Jerry Quinn wrote:
Joseph S. Myers wrote:
On Sat, 21 Mar 2009, Ian Lance Taylor wrote:
../.././gcc/config/i386/i386.c:3282: error: comparison is always true
due to limited range of data type
#define IN_RANGE(VALUE, LOWER, UPPER) \
((unsigned HOST_WIDE_INT) (VALUE) - (unsigned HOST_WIDE_INT)
(LOWER) \
<= (unsigned HOST_WIDE_INT) (UPPER) - (unsigned HOST_WIDE_INT)
(LOWER))
gcc_assert (IN_RANGE (ix86_arch, 0, 255));
It all looks fine to me.
Sounds like enums in C++ having limited ranges meaning this is an
assertion of something the compiler knows to be true. (This actually
illustrates why these warnings can sometimes be problematic - you
write a check for something that may or may not be always true
depending on the sizes of types, the handling of enumerations, etc.,
and when it is always true the compiler complains. But in other
cases they can be useful.)
However, the stage 1 compilation succeeds, and that's being compiled
with g++ 4.3.3. Wait, is it a warning in stage 1 and an error in
stage 2?
I just confirmed that it is a warning in stage 1. It would seem to me
that the thing to do here is to remove the gcc_assert. The fact that
ix86_arch is now an enum means it can't be assigned an invalid value
without an inappropriate cast somewhere. It seems like the compiler
should catch as many problems as the runtime check did, so I would think
we could ditch the runtime check. The patch below does that and fixes
bootstrap for me. Posted to gcc-patches as well.
Alternatively, the IN_RANGE macro could be modified to check that the
upper and lower bounds are within the limits of the checked value's
type. That seems like overkill to me, though.
Jerry
2009-03-21 Jerry Quinn <jlqu...@optonline.net>
* config/i386/i386.c (ix86_function_specific_save): Don't check
range of enum values.
Index: i386.c
===================================================================
--- i386.c (revision 144950)
+++ i386.c (working copy)
@@ -3279,10 +3279,6 @@
static void
ix86_function_specific_save (struct cl_target_option *ptr)
{
- gcc_assert (IN_RANGE (ix86_arch, 0, 255));
- gcc_assert (IN_RANGE (ix86_schedule, 0, 255));
- gcc_assert (IN_RANGE (ix86_tune, 0, 255));
- gcc_assert (IN_RANGE (ix86_fpmath, 0, 255));
gcc_assert (IN_RANGE (ix86_branch_cost, 0, 255));
ptr->arch = ix86_arch;
