From 4f9d2803bd5a5b2a06ecebb1f1fb63cd0de5c3d5 Mon Sep 17 00:00:00 2001
From: Dzmitry Malyshau <kvarkus@gmail.com>
Date: Wed, 8 Sep 2021 09:45:02 -0400
Subject: [PATCH] spv-out: option to skip OpName for varyings

---
 src/back/spv/mod.rs    |  5 ++++-
 src/back/spv/writer.rs |  5 ++++-
 tests/snapshots.rs     | 13 ++++++-------
 3 files changed, 14 insertions(+), 9 deletions(-)

diff --git a/src/back/spv/mod.rs b/src/back/spv/mod.rs
index 09e98ab53a..0c89821afe 100644
--- a/src/back/spv/mod.rs
+++ b/src/back/spv/mod.rs
@@ -511,6 +511,9 @@ bitflags::bitflags! {
         const DEBUG = 0x1;
         /// Flip Y coordinate of `BuiltIn::Position` output.
         const ADJUST_COORDINATE_SPACE = 0x2;
+        /// Emit `OpLabel` for input/output locations.
+        /// Some drivers treat it as semantic, not allowing any conflicts.
+        const LABEL_VARYINGS = 0x4;
     }
 }
 
@@ -535,7 +538,7 @@ pub struct Options {
 
 impl Default for Options {
     fn default() -> Self {
-        let mut flags = WriterFlags::ADJUST_COORDINATE_SPACE;
+        let mut flags = WriterFlags::ADJUST_COORDINATE_SPACE | WriterFlags::LABEL_VARYINGS;
         if cfg!(debug_assertions) {
             flags |= WriterFlags::DEBUG;
         }
diff --git a/src/back/spv/writer.rs b/src/back/spv/writer.rs
index 943b96dcfa..2501c91258 100644
--- a/src/back/spv/writer.rs
+++ b/src/back/spv/writer.rs
@@ -1038,7 +1038,10 @@ impl Writer {
         Instruction::variable(pointer_type_id, id, class, None)
             .to_words(&mut self.logical_layout.declarations);
 
-        if self.flags.contains(WriterFlags::DEBUG) {
+        if self
+            .flags
+            .contains(WriterFlags::DEBUG | WriterFlags::LABEL_VARYINGS)
+        {
             if let Some(name) = debug_name {
                 self.debugs.push(Instruction::name(id, name));
             }
diff --git a/tests/snapshots.rs b/tests/snapshots.rs
index b1b153678e..020368148c 100644
--- a/tests/snapshots.rs
+++ b/tests/snapshots.rs
@@ -176,13 +176,12 @@ fn write_output_spv(
     use naga::back::spv;
     use rspirv::binary::Disassemble;
 
-    let mut flags = spv::WriterFlags::empty();
-    if params.spv_debug {
-        flags |= spv::WriterFlags::DEBUG;
-    }
-    if params.spv_adjust_coordinate_space {
-        flags |= spv::WriterFlags::ADJUST_COORDINATE_SPACE;
-    }
+    let mut flags = spv::WriterFlags::LABEL_VARYINGS;
+    flags.set(spv::WriterFlags::DEBUG, params.spv_debug);
+    flags.set(
+        spv::WriterFlags::ADJUST_COORDINATE_SPACE,
+        params.spv_adjust_coordinate_space,
+    );
     let options = spv::Options {
         lang_version: params.spv_version,
         flags,