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* [Bug target/96026] New: overlap register bewteen DEST and SOURCE in different machine mode
@ 2020-07-02  7:16 rjiejie at me dot com
  2020-07-02 21:34 ` [Bug target/96026] " wilson at gcc dot gnu.org
  0 siblings, 1 reply; 2+ messages in thread
From: rjiejie at me dot com @ 2020-07-02  7:16 UTC (permalink / raw)
  To: gcc-bugs

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=96026

            Bug ID: 96026
           Summary: overlap register bewteen DEST and SOURCE in different
                    machine mode
           Product: gcc
           Version: 9.3.1
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: target
          Assignee: unassigned at gcc dot gnu.org
          Reporter: rjiejie at me dot com
  Target Milestone: ---

GCC seems to overlap register bewteen DEST and SOURCE in different machine
mode,

e.g. RISCV vector extension:
when VMUL > 1, most of instructions do not support with overlapped register

Is there any target hooks to control this feature ?

We can use <Constraint Modifier> ‘&’ to forbid register allocator to overlap
bewteen DEST and SOURCE,
but there are some redundancy instructions in the result code :(

^ permalink raw reply	[flat|nested] 2+ messages in thread

* [Bug target/96026] overlap register bewteen DEST and SOURCE in different machine mode
  2020-07-02  7:16 [Bug target/96026] New: overlap register bewteen DEST and SOURCE in different machine mode rjiejie at me dot com
@ 2020-07-02 21:34 ` wilson at gcc dot gnu.org
  0 siblings, 0 replies; 2+ messages in thread
From: wilson at gcc dot gnu.org @ 2020-07-02 21:34 UTC (permalink / raw)
  To: gcc-bugs

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=96026

Jim Wilson <wilson at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |wilson at gcc dot gnu.org
         Resolution|---                         |FIXED
             Status|UNCONFIRMED                 |RESOLVED

--- Comment #1 from Jim Wilson <wilson at gcc dot gnu.org> ---
This is 3 different places where you have asked the same question now.  One
place would have been good enough.  Already answered in other places.

^ permalink raw reply	[flat|nested] 2+ messages in thread

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2020-07-02  7:16 [Bug target/96026] New: overlap register bewteen DEST and SOURCE in different machine mode rjiejie at me dot com
2020-07-02 21:34 ` [Bug target/96026] " wilson at gcc dot gnu.org

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