[WebAssembly] Assembler/InstPrinter: support call_indirect type index.

A TYPE_INDEX operand (as used by call_indirect) used to be represented
by the InstPrinter as a symbol (e.g. .Ltype_index0@TYPE_INDEX) which
was a bit of a mismatch with the WasmObjectWriter which expects an
unnamed symbol, to receive the signature from and then turn into a
reloc.

There was really no good way to round-trip this information. An earlier
version of this patch tried to attach the signature information using
a .functype, but that ran into trouble when the symbol was re-emitted
without a name. Removing the name was a giant hack also.

The current version changes the assembly syntax to have an inline
signature spec for TYPEINDEX operands that is always unnamed, which
is much more elegant both in syntax and in implementation (as now the
assembler is able to follow the same path as the regular backend)

Reviewers: sbc100, dschuff, aheejin, jgravelle-google, sunfish, tlively

Subscribers: arphaman, llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D64758

llvm-svn: 367590

9 files changed, 130 insertions, 42 deletions

diff --git a/llvm/lib/Target/WebAssembly/AsmParser/WebAssemblyAsmParser.cpp b/llvm/lib/Target/WebAssembly/AsmParser/WebAssemblyAsmParser.cpp
index 09628e872dd..2fd7382fbcc 100644
--- a/llvm/lib/Target/WebAssembly/AsmParser/WebAssemblyAsmParser.cpp
+++ b/llvm/lib/Target/WebAssembly/AsmParser/WebAssemblyAsmParser.cpp
@@ -492,6 +492,27 @@ public:
       CurrentState = EndFunction;
       if (pop(Name, Function) || ensureEmptyNestingStack())
         return true;
+    } else if (Name == "call_indirect" || Name == "return_call_indirect") {
+      // This has a special TYPEINDEX operand which in text we
+      // represent as a signature, such that we can re-build this signature,
+      // attach it to an anonymous symbol, which is what WasmObjectWriter
+      // expects to be able to recreate the actual unique-ified type indices.
+      auto Loc = Parser.getTok();
+      auto Signature = make_unique<wasm::WasmSignature>();
+      if (parseSignature(Signature.get()))
+        return true;
+      auto &Ctx = getStreamer().getContext();
+      // The "true" here will cause this to be a nameless symbol.
+      MCSymbol *Sym = Ctx.createTempSymbol("typeindex", true);
+      auto *WasmSym = cast<MCSymbolWasm>(Sym);
+      WasmSym->setSignature(Signature.get());
+      addSignature(std::move(Signature));
+      WasmSym->setType(wasm::WASM_SYMBOL_TYPE_FUNCTION);
+      const MCExpr *Expr = MCSymbolRefExpr::create(
+          WasmSym, MCSymbolRefExpr::VK_WASM_TYPEINDEX, Ctx);
+      Operands.push_back(make_unique<WebAssemblyOperand>(
+          WebAssemblyOperand::Symbol, Loc.getLoc(), Loc.getEndLoc(),
+          WebAssemblyOperand::SymOp{Expr}));
     }
 
     while (Lexer.isNot(AsmToken::EndOfStatement)) {
diff --git a/llvm/lib/Target/WebAssembly/MCTargetDesc/WebAssemblyInstPrinter.cpp b/llvm/lib/Target/WebAssembly/MCTargetDesc/WebAssemblyInstPrinter.cpp
index b5d4d369b72..bc63382aa8f 100644
--- a/llvm/lib/Target/WebAssembly/MCTargetDesc/WebAssemblyInstPrinter.cpp
+++ b/llvm/lib/Target/WebAssembly/MCTargetDesc/WebAssemblyInstPrinter.cpp
@@ -15,6 +15,7 @@
 #include "MCTargetDesc/WebAssemblyMCTargetDesc.h"
 #include "WebAssembly.h"
 #include "WebAssemblyMachineFunctionInfo.h"
+#include "WebAssemblyUtilities.h"
 #include "llvm/ADT/SmallSet.h"
 #include "llvm/ADT/StringExtras.h"
 #include "llvm/CodeGen/TargetRegisterInfo.h"
@@ -232,7 +233,16 @@ void WebAssemblyInstPrinter::printOperand(const MCInst *MI, unsigned OpNo,
     }
   } else {
     assert(Op.isExpr() && "unknown operand kind in printOperand");
-    Op.getExpr()->print(O, &MAI);
+    // call_indirect instructions have a TYPEINDEX operand that we print
+    // as a signature here, such that the assembler can recover this
+    // information.
+    auto SRE = static_cast<const MCSymbolRefExpr *>(Op.getExpr());
+    if (SRE->getKind() == MCSymbolRefExpr::VK_WASM_TYPEINDEX) {
+      auto &Sym = static_cast<const MCSymbolWasm &>(SRE->getSymbol());
+      O << WebAssembly::signatureToString(Sym.getSignature());
+    } else {
+      Op.getExpr()->print(O, &MAI);
+    }
   }
 }
 
