[PATCH] D77115: [WebAssembly] Emit .llvmcmd and .llvmbc as custom sections

[Sam Clegg via Phabricator via cfe-commits]

sbc100 created this revision.
Herald added subscribers: cfe-commits, jfb, sunfish, aheejin, hiraditya, jgravelle-google, dschuff.
Herald added a project: clang.
sbc100 added reviewers: alexcrichton, sunfish.

Fixes: https://bugs.llvm.org/show_bug.cgi?id=45362


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D77115

Files:
  clang/test/Driver/embed-bitcode-wasm.c
  clang/test/Driver/fembed-bitcode.c
  llvm/lib/CodeGen/TargetLoweringObjectFileImpl.cpp
  llvm/lib/MC/WasmObjectWriter.cpp


Index: llvm/lib/MC/WasmObjectWriter.cpp
===================================================================
--- llvm/lib/MC/WasmObjectWriter.cpp
+++ llvm/lib/MC/WasmObjectWriter.cpp
@@ -436,10 +436,6 @@
   uint64_t FixupOffset = Layout.getFragmentOffset(Fragment) + Fixup.getOffset();
   MCContext &Ctx = Asm.getContext();
 
-  // The .init_array isn't translated as data, so don't do relocations in it.
-  if (FixupSection.getSectionName().startswith(".init_array"))
-    return;
-
   if (const MCSymbolRefExpr *RefB = Target.getSymB()) {
     // To get here the A - B expression must have failed evaluateAsRelocatable.
     // This means either A or B must be undefined and in WebAssembly we can't
@@ -502,6 +498,10 @@
     SymA->setUsedInReloc();
   }
 
+  // The .init_array isn't translated as data, so don't do relocations in it.
+  if (FixupSection.getSectionName().startswith(".init_array"))
+    return;
+
   if (RefA->getKind() == MCSymbolRefExpr::VK_GOT)
     SymA->setUsedInGOT();
 
@@ -1090,10 +1090,7 @@
   if (Sym.isComdat() && !Sym.isDefined())
     return false;
 
-  if (Sym.isTemporary() && Sym.getName().empty())
-    return false;
-
-  if (Sym.isTemporary() && Sym.isData() && !Sym.getSize())
+  if (Sym.isTemporary())
     return false;
 
   if (Sym.isSection())
@@ -1565,7 +1562,7 @@
         report_fatal_error("fixups in .init_array should be symbol references");
       const auto &TargetSym = cast<const MCSymbolWasm>(SymRef->getSymbol());
       if (TargetSym.getIndex() == InvalidIndex)
-        report_fatal_error("symbols in .init_array should exist in symbtab");
+        report_fatal_error("symbols in .init_array should exist in symtab");
       if (!TargetSym.isFunction())
         report_fatal_error("symbols in .init_array should be for functions");
       InitFuncs.push_back(
Index: llvm/lib/CodeGen/TargetLoweringObjectFileImpl.cpp
===================================================================
--- llvm/lib/CodeGen/TargetLoweringObjectFileImpl.cpp
+++ llvm/lib/CodeGen/TargetLoweringObjectFileImpl.cpp
@@ -1765,6 +1765,14 @@
 
   StringRef Name = GO->getSection();
 
+  // Certain data sections we treat as custom named section rather than
+  // segments within the data section.
+  // This could be avoided if all data segements in (the wasm sense) were
+  // represented as thier on sections (in the llvm sense).
+  // TODO(sbc): https://github.com/WebAssembly/tool-conventions/issues/138
+  if (Name == ".llvmcmd" || Name == ".llvmbc")
+    Kind = SectionKind::getMetadata();
+
   StringRef Group = "";
   if (const Comdat *C = getWasmComdat(GO)) {
     Group = C->getName();
Index: clang/test/Driver/fembed-bitcode.c
===================================================================
--- clang/test/Driver/fembed-bitcode.c
+++ clang/test/Driver/fembed-bitcode.c
@@ -30,3 +30,12 @@
 // RUN:     | FileCheck --check-prefix=CHECK-HEXAGON %s
 // CHECK-HEXAGON: "-target-feature"
 // CHECK-HEXAGON: "+reserved-r19"
+//
+// RUN: %clang -target wasm32-unknown-unknown -fembed-bitcode=all -pthread -c %s -o /dev/null -### 2>&1 \
+// RUN:     | FileCheck --check-prefix=CHECK-WASM %s
+
+// CHECK-WASM: "-cc1"
+// CHECK-WASM: "-target-feature" "+atomics"
+
+// CHECK-WASM: "-cc1"
+// CHECK-WASM: "-target-feature" "+atomics"
Index: clang/test/Driver/embed-bitcode-wasm.c
===================================================================
--- /dev/null
+++ clang/test/Driver/embed-bitcode-wasm.c
@@ -0,0 +1,6 @@
+// REQUIRES: webassembly-registered-target
+
+// RUN: %clang -c -target wasm32-unknown-unknown %s -fembed-bitcode -o %t.o
+// RUN: llvm-readobj -S %t.o | FileCheck --check-prefix=CHECK %s
+// CHECK:   Name: .llvmbc
+// CHECK:   Name: .llvmcmd


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