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nac3_sca
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core: Remove redundant for.cond BB for iterable loops 

Simplifies logic for creating basic blocks.
This commit is contained in:
David Mak 2023-09-05 17:07:48 +08:00
parent b4a9616648
commit b4983526bd
1 changed files with 10 additions and 16 deletions
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26
nac3core/src/codegen/stmt.rs
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@ -248,7 +248,6 @@ pub fn gen_for<'ctx, 'a, G: CodeGenerator>(
let size_t = generator.get_size_type(ctx.ctx); let size_t = generator.get_size_type(ctx.ctx);
let zero = int32.const_zero(); let zero = int32.const_zero();
let current = ctx.builder.get_insert_block().and_then(|bb| bb.get_parent()).unwrap(); let current = ctx.builder.get_insert_block().and_then(|bb| bb.get_parent()).unwrap();
let test_bb = ctx.ctx.append_basic_block(current, "for.cond");
let body_bb = ctx.ctx.append_basic_block(current, "for.body"); let body_bb = ctx.ctx.append_basic_block(current, "for.body");
let cont_bb = ctx.ctx.append_basic_block(current, "for.end"); let cont_bb = ctx.ctx.append_basic_block(current, "for.end");
// if there is no orelse, we just go to cont_bb // if there is no orelse, we just go to cont_bb
@ -258,13 +257,16 @@ pub fn gen_for<'ctx, 'a, G: CodeGenerator>(
// Whether the iterable is a range() expression // Whether the iterable is a range() expression
let is_iterable_range_expr = ctx.unifier.unioned(iter.custom.unwrap(), ctx.primitives.range); let is_iterable_range_expr = ctx.unifier.unioned(iter.custom.unwrap(), ctx.primitives.range);
// store loop bb information and restore it later // The target BB of the loop backedge
let loop_bb = if is_iterable_range_expr { let backedge_bb_target = if is_iterable_range_expr {
ctx.loop_target.replace((body_bb, cont_bb)) body_bb
} else { } else {
ctx.loop_target.replace((test_bb, cont_bb)) ctx.ctx.append_basic_block(current, "for.cond")
}; };
// store loop bb information and restore it later
let loop_bb = ctx.loop_target.replace((backedge_bb_target, cont_bb));
let iter_val = generator.gen_expr(ctx, iter)?.unwrap().to_basic_value_enum( let iter_val = generator.gen_expr(ctx, iter)?.unwrap().to_basic_value_enum(
ctx, ctx,
generator, generator,
@ -317,6 +319,8 @@ pub fn gen_for<'ctx, 'a, G: CodeGenerator>(
ctx.builder.position_at_end(cond_cont_bb); ctx.builder.position_at_end(cond_cont_bb);
ctx.builder.build_store(i, next_i); ctx.builder.build_store(i, next_i);
} else { } else {
let test_bb = backedge_bb_target;
let counter = generator.gen_var_alloc(ctx, size_t.into(), Some("for.counter.addr"))?; let counter = generator.gen_var_alloc(ctx, size_t.into(), Some("for.counter.addr"))?;
// counter = -1 // 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_value(), true));
@ -353,11 +357,7 @@ pub fn gen_for<'ctx, 'a, G: CodeGenerator>(
} }
if !ctx.is_terminated() { if !ctx.is_terminated() {
if is_iterable_range_expr { ctx.builder.build_unconditional_branch(backedge_bb_target);
ctx.builder.build_unconditional_branch(body_bb);
} else {
ctx.builder.build_unconditional_branch(test_bb);
}
} }
if !orelse.is_empty() { if !orelse.is_empty() {
@ -375,12 +375,6 @@ pub fn gen_for<'ctx, 'a, G: CodeGenerator>(
} }
} }
// Clear test_bb if unused
if is_iterable_range_expr {
ctx.builder.position_at_end(test_bb);
ctx.builder.build_unreachable();
}
ctx.builder.position_at_end(cont_bb); ctx.builder.position_at_end(cont_bb);
ctx.loop_target = loop_bb; ctx.loop_target = loop_bb;
} else { } else {