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问题描述
我的任务是改变HPC应用程序部件的精度,同时铭记它严重依赖于自动矢量化。因此,编译器告诉我何时发生任何类型的浮点转换转换(因为这可能会对性能造成严重影响)。
<$ c
$ b
然而,实际上,gfortran 5.2.0似乎只报告浮点降级,例如 REAL(8) 到 REAL(4)。
GCC的 -Wouble-promotion 标志 - 正是我需要的,但不适用于gfortran。 ()
我正在使用gfortran进行开发,但ifort可用于我。然而,我找不到任何类似的参数 -warn ()。
我怎样才能得到这些编译器在隐式提升REAL时发出警告?解析方案
您可以参考使用gfortran 5.2.0,所以让我们来看看该版本的文档而不是4.1.0。这有:
如果我在后面的程序中使用后面的标志
use,intrinsic :: iso_fortran_env,only:real32,real64
real(real64)x
x = 1._real32
end
我在问题标题
中准确地(但使用gfortran 4.8.1) (b)
$ b
However, in practice, gfortran 5.2.0 only appears to report floating point demotions, e.g. REAL(8) to REAL(4).
GCC has the -Wdouble-promotion flag - exactly what I need, but not available for gfortran. (https://gcc.gnu.org/onlinedocs/gcc/Warning-Options.html)
I am developing with gfortran, but ifort is available to me. However, I can't find any similar arguments for -warn (https://software.intel.com/en-us/node/525184).
How can I get either of these compilers to emit a warning when implicitly promoting a REAL?
解决方案
You refer to using gfortran 5.2.0, so let's look at the documentation for that version rather than 4.1.0. This has two relevant flags for what you consider:
If I use this latter flag with the following program
use, intrinsic :: iso_fortran_env, only : real32, real64
real(real64) x
x = 1._real32
end
I get exactly (albeit using gfortran 4.8.1) a warning message requested in the question title
whereas with just -Wconversion I get nothing. If I change the program slightly, however, so that the changing of representable values kicks in, I get (different) warnings with each.
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