From d4ec962a7917532f353ceac0d97f894b63d55690 Mon Sep 17 00:00:00 2001
From: msiglreith <m.siglreith@gmail.com>
Date: Sat, 19 Dec 2020 22:54:56 +0100
Subject: [PATCH] Add `location` decoration attribute

---
 crates/rustc_codegen_spirv/src/codegen_cx/entry.rs | 7 ++++++-
 crates/rustc_codegen_spirv/src/symbols.rs          | 8 ++++++++
 2 files changed, 14 insertions(+), 1 deletion(-)

diff --git a/crates/rustc_codegen_spirv/src/codegen_cx/entry.rs b/crates/rustc_codegen_spirv/src/codegen_cx/entry.rs
index 08cc9bdd0d..2350bf05f9 100644
--- a/crates/rustc_codegen_spirv/src/codegen_cx/entry.rs
+++ b/crates/rustc_codegen_spirv/src/codegen_cx/entry.rs
@@ -169,6 +169,11 @@ impl<'tcx> CodegenCx<'tcx> {
                     );
                     has_location = false;
                 }
+                SpirvAttribute::Location(index) => {
+                    // Overwrite the current location value for the given storage class.
+                    // The decoration will be assigned below.
+                    decoration_locations.insert(storage_class, index);
+                }
                 SpirvAttribute::DescriptorSet(index) => {
                     self.emit_global().decorate(
                         variable,
@@ -195,7 +200,7 @@ impl<'tcx> CodegenCx<'tcx> {
         // Assign locations from left to right, incrementing each storage class
         // individually.
         // TODO: Is this right for UniformConstant? Do they share locations with
-        // input/outpus?
+        // input/outputs?
         if has_location {
             let location = decoration_locations
                 .entry(storage_class)
diff --git a/crates/rustc_codegen_spirv/src/symbols.rs b/crates/rustc_codegen_spirv/src/symbols.rs
index 229fcd569b..1ae6421843 100644
--- a/crates/rustc_codegen_spirv/src/symbols.rs
+++ b/crates/rustc_codegen_spirv/src/symbols.rs
@@ -30,6 +30,7 @@ pub struct Symbols {
     pub spirv13: Symbol,
     pub spirv14: Symbol,
     pub spirv15: Symbol,
+    location: Symbol,
     descriptor_set: Symbol,
     binding: Symbol,
     image: Symbol,
@@ -383,6 +384,7 @@ impl Symbols {
             spirv13: Symbol::intern("spirv1.3"),
             spirv14: Symbol::intern("spirv1.4"),
             spirv15: Symbol::intern("spirv1.5"),
+            location: Symbol::intern("location"),
             descriptor_set: Symbol::intern("descriptor_set"),
             binding: Symbol::intern("binding"),
             image: Symbol::intern("image"),
@@ -442,6 +444,7 @@ pub enum SpirvAttribute {
     Builtin(BuiltIn),
     StorageClass(StorageClass),
     Entry(Entry),
+    Location(u32),
     DescriptorSet(u32),
     Binding(u32),
     ReallyUnsafeIgnoreBitcasts,
@@ -499,6 +502,11 @@ pub fn parse_attrs(
                         Some(x) => Some(SpirvAttribute::DescriptorSet(x)),
                         None => None,
                     }
+                } else if arg.has_name(cx.sym.location) {
+                    match parse_attr_int_value(cx, arg) {
+                        Some(x) => Some(SpirvAttribute::Location(x)),
+                        None => None,
+                    }
                 } else if arg.has_name(cx.sym.binding) {
                     match parse_attr_int_value(cx, arg) {
                         Some(x) => Some(SpirvAttribute::Binding(x)),