arm: Implement MVE predicates as vectors of booleans
This patch implements support for vectors of booleans to support MVE
predicates, instead of HImode. Since the ABI mandates pred16_t (aka
uint16_t) to represent predicates in intrinsics prototypes, we
introduce a new "predicate" type qualifier so that we can map relevant
builtins HImode arguments and return value to the appropriate vector
of booleans (VxBI).
We have to update test_vector_ops_duplicate, because it iterates using
an offset in bytes, where we would need to iterate in bits: we stop
iterating when we reach the end of the vector of booleans.
In addition, we have to fix the underlying definition of vectors of
booleans because ARM/MVE needs a different representation than
AArch64/SVE. With ARM/MVE the 'true' bit is duplicated over the
element size, so that a true element of V4BI is represented by
'0b1111'. This patch updates the aarch64 definition of VNx*BI as
needed.
Most of the work of this patch series was carried out while I was
working at STMicroelectronics as a Linaro assignee.
2022-02-22 Christophe Lyon <christophe.lyon@arm.com>
Richard Sandiford <richard.sandiford@arm.com>
gcc/
PR target/100757
PR target/101325
* config/aarch64/aarch64-modes.def (VNx16BI, VNx8BI, VNx4BI,
VNx2BI): Update definition.
* config/arm/arm-builtins.cc (arm_init_simd_builtin_types): Add new
simd types.
(arm_init_builtin): Map predicate vectors arguments to HImode.
(arm_expand_builtin_args): Move HImode predicate arguments to VxBI
rtx. Move return value to HImode rtx.
* config/arm/arm-builtins.h (arm_type_qualifiers): Add qualifier_predicate.
* config/arm/arm-modes.def (B2I, B4I, V16BI, V8BI, V4BI): New modes.
* config/arm/arm-simd-builtin-types.def (Pred1x16_t,
Pred2x8_t,Pred4x4_t): New.
* emit-rtl.cc (init_emit_once): Handle all boolean modes.
* genmodes.cc (mode_data): Add boolean field.
(blank_mode): Initialize it.
(make_complex_modes): Fix handling of boolean modes.
(make_vector_modes): Likewise.
(VECTOR_BOOL_MODE): Use new COMPONENT parameter.
(make_vector_bool_mode): Likewise.
(BOOL_MODE): New.
(make_bool_mode): New.
(emit_insn_modes_h): Fix generation of boolean modes.
(emit_class_narrowest_mode): Likewise.
* machmode.def: (VECTOR_BOOL_MODE): Document new COMPONENT
parameter. Use new BOOL_MODE instead of FRACTIONAL_INT_MODE to
define BImode.
* rtx-vector-builder.cc (rtx_vector_builder::find_cached_value):
Fix handling of constm1_rtx for VECTOR_BOOL.
* simplify-rtx.cc (native_encode_rtx): Fix support for VECTOR_BOOL.
(native_decode_vector_rtx): Likewise.
(test_vector_ops_duplicate): Skip vec_merge test
with vectors of booleans.
* varasm.cc (output_constant_pool_2): Likewise.