Hi,
On 26 August 2017 at 04:04, Renato Golin <renato.go...@linaro.org> wrote:
> +linaro-toolchain, hoping to get more eyes into it.
>
> cheers,
> --renato
>
> On 25 August 2017 at 17:59, Masaki Arai <masaki.a...@linaro.org> wrote:
>> Hi,
>>
>> I extended GCC 7.1(or GCC 7.2) for `hcqc'.
>> I would be grateful if you could give me a comment about whether
>> this extension is acceptable and whether this extension should be
>> pushed upstream.
I think this is a useful info. However there might be pushback from
upstream maintainers as this makes the structure bigger by adding a
field. This could have implications for memory usage of the compiler.
Alternatively, we maybe able to get this info from dwarf info when we
compile with -g ? Jim may have some input here (cc ing him).
Thanks,
Kugan
>>
>> The extended GCC's output using the option ` -fverbose-asm' is
>> as follows:
>>
>> ldr w0, [x29,48] // tmp433, j(8-byte Folded Spill)
>> ^^^^^^^^^^^^^^^^^^^
>> This code shows that this instruction accesses a memory area
>> for spill codes.
>> I made the following changes to GCC 7.1(or GCC 7.2).
>> The related files are under `hcqc/patch/gcc-7.1.0-add'.
>>
>> (1) rtl.h
>>
>> I added flag information to `struct mem_attrs' that means whether
>> it is a spill memory area or not.
>>
>> +
>> + /* True if the MEM is for spill. */
>> + bool for_spill_p;
>>
>> Also, I added an access macro for this additional field.
>>
>> + /* For a MEM rtx, true if its MEM is for spill. */
>> + #define MEM_FOR_SPILL_P(RTX) (get_mem_attrs (RTX)->for_spill_p)
>> +
>>
>> (2) emit-rtl.c
>>
>> I added a code to turn on flags for spill memory area in function
>> `set_mem_attrs_for_spill'.
>>
>> + attrs.for_spill_p = true;
>>
>> (3) final.c
>>
>> I added code to print that information in function
>> `output_asm_operand_names'
>> if the memory is a spill memory area,
>>
>> +
>> + if (MEM_P (op) && MEM_FOR_SPILL_P (op))
>> + {
>> + HOST_WIDE_INT size = MEM_SIZE (op);
>> + fprintf (asm_out_file, " (" HOST_WIDE_INT_PRINT_DEC "-byte Folded
>> Spill)", size);
>> + }
>>
>> The above changes are implemented similarly as Clang/LLVM.
>> Unfortunately, it is difficult for GCC to print the above "(?-byte Folded
>> Spill)"
>> for memory access instructions only in the same manner as Clang/LLVM.
>> The reason is that GCC executes the above `output_asm_operand_names'
>> even in situations where any instruction object(insn) does not exist when
>> outputting assembly code.
>> For example, GCC calls `output_asm_insn' directly from the `define_insn'
>> definition in the aarch64.md file without an insn object(`output_asm_insn'
>> calls `output_asm_operand_names').
>> This occurs in "*cb<optab><mode>1" and
>> "*aarch64_fcvt<su_optab><GPF:mode><GPI:mode>2_mult".
>>
>> From this fact, `hcqc' extracts and accumulates memory access
>> instructions from the assembly code with the comment "(?-byte Folded
>> Spill)".
>>
>> The above extensions are commonly available on almost any architecture.
>> Also, these extensions do not affect the execution of the resulting assembly
>> code since additional outputs are only in comments.
>>
>> Best regards,
>> --
>> --------------------------------------
>> Masaki Arai
>>
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