x64: lower i64x2.imul to VPMULLQ when possible

This adds the machinery to encode the VPMULLQ instruction which is
available in AVX512VL and AVX512DQ. When these feature sets are
available, we use this instruction instead of a lengthy 12-instruction
sequence.

cranelift/codegen/src/isa/x64/inst/args.rs

@@ -462,6 +462,7 @@ pub(crate) enum InstructionSet {
     BMI2,
     AVX512F,
     AVX512VL,
+    AVX512DQ,
 }
 
 /// Some SSE operations requiring 2 operands r/m and r.
@@ -994,13 +995,15 @@ impl fmt::Display for SseOpcode {
 #[derive(Clone)]
 pub enum Avx512Opcode {
     Vpabsq,
+    Vpmullq,
 }
 
 impl Avx512Opcode {
     /// Which `InstructionSet`s support the opcode?
     pub(crate) fn available_from(&self) -> SmallVec<[InstructionSet; 2]> {
         match self {
             Avx512Opcode::Vpabsq => smallvec![InstructionSet::AVX512F, InstructionSet::AVX512VL],
+            Avx512Opcode::Vpmullq => smallvec![InstructionSet::AVX512VL, InstructionSet::AVX512DQ],
         }
     }
 }
@@ -1009,6 +1012,7 @@ impl fmt::Debug for Avx512Opcode {
     fn fmt(&self, fmt: &mut fmt::Formatter) -> fmt::Result {
         let name = match self {
             Avx512Opcode::Vpabsq => "vpabsq",
+            Avx512Opcode::Vpmullq => "vpmullq",
         };
         write!(fmt, "{}", name)
     }

cranelift/codegen/src/isa/x64/inst/emit.rs

@@ -128,6 +128,7 @@ pub(crate) fn emit(
             InstructionSet::BMI2 => info.isa_flags.has_bmi2(),
             InstructionSet::AVX512F => info.isa_flags.has_avx512f(),
             InstructionSet::AVX512VL => info.isa_flags.has_avx512vl(),
+            InstructionSet::AVX512DQ => info.isa_flags.has_avx512dq(),
         }
     };
 
@@ -1409,6 +1410,7 @@ pub(crate) fn emit(
         Inst::XmmUnaryRmREvex { op, src, dst } => {
             let opcode = match op {
                 Avx512Opcode::Vpabsq => 0x1f,
+                _ => unimplemented!("Opcode {:?} not implemented", op),
             };
             match src {
                 RegMem::Reg { reg: src } => EvexInstruction::new()
@@ -1545,6 +1547,31 @@ pub(crate) fn emit(
             }
         }
 
+        Inst::XmmRmREvex {
+            op,
+            src1,
+            src2,
+            dst,
+        } => {
+            let opcode = match op {
+                Avx512Opcode::Vpmullq => 0x40,
+                _ => unimplemented!("Opcode {:?} not implemented", op),
+            };
+            match src1 {
+                RegMem::Reg { reg: src } => EvexInstruction::new()
+                    .length(EvexVectorLength::V128)
+                    .prefix(LegacyPrefixes::_66)
+                    .map(OpcodeMap::_0F38)
+                    .w(true)
+                    .opcode(opcode)
+                    .reg(dst.to_reg().get_hw_encoding())
+                    .rm(src.get_hw_encoding())
+                    .vvvvv(src2.get_hw_encoding())
+                    .encode(sink),
+                _ => todo!(),
+            };
+        }
+
         Inst::XmmMinMaxSeq {
             size,
             is_min,

cranelift/codegen/src/isa/x64/inst/emit_tests.rs

@@ -3555,6 +3555,12 @@ fn test_x64_emit() {
         "pmullw  %xmm14, %xmm1",
     ));
 
