From d1b1fd3a6a76ee76a27bdcca63a80db7aa15b906 Mon Sep 17 00:00:00 2001
From: Richard Feldman <oss@rtfeldman.com>
Date: Sat, 12 Sep 2020 21:57:11 -0400
Subject: [PATCH] Consistently cast string length to usize

---
 compiler/gen/src/llvm/build_str.rs | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/compiler/gen/src/llvm/build_str.rs b/compiler/gen/src/llvm/build_str.rs
index 93a26d3e0d..1b8cc4cdc0 100644
--- a/compiler/gen/src/llvm/build_str.rs
+++ b/compiler/gen/src/llvm/build_str.rs
@@ -203,6 +203,7 @@ pub fn str_concat<'a, 'ctx, 'env>(
     )
 }
 
+/// Obtain the string's length, cast from i8 to usize
 fn str_len_from_final_byte<'a, 'ctx, 'env>(
     env: &Env<'a, 'ctx, 'env>,
     final_byte: IntValue<'ctx>,
@@ -210,8 +211,9 @@ fn str_len_from_final_byte<'a, 'ctx, 'env>(
     let builder = env.builder;
     let ctx = env.context;
     let bitmask = ctx.i8_type().const_int(0b0111_1111, false);
+    let len_i8 = builder.build_and(final_byte, bitmask, "small_str_length");
 
-    builder.build_and(final_byte, bitmask, "small_str_length")
+    builder.build_int_cast(len_i8, env.ptr_int(), "len_as_usize")
 }
 
 /// Used by LowLevel::StrIsEmpty
@@ -257,11 +259,9 @@ where
     let builder = env.builder;
 
     let if_small = |final_byte| {
-        let len = str_len_from_final_byte(env, final_byte);
-
         cb(
             cast_str_wrapper_to_array(env, wrapper_ptr),
-            builder.build_int_cast(len, env.ptr_int(), "len_as_usize"),
+            str_len_from_final_byte(env, final_byte),
             Smallness::Small,
         )
     };