Apparently, LLVM{Get,Set}Ordering were first added to the LLVM C API in 3.8.

Author: nlewycky

Diff for: src/values/instruction_value.rs

@@ -1,5 +1,7 @@
 use either::{Either, Either::{Left, Right}};
-use llvm_sys::core::{LLVMGetAlignment, LLVMSetAlignment, LLVMGetOrdering, LLVMSetOrdering, LLVMGetInstructionOpcode, LLVMIsTailCall, LLVMGetPreviousInstruction, LLVMGetNextInstruction, LLVMGetInstructionParent, LLVMInstructionEraseFromParent, LLVMInstructionClone, LLVMSetVolatile, LLVMGetVolatile, LLVMGetNumOperands, LLVMGetOperand, LLVMGetOperandUse, LLVMSetOperand, LLVMValueAsBasicBlock, LLVMIsABasicBlock, LLVMGetICmpPredicate, LLVMGetFCmpPredicate, LLVMIsAAllocaInst, LLVMIsALoadInst, LLVMIsAStoreInst};
+use llvm_sys::core::{LLVMGetAlignment, LLVMSetAlignment, LLVMGetInstructionOpcode, LLVMIsTailCall, LLVMGetPreviousInstruction, LLVMGetNextInstruction, LLVMGetInstructionParent, LLVMInstructionEraseFromParent, LLVMInstructionClone, LLVMSetVolatile, LLVMGetVolatile, LLVMGetNumOperands, LLVMGetOperand, LLVMGetOperandUse, LLVMSetOperand, LLVMValueAsBasicBlock, LLVMIsABasicBlock, LLVMGetICmpPredicate, LLVMGetFCmpPredicate, LLVMIsAAllocaInst, LLVMIsALoadInst, LLVMIsAStoreInst};
+#[llvm_versions(3.8..=latest)]
+use llvm_sys::core::{LLVMGetOrdering, LLVMSetOrdering};
 #[llvm_versions(3.9..=latest)]
 use llvm_sys::core::LLVMInstructionRemoveFromParent;
 use llvm_sys::LLVMOpcode;
@@ -237,6 +239,7 @@ impl InstructionValue {
 
     // SubTypes: Only apply to memory access instructions
     /// Returns atomic ordering on a memory access instruction.
+    #[llvm_versions(3.8..=latest)]
     pub fn get_atomic_ordering(&self) -> Result<AtomicOrdering, &'static str> {
         if !self.is_a_load_inst() && !self.is_a_store_inst() {
             return Err("Value is not a load or store.");
@@ -246,6 +249,7 @@ impl InstructionValue {
 
     // SubTypes: Only apply to memory access instructions
     /// Sets atomic ordering on a memory access instruction.
+    #[llvm_versions(3.8..=latest)]
     pub fn set_atomic_ordering(&self, ordering: AtomicOrdering) -> Result<(), &'static str> {
         // Although fence and atomicrmw both have an ordering, the LLVM C API
         // does not support them. The cmpxchg instruction has two orderings and

Diff for: tests/all/test_instruction_values.rs

@@ -304,6 +304,42 @@ fn test_mem_instructions() {
     assert!(store_instruction.set_alignment(14).is_err());
     assert_eq!(store_instruction.get_alignment().unwrap(), 0);
 
+    let fadd_instruction = builder.build_float_add(load.into_float_value(), f32_val, "").as_instruction_value().unwrap();
+    assert!(fadd_instruction.get_volatile().is_err());
+    assert!(fadd_instruction.set_volatile(false).is_err());
+    assert!(fadd_instruction.get_alignment().is_err());
+    assert!(fadd_instruction.set_alignment(16).is_err());
+}
+
+#[llvm_versions(3.8..=latest)]
+#[test]
+fn test_atomic_ordering_mem_instructions() {
+    let context = Context::create();
+    let module = context.create_module("testing");
+    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(), f32_type.into()], false);
+
+    let function = module.add_function("mem_inst", 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 arg2 = function.get_nth_param(1).unwrap().into_float_value();
+
+    assert!(arg1.get_first_use().is_none());
+    assert!(arg2.get_first_use().is_none());
+
+    let f32_val = f32_type.const_float(::std::f64::consts::PI);
+
+    let store_instruction = builder.build_store(arg1, f32_val);
+    let load = builder.build_load(arg1, "");
+    let load_instruction = load.as_instruction_value().unwrap();
+
     assert_eq!(store_instruction.get_atomic_ordering().unwrap(), AtomicOrdering::NotAtomic);
     assert_eq!(load_instruction.get_atomic_ordering().unwrap(), AtomicOrdering::NotAtomic);
     assert!(store_instruction.set_atomic_ordering(AtomicOrdering::Monotonic).is_ok());
@@ -317,10 +353,6 @@ fn test_mem_instructions() {
     assert!(load_instruction.set_atomic_ordering(AtomicOrdering::Release).is_err());
 
     let fadd_instruction = builder.build_float_add(load.into_float_value(), f32_val, "").as_instruction_value().unwrap();
-    assert!(fadd_instruction.get_volatile().is_err());
-    assert!(fadd_instruction.set_volatile(false).is_err());
-    assert!(fadd_instruction.get_alignment().is_err());
-    assert!(fadd_instruction.set_alignment(16).is_err());
     assert!(fadd_instruction.get_atomic_ordering().is_err());
     assert!(fadd_instruction.set_atomic_ordering(AtomicOrdering::NotAtomic).is_err());
 }