It turns out that when doing a vector shift by 2, the optab routine
passes (const_int 2) to convert_modes with oldmode set to the mode
of the shift (e.g. something like V8HI). When the target mode is a
real integer mode like SImode, mainline just ignores that oldmode
and returns a (const_int 2) regardless, but wide-int doesn't.
Saying that (const_int 2) has a vector mode is almost certainly a bug
that ought to be trapped by an assert, but we're not trying to fight
that battle here. The current code:
if (CONST_SCALAR_INT_P (x)
&& GET_MODE_CLASS (mode) == MODE_INT
&& (oldmode == VOIDmode || GET_MODE_CLASS (oldmode) == MODE_INT))
is already coping with bogus oldmodes, just not in the way that
other routines seem to expect.
Tested on powerpc64-linux-gnu and x86_64-linux-gnu. This fixed several
testsuite changes on the ARM targets. OK to install?
Thanks,
Richard
Index: gcc/expr.c
===================================================================
--- gcc/expr.c 2013-11-02 10:34:44.083635650 +0000
+++ gcc/expr.c 2013-11-02 10:42:55.179233840 +0000
@@ -712,13 +712,12 @@ convert_modes (enum machine_mode mode, e
return x;
if (CONST_SCALAR_INT_P (x)
- && GET_MODE_CLASS (mode) == MODE_INT
- && (oldmode == VOIDmode || GET_MODE_CLASS (oldmode) == MODE_INT))
+ && GET_MODE_CLASS (mode) == MODE_INT)
{
/* If the caller did not tell us the old mode, then there is
not much to do with respect to canonization. We have to assume
that all the bits are significant. */
- if (oldmode == VOIDmode)
+ if (GET_MODE_CLASS (oldmode) != MODE_INT)
oldmode = MAX_MODE_INT;
wide_int w = wide_int::from (std::make_pair (x, oldmode),
GET_MODE_PRECISION (mode),
