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Behavior of -march=zcf on rv64. Behavior of F+Zce on RV64. #221

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topperc opened this issue Jun 26, 2023 · 8 comments
Open

Behavior of -march=zcf on rv64. Behavior of F+Zce on RV64. #221

topperc opened this issue Jun 26, 2023 · 8 comments

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@topperc
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topperc commented Jun 26, 2023

Since Zcf doesn't contain any instructions on RV64. Should toolchains reject it or accept it?

The spec says "Specifying Zce with F includes Zca, Zcb, Zcmp, Zcmt and Zcf". Zcf doesn't contain any instructions on rv64. Should toolchains only enable Zca, Zcb, Zcmp, Zcmt for Zce on rv64?
@tariqkurd-repo
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is there any precedence for empty extensions @aswaterman ? or is this the first time?

@aswaterman
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I don’t believe there is such a thing, even though it would be harmless. For my part, I’d favor rejecting it in RV64. Whichever is chosen should be clearly reflected in the spec.

@tariqkurd-repo
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yes I think that makes sense, although the wavefront spec isn't in great shape as it has incomplete SAIL code in it.
@Alasdair can we remove the SAIL code so that I can update the spec and re-release it?

@topperc
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topperc commented Jun 30, 2023

This my LLVM patch. https://reviews.llvm.org/D153742 It includes an error for Zcf on RV64. If Zce is specified with F, it only enables Zcf for RV32.

Couple additional questions.
Does Zcf imply F and does Zcd imply D?

@topperc
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topperc commented Jul 10, 2023

Any progress on getting the spec updated?

tariqkurd-repo added a commit that referenced this issue Jul 11, 2023
@tariqkurd-repo
#221 Zcf doesn't exist on RV64 as it contains no instructions
8be3419
@tariqkurd-repo
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#223

I gave up on getting the SAIL fixed so I reverted that PR, so I had a working head of main again.
Pleae have a look at the PR.

@pz9115
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pz9115 commented Jul 11, 2023 •
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This my LLVM patch. https://reviews.llvm.org/D153742 It includes an error for Zcf on RV64. If Zce is specified with F, it only enables Zcf for RV32.

Couple additional questions. Does Zcf imply F and does Zcd imply D?

As fld/fsd(sp) instruction description in ISA-spec, you have to use f/d with zcf/d.
But not sure if we need to add the imply relations with them, in GCC I just add an error to remind people missing f/d when using zcf/d.

@pz9115 pz9115 mentioned this issue Jul 13, 2023
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@pz9115
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pz9115 commented Jul 13, 2023 •
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This my LLVM patch. https://reviews.llvm.org/D153742 It includes an error for Zcf on RV64. If Zce is specified with F, it only enables Zcf for RV32.

Couple additional questions. Does Zcf imply F and does Zcd imply D?

Adding dependencies can make it easier for users to directly use Zcf/d extensions，
So I added the depending rules in this PR #224

a4lg added a commit to a4lg/binutils-gdb that referenced this issue Jul 24, 2023
@a4lg
RISC-V: Prohibit the 'Zcf' extension on RV64
fdb7a50 
As per:
<riscvarchive/riscv-code-size-reduction#221>,
the 'Zcf' extension does not exist on RV64.  This is reflected on the
version 1.0.4-1 of the code size reduction specification:
<https://github.com/riscv/riscv-code-size-reduction/releases/tag/v1.0.4-1>.

This commit prohibits the combination: RV64 (or any ISA with XLEN > 32)
and the 'Zcf' extension.

bfd/ChangeLog:

	* elfxx-riscv.c (riscv_parse_check_conflicts): Prohibit
	combination of RV64 and 'Zcf'.

gas/ChangeLog:

	* testsuite/gas/riscv/march-fail-rv64i_zcf.d: New test.
	* testsuite/gas/riscv/march-fail-rv64i_zcf.l: Likewise.
a4lg added a commit to a4lg/binutils-gdb that referenced this issue Jul 24, 2023
@a4lg
RISC-V: Prohibit the 'Zcf' extension on RV64
14d1ae2 
As per:
<riscvarchive/riscv-code-size-reduction#221>,
the 'Zcf' extension does not exist on RV64.  This is reflected on the
version 1.0.4-1 of the code size reduction specification:
<https://github.com/riscv/riscv-code-size-reduction/releases/tag/v1.0.4-1>.

This commit prohibits the combination: RV64 (or any ISA with XLEN > 32)
and the 'Zcf' extension.

bfd/ChangeLog:

	* elfxx-riscv.c (riscv_parse_check_conflicts): Prohibit
	combination of RV64 and 'Zcf'.

gas/ChangeLog:

	* testsuite/gas/riscv/march-fail-rv64i_zcf.d: New test.
	* testsuite/gas/riscv/march-fail-rv64i_zcf.l: Likewise.
wangliu-iscas pushed a commit to plctlab/patchwork-binutils-gdb that referenced this issue Jul 24, 2023
@a4lg @ouuleilei-bot
RISC-V: Prohibit the 'Zcf' extension on RV64
aa98d89 
As per:
<riscvarchive/riscv-code-size-reduction#221>,
the 'Zcf' extension does not exist on RV64.  This is reflected on the
version 1.0.4-1 of the code size reduction specification:
<https://github.com/riscv/riscv-code-size-reduction/releases/tag/v1.0.4-1>.

This commit prohibits the combination: RV64 (or any ISA with XLEN > 32)
and the 'Zcf' extension.

bfd/ChangeLog:

	* elfxx-riscv.c (riscv_parse_check_conflicts): Prohibit
	combination of RV64 and 'Zcf'.

gas/ChangeLog:

	* testsuite/gas/riscv/march-fail-rv64i_zcf.d: New test.
	* testsuite/gas/riscv/march-fail-rv64i_zcf.l: Likewise.
saagarjha pushed a commit to ahjragaas/binutils-gdb that referenced this issue Jul 24, 2023
@a4lg
RISC-V: Prohibit the 'Zcf' extension on RV64
766f6d1 
As per:
<riscvarchive/riscv-code-size-reduction#221>,
the 'Zcf' extension does not exist on RV64.  This is reflected on the
version 1.0.4-1 of the code size reduction specification:
<https://github.com/riscv/riscv-code-size-reduction/releases/tag/v1.0.4-1>.

This commit prohibits the combination: RV64 (or any ISA with XLEN > 32)
and the 'Zcf' extension.

bfd/ChangeLog:

	* elfxx-riscv.c (riscv_parse_check_conflicts): Prohibit
	combination of RV64 and 'Zcf'.

gas/ChangeLog:

	* testsuite/gas/riscv/march-fail-rv64i_zcf.d: New test.
	* testsuite/gas/riscv/march-fail-rv64i_zcf.l: Likewise.
fanghuaqi added a commit to Nuclei-Software/nuclei-sdk that referenced this issue Aug 14, 2023
@fanghuaqi
tools: zcf don't exist on rv64 config
14b6a89 
see riscvarchive/riscv-code-size-reduction#221

Signed-off-by: Huaqi Fang <[email protected]>
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@aswaterman @topperc @pz9115 @tariqkurd-repo