From b307dca0dcf4fd9be9ddc5c80ead64f12d37c393 Mon Sep 17 00:00:00 2001
From: Benjamin Barenblat <bbaren@google.com>
Date: Thu, 21 Jan 2016 15:21:36 -0500
Subject: Support generating Go code

Generate Go code for the RISC-V Go port
<https://github.com/riscv/riscv-go>.
---
 .gitignore    |  1 +
 Makefile      |  3 +++
 parse-opcodes | 52 ++++++++++++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 56 insertions(+)

diff --git a/.gitignore b/.gitignore
index 5b578f1..9512eca 100644
--- a/.gitignore
+++ b/.gitignore
@@ -1,4 +1,5 @@
 .*.swp
 inst.chisel
+inst.go
 instr-table.tex
 priv-instr-table.tex
diff --git a/Makefile b/Makefile
index 0fa58a0..cce8512 100644
--- a/Makefile
+++ b/Makefile
@@ -20,6 +20,9 @@ $(GAS_H) $(XCC_H): $(ALL_OPCODES) parse-opcodes
 inst.chisel: $(ALL_OPCODES) parse-opcodes
 	cat opcodes opcodes-custom opcodes-pseudo | ./parse-opcodes -chisel > $@
 
+inst.go: opcodes opcodes-pseudo parse-opcodes
+	cat opcodes opcodes-pseudo | ./parse-opcodes -go > $@
+
 instr-table.tex: $(ALL_OPCODES) parse-opcodes
 	cat opcodes opcodes-pseudo | ./parse-opcodes -tex > $@
 
diff --git a/parse-opcodes b/parse-opcodes
index ffc1f07..c5427d2 100755
--- a/parse-opcodes
+++ b/parse-opcodes
@@ -4,6 +4,35 @@ import math
 import sys
 import tokenize
 
+# Instructions not used by the RISC-V Go port (and which should therefore not be
+# emitted).
+GO_UNUSED_INSTRUCTIONS = set((
+    'addiw',
+    'csrrc',
+    'csrrci',
+    'csrrs',
+    'csrrsi',
+    'csrrw',
+    'csrrwi',
+    'ebreak',
+    'ecall',
+    'eret',
+    'fcvt.d.s',
+    'fcvt.s.d',
+    'fsgnjx.d',
+    'fsgnjx.s',
+    'hrts',
+    'lw',
+    'mrth',
+    'mrts',
+    'sfence.vm',
+    'slli.rv32',
+    'srai.rv32',
+    'sret',
+    'srli.rv32',
+    'wfi',
+))
+
 namelist = []
 match = {}
 mask = {}
@@ -767,6 +796,27 @@ def make_chisel():
   print '  }'
   print '}'
 
+def print_go_insn(name):
+  print '\tcase A%s:' % name.upper().replace('.', '')
+  print '\t\treturn 0x%x' % yank(match[name], 0, 7)
+
+def make_go():
+  print '// Automatically generated by parse-opcodes'
+  print
+  print 'package riscv'
+  print
+  print 'import "log"'
+  print
+  print 'func opcode(a int) uint32 {'
+  print '\tswitch a {'
+  for name in namelist:
+    if name not in GO_UNUSED_INSTRUCTIONS:
+      print_go_insn(name)
+  print '\t}'
+  print '\tlog.Fatalf("opcode: missing %v (bug in parse-opcodes)", a)'
+  print '\treturn 0'
+  print '}'
+
 for line in sys.stdin:
   line = line.partition('#')
   tokens = line[0].split()
@@ -840,5 +890,7 @@ elif sys.argv[1] == '-chisel':
   make_chisel()
 elif sys.argv[1] == '-c':
   make_c(match,mask)
+elif sys.argv[1] == '-go':
+  make_go()
 else:
   assert 0
-- 
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