[PATCH] D154734: [WebAssembly] Report error for inline assembly with unsupported opcodes

[David Mo via Phabricator via llvm-commits]

mojingran created this revision.
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For inline WebAssembly, passing a numeric operand to global.get is unsupported. This causes encodeInstruction to reach an llvm_unreachable block, leading to undefined behaviors. This patch fixes the issue for this invalid instruction encoding, making it report an error by adding an MCContext field in class WebAssemblyMCCodeEmitter.


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D154734

Files:
  llvm/lib/Target/WebAssembly/MCTargetDesc/WebAssemblyMCCodeEmitter.cpp
  llvm/lib/Target/WebAssembly/MCTargetDesc/WebAssemblyMCTargetDesc.cpp
  llvm/lib/Target/WebAssembly/MCTargetDesc/WebAssemblyMCTargetDesc.h


Index: llvm/lib/Target/WebAssembly/MCTargetDesc/WebAssemblyMCTargetDesc.h
===================================================================
--- llvm/lib/Target/WebAssembly/MCTargetDesc/WebAssemblyMCTargetDesc.h
+++ llvm/lib/Target/WebAssembly/MCTargetDesc/WebAssemblyMCTargetDesc.h
@@ -16,6 +16,7 @@
 
 #include "../WebAssemblySubtarget.h"
 #include "llvm/BinaryFormat/Wasm.h"
+#include "llvm/MC/MCContext.h"
 #include "llvm/MC/MCInstrDesc.h"
 #include "llvm/Support/DataTypes.h"
 #include <memory>
@@ -28,7 +29,7 @@
 class MCObjectTargetWriter;
 class Triple;
 
-MCCodeEmitter *createWebAssemblyMCCodeEmitter(const MCInstrInfo &MCII);
+MCCodeEmitter *createWebAssemblyMCCodeEmitter(const MCInstrInfo &MCII, MCContext &Ctx);
 
 MCAsmBackend *createWebAssemblyAsmBackend(const Triple &TT);
 
Index: llvm/lib/Target/WebAssembly/MCTargetDesc/WebAssemblyMCTargetDesc.cpp
===================================================================
--- llvm/lib/Target/WebAssembly/MCTargetDesc/WebAssemblyMCTargetDesc.cpp
+++ llvm/lib/Target/WebAssembly/MCTargetDesc/WebAssemblyMCTargetDesc.cpp
@@ -84,7 +84,7 @@
 
 static MCCodeEmitter *createCodeEmitter(const MCInstrInfo &MCII,
                                         MCContext &Ctx) {
-  return createWebAssemblyMCCodeEmitter(MCII);
+  return createWebAssemblyMCCodeEmitter(MCII, Ctx);
 }
 
 static MCAsmBackend *createAsmBackend(const Target & /*T*/,
Index: llvm/lib/Target/WebAssembly/MCTargetDesc/WebAssemblyMCCodeEmitter.cpp
===================================================================
--- llvm/lib/Target/WebAssembly/MCTargetDesc/WebAssemblyMCCodeEmitter.cpp
+++ llvm/lib/Target/WebAssembly/MCTargetDesc/WebAssemblyMCCodeEmitter.cpp
@@ -16,6 +16,7 @@
 #include "llvm/ADT/STLExtras.h"
 #include "llvm/ADT/Statistic.h"
 #include "llvm/MC/MCCodeEmitter.h"
+#include "llvm/MC/MCContext.h"
 #include "llvm/MC/MCFixup.h"
 #include "llvm/MC/MCInst.h"
 #include "llvm/MC/MCInstrInfo.h"
@@ -25,6 +26,7 @@
 #include "llvm/Support/Debug.h"
 #include "llvm/Support/EndianStream.h"
 #include "llvm/Support/LEB128.h"
+#include "llvm/Support/SMLoc.h"
 #include "llvm/Support/raw_ostream.h"
 
 using namespace llvm;
@@ -37,7 +39,7 @@
 namespace {
 class WebAssemblyMCCodeEmitter final : public MCCodeEmitter {
   const MCInstrInfo &MCII;
-
+  MCContext &Ctx;
   // Implementation generated by tablegen.
   uint64_t getBinaryCodeForInstr(const MCInst &MI,
                                  SmallVectorImpl<MCFixup> &Fixups,
@@ -48,12 +50,14 @@
                          const MCSubtargetInfo &STI) const override;
 
 public:
-  WebAssemblyMCCodeEmitter(const MCInstrInfo &MCII) : MCII(MCII) {}
+  WebAssemblyMCCodeEmitter(const MCInstrInfo &MCII, MCContext &Ctx)
+      : MCII(MCII), Ctx{Ctx} {}
 };
 } // end anonymous namespace
 
-MCCodeEmitter *llvm::createWebAssemblyMCCodeEmitter(const MCInstrInfo &MCII) {
-  return new WebAssemblyMCCodeEmitter(MCII);
+MCCodeEmitter *llvm::createWebAssemblyMCCodeEmitter(const MCInstrInfo &MCII,
+                                                    MCContext &Ctx) {
+  return new WebAssemblyMCCodeEmitter(MCII, Ctx);
 }
 
 void WebAssemblyMCCodeEmitter::encodeInstruction(
@@ -120,7 +124,9 @@
           support::endian::write<uint64_t>(OS, MO.getImm(), support::little);
           break;
         case WebAssembly::OPERAND_GLOBAL:
-          llvm_unreachable("wasm globals should only be accessed symbolicly");
+          Ctx.reportError(
+              SMLoc(),
+              Twine("Wasm globals should only be accessed symbolically!"));
         default:
           encodeULEB128(uint64_t(MO.getImm()), OS);
         }


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