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Fix clang's internal assembler adding unwanted prefix to VIA xstore

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Merge commit 2d8c18fbbdd1 from llvm git (by Jessica Clarke):

  [X86] Don't add implicit REP prefix to VIA PadLock xstore

  Commit 8fa3e8fa1492 added an implicit REP prefix to all VIA PadLock
  instructions, but GNU as doesn't add one to xstore, only all the others.
  This resulted in a kernel panic regression in FreeBSD upon updating to
  LLVM 11 (https://bugs.freebsd.org/259218) which includes the commit in
  question. This partially reverts that commit.

  Reviewed By: craig.topper

  Differential Revision: https://reviews.llvm.org/D112355

MFC after:	3 days
This commit is contained in:
Dimitry Andric 2021-10-23 20:19:26 +02:00
parent 2558bb8e91
commit 4b9725184e
1 changed files with 1 additions and 1 deletions
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2
contrib/llvm-project/llvm/lib/Target/X86/X86InstrSystem.td
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@ -585,7 +585,7 @@ def XRSTORS64 : RI<0xC7, MRM3m, (outs), (ins opaquemem:$dst),
//===----------------------------------------------------------------------===//
// VIA PadLock crypto instructions
let Defs = [RAX, RDI], Uses = [RDX, RDI], SchedRW = [WriteSystem] in
def XSTORE : I<0xa7, MRM_C0, (outs), (ins), "xstore", []>, TB, REP;
def XSTORE : I<0xa7, MRM_C0, (outs), (ins), "xstore", []>, TB;
def : InstAlias<"xstorerng", (XSTORE)>;