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 "WebAssemblyUtilities.h"
#include "llvm/ADT/Statistic.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 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	appendEndToFunction (MachineFunction &MF, const WebAssemblyInstrInfo &TII)

Detailed Description

This file implements a CFG stacking pass.

This pass inserts BLOCK, LOOP, and TRY 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 41 of file WebAssemblyCFGStackify.cpp.

Function Documentation

◆ appendEndToFunction()

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

static

Definition at line 1530 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 165 of file WebAssemblyCFGStackify.cpp.

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