3 files changed, 32 insertions, 2 deletions
diff --git a/src/codegen/c.zig b/src/codegen/c.zig
index 826b73317c..22420aca45 100644
--- a/src/codegen/c.zig
+++ b/src/codegen/c.zig
@@ -900,6 +900,7 @@ fn genBody(o: *Object, body: []const Air.Inst.Index) error{ AnalysisFail, OutOfM
             .call             => try airCall(o, inst),
             .dbg_stmt         => try airDbgStmt(o, inst),
             .intcast          => try airIntCast(o, inst),
+            .trunc            => try airTrunc(o, inst),
             .bool_to_int      => try airBoolToInt(o, inst),
             .load             => try airLoad(o, inst),
             .ret              => try airRet(o, inst),
@@ -1038,7 +1039,7 @@ fn airIntCast(o: *Object, inst: Air.Inst.Index) !CValue {
         return CValue.none;
 
     const ty_op = o.air.instructions.items(.data)[inst].ty_op;
-    const from = try o.resolveInst(ty_op.operand);
+    const operand = try o.resolveInst(ty_op.operand);
 
     const writer = o.writer();
     const inst_ty = o.air.typeOfIndex(inst);
@@ -1046,11 +1047,21 @@ fn airIntCast(o: *Object, inst: Air.Inst.Index) !CValue {
     try writer.writeAll(" = (");
     try o.dg.renderType(writer, inst_ty);
     try writer.writeAll(")");
-    try o.writeCValue(writer, from);
+    try o.writeCValue(writer, operand);
     try writer.writeAll(";\n");
     return local;
 }
 
+fn airTrunc(o: *Object, inst: Air.Inst.Index) !CValue {
+    if (o.liveness.isUnused(inst))
+        return CValue.none;
+
+    const ty_op = o.air.instructions.items(.data)[inst].ty_op;
+    const operand = try o.resolveInst(ty_op.operand);
+    _ = operand;
+    return o.dg.fail("TODO: C backend: airTrunc", .{});
+}
+
 fn airBoolToInt(o: *Object, inst: Air.Inst.Index) !CValue {
     if (o.liveness.isUnused(inst))
         return CValue.none;
diff --git a/src/codegen/llvm.zig b/src/codegen/llvm.zig
index 961ed7ee99..8b3edcfe23 100644
--- a/src/codegen/llvm.zig
+++ b/src/codegen/llvm.zig
@@ -960,6 +960,7 @@ pub const FuncGen = struct {
                 .call       => try self.airCall(inst),
                 .cond_br    => try self.airCondBr(inst),
                 .intcast    => try self.airIntCast(inst),
+                .trunc      => try self.airTrunc(inst),
                 .floatcast  => try self.airFloatCast(inst),
                 .ptrtoint   => try self.airPtrToInt(inst),
                 .load       => try self.airLoad(inst),
@@ -1615,6 +1616,16 @@ pub const FuncGen = struct {
         return self.builder.buildIntCast2(operand, try self.dg.llvmType(inst_ty), llvm.Bool.fromBool(signed), "");
     }
 
+    fn airTrunc(self: *FuncGen, inst: Air.Inst.Index) !?*const llvm.Value {
+        if (self.liveness.isUnused(inst))
+            return null;
+
+        const ty_op = self.air.instructions.items(.data)[inst].ty_op;
+        const operand = try self.resolveInst(ty_op.operand);
+        const dest_llvm_ty = try self.dg.llvmType(self.air.typeOfIndex(inst));
+        return self.builder.buildTrunc(operand, dest_llvm_ty, "");
+    }
+
     fn airFloatCast(self: *FuncGen, inst: Air.Inst.Index) !?*const llvm.Value {
         if (self.liveness.isUnused(inst))
             return null;
diff --git a/src/codegen/llvm/bindings.zig b/src/codegen/llvm/bindings.zig
index 0977d6128d..4af3cadd84 100644
--- a/src/codegen/llvm/bindings.zig
+++ b/src/codegen/llvm/bindings.zig
@@ -423,6 +423,14 @@ pub const Builder = opaque {
         Idx: c_uint,
         Name: [*:0]const u8,
     ) *const Value;
+
+    pub const buildTrunc = LLVMBuildTrunc;
+    extern fn LLVMBuildTrunc(
+        *const Builder,
+        Val: *const Value,
+        DestTy: *const Type,
+        Name: [*:0]const u8,
+    ) *const Value;
 };
 
 pub const IntPredicate = enum(c_int) {