ll -o %t.ret32.o
>> +; RUN: lld -flavor wasm -o %t.wasm %t.main.o %t.ret32.o 2>&1 | FileCheck
>> %s -check-prefix=CHECK-WARN
>> +; RUN: not lld -flavor wasm --fatal-warnings -o %t.wasm %t.main.o
>> %t.ret32.o 2>&1 | FileCheck %s -check-prefix=CHECK-FATAL
>>
>> -; CHECK-WARN: warning: Function type mismatch: _start
>> -; CHECK-FATAL: error: Function type mismatch: _start
>> +; CHECK-WARN: warning: Function type mismatch: ret32
>> +; CHECK-FATAL: error: Function type mismatch: ret32
>>
>> target triple = "wasm32-unknown-unknown"
>>
>> -define hidden i32 @_start(i32 %arg) local_unnamed_addr {
>> +define hidden void @_start() local_unnamed_addr #0 {
>> entry:
>> - ret i32 %arg
>> + %call = tail call i32 @ret32(i32 1, i64 2, i32 3) #2
>> + ret void
>> }
>>
>> +declare i32 @ret32(i32, i64, i32) local_unnamed_addr #1
>>
>> Modified: lld/trunk/test/wasm/load-undefined.test
>> URL:
>> http://llvm.org/viewvc/llvm-project/lld/trunk/test/wasm/load-undefined.test?rev=332308&r1=332307&r2=332308&view=diff
>>
>> ==============================================================================
>> --- lld/trunk/test/wasm/load-undefined.test (original)
>> +++ lld/trunk/test/wasm/load-undefined.test Mon May 14 16:01:16 2018
>> @@ -36,4 +36,4 @@
>> ; CHECK-UNDEFINED1: error: undefined symbol: symboldoesnotexist
>>
>> ; RUN: not wasm-ld %t.start.o -o %t.wasm --undefined symboldoesnotexist
>> --allow-undefined 2>&1 | FileCheck -check-prefix=CHECK-UNDEFINED2 %s
>> -; CHECK-UNDEFINED2: function forced with --undefined not found:
>> symboldoesnotexist
>> +; CHECK-UNDEFINED2: symbol forced with --undefined not found:
>> symboldoesnotexist
>>
>> Modified: lld/trunk/test/wasm/undefined-entry.test
>> URL:
>> http://llvm.org/viewvc/llvm-project/lld/trunk/test/wasm/undefined-entry.test?rev=332308&r1=332307&r2=332308&view=diff
>>
>> ==============================================================================
>> --- lld/trunk/test/wasm/undefined-entry.test (original)
>> +++ lld/trunk/test/wasm/undefined-entry.test Mon May 14 16:01:16 2018
>> @@ -1,10 +1,11 @@
>> RUN: llc -filetype=obj %p/Inputs/ret32.ll -o %t.ret32.o
>> RUN: not wasm-ld -o %t.wasm %t.ret32.o 2>&1 | FileCheck %s
>> -
>> -CHECK: error: undefined symbol: _start
>> -
>> RUN: not wasm-ld -entry=foo -o %t.wasm %t.ret32.o 2>&1 | FileCheck %s
>> -check-prefix=CHECK-CUSTOM
>> +RUN: not wasm-ld --allow-undefined -o %t.wasm %t.ret32.o 2>&1 | FileCheck
>> %s -check-prefix=CHECK-ALLOW
>>
>> +CHECK: error: undefined symbol: _start
>> CHECK-CUSTOM: error: undefined symbol: foo
>> +CHECK-ALLOW: error: entry symbol not defined (pass --no-entry to
>> supress):
>> +_start
>>
>> -RUN: wasm-ld -entry=foo --allow-undefined -o %t.wasm %t.ret32.o
>> +RUN: wasm-ld --no-entry -o %t.wasm %t.ret32.o
>>
>> Modified: lld/trunk/wasm/Driver.cpp
>> URL:
>> http://llvm.org/viewvc/llvm-project/lld/trunk/wasm/Driver.cpp?rev=332308&r1=332307&r2=332308&view=diff
>>
>> ==============================================================================
>> --- lld/trunk/wasm/Driver.cpp (original)
>> +++ lld/trunk/wasm/Driver.cpp Mon May 14 16:01:16 2018
>> @@ -360,9 +360,11 @@ void LinkerDriver::link(ArrayRef<const c
>> "__dso_handle", WASM_SYMBOL_VISIBILITY_HIDDEN);
>> WasmSym::DataEnd = Symtab->addSyntheticDataSymbol("__data_end", 0);
>>
>> + // For now, since we don't actually use the start function as the
>> + // wasm start symbol, we don't need to care about it signature.