@@ -266,7 +276,7 @@ void WebAssemblyInstPrinter::printWebAssemblySignatureOperand(const MCInst *MI,
 
 // We have various enums representing a subset of these types, use this
 // function to convert any of them to text.
-const char *llvm::WebAssembly::anyTypeToString(unsigned Ty) {
+const char *WebAssembly::anyTypeToString(unsigned Ty) {
   switch (Ty) {
   case wasm::WASM_TYPE_I32:
     return "i32";
@@ -291,6 +301,24 @@ const char *llvm::WebAssembly::anyTypeToString(unsigned Ty) {
   }
 }
 
-const char *llvm::WebAssembly::typeToString(wasm::ValType Ty) {
+const char *WebAssembly::typeToString(wasm::ValType Ty) {
   return anyTypeToString(static_cast<unsigned>(Ty));
 }
+
+std::string WebAssembly::typeListToString(ArrayRef<wasm::ValType> List) {
+  std::string S;
+  for (auto &Ty : List) {
+    if (&Ty != &List[0]) S += ", ";
+    S += WebAssembly::typeToString(Ty);
+  }
+  return S;
+}
+
+std::string WebAssembly::signatureToString(const wasm::WasmSignature *Sig) {
+  std::string S("(");
+  S += typeListToString(Sig->Params);
+  S += ") -> (";
+  S += typeListToString(Sig->Returns);
+  S += ")";
+  return S;
+}
diff --git a/llvm/lib/Target/WebAssembly/MCTargetDesc/WebAssemblyInstPrinter.h b/llvm/lib/Target/WebAssembly/MCTargetDesc/WebAssemblyInstPrinter.h
index b979de5028b..cf37778099a 100644
--- a/llvm/lib/Target/WebAssembly/MCTargetDesc/WebAssemblyInstPrinter.h
+++ b/llvm/lib/Target/WebAssembly/MCTargetDesc/WebAssemblyInstPrinter.h
@@ -58,6 +58,9 @@ namespace WebAssembly {
 const char *typeToString(wasm::ValType Ty);
 const char *anyTypeToString(unsigned Ty);
 
+std::string typeListToString(ArrayRef<wasm::ValType> List);
+std::string signatureToString(const wasm::WasmSignature *Sig);
+
 } // end namespace WebAssembly
 
 } // end namespace llvm
diff --git a/llvm/lib/Target/WebAssembly/MCTargetDesc/WebAssemblyTargetStreamer.cpp b/llvm/lib/Target/WebAssembly/MCTargetDesc/WebAssemblyTargetStreamer.cpp
index e05efef7201..40926201931 100644
--- a/llvm/lib/Target/WebAssembly/MCTargetDesc/WebAssemblyTargetStreamer.cpp
+++ b/llvm/lib/Target/WebAssembly/MCTargetDesc/WebAssemblyTargetStreamer.cpp
@@ -60,39 +60,10 @@ void WebAssemblyTargetAsmStreamer::emitLocal(ArrayRef<wasm::ValType> Types) {
 
 void WebAssemblyTargetAsmStreamer::emitEndFunc() { OS << "\t.endfunc\n"; }
 
-void WebAssemblyTargetAsmStreamer::emitSignature(
-    const wasm::WasmSignature *Sig) {
-  OS << "(";
-  emitParamList(Sig);
-  OS << ") -> (";
-  emitReturnList(Sig);
-  OS << ")";
-}
-
-void WebAssemblyTargetAsmStreamer::emitParamList(
-    const wasm::WasmSignature *Sig) {
-  auto &Params = Sig->Params;
-  for (auto &Ty : Params) {
-    if (&Ty != &Params[0])
-      OS << ", ";
-    OS << WebAssembly::typeToString(Ty);
-  }
-}
-
-void WebAssemblyTargetAsmStreamer::emitReturnList(
-    const wasm::WasmSignature *Sig) {
-  auto &Returns = Sig->Returns;
-  for (auto &Ty : Returns) {
-    if (&Ty != &Returns[0])
-      OS << ", ";
-    OS << WebAssembly::typeToString(Ty);
-  }
-}
-
 void WebAssemblyTargetAsmStreamer::emitFunctionType(const MCSymbolWasm *Sym) {
   assert(Sym->isFunction());
   OS << "\t.functype\t" << Sym->getName() << " ";
-  emitSignature(Sym->getSignature());
+  OS << WebAssembly::signatureToString(Sym->getSignature());
   OS << "\n";
 }
 
