WebAssemblyCFGStackify.cpp File Reference

This file implements a CFG stacking pass. More...

#include "MCTargetDesc/WebAssemblyMCTargetDesc.h"
#include "Utils/WebAssemblyTypeUtilities.h"
#include "WebAssembly.h"
#include "WebAssemblyExceptionInfo.h"
#include "WebAssemblyMachineFunctionInfo.h"
#include "WebAssemblySortRegion.h"
#include "WebAssemblySubtarget.h"
#include "WebAssemblyUtilities.h"
#include "llvm/ADT/Statistic.h"
#include "llvm/BinaryFormat/Wasm.h"
#include "llvm/CodeGen/MachineDominators.h"
#include "llvm/CodeGen/MachineInstrBuilder.h"
#include "llvm/CodeGen/MachineLoopInfo.h"
#include "llvm/CodeGen/WasmEHFuncInfo.h"
#include "llvm/MC/MCAsmInfo.h"
#include "llvm/Target/TargetMachine.h"

Go to the source code of this file.

Macros
#define	DEBUG_TYPE   "wasm-cfg-stackify"

Functions
	STATISTIC (NumCallUnwindMismatches, "Number of call unwind mismatches found")
	STATISTIC (NumCatchUnwindMismatches, "Number of catch unwind mismatches found")
	INITIALIZE_PASS (WebAssemblyCFGStackify, DEBUG_TYPE, "Insert BLOCK/LOOP/TRY/TRY_TABLE markers for WebAssembly scopes", false, false) FunctionPass *llvm
static bool	explicitlyBranchesTo (MachineBasicBlock *Pred, MachineBasicBlock *MBB)
	Test whether Pred has any terminators explicitly branching to MBB, as opposed to falling through.
template<typename Container >
static MachineBasicBlock::iterator	getEarliestInsertPos (MachineBasicBlock *MBB, const Container &BeforeSet, const Container &AfterSet)
template<typename Container >
static MachineBasicBlock::iterator	getLatestInsertPos (MachineBasicBlock *MBB, const Container &BeforeSet, const Container &AfterSet)
static void	unstackifyVRegsUsedInSplitBB (MachineBasicBlock &MBB, MachineBasicBlock &Split)
static void	splitEndLoopBB (MachineBasicBlock *UnwindDest)
static MachineBasicBlock *	getSingleUnwindDest (const MachineInstr *TryTable)
static void	appendEndToFunction (MachineFunction &MF, const WebAssemblyInstrInfo &TII)

Detailed Description

This file implements a CFG stacking pass.

This pass inserts BLOCK, LOOP, TRY, and TRY_TABLE markers to mark the start of scopes, since scope boundaries serve as the labels for WebAssembly's control transfers.

This is sufficient to convert arbitrary CFGs into a form that works on WebAssembly, provided that all loops are single-entry.

In case we use exceptions, this pass also fixes mismatches in unwind destinations created during transforming CFG into wasm structured format.

Definition in file WebAssemblyCFGStackify.cpp.

Macro Definition Documentation

DEBUG_TYPE

#define DEBUG_TYPE   "wasm-cfg-stackify"

Definition at line 43 of file WebAssemblyCFGStackify.cpp.

Function Documentation

appendEndToFunction()

static void appendEndToFunction ( MachineFunction &  MF, const WebAssemblyInstrInfo &  TII  )

static

Definition at line 2368 of file WebAssemblyCFGStackify.cpp.

References llvm::MachineFunction::back(), llvm::BuildMI(), llvm::MachineBasicBlock::end(), llvm::MachineBasicBlock::findPrevDebugLoc(), and TII.

explicitlyBranchesTo()

static bool explicitlyBranchesTo ( MachineBasicBlock *  Pred, MachineBasicBlock *  MBB  )

static

Test whether Pred has any terminators explicitly branching to MBB, as opposed to falling through.

Note that it's possible (eg. in unoptimized code) for a branch instruction to both branch to a block and fallthrough to it, so we check the actual branch operands to see if there are any explicit mentions.

Definition at line 194 of file WebAssemblyCFGStackify.cpp.

References MBB, MI, and llvm::MachineBasicBlock::terminators().

getEarliestInsertPos()

template<typename Container >

static MachineBasicBlock::iterator getEarliestInsertPos ( MachineBasicBlock *  MBB, const Container &  BeforeSet, const Container &  AfterSet  )

static

Definition at line 210 of file WebAssemblyCFGStackify.cpp.

References assert(), llvm::MachineBasicBlock::begin(), llvm::MachineBasicBlock::end(), and MBB.

getLatestInsertPos()

template<typename Container >

static MachineBasicBlock::iterator getLatestInsertPos ( MachineBasicBlock *  MBB, const Container &  BeforeSet, const Container &  AfterSet  )

static

Definition at line 234 of file WebAssemblyCFGStackify.cpp.

References assert(), llvm::MachineBasicBlock::begin(), llvm::MachineBasicBlock::end(), and MBB.

getSingleUnwindDest()

static MachineBasicBlock * getSingleUnwindDest ( const MachineInstr *  TryTable )

static

Definition at line 1991 of file WebAssemblyCFGStackify.cpp.

References llvm::MachineOperand::getImm(), llvm::MachineOperand::getMBB(), llvm::MachineInstr::getOperand(), llvm_unreachable, llvm::wasm::WASM_OPCODE_CATCH, llvm::wasm::WASM_OPCODE_CATCH_ALL, llvm::wasm::WASM_OPCODE_CATCH_ALL_REF, and llvm::wasm::WASM_OPCODE_CATCH_REF.

INITIALIZE_PASS()

INITIALIZE_PASS	(	WebAssemblyCFGStackify	,
		DEBUG_TYPE	,
		"Insert BLOCK/LOOP/TRY/TRY_TABLE markers for WebAssembly scopes"	,
		false	,
		false
	)

Definition at line 180 of file WebAssemblyCFGStackify.cpp.

splitEndLoopBB()

static void splitEndLoopBB ( MachineBasicBlock *  UnwindDest )

static

Definition at line 1541 of file WebAssemblyCFGStackify.cpp.

References llvm::MachineBasicBlock::begin(), llvm::MachineFunction::CreateMachineBasicBlock(), llvm::ilist_node_impl< OptionsT >::getIterator(), llvm::MachineBasicBlock::getParent(), llvm::MachineFunction::insert(), MI, and llvm::reverse().

STATISTIC() [1/2]

STATISTIC	(	NumCallUnwindMismatches	,
		"Number of call unwind mismatches found"
	)

STATISTIC() [2/2]

STATISTIC	(	NumCatchUnwindMismatches	,
		"Number of catch unwind mismatches found"
	)

unstackifyVRegsUsedInSplitBB()

static void unstackifyVRegsUsedInSplitBB ( MachineBasicBlock &  MBB, MachineBasicBlock &  Split  )

static

Definition at line 1106 of file WebAssemblyCFGStackify.cpp.

References llvm::MachineInstrBuilder::addReg(), llvm::BuildMI(), llvm::WebAssembly::getCopyOpcodeForRegClass(), llvm::MachineFunction::getInfo(), llvm::MachineBasicBlock::getParent(), llvm::MachineFunction::getRegInfo(), llvm::MachineFunction::getSubtarget(), llvm::WebAssembly::isTee(), llvm::make_early_inc_range(), MBB, MI, MRI, and TII.