spv-in parse more atomic ops (#5824)

* add parsing for spirv::Op::AtomicLoad and spirv::Op::AtomicStore

* spv-in parse AtomicExchange and AtomicCompareExchange

* add atomic i decrement

* bookend atomic store statement with emmitter.finish/emitter.start to suppress a double load expression

bookend atomic result expressions with emitter.finish/start to prevent double defs

* add atomic iadd, isub, smin, umin, smax, umax, and, or, xor

* parse atomic flag test and set, parse atomic flag clear

* remove atomic compare exchange work

* changelog

* moved spirv tests into front/spv/mod.rs

* feature gate atomic spv tests because they require wgsl-[in,out]

* BlockContext::get_contained_global_variable returns Result

* Generate spans covering the entire instruction.

Granted, there is pre-existing code in the SPIR-V front end that gets
this wrong, but:

It doesn't make sense to read `self.data_offset`, and then immediately
pass that to `self.span_from_with_op`. The point of that function is
to make the span cover the entire instruction, operands included.

* Move `From` implementation into spv front end

* doc comments, minor cleanups

* remove parsing of OpAtomicFlagClear and OpAtomicFlagTestAndSet

* sync atomic spvasm files

---------

Co-authored-by: Jim Blandy <[email protected]>

CHANGELOG.md

@@ -80,6 +80,7 @@ By @bradwerth [#6216](https://github.com/gfx-rs/wgpu/pull/6216).
 
 - Support constant evaluation for `firstLeadingBit` and `firstTrailingBit` numeric built-ins in WGSL. Front-ends that translate to these built-ins also benefit from constant evaluation. By @ErichDonGubler in [#5101](https://github.com/gfx-rs/wgpu/pull/5101).
 - Add `first` and `either` sampling types for `@interpolate(flat, …)` in WGSL. By @ErichDonGubler in [#6181](https://github.com/gfx-rs/wgpu/pull/6181).
+- Support for more atomic ops in the SPIR-V frontend. By @schell in [#5824](https://github.com/gfx-rs/wgpu/pull/5824).
 
 #### Vulkan
 

naga/src/front/atomic_upgrade.rs

@@ -44,12 +44,8 @@ pub enum Error {
     MultiMemberStruct,
     #[error("encountered unsupported global initializer in an atomic variable")]
     GlobalInitUnsupported,
-}
-
-impl From<Error> for crate::front::spv::Error {
-    fn from(source: Error) -> Self {
-        crate::front::spv::Error::AtomicUpgradeError(source)
-    }
+    #[error("expected to find a global variable")]
+    GlobalVariableMissing,
 }
 
 #[derive(Clone, Default)]

naga/src/front/spv/error.rs

@@ -159,3 +159,9 @@ impl Error {
         String::from_utf8(writer.into_inner()).unwrap()
     }
 }
+
+impl From<atomic_upgrade::Error> for Error {
+    fn from(source: atomic_upgrade::Error) -> Self {
+        crate::front::spv::Error::AtomicUpgradeError(source)
+    }
+}