@@ -107,7 +78,7 @@ void WebAssemblyTargetAsmStreamer::emitGlobalType(const MCSymbolWasm *Sym) {
 void WebAssemblyTargetAsmStreamer::emitEventType(const MCSymbolWasm *Sym) {
   assert(Sym->isEvent());
   OS << "\t.eventtype\t" << Sym->getName() << " ";
-  emitParamList(Sym->getSignature());
+  OS << WebAssembly::typeListToString(Sym->getSignature()->Params);
   OS << "\n";
 }
 
diff --git a/llvm/lib/Target/WebAssembly/MCTargetDesc/WebAssemblyTargetStreamer.h b/llvm/lib/Target/WebAssembly/MCTargetDesc/WebAssemblyTargetStreamer.h
index 5ea62b179d2..0164f8e572e 100644
--- a/llvm/lib/Target/WebAssembly/MCTargetDesc/WebAssemblyTargetStreamer.h
+++ b/llvm/lib/Target/WebAssembly/MCTargetDesc/WebAssemblyTargetStreamer.h
@@ -56,9 +56,6 @@ protected:
 /// This part is for ascii assembly output
 class WebAssemblyTargetAsmStreamer final : public WebAssemblyTargetStreamer {
   formatted_raw_ostream &OS;
-  void emitSignature(const wasm::WasmSignature *Sig);
-  void emitParamList(const wasm::WasmSignature *Sig);
-  void emitReturnList(const wasm::WasmSignature *Sig);
 
 public:
   WebAssemblyTargetAsmStreamer(MCStreamer &S, formatted_raw_ostream &OS);
diff --git a/llvm/test/CodeGen/WebAssembly/reg-stackify.ll b/llvm/test/CodeGen/WebAssembly/reg-stackify.ll
index c0668afcefe..9a96016c98f 100644
--- a/llvm/test/CodeGen/WebAssembly/reg-stackify.ll
+++ b/llvm/test/CodeGen/WebAssembly/reg-stackify.ll
@@ -655,7 +655,7 @@ define i32 @stackpointer_dependency(i8* readnone) {
 ; NOREGS-NEXT: local.tee 0
 ; NOREGS:      i32.load  0
 ; NOREGS-NEXT: i32.load  0
-; NOREGS-NEXT: i32.call_indirect
+; NOREGS-NEXT: i32.call_indirect (i32, i32) -> (i32)
 %class.call_indirect = type { i32 (...)** }
 define i32 @call_indirect_stackify(%class.call_indirect** %objptr, i32 %arg) {
   %obj = load %class.call_indirect*, %class.call_indirect** %objptr
diff --git a/llvm/test/MC/WebAssembly/basic-assembly.s b/llvm/test/MC/WebAssembly/basic-assembly.s
index 23b1a0940f6..ac01dca3755 100644
--- a/llvm/test/MC/WebAssembly/basic-assembly.s
+++ b/llvm/test/MC/WebAssembly/basic-assembly.s
@@ -34,7 +34,7 @@ test0:
     i64.const   1234
     i32.call    something2
     i32.const   0
-    call_indirect 0
+    call_indirect (i32, f64) -> ()
     i32.const   1
     i32.add
     local.tee   0
@@ -138,7 +138,7 @@ test0:
 # CHECK-NEXT:      i64.const   1234
 # CHECK-NEXT:      i32.call    something2
 # CHECK-NEXT:      i32.const   0
-# CHECK-NEXT:      call_indirect 0
+# CHECK-NEXT:      call_indirect (i32, f64) -> ()
 # CHECK-NEXT:      i32.const   1
 # CHECK-NEXT:      i32.add
 # CHECK-NEXT:      local.tee   0
diff --git a/llvm/test/MC/WebAssembly/tail-call-encodings.s b/llvm/test/MC/WebAssembly/tail-call-encodings.s
index a6e921b5434..69839adcfbf 100644
--- a/llvm/test/MC/WebAssembly/tail-call-encodings.s
+++ b/llvm/test/MC/WebAssembly/tail-call-encodings.s
@@ -16,7 +16,8 @@ foo1:
 foo2:
     .functype foo2 () -> ()
 
