#ifndef HALIDE_CODEGEN_POSIX_H
#define HALIDE_CODEGEN_POSIX_H
/** \file
* Defines a base-class for code-generators on posixy cpu platforms
*/
#include "CodeGen_LLVM.h"
namespace Halide {
namespace Internal {
/** A code generator that emits posix code from a given Halide stmt. */
class CodeGen_Posix : public CodeGen_LLVM {
public:
/** Create an posix code generator. Processor features can be
* enabled using the appropriate arguments */
CodeGen_Posix(Target t);
protected:
using CodeGen_LLVM::visit;
/** Posix implementation of Allocate. Small constant-sized allocations go
* on the stack. The rest go on the heap by calling "halide_malloc"
* and "halide_free" in the standard library. */
// @{
void visit(const Allocate *);
void visit(const Free *);
// @}
/** It can be convenient for backends to assume there is extra
* padding beyond the end of a buffer to enable faster
* loads/stores. This function gets the padding required by the
* implementing target. */
virtual int allocation_padding(Type type) const;
/** A struct describing heap or stack allocations. */
struct Allocation {
/** The memory */
llvm::Value *ptr;
/** Destructor stack slot for this allocation. */
llvm::Value *destructor;
/** Function to accomplish the destruction. */
llvm::Function *destructor_function;
/** The (Halide) type of the allocation. */
Type type;
/** How many bytes this allocation is, or 0 if not
* constant. */
int constant_bytes;
/** How many bytes of stack space used. 0 implies it was a
* heap allocation. */
int stack_bytes;
/** A unique name for this allocation. May not be equal to the
* Allocate node name in cases where we detect multiple
* Allocate nodes can share a single allocation. */
std::string name;
};
/** The allocations currently in scope. The stack gets pushed when
* we enter a new function. */
Scope<Allocation> allocations;
std::string get_allocation_name(const std::string &n);
private:
/** Stack allocations that were freed, but haven't gone out of
* scope yet. This allows us to re-use stack allocations when
* they aren't being used. */
std::vector<Allocation> free_stack_allocs;
/** current size of all alloca instances in use; this is tracked only
* for debug output purposes. */
size_t cur_stack_alloc_total{0};
/** Generates code for computing the size of an allocation from a
* list of its extents and its size. Fires a runtime assert
* (halide_error) if the size overflows 2^31 -1, the maximum
* positive number an int32_t can hold. */
llvm::Value *codegen_allocation_size(const std::string &name, Type type, const std::vector<Expr> &extents);
/** Allocates some memory on either the stack or the heap, and
* returns an Allocation object describing it. For heap
* allocations this calls halide_malloc in the runtime, and for
* stack allocations it either reuses an existing block from the
* free_stack_blocks list, or it saves the stack pointer and calls
* alloca.
*
* This call returns the allocation, pushes it onto the
* 'allocations' map, and adds an entry to the symbol table called
* name.host that provides the base pointer.
*
* When the allocation can be freed call 'free_allocation', and
* when it goes out of scope call 'destroy_allocation'. */
Allocation create_allocation(const std::string &name, Type type,
const std::vector<Expr> &extents,
Expr condition, Expr new_expr, std::string free_function);
/** Free an allocation previously allocated with
* create_allocation */
void free_allocation(const std::string &name);
};
}}
#endif