[WebAssembly] Parse llvm.ident into producers section

Summary:
Everything before the word "version" is the tool, and everything after
the word "version" is the version.

Reviewers: aheejin, dschuff

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

Differential Revision: https://reviews.llvm.org/D56742

llvm-svn: 351399

1 files changed, 30 insertions, 17 deletions

diff --git a/llvm/lib/MC/WasmObjectWriter.cpp b/llvm/lib/MC/WasmObjectWriter.cpp
index 0cca3757be9..8e45b2f3e0c 100644
--- a/llvm/lib/MC/WasmObjectWriter.cpp
+++ b/llvm/lib/MC/WasmObjectWriter.cpp
@@ -224,6 +224,7 @@ class WasmObjectWriter : public MCObjectWriter {
   // Stores output data (index, relocations, content offset) for custom
   // section.
   std::vector<WasmCustomSection> CustomSections;
+  std::unique_ptr<WasmCustomSection> ProducersSection;
   // Relocations for fixing up references in the custom sections.
   DenseMap<const MCSectionWasm *, std::vector<WasmRelocationEntry>>
       CustomSectionsRelocations;
@@ -265,6 +266,8 @@ private:
     WasmIndices.clear();
     TableIndices.clear();
     DataLocations.clear();
+    CustomSections.clear();
+    ProducersSection.reset();
     CustomSectionsRelocations.clear();
     SignatureIndices.clear();
     Signatures.clear();
@@ -311,7 +314,8 @@ private:
       ArrayRef<wasm::WasmSymbolInfo> SymbolInfos,
       ArrayRef<std::pair<uint16_t, uint32_t>> InitFuncs,
       const std::map<StringRef, std::vector<WasmComdatEntry>> &Comdats);
-  void writeCustomSections(const MCAssembler &Asm, const MCAsmLayout &Layout);
+  void writeCustomSection(WasmCustomSection &CustomSection,
+                          const MCAssembler &Asm, const MCAsmLayout &Layout);
   void writeCustomRelocSections();
   void
   updateCustomSectionRelocations(const SmallVector<WasmFunction, 4> &Functions,
@@ -1045,25 +1049,24 @@ void WasmObjectWriter::writeLinkingMetaDataSection(
   endSection(Section);
 }
 
-void WasmObjectWriter::writeCustomSections(const MCAssembler &Asm,
-                                           const MCAsmLayout &Layout) {
-  for (auto &CustomSection : CustomSections) {
-    SectionBookkeeping Section;
-    auto *Sec = CustomSection.Section;
-    startCustomSection(Section, CustomSection.Name);
+void WasmObjectWriter::writeCustomSection(WasmCustomSection &CustomSection,
+                                          const MCAssembler &Asm,
+                                          const MCAsmLayout &Layout) {
+  SectionBookkeeping Section;
+  auto *Sec = CustomSection.Section;
+  startCustomSection(Section, CustomSection.Name);
 
-    Sec->setSectionOffset(W.OS.tell() - Section.ContentsOffset);
-    Asm.writeSectionData(W.OS, Sec, Layout);
+  Sec->setSectionOffset(W.OS.tell() - Section.ContentsOffset);
+  Asm.writeSectionData(W.OS, Sec, Layout);
 
-    CustomSection.OutputContentsOffset = Section.ContentsOffset;
-    CustomSection.OutputIndex = Section.Index;
+  CustomSection.OutputContentsOffset = Section.ContentsOffset;
+  CustomSection.OutputIndex = Section.Index;
 
-    endSection(Section);
+  endSection(Section);
 
-    // Apply fixups.
-    auto &Relocations = CustomSectionsRelocations[CustomSection.Section];
-    applyRelocations(Relocations, CustomSection.OutputContentsOffset);
-  }
+  // Apply fixups.
+  auto &Relocations = CustomSectionsRelocations[CustomSection.Section];
+  applyRelocations(Relocations, CustomSection.OutputContentsOffset);
 }
 
 uint32_t WasmObjectWriter::getFunctionType(const MCSymbolWasm &Symbol) {
@@ -1282,6 +1285,13 @@ uint64_t WasmObjectWriter::writeObject(MCAssembler &Asm,
           report_fatal_error("section name and begin symbol should match: " +
                              Twine(SectionName));
       }
+
+      // Separate out the producers section
+      if (Name == "producers") {
+        ProducersSection = llvm::make_unique<WasmCustomSection>(Name, &Section);
+        continue;
+      }
+
       CustomSections.emplace_back(Name, &Section);
     }
   }
@@ -1570,11 +1580,14 @@ uint64_t WasmObjectWriter::writeObject(MCAssembler &Asm,
   writeElemSection(TableElems);
   writeCodeSection(Asm, Layout, Functions);
   writeDataSection();
-  writeCustomSections(Asm, Layout);
+  for (auto &CustomSection : CustomSections)
+    writeCustomSection(CustomSection, Asm, Layout);
   writeLinkingMetaDataSection(SymbolInfos, InitFuncs, Comdats);
   writeRelocSection(CodeSectionIndex, "CODE", CodeRelocations);
   writeRelocSection(DataSectionIndex, "DATA", DataRelocations);
   writeCustomRelocSections();
+  if (ProducersSection)
+    writeCustomSection(*ProducersSection, Asm, Layout);
 
   // TODO: Translate the .comment section to the output.
   return W.OS.tell() - StartOffset;