Fix PromoteSideEffectsToDeclTest converting for loop to loop with nested hoisted lets

When converting a for-loop to a loop, we were not cloning the for-loop's
body, but rather the statements within it. This worked fine, except if
we also hoisted a variable to a let within that body, which requires the
body to be cloned for the 'insert before' to work. This change clones
the for-loop body, which fixes the problem, but introduces a block in
the destination AST, which is ugly, but not incorrect.

Bug: tint:1300
Change-Id: I478244d87f8cf58837102004242ba1c835e21710
Reviewed-on: https://dawn-review.googlesource.com/c/tint/+/78821
Kokoro: Kokoro <noreply+kokoro@google.com>
Reviewed-by: Ben Clayton <bclayton@google.com>
Commit-Queue: Antonio Maiorano <amaiorano@google.com>

src/transform/promote_side_effects_to_decl.cc

@@ -242,9 +242,7 @@ class PromoteSideEffectsToDecl::State {
                 body_stmts.emplace_back(b.If(not_cond, break_body));
               }
               // Next emit the for-loop body
-              for (auto* body_stmt : for_loop->body->statements) {
-                body_stmts.emplace_back(ctx.Clone(body_stmt));
-              }
+              body_stmts.emplace_back(ctx.Clone(for_loop->body));
 
               // Finally create the continuing block if there was one.
               const ast::BlockStatement* continuing = nullptr;

src/transform/promote_side_effects_to_decl_test.cc

@@ -184,7 +184,9 @@ fn f() {
     if (!((f == tint_symbol[0]))) {
       break;
     }
-    var marker = 1;
+    {
+      var marker = 1;
+    }
 
     continuing {
       f = (f + 1.0);
@@ -218,7 +220,9 @@ fn f() {
     if (!((f < 10.0))) {
       break;
     }
-    var marker = 1;
+    {
+      var marker = 1;
+    }
 
     continuing {
       let tint_symbol = array<f32, 1u>(1.0);
@@ -257,7 +261,9 @@ fn f() {
       if (!((f < tint_symbol_1[0]))) {
         break;
       }
-      var marker = 1;
+      {
+        var marker = 1;
+      }
 
       continuing {
         let tint_symbol_2 = array<f32, 1u>(2.0);
@@ -678,7 +684,9 @@ fn f() {
     if (!((var_for_index[i] < 3))) {
       break;
     }
-    break;
+    {
+      break;
+    }
   }
 }
 )";
@@ -712,9 +720,54 @@ fn f() {
     if (!((var_for_index[i].x < 3.0))) {
       break;
     }
+    {
+      break;
+    }
+  }
+}
+)";
+
+  DataMap data;
+  data.Add<PromoteSideEffectsToDecl::Config>(/* type_ctor_to_let */ false,
+                                             /* dynamic_index_to_var */ true);
+  auto got = Run<PromoteSideEffectsToDecl>(src, data);
+
+  EXPECT_EQ(expect, str(got));
+}
+
+TEST_F(PromoteSideEffectsToDeclTest,
+       DynamicIndexToVar_MatrixIndexInForLoopCondWithNestedIndex) {
+  auto* src = R"(
+fn f() {
+  var i : i32;
+  let p = mat2x2(1.0, 2.0, 3.0, 4.0);
+  for(; p[i].x < 3.0; ) {
+    if (p[i].x < 1.0) {
+        var marker = 1;
+    }
     break;
   }
 }
+)";
+
+  auto* expect = R"(
+fn f() {
+  var i : i32;
+  let p = mat2x2(1.0, 2.0, 3.0, 4.0);
+  loop {
+    var var_for_index = p;
+    if (!((var_for_index[i].x < 3.0))) {
+      break;
+    }
+    {
+      var var_for_index_1 = p;
+      if ((var_for_index_1[i].x < 1.0)) {
+        var marker = 1;
+      }
+      break;
+    }
+  }
+}
 )";
 
   DataMap data;

test/statements/for/condition/array_ctor.wgsl.expected.glsl

@@ -12,6 +12,8 @@ void f() {
     if (!((i < tint_symbol[0]))) {
       break;
     }
+    {
+    }
   }
 }
 

test/statements/for/condition/array_ctor.wgsl.expected.hlsl

@@ -10,5 +10,7 @@ void f() {
     if (!((i < tint_symbol[0]))) {
       break;
     }
+    {
+    }
   }
 }

test/statements/for/condition/array_ctor.wgsl.expected.msl

@@ -12,6 +12,8 @@ void f() {
     if (!((i < tint_symbol.arr[0]))) {
       break;
     }
+    {
+    }
   }
 }
 

test/statements/for/condition/struct_ctor.wgsl.expected.glsl

@@ -16,6 +16,8 @@ void f() {
     if (!((i < tint_symbol.i))) {
       break;
     }
+    {
+    }
   }
 }
 

test/statements/for/condition/struct_ctor.wgsl.expected.hlsl

@@ -14,5 +14,7 @@ void f() {
     if (!((i < tint_symbol.i))) {
       break;
     }
+    {
+    }
   }
 }

test/statements/for/condition/struct_ctor.wgsl.expected.msl

@@ -12,6 +12,8 @@ void f() {
     if (!((i < tint_symbol.i))) {
       break;
     }
+    {
+    }
   }
 }
 

test/statements/for/continuing/array_ctor.wgsl.expected.glsl

@@ -11,6 +11,8 @@ void f() {
     if (!(false)) {
       break;
     }
+    {
+    }
     {
       int tint_symbol[1] = int[1](1);
       i = (i + tint_symbol[0]);

test/statements/for/continuing/array_ctor.wgsl.expected.hlsl

@@ -9,6 +9,8 @@ void f() {
     if (!(false)) {
       break;
     }
+    {
+    }
     {
       const int tint_symbol[1] = {1};
       i = (i + tint_symbol[0]);

test/statements/for/continuing/array_ctor.wgsl.expected.msl

@@ -11,6 +11,8 @@ void f() {
     if (!(false)) {
       break;
     }
+    {
+    }
     {
       tint_array_wrapper const tint_symbol = {.arr={1}};
       i = as_type<int>((as_type<uint>(i) + as_type<uint>(tint_symbol.arr[0])));

test/statements/for/continuing/struct_ctor.wgsl.expected.glsl

@@ -16,6 +16,8 @@ void f() {
       if (!(false)) {
         break;
       }
+      {
+      }
       {
         S tint_symbol = S(1);
         i = (i + tint_symbol.i);

test/statements/for/continuing/struct_ctor.wgsl.expected.hlsl

@@ -14,6 +14,8 @@ void f() {
       if (!(false)) {
         break;
       }
+      {
+      }
       {
         const S tint_symbol = {1};
         i = (i + tint_symbol.i);

test/statements/for/continuing/struct_ctor.wgsl.expected.msl

@@ -12,6 +12,8 @@ void f() {
       if (!(false)) {
         break;
       }
+      {
+      }
       {
         S const tint_symbol = {.i=1};
         i = as_type<int>((as_type<uint>(i) + as_type<uint>(tint_symbol.i)));