[WebAssembly] Fix for 0xc call_indirect changes

Summary:
Need to reorder the operands to have the callee as the last argument.
Adds a pseudo-instruction, and a pass to lower it into a real
call_indirect.

This is the first of two options for how to fix the problem.

Reviewers: dschuff, sunfish

Subscribers: jfb, beanz, mgorny, llvm-commits

Differential Revision: https://reviews.llvm.org/D25708

llvm-svn: 284840

llvm/lib/Target/WebAssembly/CMakeLists.txt

@@ -12,6 +12,7 @@ add_public_tablegen_target(WebAssemblyCommonTableGen)
 add_llvm_target(WebAssemblyCodeGen
   WebAssemblyArgumentMove.cpp
   WebAssemblyAsmPrinter.cpp
+  WebAssemblyCallIndirectFixup.cpp
   WebAssemblyCFGStackify.cpp
   WebAssemblyFastISel.cpp
   WebAssemblyFixIrreducibleControlFlow.cpp

llvm/lib/Target/WebAssembly/WebAssembly.h

@@ -48,6 +48,7 @@ FunctionPass *createWebAssemblyCFGStackify();
 FunctionPass *createWebAssemblyLowerBrUnless();
 FunctionPass *createWebAssemblyRegNumbering();
 FunctionPass *createWebAssemblyPeephole();
+FunctionPass *createWebAssemblyCallIndirectFixup();
 
 } // end namespace llvm
 

llvm/lib/Target/WebAssembly/WebAssemblyCallIndirectFixup.cpp

@@ -0,0 +1,117 @@
+//===-- WebAssemblyCallIndirectFixup.cpp - Fix call_indirects -------------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+///
+/// \file
+/// \brief This file converts pseudo call_indirect instructions into real
+/// call_indirects.
+///
+/// The order of arguments for a call_indirect is the arguments to the function
+/// call, followed by the function pointer. There's no natural way to express
+/// a machineinstr with varargs followed by one more arg, so we express it as
+/// the function pointer followed by varargs, then rewrite it here.
+///
+/// We need to rewrite the order of the arguments on the machineinstrs
+/// themselves so that register stackification knows the order they'll be
+/// executed in.
+///
+//===----------------------------------------------------------------------===//
+
+#include "WebAssembly.h"
+#include "MCTargetDesc/WebAssemblyMCTargetDesc.h" // for WebAssembly::ARGUMENT_*
+#include "WebAssemblyMachineFunctionInfo.h"
+#include "WebAssemblySubtarget.h"
+#include "llvm/Analysis/AliasAnalysis.h"
+#include "llvm/CodeGen/LiveIntervalAnalysis.h"
+#include "llvm/CodeGen/MachineBlockFrequencyInfo.h"
+#include "llvm/CodeGen/MachineDominators.h"
+#include "llvm/CodeGen/MachineInstrBuilder.h"
+#include "llvm/CodeGen/MachineRegisterInfo.h"
+#include "llvm/CodeGen/Passes.h"
+#include "llvm/Support/Debug.h"
+#include "llvm/Support/raw_ostream.h"
+using namespace llvm;
+
+#define DEBUG_TYPE "wasm-call-indirect-fixup"
+
+namespace {
+class WebAssemblyCallIndirectFixup final : public MachineFunctionPass {
+  StringRef getPassName() const override {
+    return "WebAssembly CallIndirect Fixup";
+  }
+
+  bool runOnMachineFunction(MachineFunction &MF) override;
+
+public:
+  static char ID; // Pass identification, replacement for typeid
+  WebAssemblyCallIndirectFixup() : MachineFunctionPass(ID) {}
+};
+} // end anonymous namespace
+
+char WebAssemblyCallIndirectFixup::ID = 0;
+FunctionPass *llvm::createWebAssemblyCallIndirectFixup() {
+  return new WebAssemblyCallIndirectFixup();
+}
+
+static unsigned GetNonPseudoCallIndirectOpcode(const MachineInstr &MI) {
+  switch (MI.getOpcode()) {
+    using namespace WebAssembly;
+  case PCALL_INDIRECT_VOID: return CALL_INDIRECT_VOID;
+  case PCALL_INDIRECT_I32: return CALL_INDIRECT_I32;
+  case PCALL_INDIRECT_I64: return CALL_INDIRECT_I64;
+  case PCALL_INDIRECT_F32: return CALL_INDIRECT_F32;
+  case PCALL_INDIRECT_F64: return CALL_INDIRECT_F64;
+  case PCALL_INDIRECT_v16i8: return CALL_INDIRECT_v16i8;
+  case PCALL_INDIRECT_v8i16: return CALL_INDIRECT_v8i16;
+  case PCALL_INDIRECT_v4i32: return CALL_INDIRECT_v4i32;
+  case PCALL_INDIRECT_v4f32: return CALL_INDIRECT_v4f32;
+  default: return INSTRUCTION_LIST_END;
+  }
+}
+
+static bool IsPseudoCallIndirect(const MachineInstr &MI) {
+  return GetNonPseudoCallIndirectOpcode(MI) !=
+         WebAssembly::INSTRUCTION_LIST_END;
+}
+
+bool WebAssemblyCallIndirectFixup::runOnMachineFunction(MachineFunction &MF) {
+  DEBUG(dbgs() << "********** Fixing up CALL_INDIRECTs **********\n"
+               << MF.getName() << '\n');
+
+  bool Changed = false;
+  const WebAssemblyInstrInfo *TII =
+      MF.getSubtarget<WebAssemblySubtarget>().getInstrInfo();
+
+  for (MachineBasicBlock &MBB : MF) {
+    for (MachineInstr &MI : MBB) {
+      if (IsPseudoCallIndirect(MI)) {
+        DEBUG(dbgs() << "Found call_indirect: " << MI << '\n');
+
+        // Rewrite pseudo to non-pseudo
+        const MCInstrDesc &Desc = TII->get(GetNonPseudoCallIndirectOpcode(MI));
+        MI.setDesc(Desc);
+
+        // Rewrite argument order
+        auto Uses = MI.explicit_uses();
+        MachineInstr::mop_iterator it = Uses.begin();
+        const MachineOperand MO = *it;
+        unsigned num = MI.getOperandNo(it);
+        MI.RemoveOperand(num);
+        MI.addOperand(MF, MO);
+
+        DEBUG(dbgs() << "  After transform: " << MI);
+        Changed = true;
+      }
+    }
+  }
+
+  DEBUG(dbgs() << "\nDone fixing up CALL_INDIRECTs\n\n");
+
+  return Changed;
+}
+

