tint/uniformity: Fix handling of continuing block
Variables declared inside a loop block were not visible to the
continuing block. Special-case the continuing block by processing it
inside the loop-body block statement, instead of afterwards.
Change-Id: I05bc906bd98b24295dc91116b9ef8d8ef02c3af3
Reviewed-on: https://dawn-review.googlesource.com/c/dawn/+/114860
Reviewed-by: Antonio Maiorano <amaiorano@google.com>
Commit-Queue: James Price <jrprice@google.com>
Kokoro: Kokoro <noreply+kokoro@google.com>
diff --git a/src/tint/resolver/uniformity.cc b/src/tint/resolver/uniformity.cc
index 263003e..42138a7 100644
--- a/src/tint/resolver/uniformity.cc
+++ b/src/tint/resolver/uniformity.cc
@@ -462,6 +462,22 @@
}
}
+ auto* parent = sem_.Get(b)->Parent();
+ auto* loop = parent ? parent->As<sem::LoopStatement>() : nullptr;
+ if (loop) {
+ // We've reached the end of a loop body. If there is a continuing block,
+ // process it before ending the block so that any variables declared in the
+ // loop body are visible to the continuing block.
+ if (auto* continuing =
+ loop->Declaration()->As<ast::LoopStatement>()->continuing) {
+ auto& loop_body_behavior = sem_.Get(b)->Behaviors();
+ if (loop_body_behavior.Contains(sem::Behavior::kNext) ||
+ loop_body_behavior.Contains(sem::Behavior::kContinue)) {
+ cf = ProcessStatement(cf, continuing);
+ }
+ }
+ }
+
if (sem_.Get<sem::FunctionBlockStatement>(b)) {
// We've reached the end of the function body.
// Add edges from pointer parameter outputs to their current value.
@@ -860,13 +876,11 @@
current_function_->variables.Set(v, in_node);
}
+ // Note: The continuing block is processed as a special case at the end of
+ // processing the loop body BlockStatement. This is so that variable declarations
+ // inside the loop body are visible to the continuing statement.
auto* cf1 = ProcessStatement(cfx, l->body);
- if (l->continuing) {
- auto* cf2 = ProcessStatement(cf1, l->continuing);
- cfx->AddEdge(cf2);
- } else {
- cfx->AddEdge(cf1);
- }
+ cfx->AddEdge(cf1);
cfx->AddEdge(cf);
// Add edges from variable loop input nodes to their values at the end of the loop.
diff --git a/src/tint/resolver/uniformity_test.cc b/src/tint/resolver/uniformity_test.cc
index b4e78c0..973ee8b 100644
--- a/src/tint/resolver/uniformity_test.cc
+++ b/src/tint/resolver/uniformity_test.cc
@@ -1545,6 +1545,71 @@
RunTest(src, true);
}
+TEST_F(UniformityAnalysisTest, Loop_NonUniformValueDeclaredInBody_UnreachableContinuing) {
+ std::string src = R"(
+@group(0) @binding(0) var<storage, read_write> non_uniform : i32;
+
+fn foo() {
+ var condition = true;
+ loop {
+ var v = non_uniform;
+ if (condition) {
+ break;
+ } else {
+ break;
+ }
+
+ continuing {
+ if (v == 0) {
+ workgroupBarrier();
+ }
+ }
+ }
+}
+)";
+
+ RunTest(src, true);
+}
+
+TEST_F(UniformityAnalysisTest, Loop_NonUniformValueDeclaredInBody_MaybeReachesContinuing) {
+ std::string src = R"(
+@group(0) @binding(0) var<storage, read_write> non_uniform : i32;
+
+fn foo() {
+ var condition = true;
+ loop {
+ var v = non_uniform;
+ if (condition) {
+ continue;
+ } else {
+ break;
+ }
+
+ continuing {
+ if (v == 0) {
+ workgroupBarrier();
+ }
+ }
+ }
+}
+)";
+
+ RunTest(src, false);
+ EXPECT_EQ(error_,
+ R"(test:16:9 warning: 'workgroupBarrier' must only be called from uniform control flow
+ workgroupBarrier();
+ ^^^^^^^^^^^^^^^^
+
+test:15:7 note: control flow depends on non-uniform value
+ if (v == 0) {
+ ^^
+
+test:7:13 note: reading from read_write storage buffer 'non_uniform' may result in a non-uniform value
+ var v = non_uniform;
+ ^^^^^^^^^^^
+)");
+}
+
TEST_F(UniformityAnalysisTest, Loop_NonUniformBreakInBody_Reconverge) {
// Loops reconverge at exit, so test that we can call workgroupBarrier() after a loop that
// contains a non-uniform conditional break.
