From 4891ab71a06a274a54fa0d34b76fe454e50d8ad4 Mon Sep 17 00:00:00 2001
From: Danny Milosavljevic <dannym@scratchpost.org>
Date: Tue, 6 Apr 2021 12:43:21 +0200
Subject: [PATCH] riscv64-asm: Add fence, fence.i, scall, sbreak, ecall,
 ebreak, wfi

---
 riscv64-asm.c |  65 ++++++++++++++++++++++++++++++-
 riscv64-tok.h | 104 ++++++++++++++++++++++++++++++++++++++++++++++++++
 tcctok.h      |   3 ++
 3 files changed, 170 insertions(+), 2 deletions(-)
 create mode 100644 riscv64-tok.h

diff --git a/riscv64-asm.c b/riscv64-asm.c
index f7ba3bee..167d5251 100644
--- a/riscv64-asm.c
+++ b/riscv64-asm.c
@@ -49,9 +49,70 @@ ST_FUNC void gen_expr32(ExprValue *pe)
     gen_le32(pe->v);
 }
 
-ST_FUNC void asm_opcode(TCCState *s1, int opcode)
+static void asm_emit_opcode(uint32_t opcode) {
+    gen_le32(opcode);
+}
+
+static void asm_nullary_opcode(TCCState *s1, int token)
 {
-    tcc_error("RISCV64 asm not implemented.");
+    switch (token) {
+    // Sync instructions
+
+    case TOK_ASM_fence: // I
+        asm_emit_opcode((0x3 << 2) | 3 | (0 << 12));
+        return;
+    case TOK_ASM_fence_i: // I
+        asm_emit_opcode((0x3 << 2) | 3| (1 << 12));
+        return;
+
+    // System calls
+
+    case TOK_ASM_scall: // I (pseudo)
+        asm_emit_opcode((0x1C << 2) | 3 | (0 << 12));
+        return;
+    case TOK_ASM_sbreak: // I (pseudo)
+        asm_emit_opcode((0x1C << 2) | 3 | (0 << 12) | (1 << 20));
+        return;
+
+    // Privileged Instructions
+
+    case TOK_ASM_ecall:
+        asm_emit_opcode((0x1C << 2) | 3 | (0 << 20));
+        return;
+    case TOK_ASM_ebreak:
+        asm_emit_opcode((0x1C << 2) | 3 | (1 << 20));
+        return;
+
+    // Other
+
+    case TOK_ASM_wfi:
+        asm_emit_opcode((0x1C << 2) | 3 | (0x105 << 20));
+        return;
+
+    default:
+        expect("nullary instruction");
+    }
+}
+
+ST_FUNC void asm_opcode(TCCState *s1, int token)
+{
+    switch (token) {
+    case TOK_ASM_fence:
+    case TOK_ASM_fence_i:
+    case TOK_ASM_scall:
+    case TOK_ASM_sbreak:
+    case TOK_ASM_ecall:
+    case TOK_ASM_ebreak:
+    case TOK_ASM_mrts:
+    case TOK_ASM_mrth:
+    case TOK_ASM_hrts:
+    case TOK_ASM_wfi:
+        asm_nullary_opcode(s1, token);
+        return;
+
+    default:
+        expect("known instruction");
+    }
 }
 
 ST_FUNC void subst_asm_operand(CString *add_str, SValue *sv, int modifier)
diff --git a/riscv64-tok.h b/riscv64-tok.h
new file mode 100644
index 00000000..af0e186b
--- /dev/null
+++ b/riscv64-tok.h
@@ -0,0 +1,104 @@
+/* ------------------------------------------------------------------ */
+/* WARNING: relative order of tokens is important.                    */
+
+// See https://riscv.org/wp-content/uploads/2017/05/riscv-spec-v2.2.pdf
+
+/* register */
+
+ DEF_ASM(x0)
+ DEF_ASM(x1)
+ DEF_ASM(x2)
+ DEF_ASM(x3)
+ DEF_ASM(x4)
+ DEF_ASM(x5)
+ DEF_ASM(x6)
+ DEF_ASM(x7)
+ DEF_ASM(x8)
+ DEF_ASM(x9)
+ DEF_ASM(x10)
+ DEF_ASM(x11)
+ DEF_ASM(x12)
+ DEF_ASM(x13)
+ DEF_ASM(x14)
+ DEF_ASM(x15)
+ DEF_ASM(x16)
+ DEF_ASM(x17)
+ DEF_ASM(x18)
+ DEF_ASM(x19)
+ DEF_ASM(x20)
+ DEF_ASM(x21)
+ DEF_ASM(x22)
+ DEF_ASM(x23)
+ DEF_ASM(x24)
+ DEF_ASM(x25)
+ DEF_ASM(x26)
+ DEF_ASM(x27)
+ DEF_ASM(x28)
+ DEF_ASM(x29)
+ DEF_ASM(x30)
+ DEF_ASM(x31)
+
+/* register macros */
+
+ DEF_ASM(zero)
+/*
+ DEF_ASM(ra)
+ DEF_ASM(sp)
+ DEF_ASM(gp)
+ DEF_ASM(tp)
+ DEF_ASM(t0)
+ DEF_ASM(t1)
+ DEF_ASM(t2)
+ DEF_ASM(fp)
+ DEF_ASM(s1)
+ DEF_ASM(a0)
+ DEF_ASM(a1)
+ DEF_ASM(a2)
+ DEF_ASM(a3)
+ DEF_ASM(a4)
+ DEF_ASM(a5)
+ DEF_ASM(a6)
+ DEF_ASM(a7)
+ DEF_ASM(s2)
+ DEF_ASM(s3)
+ DEF_ASM(s4)
+ DEF_ASM(s5)
+ DEF_ASM(s6)
+ DEF_ASM(s7)
+ DEF_ASM(s8)
+ DEF_ASM(s9)
+ DEF_ASM(s10)
+ DEF_ASM(s11)
+ DEF_ASM(t3)
+ DEF_ASM(t4)
+ DEF_ASM(t5)
+ DEF_ASM(t6)
+
+ DEF_ASM(s0) // = x8
+*/
+
+ DEF_ASM(pc)
+
+#define DEF_ASM_WITH_SUFFIX(x, y) \
+  DEF(TOK_ASM_ ## x ## _ ## y, #x #y)
+
+/* Sync */
+
+ DEF_ASM(fence)
+ DEF_ASM_WITH_SUFFIX(fence, i)
+
+/* System call */
+
+ DEF_ASM(scall)
+ DEF_ASM(sbreak)
+
+/* Privileged Instructions */
+
+ DEF_ASM(ecall)
+ DEF_ASM(ebreak)
+
+ DEF_ASM(mrts)
+ DEF_ASM(mrth)
+ DEF_ASM(hrts)
+ DEF_ASM(wfi)
+
diff --git a/tcctok.h b/tcctok.h
index 87fb2c34..e5bc5fbe 100644
--- a/tcctok.h
+++ b/tcctok.h
@@ -391,3 +391,6 @@
 #if defined TCC_TARGET_ARM || defined TCC_TARGET_ARM64
 #include "arm-tok.h"
 #endif
+#if defined TCC_TARGET_RISCV64
+#include "riscv64-tok.h"
+#endif