-    # CHECK: return_call_indirect 0 # encoding: [0x13,0x00,0x00]
-    return_call_indirect 0
+    # CHECK: return_call_indirect (i32) -> (i32) # encoding: [0x13,
+    # CHECK-NEXT: fixup A - offset: 1, value: .Ltypeindex0@TYPEINDEX, kind: fixup_uleb128_i32
+    return_call_indirect (i32) -> (i32)
 
     end_function
diff --git a/llvm/test/MC/WebAssembly/type-index.s b/llvm/test/MC/WebAssembly/type-index.s
new file mode 100644
index 00000000000..707f6aa9894
--- /dev/null
+++ b/llvm/test/MC/WebAssembly/type-index.s
@@ -0,0 +1,67 @@
+# RUN: llvm-mc -triple=wasm32-unknown-unknown -mattr=+unimplemented-simd128,+nontrapping-fptoint,+exception-handling < %s | FileCheck %s
+# Check that it converts to .o without errors:
+# RUN: llvm-mc -triple=wasm32-unknown-unknown -filetype=obj -mattr=+unimplemented-simd128,+nontrapping-fptoint,+exception-handling < %s | obj2yaml | FileCheck -check-prefix=BIN %s
+
+# Minimal test for type indices in call_indirect.
+
+test0:
+    .functype   test0 (i32) -> (i32)
+    call_indirect (f64) -> (f64)
+    end_function
+
+# CHECK:	.text
+# CHECK-LABEL: test0:
+# CHECK-NEXT:	.functype	test0 (i32) -> (i32)
+# CHECK-NEXT:	call_indirect	(f64) -> (f64)
+# CHECK-NEXT:	end_function
+
+# BIN:      --- !WASM
+# BIN-NEXT: FileHeader:
+# BIN-NEXT:   Version:         0x00000001
+# BIN-NEXT: Sections:
+# BIN-NEXT:   - Type:            TYPE
+# BIN-NEXT:     Signatures:
+# BIN-NEXT:       - Index:           0
+# BIN-NEXT:         ReturnType:      I32
+# BIN-NEXT:         ParamTypes:
+# BIN-NEXT:           - I32
+# BIN-NEXT:       - Index:           1
+# BIN-NEXT:         ReturnType:      F64
+# BIN-NEXT:         ParamTypes:
+# BIN-NEXT:           - F64
+# BIN-NEXT:   - Type:            IMPORT
+# BIN-NEXT:     Imports:
+# BIN-NEXT:       - Module:          env
+# BIN-NEXT:         Field:           __linear_memory
+# BIN-NEXT:         Kind:            MEMORY
+# BIN-NEXT:         Memory:
+# BIN-NEXT:           Initial:         0x00000000
+# BIN-NEXT:       - Module:          env
+# BIN-NEXT:         Field:           __indirect_function_table
+# BIN-NEXT:         Kind:            TABLE
+# BIN-NEXT:         Table:
+# BIN-NEXT:           ElemType:        FUNCREF
+# BIN-NEXT:           Limits:
+# BIN-NEXT:             Initial:         0x00000000
+# BIN-NEXT:   - Type:            FUNCTION
+# BIN-NEXT:     FunctionTypes:   [ 0 ]
+# BIN-NEXT:   - Type:            CODE
+# BIN-NEXT:     Relocations:
+# BIN-NEXT:       - Type:            R_WASM_TYPE_INDEX_LEB
+# BIN-NEXT:         Index:           1
+# BIN-NEXT:         Offset:          0x00000004
+# BIN-NEXT:     Functions:
+# BIN-NEXT:       - Index:           0
+# BIN-NEXT:         Locals:          []
+# BIN-NEXT:         Body:            118180808000000B
+# BIN-NEXT:   - Type:            CUSTOM
+# BIN-NEXT:     Name:            linking
+# BIN-NEXT:     Version:         2
+# BIN-NEXT:     SymbolTable:
+# BIN-NEXT:       - Index:           0
+# BIN-NEXT:         Kind:            FUNCTION
+# BIN-NEXT:         Name:            test0
+# BIN-NEXT:         Flags:           [ BINDING_LOCAL ]
+# BIN-NEXT:         Function:        0
+# BIN-NEXT: ...
+