This idea has come up in several reviews -- D115978 and D105902 -- so I
can't take any credit for the idea. Instead of using a constant pool to
lower -0.0, we can emit a sequence of two instructions:
fmv.[hwd].x freg, zero
fsgnjn.[hsd] freg, freg, freg
This is only done when the floating-point type is legal.
Reviewed By: craig.topper
Differential Revision: https://reviews.llvm.org/D117687
Add an alias of `addi [x], zero, imm` to generate pseudo
instruction li, which makes assembly mush more readable.
For existed tests, users can update them by running script
`llvm/utils/update_llc_test_checks.py`.
Reviewed By: asb
Differential Revision: https://reviews.llvm.org/D112692
Summary:
RISC-V uses a post-select peephole pass to optimise
`(load/store (ADDI $reg, %lo(addr)), 0)` into `(load/store $reg, %lo(addr))`.
This peephole wasn't firing for accesses to constant pools, which is how we
materialise most floating point constants.
This adds support for the constantpool case, which improves code generation for
lots of small FP loading examples. I have not added any tests because this
structure is well-covered by the `fp-imm.ll` testcases, as well as almost
all other uses of floating point constants in the RISC-V backend tests.
Reviewed By: luismarques, asb
Differential Revision: https://reviews.llvm.org/D79523
Summary:
RISC-V uses a post-select peephole pass to optimise
`(load/store (ADDI $reg, %lo(addr)), 0)` into `(load/store $reg, %lo(addr))`.
This peephole wasn't firing for accesses to constant pools, which is how we
materialise most floating point constants.
This adds support for the constantpool case, which improves code generation for
lots of small FP loading examples. I have not added any tests because this
structure is well-covered by the `fp-imm.ll` testcases, as well as almost
all other uses of floating point constants in the RISC-V backend tests.
Reviewed By: luismarques, asb
Differential Revision: https://reviews.llvm.org/D79523
Floating point positive zero can be selected using fmv.w.x / fmv.d.x /
fcvt.d.w and the zero source register.
Differential Revision: https://reviews.llvm.org/D75729
Fraser Cormack