This is a patch to fix PR49487.
As Denis will be off-line for some time, it'd be great if
a global reviewer would review it. It appears that he is
the only AVR maintainer who approves patches.
The reason for the ICE is as explained in the PR:
Rotate pattern use "X" as constraint for an operand which is
used as scratch. However, the operand is a match_operand
and not a match_scratch.
Because the scratch is not needed in all situations, I choose
to use match_scratch instead of match_operand and not to fix
the constraints. Fixing constraints would lead to superfluous
allocation of register if no scratch was needed.
Tested with 2 FAILs less: gcc.c-torture/compile/pr46883.c
ICEs without this patch and passes with it.
The test case in the PR passes, too. That test case
passes also the current unpatched 4.7, but it's obvious that
the constraint/operand combination is a bug.
Ok to commit and back-port to 4.6?
Johann
PR target/49487
* config/avr/avr.md (rotl<mode>3): Generate SCRATCH instead
of REG.
(*rotw<mode>): Use const_int_operand for operands2.
Use match_scatch for operands3.
(*rotb<mode>): Ditto
* config/avr/avr.c (avr_rotate_bytes): Treat SCRATCH.
