From: "Maciej W. Rozycki" <macro@embecosm.com>
To: Jeff Law <jeffreyalaw@gmail.com>
Cc: gcc-patches@gcc.gnu.org, Andrew Waterman <andrew@sifive.com>,
Jim Wilson <jim.wilson.gcc@gmail.com>,
Kito Cheng <kito.cheng@gmail.com>,
Palmer Dabbelt <palmer@dabbelt.com>
Subject: Re: [PATCH 34/44] RISC-V: Provide FP conditional-branch instructions for if-conversion
Date: Thu, 23 Nov 2023 23:26:34 +0000 (GMT) [thread overview]
Message-ID: <alpine.DEB.2.20.2311232255530.5892@tpp.orcam.me.uk> (raw)
In-Reply-To: <6c95d298-a854-4976-bc31-830b9e1cde09@gmail.com>
On Sun, 19 Nov 2023, Jeff Law wrote:
> So this is a more gradual lowering of the FP branches to allow ifcvt to do a
> better job. Seems generally reasonable. I don't expect that we're missing
> any significant simplifications, though I probably could construct a missed
> CSE/GCSE if I worked at it for a bit.
I've been thinking about it a little before submitting this patch in its
final form. I considered activating the splitter in split1 rather than
split2, but figured out it would likely make little if any difference.
We could add another, yet earlier split pass I suppose, somewhere between
ce1 and cse2. I'm not sure it would be worth it though.
> Presumably the length computation can't be handled by the generic code we've
> already got in place?
I disregarded such an option right away at the time of writing this code.
I'm sure this code could be folded, but not in a straightforward way.
Notice the different, misaligned branch spans, owing to the machine branch
instruction being the second in the ultimate instruction pair produced.
So getting rid of this extra code may not be worth the complication in the
common "length" attribute value calculation unless, perhaps, we factor the
branch case out to a C++ function.
Maciej
next prev parent reply other threads:[~2023-11-23 23:26 UTC|newest]
Thread overview: 101+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-11-19 5:35 [PATCH 00/44] RISC-V: Various if-conversion fixes and improvements Maciej W. Rozycki
2023-11-18 16:50 ` [PATCH 13/44] RISC-V/testsuite: Add branchless cases for FP cond-move operations Maciej W. Rozycki
2023-11-18 18:03 ` Jeff Law
2023-11-19 6:27 ` Maciej W. Rozycki
2023-11-19 5:37 ` Maciej W. Rozycki
2023-11-19 5:35 ` [PATCH 01/44] testsuite: Add cases for conditional-move and conditional-add operations Maciej W. Rozycki
2023-11-19 5:52 ` Kito Cheng
2023-11-20 10:16 ` Maciej W. Rozycki
2023-11-20 12:57 ` Richard Biener
2023-11-22 1:33 ` Maciej W. Rozycki
2023-11-19 5:35 ` [PATCH 02/44] RISC-V/testsuite: Add cases for integer SFB cond-move operations Maciej W. Rozycki
2023-11-19 5:53 ` Kito Cheng
2023-11-19 5:35 ` [PATCH 03/44] RISC-V: Reorder comment on SFB patterns Maciej W. Rozycki
2023-11-19 5:53 ` Kito Cheng
