From d7b499deff0eba67175eb44f7d1b0259f7f15f54 Mon Sep 17 00:00:00 2001
From: Andrei Alexandrescu <andrei@erdani.com>
Date: Sun, 24 Apr 2022 16:29:43 -0400
Subject: [PATCH] Fix CUDA_PERROR_EXIT and print failing expression (#446)

`CUDA_PERROR_EXIT ` can lead to incorrect usage (see e.g. [this description](https://www.cs.technion.ac.il/users/yechiel/c++-faq/macros-with-if.html)) because it contains an incomplete `if` expression. Consider:

```
if (condition)
    CUDA_PERROR_EXIT(cudaFree(x))
else
    free(x);
```

The author of the code forgot to add a semicolon after the macro. In that case, the `else` will bind to the `if` inside the macro definition, leading to code that the author did not intend or expect. It the author does use a semicolon, the code will not compile, which is awkward.

The change adds a `do while` around the `if`, which always requires a semicolon.

This PR also adds the text of the failing expression to the printed error message.
---
 tools/util/include/cutlass/util/debug.h | 11 ++++++-----
 1 file changed, 6 insertions(+), 5 deletions(-)

diff --git a/tools/util/include/cutlass/util/debug.h b/tools/util/include/cutlass/util/debug.h
index 3eef5289..f2ee441e 100644
--- a/tools/util/include/cutlass/util/debug.h
+++ b/tools/util/include/cutlass/util/debug.h
@@ -80,6 +80,7 @@
  * \return The CUDA error.
  */
 __host__ CUTLASS_DEVICE cudaError_t cuda_perror_impl(cudaError_t error,
+                                                     const char* expression,
                                                      const char* filename,
                                                      int line) {
   (void)filename;
@@ -87,10 +88,10 @@ __host__ CUTLASS_DEVICE cudaError_t cuda_perror_impl(cudaError_t error,
   if (error) {
 #if !defined(__CUDA_ARCH__)
     fprintf(
-        stderr, "CUDA error %d [%s, %d]: %s\n", error, filename, line, cudaGetErrorString(error));
+        stderr, "CUDA error %d [%s, %d] in expression '%s': %s\n", error, filename, line, expression, cudaGetErrorString(error));
     fflush(stderr);
 #else
-    printf("CUDA error %d [%s, %d]\n", error, filename, line);
+    printf("CUDA error %d [%s, %d] in expression '%s'\n", error, filename, line, expression);
 #endif
   }
   return error;
@@ -100,7 +101,7 @@ __host__ CUTLASS_DEVICE cudaError_t cuda_perror_impl(cudaError_t error,
  * \brief Perror macro
  */
 #ifndef CUDA_PERROR
-#define CUDA_PERROR(e) cuda_perror_impl((cudaError_t)(e), __FILE__, __LINE__)
+#define CUDA_PERROR(e) cuda_perror_impl((cudaError_t)(e), #e, __FILE__, __LINE__)
 #endif
 
 /**
@@ -108,9 +109,9 @@ __host__ CUTLASS_DEVICE cudaError_t cuda_perror_impl(cudaError_t error,
  */
 #ifndef CUDA_PERROR_EXIT
 #define CUDA_PERROR_EXIT(e)                                     \
-  if (cuda_perror_impl((cudaError_t)(e), __FILE__, __LINE__)) { \
+  do { if (cuda_perror_impl((cudaError_t)(e), #e, __FILE__, __LINE__)) { \
     exit(1);                                                    \
-  }
+  } } while (0)
 #endif
 
 /**