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Apply same reductions to while

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This commit is contained in:
Adam Goertz 2023-11-07 01:24:19 +00:00
parent 91570cc42d
commit db785e25b9
1 changed files with 32 additions and 2 deletions
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34
src/reduce/Walk.zig
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@ -559,7 +559,7 @@ fn walkExpression(w: *Walk, node: Ast.Node.Index) Error!void {
.while_simple,
.while_cont,
.@"while",
=> return walkWhile(w, ast.fullWhile(node).?),
=> return walkWhile(w, node, ast.fullWhile(node).?),
.for_simple,
.@"for",
@ -863,7 +863,37 @@ fn walkSwitchCase(w: *Walk, switch_case: Ast.full.SwitchCase) Error!void {
try walkExpression(w, switch_case.ast.target_expr);
}
fn walkWhile(w: *Walk, while_node: Ast.full.While) Error!void {
fn walkWhile(w: *Walk, node_index: Ast.Node.Index, while_node: Ast.full.While) Error!void {
assert(while_node.ast.cond_expr != 0);
assert(while_node.ast.then_expr != 0);
// Perform these transformations in this priority order:
// 1. If the `else` expression is missing or an empty block, replace the condition with `if (true)` if it is not already.
// 2. If the `then` block is empty, replace the condition with `if (false)` if it is not already.
// 3. If the condition is `if (true)`, replace the `if` expression with the contents of the `then` expression.
// 4. If the condition is `if (false)`, replace the `if` expression with the contents of the `else` expression.
if (!isTrueIdent(w.ast, while_node.ast.cond_expr) and
(while_node.ast.else_expr == 0 or isEmptyBlock(w.ast, while_node.ast.else_expr)))
{
try w.transformations.ensureUnusedCapacity(1);
w.transformations.appendAssumeCapacity(.{ .replace_with_true = while_node.ast.cond_expr });
} else if (!isFalseIdent(w.ast, while_node.ast.cond_expr) and isEmptyBlock(w.ast, while_node.ast.then_expr)) {
try w.transformations.ensureUnusedCapacity(1);
w.transformations.appendAssumeCapacity(.{ .replace_with_false = while_node.ast.cond_expr });
} else if (isTrueIdent(w.ast, while_node.ast.cond_expr)) {
try w.transformations.ensureUnusedCapacity(1);
w.transformations.appendAssumeCapacity(.{ .replace_node = .{
.to_replace = node_index,
.replacement = while_node.ast.then_expr,
} });
} else if (isFalseIdent(w.ast, while_node.ast.cond_expr)) {
try w.transformations.ensureUnusedCapacity(1);
w.transformations.appendAssumeCapacity(.{ .replace_node = .{
.to_replace = node_index,
.replacement = while_node.ast.else_expr,
} });
}
try walkExpression(w, while_node.ast.cond_expr); // condition
if (while_node.ast.cont_expr != 0) {