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

#include "Utils/WebAssemblyTypeUtilities.h"
#include "WebAssembly.h"
#include "WebAssemblyExceptionInfo.h"
#include "WebAssemblyMachineFunctionInfo.h"
#include "WebAssemblySortRegion.h"
#include "WebAssemblySubtarget.h"
#include "WebAssemblyTargetMachine.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"

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 *EndTryTableBB)
static MachineBasicBlock *	getSingleUnwindDest (const MachineInstr *TryTable)
static void	appendEndToFunction (MachineFunction &MF, const WebAssemblyInstrInfo &TII)
static void	addUnreachableAfterTryTables (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

◆ addUnreachableAfterTryTables()

void addUnreachableAfterTryTables	(	MachineFunction &	MF,
		const WebAssemblyInstrInfo &	TII )

static

Definition at line 2425 of file WebAssemblyCFGStackify.cpp.

References llvm::BuildMI(), llvm::MachineFunction::CreateMachineBasicBlock(), llvm::MachineInstr::getDebugLoc(), llvm::ilist_node_impl< OptionsT >::getIterator(), llvm::MachineInstr::getParent(), llvm::MachineFunction::insert(), MBB, MI, and TII.

◆ appendEndToFunction()

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

static

Definition at line 2397 of file WebAssemblyCFGStackify.cpp.

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

◆ explicitlyBranchesTo()

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, and MI.