[X86] Reduce some patterns by using FP instructions for integer types even when AVX2 is available and execution domain fixing will do the right thing

[craig.topper]

Summary

We have quite a few cases of using FP instructions for integer operations when only AVX1 is available. Then we switch to integer instructions with AVX2. In a lot of these cases execution domain fixing will take care of turning FP instructions into integer if its profitable.

With this patch we just keep on using the FP instructions even with AVX2. I've only handled some cases that don't require messing with patterns that are defined in the instruction definition. Those will require more subtle multiclass work possibly involving null_frag, hasSideEffects = 0, etc.

[RKSimon]

Here you're making more use of the domain pass to reduce isel patterns, but in rL354511 you added isel patterns to avoid the load folding pass - what's the difference?

[craig.topper]

I’ve never understood if the peephole pass is as powerful at folding loads as SelectionDAG. I added the extra patterns to make sure AVX1 and 2 were being handled in a consistent way.

I do know that the execution domain fixing pass is going to make a domain decision for these instructions regardless of what instruction we started with. Though I guess it doesn’t run in O0 so maybe we should pick the best domain in isel?

[RKSimon]

LGTM - as long as you are happy with the potential -O0 domain changes.

In my experience, load folding seems to get most things right but there are some cases (MOVSD vs BLENDPD etc.) where we struggle to recover from.

lib/Target/X86/X86InstrSSE.td

 
 let mayLoad = 1, hasSideEffects = 0, Predicates = [HasAVX],
     ExeDomain = SSEPackedSingle in
 def VBROADCASTF128 : AVX8I<0x1A, MRMSrcMem, (outs VR256:$dst),
                            (ins f128mem:$src),
                            "vbroadcastf128\t{$src, $dst|$dst, $src}", []>,
                            Sched<[SchedWriteFShuffle.XMM.Folded]>, VEX, VEX_L;
 
-let Predicates = [HasAVX2, NoVLX] in {
-def : Pat<(v4i64 (X86SubVBroadcast (loadv2i64 addr:$src))),
-          (VBROADCASTI128 addr:$src)>;
-def : Pat<(v8i32 (X86SubVBroadcast (loadv4i32 addr:$src))),
-          (VBROADCASTI128 addr:$src)>;
-def : Pat<(v16i16 (X86SubVBroadcast (loadv8i16 addr:$src))),
-          (VBROADCASTI128 addr:$src)>;
-def : Pat<(v32i8 (X86SubVBroadcast (loadv16i8 addr:$src))),
-          (VBROADCASTI128 addr:$src)>;
-}
-
 let Predicates = [HasAVX, NoVLX] in {
 def : Pat<(v4f64 (X86SubVBroadcast (loadv2f64 addr:$src))),
           (VBROADCASTF128 addr:$src)>;
 def : Pat<(v8f32 (X86SubVBroadcast (loadv4f32 addr:$src))),
           (VBROADCASTF128 addr:$src)>;
 }
 
-let Predicates = [HasAVX1Only] in {
+// NOTE: We're using FP instructions here, but execution domain fixing can
+// convert to integer when profitable.
+let Predicates = [HasAVX, NoVLX] in {
 def : Pat<(v4i64 (X86SubVBroadcast (loadv2i64 addr:$src))),
           (VBROADCASTF128 addr:$src)>;
 def : Pat<(v8i32 (X86SubVBroadcast (loadv4i32 addr:$src))),
           (VBROADCASTF128 addr:$src)>;
 def : Pat<(v16i16 (X86SubVBroadcast (loadv8i16 addr:$src))),
           (VBROADCASTF128 addr:$src)>;
 def : Pat<(v32i8 (X86SubVBroadcast (loadv16i8 addr:$src))),
           (VBROADCASTF128 addr:$src)>;
defm VPBLENDD : AVX2_blend_rmi<0x02, "vpblendd", X86Blendi, v4i32,
                                BlendCommuteImm4>;
 defm VPBLENDDY : AVX2_blend_rmi<0x02, "vpblendd", X86Blendi, v8i32,
                                 SchedWriteBlend.YMM, VR256, i256mem,
                                 BlendCommuteImm8>, VEX_L;
 }
 
