kateinoigakukun updated this revision to Diff 380283.
Repository:
rG LLVM Github Monorepo
CHANGES SINCE LAST ACTION
https://reviews.llvm.org/D74531/new/
https://reviews.llvm.org/D74531
Files:
clang/lib/CodeGen/ObjectFilePCHContainerOperations.cpp
clang/test/PCH/pch-wasm.c
llvm/lib/MC/WasmObjectWriter.cpp
llvm/test/MC/WebAssembly/custom-section-alignment.ll
Index: llvm/test/MC/WebAssembly/custom-section-alignment.ll
===================================================================
--- /dev/null
+++ llvm/test/MC/WebAssembly/custom-section-alignment.ll
@@ -0,0 +1,10 @@
+; RUN: llc -filetype=obj %s -o - | od -t x1 -v | FileCheck %s
+
+target triple = "wasm32-unknown-unknown"
+
+!0 = !{ !"before", !"\de\ad\be\ef" }
+!1 = !{ !"__clangast", !"\fe\ed\fa\ce" }
+!wasm.custom_sections = !{ !0, !1 }
+
+; Ensure that __clangast content is aligned by 4 bytes
+; CHECK: {{(([0-9a-f]{2} ){4})*}}fe ed fa ce
Index: llvm/lib/MC/WasmObjectWriter.cpp
===================================================================
--- llvm/lib/MC/WasmObjectWriter.cpp
+++ llvm/lib/MC/WasmObjectWriter.cpp
@@ -370,11 +370,33 @@
// The position where the section header ends, for measuring its size.
Section.PayloadOffset = W->OS.tell();
- // Custom sections in wasm also have a string identifier.
- writeString(Name);
+ // Custom sections in wasm also have a string identifier with extra paddings
+ // for alignment for special sections.
+ // TODO: support section alignment at asm and llvm level?
+ unsigned Alignment = 1;
+
+ // The on-disk hashtable in clangast needs to be aligned by 4 bytes.
+ if (Name == "__clangast")
+ Alignment = 4;
+
+ // Calculate the encoded size of name length and add pads based on it and
+ // alignment.
+ raw_null_ostream NullOS;
+ uint64_t NameSizeLength = encodeULEB128(Name.size(), NullOS);
+ uint64_t ContentsOffset =
+ Section.PayloadOffset + NameSizeLength + Name.size();
+ uint64_t Paddings = offsetToAlignment(ContentsOffset, Align(Alignment));
+ ContentsOffset += Paddings;
+
+ // LEB128 greater than 5 bytes is invalid
+ assert((NameSizeLength + Paddings) <= 5 && "too long section name to align");
+
+ encodeSLEB128(Name.size(), W->OS, NameSizeLength + Paddings);
+ W->OS << Name;
// The position where the custom section starts.
Section.ContentsOffset = W->OS.tell();
+ assert(Section.ContentsOffset == ContentsOffset && "invalid padding");
}
// Now that the section is complete and we know how big it is, patch up the
Index: clang/test/PCH/pch-wasm.c
===================================================================
--- /dev/null
+++ clang/test/PCH/pch-wasm.c
@@ -0,0 +1,7 @@
+// REQUIRES: webassembly-registered-target
+// RUN: %clang_cc1 -triple wasm32-unknown-unknown-wasm -emit-pch -fmodule-format=obj %S/pchpch1.h -o - | llvm-objdump --section-headers - | FileCheck %s
+
+// Ensure that clangast section should be emitted in a section for wasm object file
+
+// CHECK: file format wasm
+// CHECK: __clangast {{[0-9a-f]+}} {{[0-9a-f]+}}
Index: clang/lib/CodeGen/ObjectFilePCHContainerOperations.cpp
===================================================================
--- clang/lib/CodeGen/ObjectFilePCHContainerOperations.cpp
+++ clang/lib/CodeGen/ObjectFilePCHContainerOperations.cpp
@@ -270,25 +270,42 @@
assert(Buffer->IsComplete && "serialization did not complete");
auto &SerializedAST = Buffer->Data;
auto Size = SerializedAST.size();
- auto Int8Ty = llvm::Type::getInt8Ty(*VMContext);
- auto *Ty = llvm::ArrayType::get(Int8Ty, Size);
- auto *Data = llvm::ConstantDataArray::getString(
- *VMContext, StringRef(SerializedAST.data(), Size),
- /*AddNull=*/false);
- auto *ASTSym = new llvm::GlobalVariable(
- *M, Ty, /*constant*/ true, llvm::GlobalVariable::InternalLinkage, Data,
- "__clang_ast");
- // The on-disk hashtable needs to be aligned.
- ASTSym->setAlignment(llvm::Align(8));
-
- // Mach-O also needs a segment name.
- if (Triple.isOSBinFormatMachO())
- ASTSym->setSection("__CLANG,__clangast");
- // COFF has an eight character length limit.
- else if (Triple.isOSBinFormatCOFF())
- ASTSym->setSection("clangast");
- else
- ASTSym->setSection("__clangast");
+
+ if (Triple.isOSBinFormatWasm()) {
+ // Emit __clangast in custom section instead of named data segment
+ // to find it while iterating sections.
+ // This could be avoided if all data segements (the wasm sense) were
+ // represented as their own sections (in the llvm sense).
+ // TODO: https://github.com/WebAssembly/tool-conventions/issues/138
+ llvm::NamedMDNode *MD =
+ M->getOrInsertNamedMetadata("wasm.custom_sections");
+ llvm::Metadata *Ops[2] = {
+ llvm::MDString::get(*VMContext, "__clangast"),
+ llvm::MDString::get(*VMContext,
+ StringRef(SerializedAST.data(), Size))};
+ auto *NameAndContent = llvm::MDTuple::get(*VMContext, Ops);
+ MD->addOperand(NameAndContent);
+ } else {
+ auto Int8Ty = llvm::Type::getInt8Ty(*VMContext);
+ auto *Ty = llvm::ArrayType::get(Int8Ty, Size);
+ auto *Data = llvm::ConstantDataArray::getString(
+ *VMContext, StringRef(SerializedAST.data(), Size),
+ /*AddNull=*/false);
+ auto *ASTSym = new llvm::GlobalVariable(
+ *M, Ty, /*constant*/ true, llvm::GlobalVariable::InternalLinkage,
+ Data, "__clang_ast");
+ // The on-disk hashtable needs to be aligned.
+ ASTSym->setAlignment(llvm::Align(8));
+
+ // Mach-O also needs a segment name.
+ if (Triple.isOSBinFormatMachO())
+ ASTSym->setSection("__CLANG,__clangast");
+ // COFF has an eight character length limit.
+ else if (Triple.isOSBinFormatCOFF())
+ ASTSym->setSection("clangast");
+ else
+ ASTSym->setSection("__clangast");
+ }
LLVM_DEBUG({
// Print the IR for the PCH container to the debug output.
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