From: Jeff Law <jeffreyalaw@gmail.com>
To: Richard Sandiford <richard.sandiford@arm.com>,
jlaw@ventanamicro.com, gcc-patches@gcc.gnu.org
Subject: Re: [PATCH 5/6] rtl-ssa: Calculate dominance frontiers for the exit block
Date: Tue, 24 Oct 2023 11:28:48 -0600 [thread overview]
Message-ID: <a46bd4f5-c490-49a6-98f8-0850425492fe@gmail.com> (raw)
In-Reply-To: <20231024105006.3337671-6-richard.sandiford@arm.com>
On 10/24/23 04:50, Richard Sandiford wrote:
> The exit block can have multiple predecessors, for example if the
> function calls __builtin_eh_return. We might then need PHI nodes
> for values that are live on exit.
>
> RTL-SSA uses the normal dominance frontiers approach for calculating
> where PHI nodes are needed. However, dominannce.cc only calculates
> dominators for normal blocks, not the exit block.
> calculate_dominance_frontiers likewise only calculates dominance
> frontiers for normal blocks.
>
> This patch fills in the “missing” frontiers manually.
>
> gcc/
> * rtl-ssa/internals.h (build_info::exit_block_dominator): New
> member variable.
> * rtl-ssa/blocks.cc (build_info::build_info): Initialize it.
> (bb_walker::bb_walker): Use it, moving the computation of the
> dominator to...
> (function_info::process_all_blocks): ...here.
> (function_info::place_phis): Add dominance frontiers for the
> exit block.
OK
jeff
next prev parent reply other threads:[~2023-10-24 17:28 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-10-24 10:50 [PATCH 0/6] rtl-ssa: Various fixes needed for the late-combine pass Richard Sandiford
2023-10-24 10:50 ` [PATCH 1/6] rtl-ssa: Ensure global registers are live on exit Richard Sandiford
2023-10-24 17:21 ` Jeff Law
2023-10-24 10:50 ` [PATCH 2/6] rtl-ssa: Create REG_UNUSED notes after all pending changes Richard Sandiford
2023-10-24 17:22 ` Jeff Law
2023-10-24 10:50 ` [PATCH 3/6] rtl-ssa: Fix ICE when deleting memory clobbers Richard Sandiford
2023-10-24 17:24 ` Jeff Law
2023-10-24 10:50 ` [PATCH 4/6] rtl-ssa: Handle artifical uses of deleted defs Richard Sandiford
2023-10-24 17:26 ` Jeff Law
2023-10-24 10:50 ` [PATCH 5/6] rtl-ssa: Calculate dominance frontiers for the exit block Richard Sandiford
2023-10-24 17:28 ` Jeff Law [this message]
2023-10-24 10:50 ` [PATCH 6/6] rtl-ssa: Handle call clobbers in more places Richard Sandiford
2023-10-24 17:37 ` Jeff Law
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