>> if (!Config->Entry.empty())
>> - EntrySym = Symtab->addUndefinedFunction(Config->Entry, 0, nullptr,
>> - &NullSignature);
>> + EntrySym =
>> + Symtab->addUndefinedFunction(Config->Entry, 0, nullptr,
>> nullptr);
>>
>> // Handle the `--undefined <sym>` options.
>> for (auto *Arg : Args.filtered(OPT_undefined))
>> @@ -386,15 +388,19 @@ void LinkerDriver::link(ArrayRef<const c
>> if (!Config->Relocatable && !Config->AllowUndefined) {
>> Symtab->reportRemainingUndefines();
>> } else {
>> - // When we allow undefined symbols we cannot include those defined in
>> - // -u/--undefined since these undefined symbols have only names and
>> no
>> - // function signature, which means they cannot be written to the
>> final
>> - // output.
>> + // Even when using --allow-undefined we still want to report the
>> absence of
>> + // our initial set of undefined symbols (i.e. the entry point and
>> symbols
>> + // specified via --undefined).
>> + // Part of the reason for this is that these function don't have
>> signatures
>> + // so which means they cannot be written as wasm function imports.
>> for (auto *Arg : Args.filtered(OPT_undefined)) {
>> Symbol *Sym = Symtab->find(Arg->getValue());
>> if (!Sym->isDefined())
>> - error("function forced with --undefined not found: " +
>> Sym->getName());
>> + error("symbol forced with --undefined not found: " +
>> Sym->getName());
>> }
>> + if (EntrySym && !EntrySym->isDefined())
>> + error("entry symbol not defined (pass --no-entry to supress): " +
>> + EntrySym->getName());
>> }
>> if (errorCount())
>> return;
>>
>> Modified: lld/trunk/wasm/SymbolTable.cpp
>> URL:
>> http://llvm.org/viewvc/llvm-project/lld/trunk/wasm/SymbolTable.cpp?rev=332308&r1=332307&r2=332308&view=diff
>>
>> ==============================================================================
>> --- lld/trunk/wasm/SymbolTable.cpp (original)
>> +++ lld/trunk/wasm/SymbolTable.cpp Mon May 14 16:01:16 2018
>> @@ -78,14 +78,14 @@ static void reportTypeError(const Symbol
>>
>> static void checkFunctionType(const Symbol *Existing, const InputFile
>> *File,
>> const WasmSignature *NewSig) {
>> - if (!isa<FunctionSymbol>(Existing)) {
>> + auto ExistingFunction = dyn_cast<FunctionSymbol>(Existing);
>> + if (!ExistingFunction) {
>> reportTypeError(Existing, File, WASM_SYMBOL_TYPE_FUNCTION);
>> return;
>> }
>>
>> - const WasmSignature *OldSig =
>> - cast<FunctionSymbol>(Existing)->getFunctionType();
>> - if (OldSig && *NewSig != *OldSig) {
>> + const WasmSignature *OldSig = ExistingFunction->getFunctionType();
>> + if (OldSig && NewSig && *NewSig != *OldSig) {
>> warn("Function type mismatch: " + Existing->getName() +
>> "\n>>> defined as " + toString(*OldSig) + " in " +
>> toString(Existing->getFile()) + "\n>>> defined as " +
>>
>>
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