Use a demangled symbol name for OpName. (#266)

* Use a demangled symbol name for OpName.

* Rename my_smoothstep back to smoothstep.

* Update SPIR-V tests to look for the absolute fn
path.

Cargo.lock

@@ -1963,6 +1963,12 @@ dependencies = [
  "spirv_headers 1.5.0 (git+https://github.com/gfx-rs/rspirv.git?rev=01ca0d2e5b667a0e4ff1bc1804511e38f9a08759)",
 ]
 
+[[package]]
+name = "rustc-demangle"
+version = "0.1.18"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "6e3bad0ee36814ca07d7968269dd4b7ec89ec2da10c4bb613928d3077083c232"
+
 [[package]]
 name = "rustc_codegen_spirv"
 version = "0.1.0"
@@ -1971,6 +1977,7 @@ dependencies = [
  "pipe",
  "pretty_assertions",
  "rspirv",
+ "rustc-demangle",
  "spirv-tools",
  "tar",
  "tempfile",

crates/rustc_codegen_spirv/Cargo.toml

@@ -29,6 +29,7 @@ use-compiled-tools = ["spirv-tools/use-compiled-tools"]
 [dependencies]
 bimap = "0.5"
 rspirv = { git = "https://github.com/gfx-rs/rspirv.git", rev = "01ca0d2e5b667a0e4ff1bc1804511e38f9a08759" }
+rustc-demangle = "0.1.18"
 spirv-tools = { version = "0.1.0", default-features = false }
 tar = "0.4.30"
 topological-sort = "0.1"

crates/rustc_codegen_spirv/src/codegen_cx/declare.rs

@@ -91,11 +91,20 @@ impl<'tcx> CodegenCx<'tcx> {
         }
         emit.end_function().unwrap();
 
-        let human_name = format!("{}", instance);
-        emit.name(fn_id, &human_name);
+        // HACK(eddyb) this is a bit roundabout, but the easiest way to get a
+        // fully absolute path that contains at least as much information as
+        // `instance.to_string()` (at least with `-Z symbol-mangling-version=v0`).
+        // While we could use the mangled symbol insyead, like we do for linkage,
+        // `OpName` is more of a debugging aid, so not having to separately
+        // demangle the SPIR-V can help. However, if some tools assume `OpName`
+        // is always a valid identifier, we may have to offer the mangled name
+        // (as some sort of opt-in, or toggled based on the platform, etc.).
+        let symbol_name = self.tcx.symbol_name(instance).name;
+        let demangled_symbol_name = format!("{:#}", rustc_demangle::demangle(symbol_name));
+        emit.name(fn_id, &demangled_symbol_name);
+
         drop(emit); // set_linkage uses emit
         if let Some(linkage) = linkage {
-            let symbol_name = self.tcx.symbol_name(instance).name;
             self.set_linkage(fn_id, symbol_name.to_owned(), linkage);
         }
 
@@ -104,7 +113,8 @@ impl<'tcx> CodegenCx<'tcx> {
         for attr in parse_attrs(self, self.tcx.get_attrs(instance.def_id())) {
             match attr {
                 SpirvAttribute::Entry(entry) => {
-                    self.entry_stub(&instance, &fn_abi, declared, human_name.clone(), entry)
+                    let crate_relative_name = instance.to_string();
+                    self.entry_stub(&instance, &fn_abi, declared, crate_relative_name, entry)
                 }
                 SpirvAttribute::ReallyUnsafeIgnoreBitcasts => {
                     self.really_unsafe_ignore_bitcasts

crates/spirv-builder/src/lib.rs

@@ -143,7 +143,7 @@ fn invoke_rustc(builder: &SpirvBuilder) -> Result<PathBuf, SpirvBuilderError> {
         format!(" -C target-feature={}", target_features.join(","))
     };
     let rustflags = format!(
-        "-Z codegen-backend={}{}",
+        "-Z codegen-backend={} -Z symbol-mangling-version=v0{}",
         rustc_codegen_spirv.display(),
         feature_flag,
     );

crates/spirv-builder/src/test/mod.rs

@@ -113,12 +113,13 @@ fn assert_str_eq(expected: &str, result: &str) {
 fn dis_fn(src: &str, func: &str, expect: &str) {
     let _lock = global_lock();
     let module = read_module(&build(src)).unwrap();
+    let abs_func_path = format!("test_project::{}", func);
     let id = module
         .debugs
         .iter()
         .find(|inst| {
             inst.class.opcode == rspirv::spirv::Op::Name
-                && inst.operands[1].unwrap_literal_string() == func
+                && inst.operands[1].unwrap_literal_string() == abs_func_path
         })
         .expect("No function with that name found")
         .operands[0]

examples/shaders/shared/src/lib.rs

@@ -39,8 +39,7 @@ pub fn acos_approx(v: f32) -> f32 {
     }
 }
 
-/// renamed because of cross-compilation issues with spirv-cross/ moltenvk
-pub fn my_smoothstep(edge0: f32, edge1: f32, x: f32) -> f32 {
+pub fn smoothstep(edge0: f32, edge1: f32, x: f32) -> f32 {
     // Scale, bias and saturate x to 0..1 range
     let x = ((x - edge0) / (edge1 - edge0)).saturate();
     // Evaluate polynomial

examples/shaders/sky-shader/src/lib.rs

@@ -97,7 +97,7 @@ fn sky(dir: Vec3, sun_position: Vec3) -> Vec3 {
 
     // Composition + solar disc
     let sun_angular_diameter_cos = SUN_ANGULAR_DIAMETER_DEGREES.cos();
-    let sundisk = my_smoothstep(
+    let sundisk = smoothstep(
         sun_angular_diameter_cos,
         sun_angular_diameter_cos + 0.00002,
         cos_theta,