cmd/compile: add new ops for experiment with late call expansion

Added Dereference, StaticLECall, SelectN, SelectNAddr

Change-Id: I5426ae488e83956539aa07f7415b8acc26c933e6
Reviewed-on: https://go-review.googlesource.com/c/go/+/239082
Trust: David Chase <[email protected]>
Run-TryBot: David Chase <[email protected]>
Reviewed-by: Cherry Zhang <[email protected]>
TryBot-Result: Go Bot <[email protected]>

Author: dr2chase

src/cmd/compile/internal/ssa/gen/genericOps.go

@@ -346,6 +346,7 @@ var genericOps = []opData{
 
 	// Memory operations
 	{name: "Load", argLength: 2},                          // Load from arg0.  arg1=memory
+	{name: "Dereference", argLength: 2},                   // Load from arg0.  arg1=memory.  Helper op for arg/result passing, result is an otherwise not-SSA-able "value".
 	{name: "Store", argLength: 3, typ: "Mem", aux: "Typ"}, // Store arg1 to arg0.  arg2=memory, aux=type.  Returns memory.
 	// The source and destination of Move may overlap in some cases. See e.g.
 	// memmove inlining in generic.rules. When inlineablememmovesize (in ../rewrite.go)
@@ -387,9 +388,11 @@ var genericOps = []opData{
 	// as a phantom first argument.
 	// TODO(josharian): ClosureCall and InterCall should have Int32 aux
 	// to match StaticCall's 32 bit arg size limit.
-	{name: "ClosureCall", argLength: 3, aux: "CallOff", call: true}, // arg0=code pointer, arg1=context ptr, arg2=memory.  auxint=arg size.  Returns memory.
-	{name: "StaticCall", argLength: 1, aux: "CallOff", call: true},  // call function aux.(*obj.LSym), arg0=memory.  auxint=arg size.  Returns memory.
-	{name: "InterCall", argLength: 2, aux: "CallOff", call: true},   // interface call.  arg0=code pointer, arg1=memory, auxint=arg size.  Returns memory.
+	// TODO(drchase,josharian): could the arg size limit be bundled into the rules for CallOff?
+	{name: "ClosureCall", argLength: 3, aux: "CallOff", call: true},   // arg0=code pointer, arg1=context ptr, arg2=memory.  auxint=arg size.  Returns memory.
+	{name: "StaticCall", argLength: 1, aux: "CallOff", call: true},    // call function aux.(*obj.LSym), arg0=memory.  auxint=arg size.  Returns memory.
+	{name: "InterCall", argLength: 2, aux: "CallOff", call: true},     // interface call.  arg0=code pointer, arg1=memory, auxint=arg size.  Returns memory.
+	{name: "StaticLECall", argLength: -1, aux: "CallOff", call: true}, // late-expanded static call function aux.(*ssa.AuxCall.Fn). arg0..argN-1 are inputs, argN is mem. auxint = arg size. Result is tuple of result(s), plus mem.
 
 	// Conversions: signed extensions, zero (unsigned) extensions, truncations
 	{name: "SignExt8to16", argLength: 1, typ: "Int16"},
@@ -531,8 +534,10 @@ var genericOps = []opData{
 	{name: "Cvt64Fto64U", argLength: 1}, // float64 -> uint64, only used on archs that has the instruction
 
 	// pseudo-ops for breaking Tuple
-	{name: "Select0", argLength: 1, zeroWidth: true}, // the first component of a tuple
-	{name: "Select1", argLength: 1, zeroWidth: true}, // the second component of a tuple
+	{name: "Select0", argLength: 1, zeroWidth: true},  // the first component of a tuple
+	{name: "Select1", argLength: 1, zeroWidth: true},  // the second component of a tuple
+	{name: "SelectN", argLength: 1, aux: "Int64"},     // arg0=tuple, auxint=field index.  Returns the auxint'th member.
+	{name: "SelectNAddr", argLength: 1, aux: "Int64"}, // arg0=tuple, auxint=field index.  Returns the address of auxint'th member. Used for un-SSA-able result types.
 
 	// Atomic operations used for semantically inlining runtime/internal/atomic.
 	// Atomic loads return a new memory so that the loads are properly ordered