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HoistToDeclBefore: revert hoisting of references 

The goal of this utility is to hoist copies of expressions to ensure
order of evaluation of expressions. Hoisting references makes no
difference.

Bug: tint:1300
Change-Id: I3e7c2e53c9618aeb06836604e39383de016b072c
Reviewed-on: https://dawn-review.googlesource.com/c/tint/+/81040
Reviewed-by: Ben Clayton <bclayton@google.com>
Kokoro: Kokoro <noreply+kokoro@google.com>
Commit-Queue: Antonio Maiorano <amaiorano@google.com>
This commit is contained in:
Antonio Maiorano 2022-03-15 13:36:53 +00:00 committed by Tint LUCI CQ
parent b86895da5f
commit 30747f607d
2 changed files with 8 additions and 23 deletions
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23
src/tint/transform/utils/hoist_to_decl_before.cc
View File

@ -266,23 +266,12 @@ class HoistToDeclBefore::State {
bool HoistToDeclBefore(const sem::Expression* before_expr,
const ast::Expression* expr,
bool as_const,
const char* decl_name = "") {
const char* decl_name) {
auto name = b.Symbols().New(decl_name);
auto* sem_expr = ctx.src->Sem().Get(expr);
bool is_ref =
sem_expr &&
!sem_expr->Is<sem::VariableUser>() // Don't need to take a ref to a var
&& sem_expr->Type()->Is<sem::Reference>();
auto* expr_clone = ctx.Clone(expr);
if (is_ref) {
expr_clone = b.AddressOf(expr_clone);
}
// Construct the let/var that holds the hoisted expr
auto* v = as_const ? b.Const(name, nullptr, expr_clone)
: b.Var(name, nullptr, expr_clone);
auto* v = as_const ? b.Const(name, nullptr, ctx.Clone(expr))
: b.Var(name, nullptr, ctx.Clone(expr));
auto* decl = b.Decl(v);
if (!InsertBefore(before_expr, decl)) {
@ -290,11 +279,7 @@ class HoistToDeclBefore::State {
}
// Replace the initializer expression with a reference to the let
const ast::Expression* new_expr = b.Expr(name);
if (is_ref) {
new_expr = b.Deref(new_expr);
}
ctx.Replace(expr, new_expr);
ctx.Replace(expr, b.Expr(name));
return true;
}

8
src/tint/transform/utils/hoist_to_decl_before_test.cc
View File

@ -243,8 +243,8 @@ TEST_F(HoistToDeclBeforeTest, Array1D) {
auto* expect = R"(
fn f() {
var a : array<i32, 10>;
let tint_symbol = &(a[0]);
var b = *(tint_symbol);
let tint_symbol = a[0];
var b = tint_symbol;
}
)";
@ -279,8 +279,8 @@ TEST_F(HoistToDeclBeforeTest, Array2D) {
auto* expect = R"(
fn f() {
var a : array<array<i32, 10>, 10>;
let tint_symbol = &(a[0][0]);
var b = *(tint_symbol);
let tint_symbol = a[0][0];
var b = tint_symbol;
}
)";