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RE: [PATCH][ARC] Refurbish emitting DWARF2 for epilogue.

From: Claudiu Zissulescu <Claudiu dot Zissulescu at synopsys dot com>
To: Joern Wolfgang Rennecke <gnu at amylaar dot uk>, "gcc-patches at gcc dot gnu dot org" <gcc-patches at gcc dot gnu dot org>
Cc: "Francois dot Bedard at synopsys dot com" <Francois dot Bedard at synopsys dot com>, "jeremy dot bennett at embecosm dot com" <jeremy dot bennett at embecosm dot com>
Date: Mon, 7 Dec 2015 09:19:47 +0000
Subject: RE: [PATCH][ARC] Refurbish emitting DWARF2 for epilogue.
Authentication-results: sourceware.org; auth=none
References: <1448632380-7353-1-git-send-email-claziss at synopsys dot com> <5660BB51 dot 6000304 at amylaar dot uk>

Hi Joern,

> > +      insn = emit_insn (gen_blockage ());
> 
> Is this actually part of the patch to fix cfi generation?

This instruction prevents the delay branch scheduler to speculatively use epilogue instructions to fill up the delay slots. Hence, generating an assert during dwarf2cfi execution. This behavior is experiment by dg.exp/pr49994-1.s test.

At a closer inspection of the patch, I've refurbish it in a more generic fashion (attached), where the blockage guards the entire expand epilogue process.

It may be questionable if emitting blockage in epilogue is part of the cfi refactoring of the epilogue. However, without it we may still get errors in dwarf2cfi.

Thanks,
Claudiu

Attachment: 0001-Refurbish-emitting-DWARF2-related-information-when-e.patch
Description: 0001-Refurbish-emitting-DWARF2-related-information-when-e.patch

Follow-Ups:
- Re: [PATCH][ARC] Refurbish emitting DWARF2 for epilogue.
  - From: Joern Wolfgang Rennecke

References:
- Re: [PATCH][ARC] Refurbish emitting DWARF2 for epilogue.
  - From: Joern Wolfgang Rennecke

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