Add set_field_at_index for llvm-plugin

Signed-off-by: Alex Saveau <[email protected]>

src/values/struct_value.rs

@@ -1,4 +1,4 @@
-use llvm_sys::core::{LLVMGetNumOperands, LLVMGetOperand};
+use llvm_sys::core::{LLVMGetNumOperands, LLVMGetOperand, LLVMSetOperand};
 
 use llvm_sys::prelude::LLVMValueRef;
 
@@ -7,7 +7,7 @@ use std::fmt::{self, Display};
 
 use crate::types::StructType;
 use crate::values::traits::AsValueRef;
-use crate::values::{InstructionValue, Value};
+use crate::values::{BasicValue, InstructionValue, Value};
 
 use super::{AnyValue, BasicValueEnum};
 
@@ -52,6 +52,17 @@ impl<'ctx> StructValue<'ctx> {
         unsafe { Some(BasicValueEnum::new(LLVMGetOperand(self.as_value_ref(), index))) }
     }
 
+    /// Sets the value of a field belonging to this `StructValue`.
+    pub fn set_field_at_index<BV: BasicValue<'ctx>>(self, index: u32, val: BV) -> bool {
+        if index >= self.count_fields() {
+            return false;
+        }
+
+        unsafe { LLVMSetOperand(self.as_value_ref(), index, val.as_value_ref()) }
+
+        true
+    }
+
     /// Counts the number of fields.
     ///
     /// ```no_run