[llvm] r329315 - [WebAssembly] Allow for the creation of user-defined custom sections
Sam Clegg via llvm-commits
llvm-commits at lists.llvm.org
Thu Apr 5 10:01:39 PDT 2018
Author: sbc
Date: Thu Apr 5 10:01:39 2018
New Revision: 329315
URL: http://llvm.org/viewvc/llvm-project?rev=329315&view=rev
Log:
[WebAssembly] Allow for the creation of user-defined custom sections
This patch adds a way for users to create their own custom sections to
be added to wasm files. At the LLVM IR layer, they are defined through
the "wasm.custom_sections" named metadata. The expected use case for
this is bindings generators such as wasm-bindgen.
Patch by Dan Gohman
Differential Revision: https://reviews.llvm.org/D45297
Added:
llvm/trunk/test/CodeGen/WebAssembly/custom-sections.ll
llvm/trunk/test/MC/WebAssembly/custom-sections.ll
Modified:
llvm/trunk/lib/MC/WasmObjectWriter.cpp
llvm/trunk/lib/Target/WebAssembly/WebAssemblyAsmPrinter.cpp
Modified: llvm/trunk/lib/MC/WasmObjectWriter.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/MC/WasmObjectWriter.cpp?rev=329315&r1=329314&r2=329315&view=diff
==============================================================================
--- llvm/trunk/lib/MC/WasmObjectWriter.cpp (original)
+++ llvm/trunk/lib/MC/WasmObjectWriter.cpp Thu Apr 5 10:01:39 2018
@@ -167,6 +167,14 @@ struct WasmRelocationEntry {
#endif
};
+struct WasmCustomSection {
+ StringRef Name;
+ const SmallVectorImpl<char> &Contents;
+
+ WasmCustomSection(StringRef Name, const SmallVectorImpl<char> &Contents)
+ : Name(Name), Contents(Contents) {}
+};
+
#if !defined(NDEBUG)
raw_ostream &operator<<(raw_ostream &OS, const WasmRelocationEntry &Rel) {
Rel.print(OS);
@@ -202,6 +210,7 @@ class WasmObjectWriter : public MCObject
SmallVector<WasmFunctionType, 4> FunctionTypes;
SmallVector<WasmGlobal, 4> Globals;
SmallVector<WasmDataSegment, 4> DataSegments;
+ std::vector<WasmCustomSection> CustomSections;
unsigned NumFunctionImports = 0;
unsigned NumGlobalImports = 0;
@@ -277,6 +286,7 @@ private:
ArrayRef<wasm::WasmSymbolInfo> SymbolInfos,
ArrayRef<std::pair<uint16_t, uint32_t>> InitFuncs,
const std::map<StringRef, std::vector<WasmComdatEntry>> &Comdats);
+ void writeUserCustomSections(ArrayRef<WasmCustomSection> CustomSections);
uint32_t getProvisionalValue(const WasmRelocationEntry &RelEntry);
void applyRelocations(ArrayRef<WasmRelocationEntry> Relocations,
@@ -314,7 +324,7 @@ void WasmObjectWriter::startSection(Sect
// Custom sections in wasm also have a string identifier.
if (SectionId == wasm::WASM_SEC_CUSTOM) {
assert(Name);
- writeString(StringRef(Name));
+ writeString(Name);
}
}
@@ -936,6 +946,17 @@ void WasmObjectWriter::writeLinkingMetaD
endSection(Section);
}
+void WasmObjectWriter::writeUserCustomSections(
+ ArrayRef<WasmCustomSection> CustomSections) {
+ for (const auto &CustomSection : CustomSections) {
+ SectionBookkeeping Section;
+ startSection(Section, wasm::WASM_SEC_CUSTOM,
+ CustomSection.Name.str().c_str());
+ writeBytes(CustomSection.Contents);
+ endSection(Section);
+ }
+}
+
uint32_t WasmObjectWriter::getFunctionType(const MCSymbolWasm& Symbol) {
assert(Symbol.isFunction());
assert(TypeIndices.count(&Symbol));
@@ -1041,6 +1062,26 @@ void WasmObjectWriter::writeObject(MCAss
// Populate DataSegments, which must be done before populating DataLocations.
