[hlsl-out] fix fallthrough in switch statements

gfx-rs · May 30, 2022 · 91ee407 · 91ee407
1 parent 7c7e962
commit 91ee407
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Showing 7 changed files with 162 additions and 130 deletions.
diff --git a/src/back/hlsl/writer.rs b/src/back/hlsl/writer.rs
@@ -1651,7 +1651,7 @@ impl<'a, W: fmt::Write> super::Writer<'a, W> {
                 let indent_level_1 = level.next();
                 let indent_level_2 = indent_level_1.next();
 
-                for case in cases {
+                for (i, case) in cases.iter().enumerate() {
                     match case.value {
                         crate::SwitchValue::Integer(value) => writeln!(
                             self.out,
@@ -1663,25 +1663,35 @@ impl<'a, W: fmt::Write> super::Writer<'a, W> {
                         }
                     }
 
+                    // FXC doesn't support fallthrough so we duplicate the body of the following case blocks
                     if case.fall_through {
-                        // Generate each fallthrough case statement in a new block. This is done to
-                        // prevent symbol collision of variables declared in these cases statements.
-                        writeln!(self.out, "{}/* fallthrough */", indent_level_2)?;
-                        writeln!(self.out, "{}{{", indent_level_2)?;
-                    }
-                    for sta in case.body.iter() {
-                        self.write_stmt(
-                            module,
-                            sta,
-                            func_ctx,
-                            back::Level(indent_level_2.0 + usize::from(case.fall_through)),
-                        )?;
-                    }
+                        let curr_len = i + 1;
+                        let end_case_idx = curr_len
+                            + cases
+                                .iter()
+                                .skip(curr_len)
+                                .position(|case| !case.fall_through)
+                                .unwrap();
+                        let indent_level_3 = indent_level_2.next();
+                        for case in &cases[i..=end_case_idx] {
+                            writeln!(self.out, "{}{{", indent_level_2)?;
+                            for sta in case.body.iter() {
+                                self.write_stmt(module, sta, func_ctx, indent_level_3)?;
+                            }
+                            writeln!(self.out, "{}}}", indent_level_2)?;
+                        }
 
-                    if case.fall_through {
-                        writeln!(self.out, "{}}}", indent_level_2)?;
-                    } else if case.body.last().map_or(true, |s| !s.is_terminator()) {
-                        writeln!(self.out, "{}break;", indent_level_2)?;
+                        let last_case = &cases[end_case_idx];
+                        if last_case.body.last().map_or(true, |s| !s.is_terminator()) {
+                            writeln!(self.out, "{}break;", indent_level_2)?;
+                        }
+                    } else {
+                        for sta in case.body.iter() {
+                            self.write_stmt(module, sta, func_ctx, indent_level_2)?;
+                        }
+                        if case.body.last().map_or(true, |s| !s.is_terminator()) {
+                            writeln!(self.out, "{}break;", indent_level_2)?;
+                        }
                     }
 
                     writeln!(self.out, "{}}}", indent_level_1)?;

diff --git a/tests/in/control-flow.wgsl b/tests/in/control-flow.wgsl
@@ -26,9 +26,12 @@ fn main(@builtin(global_invocation_id) global_id: vec3<u32>) {
             pos = 2;
             fallthrough;
         }
-        case 4: {}
-        default: {
+        case 4: {
             pos = 3;
+            fallthrough;
+        }
+        default: {
+            pos = 4;
         }
     }
 

diff --git a/tests/out/glsl/control-flow.main.Compute.glsl b/tests/out/glsl/control-flow.main.Compute.glsl
@@ -59,9 +59,10 @@ void main() {
             pos = 2;
             /* fallthrough */
         case 4:
-            break;
-        default:
             pos = 3;
+            /* fallthrough */
+        default:
+            pos = 4;
             break;
     }
     switch(0u) {
@@ -70,8 +71,8 @@ void main() {
         default:
             break;
     }
-    int _e10 = pos;
-    switch(_e10) {
+    int _e11 = pos;
+    switch(_e11) {
         case 1:
             pos = 0;
             break;

diff --git a/tests/out/hlsl/control-flow.hlsl b/tests/out/hlsl/control-flow.hlsl
@@ -60,16 +60,28 @@ void main(uint3 global_id : SV_DispatchThreadID)
             break;
         }
         case 3: {
-            /* fallthrough */
             {
                 pos = 2;
             }
+            {
+                pos = 3;
+            }
+            {
+                pos = 4;
+            }
+            break;
         }
         case 4: {
+            {
+                pos = 3;
+            }
+            {
+                pos = 4;
+            }
             break;
         }
         default: {
-            pos = 3;
+            pos = 4;
             break;
         }
     }
@@ -81,8 +93,8 @@ void main(uint3 global_id : SV_DispatchThreadID)
             break;
         }
     }
-    int _expr10 = pos;
-    switch(_expr10) {
+    int _expr11 = pos;
+    switch(_expr11) {
         case 1: {
             pos = 0;
             break;
@@ -92,10 +104,12 @@ void main(uint3 global_id : SV_DispatchThreadID)
             return;
         }
         case 3: {
-            /* fallthrough */
             {
                 pos = 2;
             }
+            {
+                return;
+            }
         }
         case 4: {
             return;

diff --git a/tests/out/msl/control-flow.msl b/tests/out/msl/control-flow.msl
@@ -72,10 +72,10 @@ kernel void main_(
             pos = 2;
         }
         case 4: {
-            break;
+            pos = 3;
         }
         default: {
-            pos = 3;
+            pos = 4;
             break;
         }
     }
@@ -87,8 +87,8 @@ kernel void main_(
             break;
         }
     }
-    int _e10 = pos;
-    switch(_e10) {
+    int _e11 = pos;
+    switch(_e11) {
         case 1: {
             pos = 0;
             break;