cmd/compile/internal/ssa: Mark ADD[Q|L]const as rematerializeable

We can rematerialize only ops that have SP or SB as their only argument.
There are some ADDQconst(SP) that can be rematerialized, but are spilled/filled instead,
so mark addconst as rematerializeable. This shaves ~1kb from go tool.

Change-Id: Ib4cf4fe5f2ec9d3d7e5f0f77f1193eba66ca2f08
Reviewed-on: https://go-review.googlesource.com/54393
Run-TryBot: Ilya Tocar <ilya.tocar@intel.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Keith Randall <khr@golang.org>

src/cmd/compile/internal/ssa/gen/AMD64Ops.go

@@ -189,8 +189,8 @@ func init() {
 		// binary ops
 		{name: "ADDQ", argLength: 2, reg: gp21sp, asm: "ADDQ", commutative: true, clobberFlags: true},                                                           // arg0 + arg1
 		{name: "ADDL", argLength: 2, reg: gp21sp, asm: "ADDL", commutative: true, clobberFlags: true},                                                           // arg0 + arg1
-		{name: "ADDQconst", argLength: 1, reg: gp11sp, asm: "ADDQ", aux: "Int64", typ: "UInt64", clobberFlags: true},                                            // arg0 + auxint
-		{name: "ADDLconst", argLength: 1, reg: gp11sp, asm: "ADDL", aux: "Int32", clobberFlags: true},                                                           // arg0 + auxint
+		{name: "ADDQconst", argLength: 1, reg: gp11sp, asm: "ADDQ", aux: "Int64", typ: "UInt64", clobberFlags: true, rematerializeable: true},                   // arg0 + auxint
+		{name: "ADDLconst", argLength: 1, reg: gp11sp, asm: "ADDL", aux: "Int32", clobberFlags: true, rematerializeable: true},                                  // arg0 + auxint
 		{name: "ADDQconstmem", argLength: 2, reg: gpstoreconst, asm: "ADDQ", aux: "SymValAndOff", clobberFlags: true, faultOnNilArg0: true, symEffect: "Write"}, // add ValAndOff(AuxInt).Val() to arg0+ValAndOff(AuxInt).Off()+aux, arg1=mem
 		{name: "ADDLconstmem", argLength: 2, reg: gpstoreconst, asm: "ADDL", aux: "SymValAndOff", clobberFlags: true, faultOnNilArg0: true, symEffect: "Write"}, // add ValAndOff(AuxInt).Val() to arg0+ValAndOff(AuxInt).Off()+aux, arg1=mem
 

src/cmd/compile/internal/ssa/opGen.go

@@ -4852,6 +4852,7 @@ var opcodeTable = [...]opInfo{
 		name:              "ADDQconst",
 		auxType:           auxInt64,
 		argLen:            1,
+		rematerializeable: true,
 		clobberFlags:      true,
 		asm:               x86.AADDQ,
 		reg: regInfo{
@@ -4867,6 +4868,7 @@ var opcodeTable = [...]opInfo{
 		name:              "ADDLconst",
 		auxType:           auxInt32,
 		argLen:            1,
+		rematerializeable: true,
 		clobberFlags:      true,
 		asm:               x86.AADDL,
 		reg: regInfo{