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Re: [PATCH PR62151]Fix uninitialized register issue caused by distribute_notes in combine pass

From: Jeff Law <law at redhat dot com>
To: Segher Boessenkool <segher at kernel dot crashing dot org>
Cc: "Bin.Cheng" <amker dot cheng at gmail dot com>, Richard Earnshaw <rearnsha at arm dot com>, Bin Cheng <bin dot cheng at arm dot com>, "gcc-patches at gcc dot gnu dot org" <gcc-patches at gcc dot gnu dot org>, Ulrich Weigand <uweigand at de dot ibm dot com>
Date: Mon, 01 Sep 2014 21:35:05 -0600
Subject: Re: [PATCH PR62151]Fix uninitialized register issue caused by distribute_notes in combine pass
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References: <000a01cfc1de$cac1c230$60454690$ at arm dot com> <53FDB440 dot 5030904 at arm dot com> <CAHFci28BS75pySKVtLTeY8BQsYupJHvXs73ZdYq1RkfHLbXocQ at mail dot gmail dot com> <5401680D dot 60907 at redhat dot com> <20140831121844 dot GA8949 at gate dot crashing dot org> <CAHFci28OzU8wOyYnWxF1jSOn7jnUTubZ=Mjv=y7NhZR=C2G5BQ at mail dot gmail dot com> <20140901113850 dot GA15134 at gate dot crashing dot org> <5404A12E dot 1020501 at redhat dot com> <20140901175036 dot GA6643 at gate dot crashing dot org>

On 09/01/14 11:50, Segher Boessenkool wrote:

Another question is why is r84 set twice in the first place?

Various transformations can set that kind of situation up.


Sure -- but also lazy expanders can reuse a register instead of doing
gen_reg_rtx.  Which is why I asked :-)

Which comes back to my original train of thought. Fix the handling ofr84 and disallow the combination when we've got multiple sets of a pseudo.


jeff

References:
- Re: [PATCH PR62151]Fix uninitialized register issue caused by distribute_notes in combine pass
  - From: Bin.Cheng
- Re: [PATCH PR62151]Fix uninitialized register issue caused by distribute_notes in combine pass
  - From: Segher Boessenkool
- Re: [PATCH PR62151]Fix uninitialized register issue caused by distribute_notes in combine pass
  - From: Jeff Law
- Re: [PATCH PR62151]Fix uninitialized register issue caused by distribute_notes in combine pass
  - From: Segher Boessenkool

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