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Diffstat (limited to 'gcc/ada/doc/gnat_ugn/gnat_and_program_execution.rst')
| -rw-r--r-- | gcc/ada/doc/gnat_ugn/gnat_and_program_execution.rst | 30 |
1 files changed, 9 insertions, 21 deletions
diff --git a/gcc/ada/doc/gnat_ugn/gnat_and_program_execution.rst b/gcc/ada/doc/gnat_ugn/gnat_and_program_execution.rst index 6f33d0b4ce3..6161073367b 100644 --- a/gcc/ada/doc/gnat_ugn/gnat_and_program_execution.rst +++ b/gcc/ada/doc/gnat_ugn/gnat_and_program_execution.rst @@ -1447,26 +1447,20 @@ some guidelines on debugging optimized code. Controlling Run-Time Checks ^^^^^^^^^^^^^^^^^^^^^^^^^^^ -By default, GNAT generates all run-time checks, except integer overflow -checks, stack overflow checks, and checks for access before elaboration on -subprogram calls. The latter are not required in default mode, because all +By default, GNAT generates all run-time checks, except stack overflow +checks, and checks for access before elaboration on subprogram +calls. The latter are not required in default mode, because all necessary checking is done at compile time. .. index:: -gnatp (gcc) .. index:: -gnato (gcc) -Two gnat switches, *-gnatp* and *-gnato* allow this default to -be modified. See :ref:`Run-Time_Checks`. +The gnat switch, *-gnatp* allows this default to be modified. See +:ref:`Run-Time_Checks`. Our experience is that the default is suitable for most development purposes. -We treat integer overflow specially because these -are quite expensive and in our experience are not as important as other -run-time checks in the development process. Note that division by zero -is not considered an overflow check, and divide by zero checks are -generated where required by default. - Elaboration checks are off by default, and also not needed by default, since GNAT uses a static elaboration analysis approach that avoids the need for run-time checking. This manual contains a full chapter discussing the issue @@ -1942,11 +1936,9 @@ contain a single nested loop, if it can be vectorized when considered alone: The vectorizable operations depend on the targeted SIMD instruction set, but the adding and some of the multiplying operators are generally supported, as -well as the logical operators for modular types. Note that, in the former -case, enabling overflow checks, for example with *-gnato*, totally -disables vectorization. The other checks are not supposed to have the same -definitive effect, although compiling with *-gnatp* might well reveal -cases where some checks do thwart vectorization. +well as the logical operators for modular types. Note that compiling +with *-gnatp* might well reveal cases where some checks do thwart +vectorization. Type conversions may also prevent vectorization if they involve semantics that are not directly supported by the code generator or the SIMD instruction set. @@ -3197,10 +3189,6 @@ If no digits follow the *-gnato*, then it is equivalent to causing all intermediate operations to be computed using the base type (`STRICT` mode). -In addition to setting the mode used for computation of intermediate -results, the `-gnato` switch also enables overflow checking (which -is suppressed by default). It thus combines the effect of using -a pragma `Overflow_Mode` and pragma `Unsuppress`. .. _Default_Settings: @@ -3884,7 +3872,7 @@ execution of this erroneous program: it to obtain accurate dynamic memory usage history at a minimal cost to the execution speed. Note however, that `gnatmem` is not supported on all platforms (currently, it is supported on AIX, HP-UX, GNU/Linux, Solaris and - Windows NT/2000/XP (x86). + Windows. The `gnatmem` command has the form |