No-op implementation of vprintf (#527)

ptx/lib/zluda_ptx_impl.cpp

@@ -855,4 +855,12 @@ typedef uint32_t ShflSyncResult __attribute__((ext_vector_type(2)));
 
         return output.u32;
     }
+
+    int FUNC(vprintf)(const char *format __attribute__((unused)), void *vlist __attribute__((unused)))
+    {
+        // TODO: replace calls to vprintf with a raising pass to printf when we have a mechanism
+        // to write SSA passes
+        // Use https://github.com/ROCm/llvm-project/blob/99a81d16b9d811cadd420190bed16981a0a57bc6/llvm/lib/Transforms/Utils/AMDGPUEmitPrintf.cpp#L426
+        return -1;
+    }
 }

ptx/src/pass/llvm/emit.rs

@@ -2869,6 +2869,7 @@ impl<'a> MethodEmitContext<'a> {
 
     fn emit_trap(&mut self) -> Result<(), TranslateError> {
         self.emit_intrinsic(c"llvm.trap", None, None, vec![])?;
+        unsafe { LLVMBuildUnreachable(self.builder) };
         Ok(())
     }
 

ptx/src/pass/replace_known_functions.rs

@@ -21,7 +21,7 @@ fn replace_with_ptx_impl<'input>(
     resolver: &mut GlobalStringIdentResolver2<'input>,
     fn_name: SpirvWord,
 ) {
-    let known_names = ["__assertfail"];
+    let known_names = ["__assertfail", "vprintf"];
     if let Some(super::IdentEntry {
         name: Some(name), ..
     }) = resolver.ident_map.get_mut(&fn_name)