Struct llvm_plugin_inkwell::values::BasicValueUse

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pub struct BasicValueUse<'ctx>(_, _);

Expand description

A usage of a BasicValue in another value.

Implementations

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impl<'ctx> BasicValueUse<'ctx>

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pub fn get_next_use(self) -> Option<Self>

Gets the next use of a BasicBlock, InstructionValue or BasicValue if any.

The following example,

use inkwell::AddressSpace;
use inkwell::context::Context;
use inkwell::values::BasicValue;

let context = Context::create();
let module = context.create_module("ivs");
let builder = context.create_builder();
let void_type = context.void_type();
let f32_type = context.f32_type();
let f32_ptr_type = f32_type.ptr_type(AddressSpace::Generic);
let fn_type = void_type.fn_type(&[f32_ptr_type.into()], false);

let function = module.add_function("take_f32_ptr", fn_type, None);
let basic_block = context.append_basic_block(function, "entry");

builder.position_at_end(basic_block);

let arg1 = function.get_first_param().unwrap().into_pointer_value();
let f32_val = f32_type.const_float(::std::f64::consts::PI);
let store_instruction = builder.build_store(arg1, f32_val);
let free_instruction = builder.build_free(arg1);
let return_instruction = builder.build_return(None);

let arg1_first_use = arg1.get_first_use().unwrap();

assert!(arg1_first_use.get_next_use().is_some());

will generate LLVM IR roughly like (varying slightly across LLVM versions):

; ModuleID = 'ivs'
source_filename = "ivs"

define void @take_f32_ptr(float* %0) {
entry:
  store float 0x400921FB60000000, float* %0
  %1 = bitcast float* %0 to i8*
  tail call void @free(i8* %1)
  ret void
}

declare void @free(i8*)

which makes the arg1 (%0) uses clear:

In the store instruction
In the pointer bitcast

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pub fn get_user(self) -> AnyValueEnum<'ctx>

Gets the user (an AnyValueEnum) of this use.

use inkwell::AddressSpace;
use inkwell::context::Context;
use inkwell::values::BasicValue;

let context = Context::create();
let module = context.create_module("ivs");
let builder = context.create_builder();
let void_type = context.void_type();
let f32_type = context.f32_type();
let f32_ptr_type = f32_type.ptr_type(AddressSpace::Generic);
let fn_type = void_type.fn_type(&[f32_ptr_type.into()], false);

let function = module.add_function("take_f32_ptr", fn_type, None);
let basic_block = context.append_basic_block(function, "entry");

builder.position_at_end(basic_block);

let arg1 = function.get_first_param().unwrap().into_pointer_value();
let f32_val = f32_type.const_float(::std::f64::consts::PI);
let store_instruction = builder.build_store(arg1, f32_val);
let free_instruction = builder.build_free(arg1);
let return_instruction = builder.build_return(None);

let store_operand_use0 = store_instruction.get_operand_use(0).unwrap();
let store_operand_use1 = store_instruction.get_operand_use(1).unwrap();

assert_eq!(store_operand_use0.get_user(), store_instruction);
assert_eq!(store_operand_use1.get_user(), store_instruction);

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pub fn get_used_value(self) -> Either<BasicValueEnum<'ctx>, BasicBlock<'ctx>>

Gets the used value (a BasicValueEnum or BasicBlock) of this use.

use inkwell::AddressSpace;
use inkwell::context::Context;
use inkwell::values::BasicValue;

let context = Context::create();
let module = context.create_module("ivs");
let builder = context.create_builder();
let void_type = context.void_type();
let f32_type = context.f32_type();
let f32_ptr_type = f32_type.ptr_type(AddressSpace::Generic);
let fn_type = void_type.fn_type(&[f32_ptr_type.into()], false);

let function = module.add_function("take_f32_ptr", fn_type, None);
let basic_block = context.append_basic_block(function, "entry");

builder.position_at_end(basic_block);

let arg1 = function.get_first_param().unwrap().into_pointer_value();
let f32_val = f32_type.const_float(::std::f64::consts::PI);
let store_instruction = builder.build_store(arg1, f32_val);
let free_instruction = builder.build_free(arg1);
let return_instruction = builder.build_return(None);

let free_operand0 = free_instruction.get_operand(0).unwrap().left().unwrap();
let free_operand0_instruction = free_operand0.as_instruction_value().unwrap();
let bitcast_use_value = free_operand0_instruction
    .get_first_use()
    .unwrap()
    .get_used_value()
    .left()
    .unwrap();

assert_eq!(bitcast_use_value, free_operand0);