rusticl/platform: add perf debug option

Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/30324>

docs/envvars.rst

@@ -1119,6 +1119,8 @@ Rusticl environment variables
 
    - ``allow_invalid_spirv`` disables validation of any input SPIR-V
    - ``clc`` dumps all OpenCL C source being compiled
+   - ``perf`` prints a warning when hitting slow paths once
+   - ``perfspam`` same as perf, but doesn't skip same warnings
    - ``program`` dumps compilation logs to stderr
    - ``sync`` waits on the GPU to complete after every event
    - ``validate`` validates any internally generated SPIR-Vs, e.g. through compiling OpenCL C code

src/gallium/frontends/rusticl/core/platform.rs

@@ -17,9 +17,16 @@ pub struct Platform {
     pub devs: Vec<Device>,
 }
 
+pub enum PerfDebugLevel {
+    None,
+    Once,
+    Spam,
+}
+
 pub struct PlatformDebug {
     pub allow_invalid_spirv: bool,
     pub clc: bool,
+    pub perf: PerfDebugLevel,
     pub program: bool,
     pub max_grid_size: u64,
     pub sync_every_event: bool,
@@ -66,6 +73,7 @@ static mut PLATFORM: Platform = Platform {
 static mut PLATFORM_DBG: PlatformDebug = PlatformDebug {
     allow_invalid_spirv: false,
     clc: false,
+    perf: PerfDebugLevel::None,
     program: false,
     max_grid_size: 0,
     sync_every_event: false,
@@ -84,6 +92,8 @@ fn load_env() {
             match flag {
                 "allow_invalid_spirv" => debug.allow_invalid_spirv = true,
                 "clc" => debug.clc = true,
+                "perf" => debug.perf = PerfDebugLevel::Once,
+                "perfspam" => debug.perf = PerfDebugLevel::Spam,
                 "program" => debug.program = true,
                 "sync" => debug.sync_every_event = true,
                 "validate" => debug.validate_spirv = true,
@@ -169,3 +179,23 @@ impl GetPlatformRef for cl_platform_id {
         }
     }
 }
+
+#[macro_export]
+macro_rules! perf_warning {
+    (@PRINT $format:tt, $($arg:tt)*) => {
+        eprintln!(std::concat!("=== Rusticl perf warning: ", $format, " ==="), $($arg)*)
+    };
+
+    ($format:tt $(, $arg:tt)*) => {
+        match $crate::core::platform::Platform::dbg().perf {
+            $crate::core::platform::PerfDebugLevel::Once => {
+                static PERF_WARN_ONCE: std::sync::Once = std::sync::Once::new();
+                PERF_WARN_ONCE.call_once(|| {
+                    perf_warning!(@PRINT $format, $($arg)*);
+                })
+            },
+            $crate::core::platform::PerfDebugLevel::Spam => perf_warning!(@PRINT $format, $($arg)*),
+            _ => (),
+        }
+    };
+}