cmd/internal/obj/riscv: fix up instruction groupings

Some of the instructions were incorrectly grouped - untangle this and
separate the RV64I instructions, which are under separate sections of
the RISC-V specification.

Change-Id: I232962ab4054bf0b4745887506f51e74ea73f73d
Reviewed-on: https://go-review.googlesource.com/c/go/+/194238
Reviewed-by: Cherry Zhang <cherryyz@google.com>

src/cmd/internal/obj/riscv/anames.go

@@ -5,21 +5,7 @@ package riscv
 import "cmd/internal/obj"
 
 var Anames = []string{
-	obj.A_ARCHSPECIFIC: "SLLIRV32",
+	obj.A_ARCHSPECIFIC: "ADDI",
-	"SRLIRV32",
-	"SRAIRV32",
-	"JAL",
-	"JALR",
-	"BEQ",
-	"BNE",
-	"BLT",
-	"BLTU",
-	"BGE",
-	"BGEU",
-	"FENCE",
-	"FENCEI",
-	"FENCETSO",
-	"ADDI",
 	"SLTI",
 	"SLTIU",
 	"ANDI",
@@ -40,6 +26,29 @@ var Anames = []string{
 	"SRL",
 	"SUB",
 	"SRA",
+	"SLLIRV32",
+	"SRLIRV32",
+	"SRAIRV32",
+	"JAL",
+	"JALR",
+	"BEQ",
+	"BNE",
+	"BLT",
+	"BLTU",
+	"BGE",
+	"BGEU",
+	"LW",
+	"LWU",
+	"LH",
+	"LHU",
+	"LB",
+	"LBU",
+	"SW",
+	"SH",
+	"SB",
+	"FENCE",
+	"FENCEI",
+	"FENCETSO",
 	"ADDIW",
 	"SLLIW",
 	"SRLIW",
@@ -50,22 +59,7 @@ var Anames = []string{
 	"SUBW",
 	"SRAW",
 	"LD",
-	"LW",
-	"LWU",
-	"LH",
-	"LHU",
-	"LB",
-	"LBU",
 	"SD",
-	"SW",
-	"SH",
-	"SB",
-	"RDCYCLE",
-	"RDCYCLEH",
-	"RDTIME",
-	"RDTIMEH",
-	"RDINSTRET",
-	"RDINSTRETH",
 	"MUL",
 	"MULH",
 	"MULHU",
@@ -101,6 +95,12 @@ var Anames = []string{
 	"AMOMAXUW",
 	"AMOMINW",
 	"AMOMINUW",
+	"RDCYCLE",
+	"RDCYCLEH",
+	"RDTIME",
+	"RDTIMEH",
+	"RDINSTRET",
+	"RDINSTRETH",
 	"FRCSR",
 	"FSCSR",
 	"FRRM",

src/cmd/internal/obj/riscv/cpu.go

@@ -211,27 +211,7 @@ const (
 	// Unprivileged ISA (Document Version 20190608-Base-Ratified)
 
 	// 2.4: Integer Computational Instructions
-	ASLLIRV32 = obj.ABaseRISCV + obj.A_ARCHSPECIFIC + iota
+	AADDI = obj.ABaseRISCV + obj.A_ARCHSPECIFIC + iota
-	ASRLIRV32
-	ASRAIRV32
-
-	// 2.5: Control Transfer Instructions
-	AJAL
-	AJALR
-	ABEQ
-	ABNE
-	ABLT
-	ABLTU
-	ABGE
-	ABGEU
-
-	// 2.7: Memory Ordering Instructions
-	AFENCE
-	AFENCEI
-	AFENCETSO
-
-	// 5.2: Integer Computational Instructions
-	AADDI
 	ASLTI
 	ASLTIU
 	AANDI
@@ -252,6 +232,40 @@ const (
 	ASRL
 	ASUB
 	ASRA
+
+	// The SLL/SRL/SRA instructions differ slightly between RV32 and RV64,
+	// hence there are pseudo-opcodes for the RV32 specific versions.
+	ASLLIRV32
+	ASRLIRV32
+	ASRAIRV32
+
+	// 2.5: Control Transfer Instructions
+	AJAL
+	AJALR
+	ABEQ
+	ABNE
+	ABLT
+	ABLTU
+	ABGE
+	ABGEU
+
+	// 2.6: Load and Store Instructions
+	ALW
+	ALWU
+	ALH
+	ALHU
+	ALB
+	ALBU
+	ASW
+	ASH
+	ASB
+
+	// 2.7: Memory Ordering Instructions
+	AFENCE
+	AFENCEI
+	AFENCETSO
+
+	// 5.2: Integer Computational Instructions (RV64I)
 	AADDIW
 	ASLLIW
 	ASRLIW
@@ -262,18 +276,9 @@ const (
 	ASUBW
 	ASRAW
 
-	// 5.3: Load and Store Instructions
+	// 5.3: Load and Store Instructions (RV64I)
 	ALD
-	ALW
-	ALWU
-	ALH
-	ALHU
-	ALB
-	ALBU
 	ASD
-	ASW
-	ASH
-	ASB
 
 	// 7.1: Multiplication Operations
 	AMUL