[Qemu-devel] [PATCH for-4.0 0/5] tcg/i386: Improve guest_base handling

[Richard Henderson]

This tidies guest_base handling such that (1) we require no scratch
registers, (2) we require no extra instructions besides the memory op,
and (3) we reduce the size of the memory op by omitting a prefix.

In principal point 3 is offset by adding additional opcodes to handle
zero-extension when converting 64-bit guest values back to 32-bit guest
addresses.  But those turn out to be hen's teeth, since 32-bit guests
often have no way of even producing 64-bit guest values.

In particular, I saw none in a simple pass through linux-user-test-0.3
for i386, arm, sh4, sparc.


r~


Richard Henderson (5):
  tcg/i386: Propagate is64 to tcg_out_qemu_ld_direct
  tcg/i386: Implement INDEX_op_extr{lh}_i64_i32 for 32-bit guests
  tcg/i386: Assume 32-bit values are zero-extended
  tcg/i386: Precompute all guest_base parameters
  tcg/i386: Add setup_guest_base_seg for FreeBSD

 tcg/i386/tcg-target.h     |   5 +-
 tcg/i386/tcg-target.inc.c | 188 ++++++++++++++++----------------------
 2 files changed, 83 insertions(+), 110 deletions(-)

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2.17.2