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bpf: Define instruction patterns for extensions and truncations between i32 to i64 

For transformations between i32 and i64, if it is explicit signed extension:
  - first cast the operand to i64
  - then use SLL + SRA to finish the extension.

if it is explicit zero extension:
  - first cast the operand to i64
  - then use SLL + SRL to finish the extension.

if it is explicit any extension:
  - just refer to 64-bit register.

if it is explicit truncation:
  - just refer to 32-bit subregister.

NOTE: Some of the zero extension sequences might be unnecessary, they will be
removed by an peephole pass on MachineInstruction layer.

Signed-off-by: Jiong Wang <jiong.wang@netronome.com>
Reviewed-by: Yonghong Song <yhs@fb.com>
llvm-svn: 325981
This commit is contained in:
Yonghong Song 2018-02-23 23:49:21 +00:00
parent 3a564a8f6e
commit 0252f35362
1 changed files with 20 additions and 0 deletions
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20
llvm/lib/Target/BPF/BPFInstrInfo.td
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@ -583,3 +583,23 @@ def LD_ABS_W : LOAD_ABS<BPF_W, "u32", int_bpf_load_word>;
def LD_IND_B : LOAD_IND<BPF_B, "u8", int_bpf_load_byte>;
def LD_IND_H : LOAD_IND<BPF_H, "u16", int_bpf_load_half>;
def LD_IND_W : LOAD_IND<BPF_W, "u32", int_bpf_load_word>;
let isCodeGenOnly = 1 in {
def MOV_32_64 : ALU_RR<BPF_ALU, BPF_MOV,
(outs GPR:$dst), (ins GPR32:$src),
"$dst = $src", []>;
}
def : Pat<(i64 (sext GPR32:$src)),
(SRA_ri (SLL_ri (MOV_32_64 GPR32:$src), 32), 32)>;
def : Pat<(i64 (zext GPR32:$src)),
(SRL_ri (SLL_ri (MOV_32_64 GPR32:$src), 32), 32)>;
// For i64 -> i32 truncation, use the 32-bit subregister directly.
def : Pat<(i32 (trunc GPR:$src)),
(i32 (EXTRACT_SUBREG GPR:$src, sub_32))>;
// For i32 -> i64 anyext, we don't care about the high bits.
def : Pat<(i64 (anyext GPR32:$src)),
(INSERT_SUBREG (i64 (IMPLICIT_DEF)), GPR32:$src, sub_32)>;