The number of actual invocations does not warrent an opcode,
and the backends generating it. But at least we can eliminate
redundant helpers.
Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
Signed-off-by: Richard Henderson <rth@twiddle.net>
The ISA manual documents the output is undefined if the input was zero.
However, we document in target-i386 that the behavior of real silicon
is to preserve the contents of the output register. We also mention
that there are real applications that depend on this. That this is
baked into silicon is mentioned as a potential cause for some false
sharing behaviour wrt lzcnt/tzcnt.
Taking advantage of this allows us to save 2 insns in the normal case,
and 4 insns for i686 emulating a 64-bit clz.
Signed-off-by: Richard Henderson <rth@twiddle.net>
Previously we could not have different constraints for different ISA levels,
which prevented us from eliding the matching constraint for shifts.
We do now have to make sure that the operands match for constant shifts.
We can also handle some small left shifts via lea.
Signed-off-by: Richard Henderson <rth@twiddle.net>
Use a switch instead of searching a table. Share constraints between
32-bit and 64-bit, when at all possible.
Signed-off-by: Richard Henderson <rth@twiddle.net>
This allows an output operand to match an input operand
only when the input operand needs a register.
Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
Signed-off-by: Richard Henderson <rth@twiddle.net>
This will let us choose how to interpret a given constraint
depending on whether the opcode is 32- or 64-bit. Which will
let us share more constraint combinations between opcodes.
At the same time, change the interface to return the advanced
pointer instead of passing it in/out by reference.
Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
Signed-off-by: Richard Henderson <rth@twiddle.net>
This will allow the target to tailor the constraints to the
auto-detected ISA extensions.
Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
Signed-off-by: Richard Henderson <rth@twiddle.net>
This is the same concept as, and same markup as, the
early clobber markup in gcc.
Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
Signed-off-by: Richard Henderson <rth@twiddle.net>
Use the new primitives for RDWINM and RLDICL.
Reviewed-by: David Gibson <david@gibson.dropbear.id.au>
Signed-off-by: Richard Henderson <rth@twiddle.net>
A couple of places where it was easy to identify a right-shift
followed by an extract or and-with-immediate, and the obvious
sign-extract from a high byte register.
Acked-by: Eduardo Habkost <ehabkost@redhat.com>
Signed-off-by: Richard Henderson <rth@twiddle.net>
Since we can no longer use matching constraints, this does
mean we must handle that data movement by hand.
Signed-off-by: Richard Henderson <rth@twiddle.net>
This lets us expose facilities to TCG_TARGET_HAS_* defines
directly, rather than hiding behind function calls.
Signed-off-by: Richard Henderson <rth@twiddle.net>
This allows us to use this detection within the TCG_TARGET_HAS_*
macros, instead of requiring a function call into tcg-target.inc.c.
Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
Signed-off-by: Richard Henderson <rth@twiddle.net>
While we don't require a new opcode, it is handy to have an expander
that knows the first source is zero.
Signed-off-by: Richard Henderson <rth@twiddle.net>
