[WebAssembly] Write DWARF data into wasm object file

- Writes ".debug_XXX" into corresponding custom sections.
- Writes relocation records into "reloc.debug_XXX" sections.

Patch by Yury Delendik!

Differential Revision: https://reviews.llvm.org/D44184

llvm-svn: 330982

1 files changed, 28 insertions, 1 deletions

diff --git a/llvm/lib/Target/WebAssembly/MCTargetDesc/WebAssemblyWasmObjectWriter.cpp b/llvm/lib/Target/WebAssembly/MCTargetDesc/WebAssemblyWasmObjectWriter.cpp
index 39abde26df7..ab0125e7c28 100644
--- a/llvm/lib/Target/WebAssembly/MCTargetDesc/WebAssemblyWasmObjectWriter.cpp
+++ b/llvm/lib/Target/WebAssembly/MCTargetDesc/WebAssemblyWasmObjectWriter.cpp
@@ -20,9 +20,10 @@
 #include "llvm/MC/MCFixup.h"
 #include "llvm/MC/MCFixupKindInfo.h"
 #include "llvm/MC/MCObjectWriter.h"
+#include "llvm/MC/MCSectionWasm.h"
 #include "llvm/MC/MCSymbolWasm.h"
-#include "llvm/MC/MCWasmObjectWriter.h"
 #include "llvm/MC/MCValue.h"
+#include "llvm/MC/MCWasmObjectWriter.h"
 #include "llvm/Support/Casting.h"
 #include "llvm/Support/ErrorHandling.h"
 
@@ -61,6 +62,25 @@ static bool IsFunctionType(const MCValue &Target) {
   return RefA && RefA->getKind() == MCSymbolRefExpr::VK_WebAssembly_TYPEINDEX;
 }
 
+static const MCSection *GetFixupSection(const MCExpr *Expr) {
+  if (auto SyExp = dyn_cast<MCSymbolRefExpr>(Expr)) {
+    if (SyExp->getSymbol().isInSection())
+      return &SyExp->getSymbol().getSection();
+    return nullptr;
+  }
+
+  if (auto BinOp = dyn_cast<MCBinaryExpr>(Expr)) {
+    auto SectionLHS = GetFixupSection(BinOp->getLHS());
+    auto SectionRHS = GetFixupSection(BinOp->getRHS());
+    return SectionLHS == SectionRHS ? nullptr : SectionLHS;
+  }
+
+  if (auto UnOp = dyn_cast<MCUnaryExpr>(Expr))
+    return GetFixupSection(UnOp->getSubExpr());
+
+  return nullptr;
+}
+
 unsigned
 WebAssemblyWasmObjectWriter::getRelocType(const MCValue &Target,
                                           const MCFixup &Fixup) const {
@@ -86,6 +106,13 @@ WebAssemblyWasmObjectWriter::getRelocType(const MCValue &Target,
   case FK_Data_4:
     if (IsFunction)
       return wasm::R_WEBASSEMBLY_TABLE_INDEX_I32;
+    if (auto Section = static_cast<const MCSectionWasm *>(
+            GetFixupSection(Fixup.getValue()))) {
+      if (Section->getKind().isText())
+        return wasm::R_WEBASSEMBLY_FUNCTION_OFFSET_I32;
+      else if (!Section->isWasmData())
+        return wasm::R_WEBASSEMBLY_SECTION_OFFSET_I32;
+    }
     return wasm::R_WEBASSEMBLY_MEMORY_ADDR_I32;
   case FK_Data_8:
     llvm_unreachable("FK_Data_8 not implemented yet");