 // For insertion into the zero index (low half) of a 256-bit vector, it is
 // more efficient to generate a blend with immediate instead of an insert*128.
-let Predicates = [HasAVX2] in {
-def : Pat<(insert_subvector (v8i32 VR256:$src1), (v4i32 VR128:$src2), (iPTR 0)),
-          (VPBLENDDYrri VR256:$src1,
-                        (INSERT_SUBREG (v8i32 (IMPLICIT_DEF)),
-                                       VR128:$src2, sub_xmm), 0xf)>;
-def : Pat<(insert_subvector (v4i64 VR256:$src1), (v2i64 VR128:$src2), (iPTR 0)),
-          (VPBLENDDYrri VR256:$src1,
-                        (INSERT_SUBREG (v8i32 (IMPLICIT_DEF)),
-                                       VR128:$src2, sub_xmm), 0xf)>;
-def : Pat<(insert_subvector (v16i16 VR256:$src1), (v8i16 VR128:$src2), (iPTR 0)),
-          (VPBLENDDYrri VR256:$src1,
-                        (INSERT_SUBREG (v8i32 (IMPLICIT_DEF)),
-                                       VR128:$src2, sub_xmm), 0xf)>;
-def : Pat<(insert_subvector (v32i8 VR256:$src1), (v16i8 VR128:$src2), (iPTR 0)),
-          (VPBLENDDYrri VR256:$src1,
-                        (INSERT_SUBREG (v8i32 (IMPLICIT_DEF)),
-                                       VR128:$src2, sub_xmm), 0xf)>;
-
-def : Pat<(insert_subvector (loadv8i32 addr:$src2), (v4i32 VR128:$src1), (iPTR 0)),
-          (VPBLENDDYrmi (INSERT_SUBREG (v8i32 (IMPLICIT_DEF)),
-                                       VR128:$src1, sub_xmm), addr:$src2, 0xf0)>;
-def : Pat<(insert_subvector (loadv4i64 addr:$src2), (v2i64 VR128:$src1), (iPTR 0)),
-          (VPBLENDDYrmi (INSERT_SUBREG (v8i32 (IMPLICIT_DEF)),
-                                       VR128:$src1, sub_xmm), addr:$src2, 0xf0)>;
-def : Pat<(insert_subvector (loadv16i16 addr:$src2), (v8i16 VR128:$src1), (iPTR 0)),
-          (VPBLENDDYrmi (INSERT_SUBREG (v8i32 (IMPLICIT_DEF)),
-                                       VR128:$src1, sub_xmm), addr:$src2, 0xf0)>;
-def : Pat<(insert_subvector (loadv32i8 addr:$src2), (v16i8 VR128:$src1), (iPTR 0)),
-          (VPBLENDDYrmi (INSERT_SUBREG (v8i32 (IMPLICIT_DEF)),
-                                       VR128:$src1, sub_xmm), addr:$src2, 0xf0)>;
-}
-
-let Predicates = [HasAVX1Only] in {
+// NOTE: We're using FP instructions here, but exeuction domain fixing should
+// take care of using integer instructions when profitable.
+let Predicates = [HasAVX] in {
 def : Pat<(insert_subvector (v8i32 VR256:$src1), (v4i32 VR128:$src2), (iPTR 0)),
           (VBLENDPSYrri VR256:$src1,
                         (INSERT_SUBREG (v8i32 (IMPLICIT_DEF)),
                                        VR128:$src2, sub_xmm), 0xf)>;
 def : Pat<(insert_subvector (v4i64 VR256:$src1), (v2i64 VR128:$src2), (iPTR 0)),
           (VBLENDPSYrri VR256:$src1,
                         (INSERT_SUBREG (v8i32 (IMPLICIT_DEF)),
                                        VR128:$src2, sub_xmm), 0xf)>;
let Predicates = [HasAVX2] in {
   defm : maskmov_lowering<"VPMASKMOVQ", VR128, v2i64, v2i64, "VBLENDVPD", v4i32>;
 }
 
 //===----------------------------------------------------------------------===//
 // SubVector Broadcasts
 // Provide fallback in case the load node that is used in the patterns above
 // is used by additional users, which prevents the pattern selection.
 
-let Predicates = [HasAVX2, NoVLX] in {
-def : Pat<(v4i64 (X86SubVBroadcast (v2i64 VR128:$src))),
-          (VINSERTI128rr (INSERT_SUBREG (v4i64 (IMPLICIT_DEF)), VR128:$src, sub_xmm),
-                         (v2i64 VR128:$src), 1)>;
-def : Pat<(v8i32 (X86SubVBroadcast (v4i32 VR128:$src))),
-          (VINSERTI128rr (INSERT_SUBREG (v8i32 (IMPLICIT_DEF)), VR128:$src, sub_xmm),
-                         (v4i32 VR128:$src), 1)>;
-def : Pat<(v16i16 (X86SubVBroadcast (v8i16 VR128:$src))),
-          (VINSERTI128rr (INSERT_SUBREG (v16i16 (IMPLICIT_DEF)), VR128:$src, sub_xmm),
-                         (v8i16 VR128:$src), 1)>;
-def : Pat<(v32i8 (X86SubVBroadcast (v16i8 VR128:$src))),
-          (VINSERTI128rr (INSERT_SUBREG (v32i8 (IMPLICIT_DEF)), VR128:$src, sub_xmm),
-                         (v16i8 VR128:$src), 1)>;
-}
-
 let Predicates = [HasAVX, NoVLX] in {
 def : Pat<(v4f64 (X86SubVBroadcast (v2f64 VR128:$src))),
           (VINSERTF128rr (INSERT_SUBREG (v4f64 (IMPLICIT_DEF)), VR128:$src, sub_xmm),
                          (v2f64 VR128:$src), 1)>;
 def : Pat<(v8f32 (X86SubVBroadcast (v4f32 VR128:$src))),
           (VINSERTF128rr (INSERT_SUBREG (v8f32 (IMPLICIT_DEF)), VR128:$src, sub_xmm),
                          (v4f32 VR128:$src), 1)>;
 }
 
-let Predicates = [HasAVX1Only] in {
+// NOTE: We're using FP instructions here, but execution domain fixing can
+// convert to integer when profitable.
+let Predicates = [HasAVX, NoVLX] in {
 def : Pat<(v4i64 (X86SubVBroadcast (v2i64 VR128:$src))),
           (VINSERTF128rr (INSERT_SUBREG (v4i64 (IMPLICIT_DEF)), VR128:$src, sub_xmm),
                          (v2i64 VR128:$src), 1)>;
 def : Pat<(v8i32 (X86SubVBroadcast (v4i32 VR128:$src))),
           (VINSERTF128rr (INSERT_SUBREG (v8i32 (IMPLICIT_DEF)), VR128:$src, sub_xmm),
                          (v4i32 VR128:$src), 1)>;
 def : Pat<(v16i16 (X86SubVBroadcast (v8i16 VR128:$src))),
           (VINSERTF128rr (INSERT_SUBREG (v16i16 (IMPLICIT_DEF)), VR128:$src, sub_xmm),