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[PATCH, i386]: Workaround PR 63620 by allowing only direct immediate values in FP push patterns

From: Uros Bizjak <ubizjak at gmail dot com>
To: "gcc-patches at gcc dot gnu dot org" <gcc-patches at gcc dot gnu dot org>
Cc: Jeff Law <law at redhat dot com>
Date: Fri, 31 Oct 2014 20:45:54 +0100
Subject: [PATCH, i386]: Workaround PR 63620 by allowing only direct immediate values in FP push patterns
Authentication-results: sourceware.org; auth=none

Hello!

Attached patch works around PR 63620. Patched gcc will allow only a
subset of CONST_DOUBLEs in FP push patterns. This subset will result
in direct immediates that can always be encoded directly in the insn
stream. These won't be reloaded through memory, and will avoid PIC
register re-materialization issues. OTOH, the patch will generate
non-optimal push sequences when general registers are available.

2014-10-31  Uros Bizjak  <ubizjak@gmail.com>

    PR target/63620
    * config/i386/i386.md (*pushtf): Allow only CONST_DOUBLES that won't
    be reloaded through memory.
    (*pushxf): Ditto.
    (*pushdf): Ditto.

The patch was bootstrapped and regression tested on x86_64-linux-gnu
{-m32}. The patch was also checked with Darwin crosscompiler on the
testcases in the PR.

Committed to mainline.

Uros

Attachment: p.diff.txt
Description: Text document

Follow-Ups:
- Re: [PATCH, i386]: Workaround PR 63620 by allowing only direct immediate values in FP push patterns
  - From: Jakub Jelinek

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