#include "clang/CIR/Dialect/Analysis/CIRBasicAliasAnalysis.h"
#include "mlir/Interfaces/SideEffectInterfaces.h"
#include "clang/CIR/Dialect/IR/CIRAttrs.h"
#include "clang/CIR/Dialect/IR/CIRDialect.h"
#include "llvm/Support/DebugLog.h"
#include "llvm/Support/MathExtras.h"
#include <limits>

Macros
#define	DEBUG_TYPE "cir-basic-alias-analysis"

Functions
static std::optional< int64_t >	getTypeSizeInBytes (mlir::Type type, const mlir::DataLayout &dataLayout)
	Return the size in bytes of `type`, or std::nullopt when that size isn't statically known (void, function types, incomplete records, ...).
static std::optional< int64_t >	getConstantIndex (mlir::Value val)
	If `val` is a constant integer that fits in an int64_t, return its value.
static std::optional< int64_t >	scaleOffset (std::optional< int64_t > count, std::optional< int64_t > size)
	Return count * size, or std::nullopt if either input is unknown or the product overflows.
static void	addToOffset (std::optional< int64_t > &offset, std::optional< int64_t > delta)
	Add `delta` bytes to `offset`, making the offset unknown if `delta` is unknown or if the sum overflows.
static PointerOffset	decomposePointer (mlir::Value val, const mlir::DataLayout &dataLayout)
	Trace `val` back to the object it points into, accumulating the byte offset of `val` from the start of that object.
static bool	areDistinctObjects (mlir::Value lhs, mlir::Value rhs)
	Return true if `lhs` and `rhs` are provably different objects.

Variables
static constexpr unsigned	MaxLookupDepth = 6

Macro Definition Documentation

◆ DEBUG_TYPE

#define DEBUG_TYPE "cir-basic-alias-analysis"

Definition at line 18 of file CIRBasicAliasAnalysis.cpp.

Function Documentation

◆ addToOffset()

void addToOffset	(	std::optional< int64_t > &	offset,
		std::optional< int64_t >	delta )

static

Add delta bytes to offset, making the offset unknown if delta is unknown or if the sum overflows.

Definition at line 74 of file CIRBasicAliasAnalysis.cpp.

Referenced by decomposePointer().

◆ areDistinctObjects()

bool areDistinctObjects	(	mlir::Value	lhs,
		mlir::Value	rhs )

static

Return true if lhs and rhs are provably different objects.

TODO: Extend to cover global addresses, function arguments with noalias, and heap allocations.

Definition at line 230 of file CIRBasicAliasAnalysis.cpp.

Referenced by cir::CIRBasicAliasAnalysis::alias().

◆ decomposePointer()

PointerOffset decomposePointer	(	mlir::Value	val,
		const mlir::DataLayout &	dataLayout )

static

Trace val back to the object it points into, accumulating the byte offset of val from the start of that object.

The walk stops at a block argument, at an allocation, or at any operation whose result cannot be described as an offset from one of its operands. The returned base and offset always describe val, even when the walk stops early because the depth limit was reached.

Operations contributing an offset that isn't a compile-time constant (a dynamic cir.ptr_stride index, for example) are still traced through, leaving the offset unknown. Knowing which object a pointer points into is useful even when the offset within that object is not known.

Definition at line 115 of file CIRBasicAliasAnalysis.cpp.

References addToOffset(), getConstantIndex(), getTypeSizeInBytes(), MaxLookupDepth, and scaleOffset().

Referenced by cir::CIRBasicAliasAnalysis::alias().