llvm/lib/Target/WebAssembly/WebAssemblyFastISel.cpp

@@ -668,7 +668,7 @@ bool WebAssemblyFastISel::selectCall(const Instruction *I) {
   bool IsVoid = FuncTy->getReturnType()->isVoidTy();
   unsigned ResultReg;
   if (IsVoid) {
-    Opc = IsDirect ? WebAssembly::CALL_VOID : WebAssembly::CALL_INDIRECT_VOID;
+    Opc = IsDirect ? WebAssembly::CALL_VOID : WebAssembly::PCALL_INDIRECT_VOID;
   } else {
     if (!Subtarget->hasSIMD128() && Call->getType()->isVectorTy())
       return false;
@@ -679,39 +679,39 @@ bool WebAssemblyFastISel::selectCall(const Instruction *I) {
     case MVT::i8:
     case MVT::i16:
     case MVT::i32:
-      Opc = IsDirect ? WebAssembly::CALL_I32 : WebAssembly::CALL_INDIRECT_I32;
+      Opc = IsDirect ? WebAssembly::CALL_I32 : WebAssembly::PCALL_INDIRECT_I32;
       ResultReg = createResultReg(&WebAssembly::I32RegClass);
       break;
     case MVT::i64:
-      Opc = IsDirect ? WebAssembly::CALL_I64 : WebAssembly::CALL_INDIRECT_I64;
+      Opc = IsDirect ? WebAssembly::CALL_I64 : WebAssembly::PCALL_INDIRECT_I64;
       ResultReg = createResultReg(&WebAssembly::I64RegClass);
       break;
     case MVT::f32:
-      Opc = IsDirect ? WebAssembly::CALL_F32 : WebAssembly::CALL_INDIRECT_F32;
+      Opc = IsDirect ? WebAssembly::CALL_F32 : WebAssembly::PCALL_INDIRECT_F32;
       ResultReg = createResultReg(&WebAssembly::F32RegClass);
       break;
     case MVT::f64:
-      Opc = IsDirect ? WebAssembly::CALL_F64 : WebAssembly::CALL_INDIRECT_F64;
+      Opc = IsDirect ? WebAssembly::CALL_F64 : WebAssembly::PCALL_INDIRECT_F64;
       ResultReg = createResultReg(&WebAssembly::F64RegClass);
       break;
     case MVT::v16i8:
       Opc =
-          IsDirect ? WebAssembly::CALL_v16i8 : WebAssembly::CALL_INDIRECT_v16i8;
+          IsDirect ? WebAssembly::CALL_v16i8 : WebAssembly::PCALL_INDIRECT_v16i8;
       ResultReg = createResultReg(&WebAssembly::V128RegClass);
       break;
     case MVT::v8i16:
       Opc =
-          IsDirect ? WebAssembly::CALL_v8i16 : WebAssembly::CALL_INDIRECT_v8i16;
+          IsDirect ? WebAssembly::CALL_v8i16 : WebAssembly::PCALL_INDIRECT_v8i16;
       ResultReg = createResultReg(&WebAssembly::V128RegClass);
       break;
     case MVT::v4i32:
       Opc =
-          IsDirect ? WebAssembly::CALL_v4i32 : WebAssembly::CALL_INDIRECT_v4i32;
+          IsDirect ? WebAssembly::CALL_v4i32 : WebAssembly::PCALL_INDIRECT_v4i32;
       ResultReg = createResultReg(&WebAssembly::V128RegClass);
       break;
     case MVT::v4f32:
       Opc =
-          IsDirect ? WebAssembly::CALL_v4f32 : WebAssembly::CALL_INDIRECT_v4f32;
+          IsDirect ? WebAssembly::CALL_v4f32 : WebAssembly::PCALL_INDIRECT_v4f32;
       ResultReg = createResultReg(&WebAssembly::V128RegClass);
       break;
     default:

llvm/lib/Target/WebAssembly/WebAssemblyInstrCall.td

@@ -29,9 +29,14 @@ multiclass CALL<WebAssemblyRegClass vt, string prefix> {
   def CALL_#vt : I<(outs vt:$dst), (ins i32imm:$callee, variable_ops),
                    [(set vt:$dst, (WebAssemblycall1 (i32 imm:$callee)))],
                    !strconcat(prefix, "call\t$dst, $callee")>;
-  def CALL_INDIRECT_#vt : I<(outs vt:$dst), (ins I32:$callee, variable_ops),
+  let isCodeGenOnly = 1 in {
-                            [(set vt:$dst, (WebAssemblycall1 I32:$callee))],
+    def PCALL_INDIRECT_#vt : I<(outs vt:$dst), (ins I32:$callee, variable_ops),
-                            !strconcat(prefix, "call_indirect\t$dst, $callee")>;
+                              [(set vt:$dst, (WebAssemblycall1 I32:$callee))],
+                              "PSEUDO CALL INDIRECT\t$callee">;
+  } // isCodeGenOnly = 1
+  def CALL_INDIRECT_#vt : I<(outs vt:$dst), (ins variable_ops),
+                            [],
+                            !strconcat(prefix, "call_indirect\t$dst")>;
 }
 
 multiclass SIMD_CALL<ValueType vt, string prefix> {
@@ -39,12 +44,17 @@ multiclass SIMD_CALL<ValueType vt, string prefix> {
                          [(set (vt V128:$dst),
                                (WebAssemblycall1 (i32 imm:$callee)))],
                          !strconcat(prefix, "call\t$dst, $callee")>;
+  let isCodeGenOnly = 1 in {
+    def PCALL_INDIRECT_#vt : SIMD_I<(outs V128:$dst),
+                                    (ins I32:$callee, variable_ops),
+                                    [(set (vt V128:$dst),
+                                          (WebAssemblycall1 I32:$callee))],
+                                    "PSEUDO CALL INDIRECT\t$callee">;
+  } // isCodeGenOnly = 1
   def CALL_INDIRECT_#vt : SIMD_I<(outs V128:$dst),
-                                  (ins I32:$callee, variable_ops),
+                                  (ins variable_ops),
-                                  [(set (vt V128:$dst),
+                                  [],
-                                        (WebAssemblycall1 I32:$callee))],
+                                  !strconcat(prefix, "call_indirect\t$dst")>;
-                                  !strconcat(prefix,
-                                             "call_indirect\t$dst, $callee")>;
 }
 