+    insns.push((
+        Inst::xmm_rm_r_evex(Avx512Opcode::Vpmullq, RegMem::reg(xmm14), xmm10, w_xmm1),
+        "62D2AD0840CE",
+        "vpmullq %xmm14, %xmm10, %xmm1",
+    ));
+
     insns.push((
         Inst::xmm_rm_r(SseOpcode::Pmuludq, RegMem::reg(xmm8), w_xmm9),
         "66450FF4C8",
@@ -4283,6 +4289,7 @@ fn test_x64_emit() {
     isa_flag_builder.enable("has_ssse3").unwrap();
     isa_flag_builder.enable("has_sse41").unwrap();
     isa_flag_builder.enable("has_avx512f").unwrap();
+    isa_flag_builder.enable("has_avx512dq").unwrap();
     let isa_flags = x64::settings::Flags::new(&flags, isa_flag_builder);
 
     let rru = regs::create_reg_universe_systemv(&flags);

cranelift/codegen/src/isa/x64/inst/mod.rs

@@ -212,6 +212,13 @@ pub enum Inst {
         dst: Writable<Reg>,
     },
 
+    XmmRmREvex {
+        op: Avx512Opcode,
+        src1: RegMem,
+        src2: Reg,
+        dst: Writable<Reg>,
+    },
+
     /// XMM (scalar or vector) unary op: mov between XMM registers (32 64) (reg addr) reg, sqrt,
     /// etc.
     ///
@@ -577,7 +584,7 @@ impl Inst {
             | Inst::XmmToGpr { op, .. }
             | Inst::XmmUnaryRmR { op, .. } => smallvec![op.available_from()],
 
-            Inst::XmmUnaryRmREvex { op, .. } => op.available_from(),
+            Inst::XmmUnaryRmREvex { op, .. } | Inst::XmmRmREvex { op, .. } => op.available_from(),
         }
     }
 }
@@ -724,6 +731,23 @@ impl Inst {
         Inst::XmmRmR { op, src, dst }
     }
 
+    pub(crate) fn xmm_rm_r_evex(
+        op: Avx512Opcode,
+        src1: RegMem,
+        src2: Reg,
+        dst: Writable<Reg>,
+    ) -> Self {
+        src1.assert_regclass_is(RegClass::V128);
+        debug_assert!(src2.get_class() == RegClass::V128);
+        debug_assert!(dst.to_reg().get_class() == RegClass::V128);
+        Inst::XmmRmREvex {
+            op,
+            src1,
+            src2,
+            dst,
+        }
+    }
+
     pub(crate) fn xmm_uninit_value(dst: Writable<Reg>) -> Self {
         debug_assert!(dst.to_reg().get_class() == RegClass::V128);
         Inst::XmmUninitializedValue { dst }
@@ -1425,6 +1449,20 @@ impl PrettyPrint for Inst {
                 show_ireg_sized(dst.to_reg(), mb_rru, 8),
             ),
 
+            Inst::XmmRmREvex {
+                op,
+                src1,
+                src2,
+                dst,
+                ..
+            } => format!(
+                "{} {}, {}, {}",
+                ljustify(op.to_string()),
+                src1.show_rru_sized(mb_rru, 8),
+                show_ireg_sized(*src2, mb_rru, 8),
+                show_ireg_sized(dst.to_reg(), mb_rru, 8),
+            ),
+
             Inst::XmmMinMaxSeq {
                 lhs,
                 rhs_dst,
@@ -1898,6 +1936,13 @@ fn x64_get_regs(inst: &Inst, collector: &mut RegUsageCollector) {
                 collector.add_mod(*dst);
             }
         }
+        Inst::XmmRmREvex {
+            src1, src2, dst, ..
+        } => {
+            src1.get_regs_as_uses(collector);
+            collector.add_use(*src2);
+            collector.add_def(*dst);
+        }
         Inst::XmmRmRImm { op, src, dst, .. } => {
             if inst.produces_const() {
                 // No need to account for src, since src == dst.
@@ -2283,6 +2328,16 @@ fn x64_map_regs<RUM: RegUsageMapper>(inst: &mut Inst, mapper: &RUM) {
                 map_mod(mapper, dst);
             }
         }
+        Inst::XmmRmREvex {
+            ref mut src1,
+            ref mut src2,
+            ref mut dst,
+            ..
+        } => {
+            src1.map_uses(mapper);
+            map_use(mapper, src2);
+            map_def(mapper, dst);
+        }
         Inst::XmmRmiReg {
             ref mut src,
             ref mut dst,