CODEWITHSUNDEEP
c++warningsnvcc
Anycorn
Anycorn

Reputation: 51435

CUDA: NVCC gives controlling expression is constant warning on assert

I get the warning controlling expression is constant on assert statement like this:

assert(... && "error message");

Why this warning on this assert? How can I suppress this warning?

NVCC is the NVIDIA cuda compiler, I think it is based on LLVM. Why does it give this warning, when the same compiles fine with GCC or Visual C++ compilers?

Upvotes: 7

Views: 3491

Answers (5)

Kevin Holt
Kevin Holt

Reputation: 814

Add the following somewhere near the beginning of your code:

#pragma diag_suppress boolean_controlling_expr_is_constant

Note that this will suppress all compiler warnings for "controlling expression is constant", not just the warning associated with your assertions.

I sometimes get this warning when checking constants or properties that are defined (or can be derived) at compile time, so in my experience the warning has been generally benign and OK to ignore.

Upvotes: 3

user2333829
user2333829

Reputation: 1401

I ran into this exact problem and finally found a way to disable warnings on the device. Here are the details...

To disable a specific warning, you need to use the -Xcudafe flag combined with a token listed on this page (http://www.ssl.berkeley.edu/~jimm/grizzly_docs/SSL/opt/intel/cc/9.0/lib/locale/en_US/mcpcom.msg). For example, to disable the "controlling expression is constant" warning, pass the following to NVCC:

-Xcudafe "--diag_suppress=boolean_controlling_expr_is_constant"

This worked for me! For other warnings, see the above link.

Upvotes: 3

Georg Fritzsche
Georg Fritzsche

Reputation: 98964

A portable alternative (possibly wrapped in a macro) would be something like:

 {
     const bool error_message = true;
     assert([...] && error_message);
 }

To clear up what i meant:

#define myAssert(msg, exp) { const bool msg(true); assert(msg && (exp)); }
// usage:
myAssert(ouch, a && b);

... gives e.g.:

assertion "ouch && (a && b)" failed [...]

Upvotes: 3

Crashworks
Crashworks

Reputation: 41374

Try #pragma warning.

Upvotes: 0

Frank Krueger
Frank Krueger

Reputation: 70973

If it is LLVM based, then you can use something like this:

#pragma clang diagnostic push
#pragma clang diagnostic ignored "-Wmultichar"

char b = 'df'; // no warning.

#pragma clang diagnostic pop

From Controlling Diagnostics via Pragmas.

Upvotes: 0

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