all: AVX-512 (#217)

Extends avo to support most AVX-512 instruction sets.

The instruction type is extended to support suffixes. The K family of opmask
registers is added to the register package, and the operand package is updated
to support the new operand types. Move instruction deduction in `Load` and
`Store` is extended to support KMOV* and VMOV* forms.

Internal code generation packages were overhauled. Instruction database loading
required various messy changes to account for the additional complexities of the
AVX-512 instruction sets. The internal/api package was added to introduce a
separation between instruction forms in the database, and the functions avo
provides to create them. This was required since with instruction suffixes there
is no longer a one-to-one mapping between instruction constructors and opcodes.

AVX-512 bloated generated source code size substantially, initially increasing
compilation and CI test times to an unacceptable level. Two changes were made to
address this:

1.  Instruction constructors in the `x86` package moved to an optab-based
    approach. This compiles substantially faster than the verbose code
    generation we had before.

2.  The most verbose code-generated tests are moved under build tags and
    limited to a stress test mode. Stress test builds are run on
    schedule but not in regular CI.

An example of AVX-512 accelerated 16-lane MD5 is provided to demonstrate and
test the new functionality.

Updates #20 #163 #229

Co-authored-by: Vaughn Iverson <vsivsi@yahoo.com>

internal/gen/testing.go

@@ -0,0 +1,85 @@
+package gen
+
+import (
+	"github.com/mmcloughlin/avo/internal/api"
+	"github.com/mmcloughlin/avo/internal/inst"
+	"github.com/mmcloughlin/avo/internal/prnt"
+)
+
+// DeclareTestArguments prints a block of variables declaring a valid operand of
+// each operand type.
+func DeclareTestArguments(g *prnt.Generator) {
+	g.Printf("var (\n")
+	for _, arg := range validArgs {
+		g.Printf("\t%s operand.Op = %s\n", TestArgumentName(arg.Type), arg.Code)
+	}
+	g.Printf(")\n")
+}
+
+// TestSignature returns a function signature with arguments matching the given
+// instruction form. Requires variables declared by DeclareTestArguments().
+func TestSignature(f inst.Form) api.Signature {
+	var names []string
+	for _, op := range f.Operands {
+		names = append(names, TestArgumentName(op.Type))
+	}
+	return api.ArgsList(names)
+}
+
+// TestArgumentName returns the name of the variable of operand type t declared
+// by DeclareTestArguments().
+func TestArgumentName(t string) string {
+	return "op" + t
+}
+
+var validArgs = []struct {
+	Type string
+	Code string
+}{
+	// Immediates
+	{"1", "operand.Imm(1)"},
+	{"3", "operand.Imm(3)"},
+	{"imm2u", "operand.Imm(3)"},
+	{"imm8", "operand.Imm(math.MaxInt8)"},
+	{"imm16", "operand.Imm(math.MaxInt16)"},
+	{"imm32", "operand.Imm(math.MaxInt32)"},
+	{"imm64", "operand.Imm(math.MaxInt64)"},
+
+	// Registers
+	{"al", "reg.AL"},
+	{"cl", "reg.CL"},
+	{"ax", "reg.AX"},
+	{"eax", "reg.EAX"},
+	{"rax", "reg.RAX"},
+	{"r8", "reg.CH"},
+	{"r16", "reg.R9W"},
+	{"r32", "reg.R10L"},
+	{"r64", "reg.R11"},
+	{"xmm0", "reg.X0"},
+	{"xmm", "reg.X7"},
+	{"ymm", "reg.Y15"},
+	{"zmm", "reg.Z31"},
+	{"k", "reg.K7"},
+
+	// Memory
+	{"m", "operand.Mem{Base: reg.BX, Index: reg.CX, Scale: 2}"},
+	{"m8", "operand.Mem{Base: reg.BL, Index: reg.CH, Scale: 1}"},
+	{"m16", "operand.Mem{Base: reg.BX, Index: reg.CX, Scale: 2}"},
+	{"m32", "operand.Mem{Base: reg.EBX, Index: reg.ECX, Scale: 4}"},
+	{"m64", "operand.Mem{Base: reg.RBX, Index: reg.RCX, Scale: 8}"},
+	{"m128", "operand.Mem{Base: reg.RBX, Index: reg.RCX, Scale: 8}"},
+	{"m256", "operand.Mem{Base: reg.RBX, Index: reg.RCX, Scale: 8}"},
+	{"m512", "operand.Mem{Base: reg.RBX, Index: reg.RCX, Scale: 8}"},
+
+	// Vector memory
+	{"vm32x", "operand.Mem{Base: reg.R13, Index: reg.X4, Scale: 1}"},
+	{"vm64x", "operand.Mem{Base: reg.R13, Index: reg.X8, Scale: 1}"},
+	{"vm32y", "operand.Mem{Base: reg.R13, Index: reg.Y4, Scale: 1}"},
+	{"vm64y", "operand.Mem{Base: reg.R13, Index: reg.Y8, Scale: 1}"},
+	{"vm32z", "operand.Mem{Base: reg.R13, Index: reg.Z4, Scale: 1}"},
+	{"vm64z", "operand.Mem{Base: reg.R13, Index: reg.Z8, Scale: 1}"},
+
+	// Relative
+	{"rel8", "operand.Rel(math.MaxInt8)"},
+	{"rel32", "operand.LabelRef(\"lbl\")"},
+}