[Qemu-devel] [PATCH 0/4] tcg: Add muluh and mulsh opcodes

[Richard Henderson]

We have -- or will have -- several targets which have a native
multiply-highpart instruction: ppc*, ia64, aarch64, alpha.

If we leave only the mul[us]2 opcode with which to expose this,
we have to handle the register allocation bits in the backends.
Better, IMO, to expose the two parts at the TCG opcode level,
simplifying the backends.

I've left tcg_gen_mul[us]_i{32,64} as the "public" interface to
these opcodes at the translator level.  If the guest does not
need both results, they can just be ignored.  If the host has a
combined mult insn (i386, arm) then one output is garbage; if
the host has separate mult insns, then the optimizer can delete
the unused opcode.

Really only tested with x86_64 and ppc64.
The linux-user-test image for alpha sees:

IN: 
0x0000004000814148:  umulh      t5,t0,t0

OP:
 ld_i32 tmp0,env,$0xffffffffffffffa8
 movi_i32 tmp1,$0x0
 brcond_i32 tmp0,tmp1,ne,$0x0
 ---- 0x4000814148
 mul_i64 tmp3,ir6,ir1
 muluh_i64 ir1,ir6,ir1
 mov_i64 tmp2,tmp3
 movi_i64 pc,$0x400081414c
 exit_tb $0x0
 set_label $0x0
 exit_tb $0x3fff8c244483

OP after optimization and liveness analysis:
 ld_i32 tmp0,env,$0xffffffffffffffa8
 movi_i32 tmp1,$0x0
 brcond_i32 tmp0,tmp1,ne,$0x0
 ---- 0x4000814148
 nopn $0x3,$0xd,$0x3
 muluh_i64 ir1,ir1,ir6
 nopn $0x2,$0x2
 movi_i64 pc,$0x400081414c
 exit_tb $0x0
 set_label $0x0
 exit_tb $0x3fff8c244483
 end 

OUT: [size=76]
0x6011b0f0:  lwz     r14,-88(r27)
0x6011b0f4:  cmpwi   cr7,r14,0
0x6011b0f8:  bne-    cr7,0x6011b128
0x6011b0fc:  ld      r14,8(r27)
0x6011b100:  ld      r15,48(r27)
0x6011b104:  mulhdu  r14,r14,r15
0x6011b108:  std     r14,8(r27)
...



r~


Richard Henderson (4):
  tcg: Add muluh and mulsh opcodes
  tcg-mips: Implement mulsh, muluh
  tcg-ppc64: Implement muluh, mulsh
  tcg: Constant fold div, rem

 tcg/aarch64/tcg-target.h |  4 ++++
 tcg/arm/tcg-target.h     |  2 ++
 tcg/hppa/tcg-target.h    |  2 ++
 tcg/i386/tcg-target.h    |  4 ++++
 tcg/ia64/tcg-target.h    |  4 ++++
 tcg/mips/tcg-target.c    | 10 ++++++++++
 tcg/mips/tcg-target.h    |  2 ++
 tcg/optimize.c           | 43 +++++++++++++++++++++++++++++++++++++++++++
 tcg/ppc/tcg-target.h     |  2 ++
 tcg/ppc64/tcg-target.c   | 32 +++++++-------------------------
 tcg/ppc64/tcg-target.h   |  8 ++++++--
 tcg/s390/tcg-target.h    |  4 ++++
 tcg/sparc/tcg-target.h   |  4 ++++
 tcg/tcg-op.h             | 40 ++++++++++++++++++++++++++++++++++++----
 tcg/tcg-opc.h            |  4 ++++
 tcg/tcg.c                | 36 ++++++++++++++++++++++++++++++------
 tcg/tcg.h                |  2 ++
 tcg/tci/tcg-target.h     |  5 ++++-
 18 files changed, 170 insertions(+), 38 deletions(-)

-- 
1.8.1.4