2023-11-19 5:36 ` [PATCH 04/44] RISC-V: Sanitise NEED_EQ_NE_P case with `riscv_emit_int_compare' Maciej W. Rozycki
2023-11-19 5:53 ` Kito Cheng
2023-11-19 5:36 ` [PATCH 05/44] RISC-V: Fix `mode' usage in `riscv_expand_conditional_move' Maciej W. Rozycki
2023-11-19 5:54 ` Kito Cheng
2023-11-19 5:36 ` [PATCH 06/44] RISC-V: Avoid repeated GET_MODE calls " Maciej W. Rozycki
2023-11-19 5:55 ` Kito Cheng
2023-11-19 5:36 ` [PATCH 07/44] RISC-V: Use `nullptr' " Maciej W. Rozycki
2023-11-19 5:53 ` Kito Cheng
2023-11-19 5:36 ` [PATCH 08/44] RISC-V: Simplify EQ vs NE selection " Maciej W. Rozycki
2023-11-19 5:56 ` Kito Cheng
2023-11-19 5:36 ` [PATCH 09/44] RISC-V: Rework branch costing model for if-conversion Maciej W. Rozycki
2023-11-19 18:52 ` Jeff Law
2023-11-23 18:34 ` Maciej W. Rozycki
2023-11-29 1:19 ` Jeff Law
2023-11-29 12:01 ` Maciej W. Rozycki
2023-11-19 5:37 ` [PATCH 10/44] RISC-V/testsuite: Add branched cases for integer cond-move operations Maciej W. Rozycki
2023-11-19 6:44 ` Kito Cheng
2023-11-19 5:37 ` [PATCH 11/44] RISC-V/testsuite: Add branchless " Maciej W. Rozycki
2023-11-19 6:47 ` Kito Cheng
2023-11-23 19:18 ` Maciej W. Rozycki
2023-11-19 5:37 ` [PATCH 12/44] RISC-V/testsuite: Add branched cases for FP " Maciej W. Rozycki
2023-11-19 6:48 ` Kito Cheng
2023-11-19 5:38 ` [PATCH 14/44] RISC-V: Also invert the cond-move condition for GEU and LEU Maciej W. Rozycki
2023-11-19 6:50 ` Kito Cheng
2023-11-19 5:38 ` [PATCH 15/44] RISC-V/testsuite: Add branched cases for GEU and LEU cond-move operations Maciej W. Rozycki
2023-11-19 17:42 ` Jeff Law
2023-11-19 5:38 ` [PATCH 16/44] RISC-V/testsuite: Add branchless " Maciej W. Rozycki
2023-11-19 7:22 ` Kito Cheng
2023-11-19 5:38 ` [PATCH 17/44] RISC-V: Avoid extraneous EQ or NE operation in cond-move expansion Maciej W. Rozycki
2023-11-19 17:45 ` Jeff Law
2023-11-19 5:38 ` [PATCH 18/44] RISC-V/testsuite: Add branched cases for equality cond-move operations Maciej W. Rozycki
2023-11-19 17:45 ` Jeff Law
2023-11-19 5:39 ` [PATCH 19/44] RISC-V/testsuite: Add branchless " Maciej W. Rozycki
2023-11-19 17:46 ` Jeff Law
2023-11-19 5:39 ` [PATCH 20/44] RISC-V: Also accept constants for T-Head cond-move comparison operands Maciej W. Rozycki
2023-11-19 17:48 ` Jeff Law
2023-11-19 5:39 ` [PATCH 21/44] RISC-V: Also accept constants for T-Head cond-move data input operands Maciej W. Rozycki
2023-11-19 17:50 ` Jeff Law
2023-11-19 5:40 ` [PATCH 22/44] RISC-V: Fold all the cond-move variants together Maciej W. Rozycki
2023-11-19 18:35 ` Jeff Law
2023-11-19 5:40 ` [PATCH 23/44] RISC-V/testsuite: Add branched cases for T-Head non-equality cond moves Maciej W. Rozycki
2023-11-19 17:54 ` Jeff Law
2023-11-19 5:40 ` [PATCH 24/44] RISC-V/testsuite: Add branchless " Maciej W. Rozycki
2023-11-19 17:54 ` Jeff Law
2023-11-19 5:40 ` [PATCH 25/44] RISC-V: Implement `riscv_emit_unary' helper Maciej W. Rozycki
