[arm] early split most DImode comparison operations

Programming / Compilers / GCC - rearnsha [138bc75d-0d04-0410-961f-82ee72b054a4] - 18 October 2019 19:03 EDT

This patch does most of the work for early splitting the DImode comparisons. We now handle EQ, NE, LT, GE, LTU and GEU during early expansion, in addition to EQ and NE, for which the expansion has now been reworked to use a standard conditional-compare pattern already in the back-end.

To handle this we introduce two new condition flag modes that are used when comparing the upper words of decomposed DImode values: one for signed, and one for unsigned comparisons. CC_Bmode (B for Borrow) is essentially the inverse of CC_Cmode and is used when the carry flag is set by a subtraction of unsigned values.

- config/arm/arm-modes.def (CC_NV, CC_B): New CC modes.
- config/arm/arm.c (arm_select_cc_mode): Recognize constructs that need these modes. (arm_gen_dicompare_reg): New code to early expand the sub-operations of EQ, NE, LT, GE, LTU and GEU.
- config/arm/iterators.md (CC_EXTEND): New code attribute.
- config/arm/predicates.md (arm_adcimm_operand): New predicate..
- config/arm/arm.md (cmpsi3_carryin_out): New pattern. (cmpsi3_imm_carryin_out): Likewise. (cmpsi3_0_carryin_out): Likewise.

060a96ad617 [arm] early split most DImode comparison operations.
gcc/ChangeLog | 13 +++
gcc/config/arm/arm-modes.def | 6 ++
gcc/config/arm/arm.c | 220 ++++++++++++++++++++++++++++++++++++++++++-
gcc/config/arm/arm.md | 45 +++++++++
gcc/config/arm/iterators.md | 4 +
gcc/config/arm/predicates.md | 6 ++
6 files changed, 291 insertions(+), 3 deletions(-)

Upstream: gcc.gnu.org

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