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coverage: Remove the expression simplifier from CoverageCounters

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These simplifications are now handled by the transcribe step.
This commit is contained in:
Zalathar 2024-12-01 15:50:57 +11:00
parent d7090f335c
commit ba08056d47
1 changed files with 4 additions and 51 deletions
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55
compiler/rustc_mir_transform/src/coverage/counters.rs
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@ -102,57 +102,10 @@ impl CoverageCounters {
fn make_expression(&mut self, lhs: BcbCounter, op: Op, rhs: BcbCounter) -> BcbCounter {
let new_expr = BcbExpression { lhs, op, rhs };
*self
.expressions_memo
.entry(new_expr)
.or_insert_with(|| Self::make_expression_inner(&mut self.expressions, new_expr))
}
/// This is an associated function so that we can call it while borrowing
/// `&mut self.expressions_memo`.
fn make_expression_inner(
expressions: &mut IndexVec<ExpressionId, BcbExpression>,
new_expr: BcbExpression,
) -> BcbCounter {
// Simplify expressions using basic algebra.
//
// Some of these cases might not actually occur in practice, depending
// on the details of how the instrumentor builds expressions.
let BcbExpression { lhs, op, rhs } = new_expr;
if let BcbCounter::Expression { id } = lhs {
let lhs_expr = &expressions[id];
// Simplify `(a - b) + b` to `a`.
if lhs_expr.op == Op::Subtract && op == Op::Add && lhs_expr.rhs == rhs {
return lhs_expr.lhs;
}
// Simplify `(a + b) - b` to `a`.
if lhs_expr.op == Op::Add && op == Op::Subtract && lhs_expr.rhs == rhs {
return lhs_expr.lhs;
}
// Simplify `(a + b) - a` to `b`.
if lhs_expr.op == Op::Add && op == Op::Subtract && lhs_expr.lhs == rhs {
return lhs_expr.rhs;
}
}
if let BcbCounter::Expression { id } = rhs {
let rhs_expr = &expressions[id];
// Simplify `a + (b - a)` to `b`.
if op == Op::Add && rhs_expr.op == Op::Subtract && lhs == rhs_expr.rhs {
return rhs_expr.lhs;
}
// Simplify `a - (a - b)` to `b`.
if op == Op::Subtract && rhs_expr.op == Op::Subtract && lhs == rhs_expr.lhs {
return rhs_expr.rhs;
}
}
// Simplification failed, so actually create the new expression.
let id = expressions.push(new_expr);
BcbCounter::Expression { id }
*self.expressions_memo.entry(new_expr).or_insert_with(|| {
let id = self.expressions.push(new_expr);
BcbCounter::Expression { id }
})
}
/// Creates a counter that is the sum of the given counters.