core: Simplify loop condition check for list comprehension

nac3core/src/codegen/expr.rs

@@ -3,6 +3,7 @@ use std::{collections::HashMap, convert::TryInto, iter::once, iter::zip};
 use crate::{
     codegen::{
         concrete_type::{ConcreteFuncArg, ConcreteTypeEnum, ConcreteTypeStore},
+        gen_in_range_check,
         get_llvm_type,
         get_llvm_abi_type,
         irrt::*,
@@ -963,11 +964,14 @@ pub fn gen_comprehension<'ctx, 'a, G: CodeGenerator>(
 
             let i = generator.gen_store_target(ctx, target, Some("i.addr"))?;
             ctx.builder.build_store(i, ctx.builder.build_int_sub(start, step, "start_init"));
-            ctx.builder.build_unconditional_branch(test_bb);
+
+            ctx.builder.build_conditional_branch(
+                gen_in_range_check(ctx, start, stop, step),
+                test_bb,
+                cont_bb,
+            );
 
             ctx.builder.position_at_end(test_bb);
-            let sign =
-                ctx.builder.build_int_compare(IntPredicate::SGT, step, zero_32, "sign");
             // add and test
             let tmp = ctx.builder.build_int_add(
                 ctx.builder.build_load(i, "i").into_int_value(),
@@ -975,14 +979,8 @@ pub fn gen_comprehension<'ctx, 'a, G: CodeGenerator>(
                 "start_loop",
             );
             ctx.builder.build_store(i, tmp);
-            // if step > 0, continue when i < end
-            let cmp1 = ctx.builder.build_int_compare(IntPredicate::SLT, tmp, stop, "cmp1");
-            // if step < 0, continue when i > end
-            let cmp2 = ctx.builder.build_int_compare(IntPredicate::SGT, tmp, stop, "cmp2");
-            let pos = ctx.builder.build_and(sign, cmp1, "pos");
-            let neg = ctx.builder.build_and(ctx.builder.build_not(sign, "inv"), cmp2, "neg");
             ctx.builder.build_conditional_branch(
-                ctx.builder.build_or(pos, neg, "or"),
+                gen_in_range_check(ctx, tmp, stop, step),
                 body_bb,
                 cont_bb,
             );
@@ -1001,7 +999,7 @@ pub fn gen_comprehension<'ctx, 'a, G: CodeGenerator>(
                 ctx.build_gep_and_load(list, &[zero_size_t, zero_32], Some("list_content")).into_pointer_value();
             let counter = generator.gen_var_alloc(ctx, size_t.into(), Some("counter.addr"))?;
             // counter = -1
-            ctx.builder.build_store(counter, size_t.const_int(u64::max_value(), true));
+            ctx.builder.build_store(counter, size_t.const_int(u64::MAX, true));
             ctx.builder.build_unconditional_branch(test_bb);
 
             ctx.builder.position_at_end(test_bb);

nac3core/src/codegen/mod.rs

@@ -899,3 +899,31 @@ fn bool_to_i8<'ctx>(
         ),
     }
 }
+
+/// Generates a sequence of IR which checks whether `value` does not exceed the upper bound of the
+/// range as defined by `stop` and `step`.
+///
+/// Note that the generated IR will **not** check whether value is part of the range or whether
+/// value exceeds the lower bound of the range (as evident by the missing `start` argument).
+///
+/// The generated IR is equivalent to the following Rust code:
+///
+/// ```rust,ignore
+/// let sign = step > 0;
+/// let (lo, hi) = if sign { (value, stop) } else { (stop, value) };
+/// let cmp = lo < hi;
+/// ```
+///
+/// Returns an `i1` [IntValue] representing the result of whether the `value` is in the range.
+fn gen_in_range_check<'ctx, 'a>(
+    ctx: &CodeGenContext<'ctx, 'a>,
+    value: IntValue<'ctx>,
+    stop: IntValue<'ctx>,
+    step: IntValue<'ctx>,
+) -> IntValue<'ctx> {
+    let sign = ctx.builder.build_int_compare(IntPredicate::SGT, step, ctx.ctx.i32_type().const_zero(), "");
+    let lo = ctx.builder.build_select(sign, value, stop, "").into_int_value();
+    let hi = ctx.builder.build_select(sign, stop, value, "").into_int_value();
+
+    ctx.builder.build_int_compare(IntPredicate::SLT, lo, hi, "cmp")
+}

nac3core/src/codegen/stmt.rs

@@ -5,7 +5,10 @@ use super::{
     CodeGenContext, CodeGenerator,
 };
 use crate::{
-    codegen::expr::gen_binop_expr,
+    codegen::{
+        expr::gen_binop_expr,
+        gen_in_range_check,
+    },
     toplevel::{DefinitionId, TopLevelDef},
     typecheck::typedef::{FunSignature, Type, TypeEnum},
 };
@@ -13,7 +16,7 @@ use inkwell::{
     attributes::{Attribute, AttributeLoc},
     basic_block::BasicBlock,
     types::BasicTypeEnum,
-    values::{BasicValue, BasicValueEnum, FunctionValue, IntValue, PointerValue},
+    values::{BasicValue, BasicValueEnum, FunctionValue, PointerValue},
     IntPredicate,
 };
 use nac3parser::ast::{
@@ -232,34 +235,6 @@ pub fn gen_assign<'ctx, 'a, G: CodeGenerator>(
     Ok(())
 }
 
-/// Generates a sequence of IR which checks whether `value` does not exceed the upper bound of the
-/// range as defined by `stop` and `step`.
-///
-/// Note that the generated IR will **not** check whether value is part of the range or whether
-/// value exceeds the lower bound of the range (as evident by the missing `start` argument).
-///
-/// The generated IR is equivalent to the following Rust code:
-///
-/// ```rust,ignore
-/// let sign = step > 0;
-/// let (lo, hi) = if sign { (value, stop) } else { (stop, value) };
-/// let cmp = lo < hi;
-/// ```
-///
-/// Returns an `i1` [IntValue] representing the result of whether the `value` is in the range.
-fn gen_in_range_check<'ctx, 'a>(
-    ctx: &CodeGenContext<'ctx, 'a>,
-    value: IntValue<'ctx>,
-    stop: IntValue<'ctx>,
-    step: IntValue<'ctx>,
-) -> IntValue<'ctx> {
-    let sign = ctx.builder.build_int_compare(IntPredicate::SGT, step, ctx.ctx.i32_type().const_zero(), "");
-    let lo = ctx.builder.build_select(sign, value, stop, "").into_int_value();
-    let hi = ctx.builder.build_select(sign, stop, value, "").into_int_value();
-
-    ctx.builder.build_int_compare(IntPredicate::SLT, lo, hi, "cmp")
-}
-
 /// See [CodeGenerator::gen_for].
 pub fn gen_for<'ctx, 'a, G: CodeGenerator>(
     generator: &mut G,