1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
use either::{
    Either,
    Either::{Left, Right},
};
use llvm_sys::core::{LLVMGetNextUse, LLVMGetUsedValue, LLVMGetUser, LLVMIsABasicBlock, LLVMValueAsBasicBlock};
use llvm_sys::prelude::LLVMUseRef;

use std::marker::PhantomData;

use crate::basic_block::BasicBlock;
use crate::values::{AnyValueEnum, BasicValueEnum};

/// A usage of a `BasicValue` in another value.
#[derive(Clone, Copy, Debug, Eq, PartialEq)]
pub struct BasicValueUse<'ctx>(LLVMUseRef, PhantomData<&'ctx ()>);

impl<'ctx> BasicValueUse<'ctx> {
    /// Get a value from an [LLVMUseRef].
    ///
    /// # Safety
    ///
    /// The ref must be valid and of type basic value.
    pub unsafe fn new(use_: LLVMUseRef) -> Self {
        debug_assert!(!use_.is_null());

        BasicValueUse(use_, PhantomData)
    }

    /// Gets the next use of a `BasicBlock`, `InstructionValue` or `BasicValue` if any.
    ///
    /// The following example,
    ///
    /// ```no_run
    /// 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::default());
    /// 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).unwrap();
    /// let free_instruction = builder.build_free(arg1).unwrap();
    /// let return_instruction = builder.build_return(None).unwrap();
    ///
    /// 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):
    ///
    /// ```ir
    /// ; 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:
    /// 1) In the store instruction
    /// 2) In the pointer bitcast
    pub fn get_next_use(self) -> Option<Self> {
        let use_ = unsafe { LLVMGetNextUse(self.0) };

        if use_.is_null() {
            return None;
        }

        unsafe { Some(Self::new(use_)) }
    }

    /// Gets the user (an `AnyValueEnum`) of this use.
    ///
    /// ```no_run
    /// 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::default());
    /// 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).unwrap();
    /// let free_instruction = builder.build_free(arg1).unwrap();
    /// let return_instruction = builder.build_return(None).unwrap();
    ///
    /// 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);
    /// ```
    pub fn get_user(self) -> AnyValueEnum<'ctx> {
        unsafe { AnyValueEnum::new(LLVMGetUser(self.0)) }
    }

    /// Gets the used value (a `BasicValueEnum` or `BasicBlock`) of this use.
    ///
    /// ```no_run
    /// 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::default());
    /// 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).unwrap();
    /// let free_instruction = builder.build_free(arg1).unwrap();
    /// let return_instruction = builder.build_return(None).unwrap();
    ///
    /// 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);
    /// ```
    pub fn get_used_value(self) -> Either<BasicValueEnum<'ctx>, BasicBlock<'ctx>> {
        let used_value = unsafe { LLVMGetUsedValue(self.0) };

        let is_basic_block = unsafe { !LLVMIsABasicBlock(used_value).is_null() };

        if is_basic_block {
            let bb = unsafe { BasicBlock::new(LLVMValueAsBasicBlock(used_value)) };

            Right(bb.expect("BasicBlock should always be valid"))
        } else {
            unsafe { Left(BasicValueEnum::new(used_value)) }
        }
    }
}