From 50aa85e560ca709065b8815ade3dd16eb22299d4 Mon Sep 17 00:00:00 2001
From: Laurent Vivier <laurent@vivier.eu>
Date: Sun, 14 Jun 2020 21:13:27 -0400
Subject: [PATCH] target/m68k: implement opcode fetoxm1

Example provided in the launchpad bug fails with:

qemu: uncaught target signal 4 (Illegal instruction) - core dumped
Illegal instruction (core dumped)

It appears fetoxm1 is not implemented:

IN: expm1f
0x800005cc: fetoxm1x %fp2,%fp0
Disassembler disagrees with translator over instruction decoding
Please report this to qemu-devel@nongnu.org

(gdb) x/2hx 0x800005cc
0x800005cc: 0xf200 0x0808

This patch adds the instruction.

Backports commit 250b1da35d579f42319af234f36207902ca4baa4 from qemu
---
 qemu/target/m68k/fpu_helper.c | 5 +++++
 qemu/target/m68k/helper.h     | 1 +
 qemu/target/m68k/translate.c  | 3 +++
 3 files changed, 9 insertions(+)

diff --git a/qemu/target/m68k/fpu_helper.c b/qemu/target/m68k/fpu_helper.c
index f8030edd..60da343f 100644
--- a/qemu/target/m68k/fpu_helper.c
+++ b/qemu/target/m68k/fpu_helper.c
@@ -652,6 +652,11 @@ void HELPER(fatanh)(CPUM68KState *env, FPReg *res, FPReg *val)
     res->d = floatx80_atanh(val->d, &env->fp_status);
 }
 
+void HELPER(fetoxm1)(CPUM68KState *env, FPReg *res, FPReg *val)
+{
+    res->d = floatx80_etoxm1(val->d, &env->fp_status);
+}
+
 void HELPER(ftanh)(CPUM68KState *env, FPReg *res, FPReg *val)
 {
     res->d = floatx80_tanh(val->d, &env->fp_status);
diff --git a/qemu/target/m68k/helper.h b/qemu/target/m68k/helper.h
index 26f97f58..1d76a136 100644
--- a/qemu/target/m68k/helper.h
+++ b/qemu/target/m68k/helper.h
@@ -85,6 +85,7 @@ DEF_HELPER_3(fatan, void, env, fp, fp)
 DEF_HELPER_3(fasin, void, env, fp, fp)
 DEF_HELPER_3(facos, void, env, fp, fp)
 DEF_HELPER_3(fatanh, void, env, fp, fp)
+DEF_HELPER_3(fetoxm1, void, env, fp, fp)
 DEF_HELPER_3(ftanh, void, env, fp, fp)
 DEF_HELPER_3(fsinh, void, env, fp, fp)
 DEF_HELPER_3(fcosh, void, env, fp, fp)
diff --git a/qemu/target/m68k/translate.c b/qemu/target/m68k/translate.c
index 5578bc1d..54af719f 100644
--- a/qemu/target/m68k/translate.c
+++ b/qemu/target/m68k/translate.c
@@ -5371,6 +5371,9 @@ DISAS_INSN(fpu)
     case 0x06: /* flognp1 */
         gen_helper_flognp1(tcg_ctx, tcg_ctx->cpu_env, cpu_dest, cpu_src);
         break;
+    case 0x08: /* fetoxm1 */
+        gen_helper_fetoxm1(tcg_ctx, tcg_ctx->cpu_env, cpu_dest, cpu_src);
+        break;
     case 0x09: /* ftanh */
         gen_helper_ftanh(tcg_ctx, tcg_ctx->cpu_env, cpu_dest, cpu_src);
         break;