 let Uses = [SP32, SP64], isCall = 1 in {
@@ -60,9 +70,14 @@ let Uses = [SP32, SP64], isCall = 1 in {
   def CALL_VOID : I<(outs), (ins i32imm:$callee, variable_ops),
                     [(WebAssemblycall0 (i32 imm:$callee))],
                     "call    \t$callee">;
-  def CALL_INDIRECT_VOID : I<(outs), (ins I32:$callee, variable_ops),
+  let isCodeGenOnly = 1 in {
-                             [(WebAssemblycall0 I32:$callee)],
+    def PCALL_INDIRECT_VOID : I<(outs), (ins I32:$callee, variable_ops),
-                             "call_indirect\t$callee">;
+                      [(WebAssemblycall0 I32:$callee)],
+                      "PSEUDO CALL INDIRECT\t$callee">;
+  } // isCodeGenOnly = 1
+  def CALL_INDIRECT_VOID : I<(outs), (ins variable_ops),
+                             [],
+                             "call_indirect\t">;
 } // Uses = [SP32,SP64], isCall = 1
 
 } // Defs = [ARGUMENTS]

llvm/lib/Target/WebAssembly/WebAssemblyTargetMachine.cpp

@@ -229,6 +229,11 @@ void WebAssemblyPassConfig::addPreEmitPass() {
   // colored, and numbered with the rest of the registers.
   addPass(createWebAssemblyReplacePhysRegs());
 
+  // Rewrite pseudo call_indirect instructions as real instructions.
+  // This needs to run before register stackification, because we change the
+  // order of the arguments.
+  addPass(createWebAssemblyCallIndirectFixup());
+
   if (getOptLevel() != CodeGenOpt::None) {
     // LiveIntervals isn't commonly run this late. Re-establish preconditions.
     addPass(createWebAssemblyPrepareForLiveIntervals());

llvm/test/CodeGen/WebAssembly/call.ll

@@ -97,6 +97,24 @@ define i32 @call_indirect_i32(i32 ()* %callee) {
   ret i32 %t
 }
 
+; CHECK-LABEL: call_indirect_arg:
+; CHECK-NEXT: .param i32, i32{{$}}
+; CHECK-NEXT: {{^}} call_indirect $1, $0{{$}}
+; CHECK-NEXT: return{{$}}
+define void @call_indirect_arg(void (i32)* %callee, i32 %arg) {
+  call void %callee(i32 %arg)
+  ret void
+}
+
+; CHECK-LABEL: call_indirect_arg_2:
+; CHECK-NEXT: .param i32, i32, i32{{$}}
+; CHECK-NEXT: {{^}} i32.call_indirect $drop=, $1, $2, $0{{$}}
+; CHECK-NEXT: return{{$}}
+define void @call_indirect_arg_2(i32 (i32, i32)* %callee, i32 %arg, i32 %arg2) {
+  call i32 %callee(i32 %arg, i32 %arg2)
+  ret void
+}
+
 ; CHECK-LABEL: tail_call_void_nullary:
 ; CHECK-NEXT: {{^}} call void_nullary@FUNCTION{{$}}
 ; CHECK-NEXT: return{{$}}

llvm/test/CodeGen/WebAssembly/reg-stackify.ll

@@ -459,6 +459,25 @@ define i32 @stackpointer_dependency(i8* readnone) {
   ret i32 %3
 }
 
+; Stackify a call_indirect with respect to its ordering
+
+; CHECK-LABEL: call_indirect_stackify:
+; CHECK: i32.load  $push[[L4:.+]]=, 0($0)
+; CHECK-NEXT: tee_local $push[[L3:.+]]=, $0=, $pop[[L4]]
+; CHECK-NEXT: i32.load  $push[[L0:.+]]=, 0($0)
+; CHECK-NEXT: i32.load  $push[[L1:.+]]=, 0($pop[[L0]])
+; CHECK-NEXT: i32.call_indirect $push{{.+}}=, $pop[[L3]], $1, $pop[[L1]]
+%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
+  %addr = bitcast %class.call_indirect* %obj to i32(%class.call_indirect*, i32)***
+  %vtable = load i32(%class.call_indirect*, i32)**, i32(%class.call_indirect*, i32)*** %addr
+  %vfn = getelementptr inbounds i32(%class.call_indirect*, i32)*, i32(%class.call_indirect*, i32)** %vtable, i32 0
+  %f = load i32(%class.call_indirect*, i32)*, i32(%class.call_indirect*, i32)** %vfn
+  %ret = call i32 %f(%class.call_indirect* %obj, i32 %arg)
+  ret i32 %ret
+}
+
 !llvm.module.flags = !{!0}
 !llvm.dbg.cu = !{!1}