for (MCSection &Sec : Asm) {
auto &Section = static_cast<MCSectionWasm &>(Sec);
+
+ if (cast<MCSectionWasm>(Sec).getSectionName().startswith(
+ ".custom_section.")) {
+ if (Section.getFragmentList().empty())
+ continue;
+ if (Section.getFragmentList().size() != 1)
+ report_fatal_error(
+ "only one .custom_section section fragment supported");
+ const MCFragment &Frag = *Section.begin();
+ if (Frag.hasInstructions() || Frag.getKind() != MCFragment::FT_Data)
+ report_fatal_error("only data supported in .custom_section section");
+ const auto &DataFrag = cast<MCDataFragment>(Frag);
+ if (!DataFrag.getFixups().empty())
+ report_fatal_error("fixups not supported in .custom_section section");
+ StringRef UserName = Section.getSectionName().substr(16);
+ const SmallVectorImpl<char> &Contents = DataFrag.getContents();
+ CustomSections.push_back(WasmCustomSection(UserName, Contents));
+ continue;
+ }
+
if (!Section.isWasmData())
continue;
@@ -1310,6 +1351,7 @@ void WasmObjectWriter::writeObject(MCAss
writeElemSection(TableElems);
writeCodeSection(Asm, Layout, Functions);
writeDataSection();
+ writeUserCustomSections(CustomSections);
writeLinkingMetaDataSection(SymbolInfos, InitFuncs, Comdats);
writeCodeRelocSection();
writeDataRelocSection();
Modified: llvm/trunk/lib/Target/WebAssembly/WebAssemblyAsmPrinter.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Target/WebAssembly/WebAssemblyAsmPrinter.cpp?rev=329315&r1=329314&r2=329315&view=diff
==============================================================================
--- llvm/trunk/lib/Target/WebAssembly/WebAssemblyAsmPrinter.cpp (original)
+++ llvm/trunk/lib/Target/WebAssembly/WebAssemblyAsmPrinter.cpp Thu Apr 5 10:01:39 2018
@@ -31,10 +31,11 @@
#include "llvm/IR/DataLayout.h"
#include "llvm/IR/GlobalVariable.h"
#include "llvm/MC/MCContext.h"
+#include "llvm/MC/MCSectionWasm.h"
#include "llvm/MC/MCStreamer.h"
#include "llvm/MC/MCSymbol.h"
-#include "llvm/MC/MCSymbolWasm.h"
#include "llvm/MC/MCSymbolELF.h"
+#include "llvm/MC/MCSymbolWasm.h"
#include "llvm/Support/Debug.h"
#include "llvm/Support/TargetRegistry.h"
#include "llvm/Support/raw_ostream.h"
@@ -107,6 +108,26 @@ void WebAssemblyAsmPrinter::EmitEndOfAsm
}
}
}
+
+ if (const NamedMDNode *Named = M.getNamedMetadata("wasm.custom_sections")) {
+ for (const Metadata *MD : Named->operands()) {
+ const MDTuple *Tuple = dyn_cast<MDTuple>(MD);
+ if (!Tuple || Tuple->getNumOperands() != 2)
+ continue;
+ const MDString *Name = dyn_cast<MDString>(Tuple->getOperand(0));
+ const MDString *Contents = dyn_cast<MDString>(Tuple->getOperand(1));
+ if (!Name || !Contents)
+ continue;
+
+ OutStreamer->PushSection();
+ std::string SectionName = (".custom_section." + Name->getString()).str();
+ MCSectionWasm *mySection =
+ OutContext.getWasmSection(SectionName, SectionKind::getMetadata());
+ OutStreamer->SwitchSection(mySection);
+ OutStreamer->EmitBytes(Contents->getString());
+ OutStreamer->PopSection();
+ }
+ }
}
void WebAssemblyAsmPrinter::EmitConstantPool() {
Added: llvm/trunk/test/CodeGen/WebAssembly/custom-sections.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/CodeGen/WebAssembly/custom-sections.ll?rev=329315&view=auto
==============================================================================
--- llvm/trunk/test/CodeGen/WebAssembly/custom-sections.ll (added)
+++ llvm/trunk/test/CodeGen/WebAssembly/custom-sections.ll Thu Apr 5 10:01:39 2018
@@ -0,0 +1,20 @@
+; RUN: llc < %s -asm-verbose=false | FileCheck %s
+
+; Test the mechanism for defining user custom sections.
+
+target datalayout = "e-m:e-p:32:32-i64:64-n32:64-S128"
+target triple = "wasm32-unknown-unknown-wasm"
+
+!0 = !{ !"red", !"foo" }
+!1 = !{ !"green", !"bar" }
+!2 = !{ !"green", !"qux" }
+!wasm.custom_sections = !{ !0, !1, !2 }
+
+; CHECK: .section .custom_section.red,"",@
+; CHECK-NEXT: .ascii "foo"
+
+; CHECK: .section .custom_section.green,"",@
+; CHECK-NEXT: .ascii "bar"
+
+; CHECK: .section .custom_section.green,"",@
+; CHECK-NEXT: .ascii "qux"
Added: llvm/trunk/test/MC/WebAssembly/custom-sections.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/MC/WebAssembly/custom-sections.ll?rev=329315&view=auto
==============================================================================
--- llvm/trunk/test/MC/WebAssembly/custom-sections.ll (added)
+++ llvm/trunk/test/MC/WebAssembly/custom-sections.ll Thu Apr 5 10:01:39 2018
@@ -0,0 +1,23 @@
+; RUN: llc -filetype=obj %s -o - | llvm-readobj -s | FileCheck %s
+
+; Test the mechanism for defining user custom sections.
+
+target triple = "wasm32-unknown-unknown-wasm"
+
+!0 = !{ !"red", !"foo" }
+!1 = !{ !"green", !"bar" }
+!2 = !{ !"green", !"qux" }
+!wasm.custom_sections = !{ !0, !1, !2 }
+
+; CHECK: Section {
+; CHECK: Type: CUSTOM (0x0)
+; CHECK: Size: 7
+; CHECK: Offset: 72
+; CHECK: Name: red
+; CHECK: }
+; CHECK: Section {
+; CHECK: Type: CUSTOM (0x0)
+; CHECK: Size: 12
+; CHECK: Offset: 85
+; CHECK: Name: green
+; CHECK: }
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