2023-11-19 17:54 ` Jeff Law
2023-11-19 5:40 ` [PATCH 26/44] RISC-V: Add `movMODEcc' implementation for generic targets Maciej W. Rozycki
2023-11-19 18:18 ` Jeff Law
2023-11-23 22:16 ` Maciej W. Rozycki
2023-11-19 5:40 ` [PATCH 27/44] RISC-V/testsuite: Add branched cases for generic integer cond moves Maciej W. Rozycki
2023-11-19 18:18 ` Jeff Law
2023-11-19 5:41 ` [PATCH 28/44] RISC-V/testsuite: Add branchless " Maciej W. Rozycki
2023-11-19 18:19 ` Jeff Law
2023-11-19 5:41 ` [PATCH 29/44] RISC-V: Add `addMODEcc' implementation for generic targets Maciej W. Rozycki
2023-11-19 18:23 ` Jeff Law
2023-11-23 22:36 ` Maciej W. Rozycki
2023-11-19 5:41 ` [PATCH 30/44] RISC-V/testsuite: Add branched cases for generic integer cond adds Maciej W. Rozycki
2023-11-19 18:23 ` Jeff Law
2023-11-19 5:41 ` [PATCH 31/44] RISC-V/testsuite: Add branchless " Maciej W. Rozycki
2023-11-19 18:25 ` Jeff Law
2023-11-23 22:48 ` Maciej W. Rozycki
2023-11-19 5:42 ` [PATCH 32/44] RISC-V: Only use SUBREG if applicable in `riscv_expand_float_scc' Maciej W. Rozycki
2023-11-19 18:26 ` Jeff Law
2023-11-19 5:42 ` [PATCH 33/44] RISC-V: Also allow FP conditions in `riscv_expand_conditional_move' Maciej W. Rozycki
2023-11-19 18:30 ` Jeff Law
2023-11-23 22:55 ` Maciej W. Rozycki
2023-11-19 5:42 ` [PATCH 34/44] RISC-V: Provide FP conditional-branch instructions for if-conversion Maciej W. Rozycki
2023-11-19 19:42 ` Jeff Law
2023-11-23 23:26 ` Maciej W. Rozycki [this message]
2023-11-19 5:42 ` [PATCH 35/44] RISC-V: Avoid extraneous integer comparison for FP comparisons Maciej W. Rozycki
2023-11-19 19:44 ` Jeff Law
2023-11-19 5:42 ` [PATCH 36/44] RISC-V/testsuite: Add branched cases for generic FP cond moves Maciej W. Rozycki
2023-11-19 19:45 ` Jeff Law
2023-11-19 5:43 ` [PATCH 37/44] RISC-V/testsuite: Add branchless " Maciej W. Rozycki
2023-11-19 19:46 ` Jeff Law
2023-11-19 5:43 ` [PATCH 38/44] RISC-V/testsuite: Add branched cases for generic FP cond adds Maciej W. Rozycki
2023-11-19 19:46 ` Jeff Law
2023-11-19 5:43 ` [PATCH 39/44] RISC-V/testsuite: Add branchless " Maciej W. Rozycki
2023-11-19 19:47 ` Jeff Law
2023-11-19 5:43 ` [PATCH 40/44] RISC-V: Handle FP NE operator via inversion in cond-operation expansion Maciej W. Rozycki
2023-11-19 19:51 ` Jeff Law
2023-11-22 1:37 ` Maciej W. Rozycki
2023-11-19 5:43 ` [PATCH 41/44] RISC-V/testsuite: Add branched cases for FP NE cond-move operations Maciej W. Rozycki
2023-11-19 5:43 ` [PATCH 42/44] " Maciej W. Rozycki
2023-11-19 5:44 ` [PATCH 43/44] RISC-V/testsuite: Add branched cases for FP NE cond-add operation Maciej W. Rozycki
2023-11-19 5:44 ` [PATCH 44/44] RISC-V/testsuite: Add branchless " Maciej W. Rozycki
2023-11-19 5:52 ` [PATCH 00/44] RISC-V: Various if-conversion fixes and improvements Kito Cheng
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