[llvm] 5a082d9 - [WebAssembly][Object] Remove requirement that objects must have code sections
Derek Schuff via llvm-commits
llvm-commits at lists.llvm.org
Thu Jun 23 13:56:26 PDT 2022
Author: Derek Schuff
Date: 2022-06-23T13:56:17-07:00
New Revision: 5a082d9c1c14df5cee5a45683aee524e9b57a662
URL: https://github.com/llvm/llvm-project/commit/5a082d9c1c14df5cee5a45683aee524e9b57a662
DIFF: https://github.com/llvm/llvm-project/commit/5a082d9c1c14df5cee5a45683aee524e9b57a662.diff
LOG: [WebAssembly][Object] Remove requirement that objects must have code sections
When parsing name and linking sections, we currently require that the object
must have a code section (it seems that this was intended to verify section
ordering). However it can be useful for binaries to have their code sections
stripped out (e.g. if we just want the debug info). In that case we need
the rest of the known sections (so e.g. we know how many functions there
are, to verify the name section) but not the actual code.
I've removed the restriction completely. I think this is OK because the
section-parsing code already checks function and global indices in many
places for validity and will return appropriate errors if the relevant sections
are missing. Also we can't just replace the requirement of seeing a code section
with a requirement that we see a function or global section, because a binary
may just not have any functions or globals.
But there's only an problem if the name or linking section tries to name a
nonexistent function.
Part of a fix for https://github.com/emscripten-core/emscripten/issues/13084
Differential Revision: https://reviews.llvm.org/D128094
Added:
llvm/test/tools/llvm-objdump/wasm/no-codesec.test
Modified:
llvm/include/llvm/Object/Wasm.h
llvm/lib/Object/WasmObjectFile.cpp
Removed:
################################################################################
diff --git a/llvm/include/llvm/Object/Wasm.h b/llvm/include/llvm/Object/Wasm.h
index e4802c087b8b4..abe0f6f528cc6 100644
--- a/llvm/include/llvm/Object/Wasm.h
+++ b/llvm/include/llvm/Object/Wasm.h
@@ -287,7 +287,6 @@ class WasmObjectFile : public ObjectFile {
uint32_t StartFunction = -1;
bool HasLinkingSection = false;
bool HasDylinkSection = false;
- bool SeenCodeSection = false;
bool HasMemory64 = false;
wasm::WasmLinkingData LinkingData;
uint32_t NumImportedGlobals = 0;
diff --git a/llvm/lib/Object/WasmObjectFile.cpp b/llvm/lib/Object/WasmObjectFile.cpp
index cc80ae901e225..ce816b0976912 100644
--- a/llvm/lib/Object/WasmObjectFile.cpp
+++ b/llvm/lib/Object/WasmObjectFile.cpp
@@ -451,10 +451,6 @@ Error WasmObjectFile::parseNameSection(ReadContext &Ctx) {
llvm::DenseSet<uint64_t> SeenFunctions;
llvm::DenseSet<uint64_t> SeenGlobals;
llvm::DenseSet<uint64_t> SeenSegments;
- if (Functions.size() && !SeenCodeSection) {
- return make_error<GenericBinaryError>("names must come after code section",
- object_error::parse_failed);
- }
while (Ctx.Ptr < Ctx.End) {
uint8_t Type = readUint8(Ctx);
@@ -474,7 +470,7 @@ Error WasmObjectFile::parseNameSection(ReadContext &Ctx) {
return make_error<GenericBinaryError>(
"function named more than once", object_error::parse_failed);
if (!isValidFunctionIndex(Index) || Name.empty())
- return make_error<GenericBinaryError>("invalid name entry",
+ return make_error<GenericBinaryError>("invalid function name entry",
object_error::parse_failed);
if (isDefinedFunctionIndex(Index))
@@ -485,7 +481,7 @@ Error WasmObjectFile::parseNameSection(ReadContext &Ctx) {
return make_error<GenericBinaryError>("global named more than once",
object_error::parse_failed);
if (!isValidGlobalIndex(Index) || Name.empty())
- return make_error<GenericBinaryError>("invalid name entry",
+ return make_error<GenericBinaryError>("invalid global name entry",
object_error::parse_failed);
} else {
nameType = wasm::NameType::DATA_SEGMENT;
@@ -493,7 +489,7 @@ Error WasmObjectFile::parseNameSection(ReadContext &Ctx) {
return make_error<GenericBinaryError>(
"segment named more than once", object_error::parse_failed);
if (Index > DataSegments.size())
- return make_error<GenericBinaryError>("invalid named data segment",
+ return make_error<GenericBinaryError>("invalid data segment name entry",
object_error::parse_failed);
}
DebugNames.push_back(wasm::WasmDebugName{nameType, Index, Name});
@@ -519,11 +515,6 @@ Error WasmObjectFile::parseNameSection(ReadContext &Ctx) {
Error WasmObjectFile::parseLinkingSection(ReadContext &Ctx) {
HasLinkingSection = true;
- if (Functions.size() && !SeenCodeSection) {
- return make_error<GenericBinaryError>(
- "linking data must come after code section",
- object_error::parse_failed);
- }
LinkingData.Version = readVaruint32(Ctx);
if (LinkingData.Version != wasm::WasmMetadataVersion) {
@@ -1410,7 +1401,6 @@ Error WasmObjectFile::parseStartSection(ReadContext &Ctx) {
}
Error WasmObjectFile::parseCodeSection(ReadContext &Ctx) {
- SeenCodeSection = true;
CodeSection = Sections.size();
uint32_t FunctionCount = readVaruint32(Ctx);
if (FunctionCount != Functions.size()) {
diff --git a/llvm/test/tools/llvm-objdump/wasm/no-codesec.test b/llvm/test/tools/llvm-objdump/wasm/no-codesec.test
new file mode 100644
index 0000000000000..e66a8ddd8a066
--- /dev/null
+++ b/llvm/test/tools/llvm-objdump/wasm/no-codesec.test
@@ -0,0 +1,26 @@
+## Test that sections that use function indices (e.g. name) work without the code section
+# RUN: yaml2obj %s -o %t
+# RUN: llvm-objdump -h %t | FileCheck %s
+
+# CHECK: Sections:
+# CHECK-NEXT: Idx Name Size VMA Type
+# CHECK-NEXT: 0 TYPE 00000004 00000000
+# CHECK-NEXT: 1 FUNCTION 00000002 00000000
+# CHECK-NEXT: 2 name 00000008 00000000
+
+--- !WASM
+FileHeader:
+ Version: 0x00000001
+Sections:
+ - Type: TYPE
+ Signatures:
+ - Index: 0
+ ParamTypes: []
+ ReturnTypes: []
+ - Type: FUNCTION
+ FunctionTypes: [ 0 ]
+ - Type: CUSTOM
+ Name: name
+ FunctionNames:
+ - Index: 0
+ Name: foo
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