1 //===-- WebAssemblyCallIndirectFixup.cpp - Fix call_indirects -------------===//
3 // The LLVM Compiler Infrastructure
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
8 //===----------------------------------------------------------------------===//
11 /// This file converts pseudo call_indirect instructions into real
14 /// The order of arguments for a call_indirect is the arguments to the function
15 /// call, followed by the function pointer. There's no natural way to express
16 /// a machineinstr with varargs followed by one more arg, so we express it as
17 /// the function pointer followed by varargs, then rewrite it here.
19 /// We need to rewrite the order of the arguments on the machineinstrs
20 /// themselves so that register stackification knows the order they'll be
23 //===----------------------------------------------------------------------===//
25 #include "MCTargetDesc/WebAssemblyMCTargetDesc.h" // for WebAssembly::ARGUMENT_*
26 #include "WebAssembly.h"
27 #include "WebAssemblyMachineFunctionInfo.h"
28 #include "WebAssemblySubtarget.h"
29 #include "llvm/Analysis/AliasAnalysis.h"
30 #include "llvm/CodeGen/LiveIntervals.h"
31 #include "llvm/CodeGen/MachineBlockFrequencyInfo.h"
32 #include "llvm/CodeGen/MachineDominators.h"
33 #include "llvm/CodeGen/MachineInstrBuilder.h"
34 #include "llvm/CodeGen/MachineRegisterInfo.h"
35 #include "llvm/CodeGen/Passes.h"
36 #include "llvm/Support/Debug.h"
37 #include "llvm/Support/raw_ostream.h"
40 #define DEBUG_TYPE "wasm-call-indirect-fixup"
43 class WebAssemblyCallIndirectFixup final : public MachineFunctionPass {
44 StringRef getPassName() const override {
45 return "WebAssembly CallIndirect Fixup";
48 bool runOnMachineFunction(MachineFunction &MF) override;
51 static char ID; // Pass identification, replacement for typeid
52 WebAssemblyCallIndirectFixup() : MachineFunctionPass(ID) {}
54 } // end anonymous namespace
56 char WebAssemblyCallIndirectFixup::ID = 0;
57 INITIALIZE_PASS(WebAssemblyCallIndirectFixup, DEBUG_TYPE,
58 "Rewrite call_indirect argument orderings", false, false)
60 FunctionPass *llvm::createWebAssemblyCallIndirectFixup() {
61 return new WebAssemblyCallIndirectFixup();
64 static unsigned GetNonPseudoCallIndirectOpcode(const MachineInstr &MI) {
65 switch (MI.getOpcode()) {
66 using namespace WebAssembly;
67 case PCALL_INDIRECT_VOID:
68 return CALL_INDIRECT_VOID;
69 case PCALL_INDIRECT_I32:
70 return CALL_INDIRECT_I32;
71 case PCALL_INDIRECT_I64:
72 return CALL_INDIRECT_I64;
73 case PCALL_INDIRECT_F32:
74 return CALL_INDIRECT_F32;
75 case PCALL_INDIRECT_F64:
76 return CALL_INDIRECT_F64;
77 case PCALL_INDIRECT_v16i8:
78 return CALL_INDIRECT_v16i8;
79 case PCALL_INDIRECT_v8i16:
80 return CALL_INDIRECT_v8i16;
81 case PCALL_INDIRECT_v4i32:
82 return CALL_INDIRECT_v4i32;
83 case PCALL_INDIRECT_v2i64:
84 return CALL_INDIRECT_v2i64;
85 case PCALL_INDIRECT_v4f32:
86 return CALL_INDIRECT_v4f32;
87 case PCALL_INDIRECT_v2f64:
88 return CALL_INDIRECT_v2f64;
90 return INSTRUCTION_LIST_END;
94 static bool IsPseudoCallIndirect(const MachineInstr &MI) {
95 return GetNonPseudoCallIndirectOpcode(MI) !=
96 WebAssembly::INSTRUCTION_LIST_END;
99 bool WebAssemblyCallIndirectFixup::runOnMachineFunction(MachineFunction &MF) {
100 LLVM_DEBUG(dbgs() << "********** Fixing up CALL_INDIRECTs **********\n"
101 << "********** Function: " << MF.getName() << '\n');
103 bool Changed = false;
104 const WebAssemblyInstrInfo *TII =
105 MF.getSubtarget<WebAssemblySubtarget>().getInstrInfo();
107 for (MachineBasicBlock &MBB : MF) {
108 for (MachineInstr &MI : MBB) {
109 if (IsPseudoCallIndirect(MI)) {
110 LLVM_DEBUG(dbgs() << "Found call_indirect: " << MI << '\n');
112 // Rewrite pseudo to non-pseudo
113 const MCInstrDesc &Desc = TII->get(GetNonPseudoCallIndirectOpcode(MI));
116 // Rewrite argument order
117 SmallVector<MachineOperand, 8> Ops;
119 // Set up a placeholder for the type signature immediate.
120 Ops.push_back(MachineOperand::CreateImm(0));
122 // Set up the flags immediate, which currently has no defined flags
123 // so it's always zero.
124 Ops.push_back(MachineOperand::CreateImm(0));
126 for (const MachineOperand &MO :
127 make_range(MI.operands_begin() + MI.getDesc().getNumDefs() + 1,
128 MI.operands_begin() + MI.getNumExplicitOperands()))
130 Ops.push_back(MI.getOperand(MI.getDesc().getNumDefs()));
132 // Replace the instructions operands.
133 while (MI.getNumOperands() > MI.getDesc().getNumDefs())
134 MI.RemoveOperand(MI.getNumOperands() - 1);
135 for (const MachineOperand &MO : Ops)
138 LLVM_DEBUG(dbgs() << " After transform: " << MI);
144 LLVM_DEBUG(dbgs() << "\nDone fixing up CALL_INDIRECTs\n\n");