target/m68k: Map FPU exceptions to FPSR register

Add helpers for reading/writing the 68881 FPSR register so that
changes in floating point exception state can be seen by the
application.

Call these helpers in pre_load/post_load hooks to synchronize
exception state.

Signed-off-by: Keith Packard <keithp@keithp.com>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Message-Id: <20230803035231.429697-1-keithp@keithp.com>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
(cherry picked from commit 5888357942da1fd5a50efb6e4a6af8b1a27a5af8)
Signed-off-by: Michael Tokarev <mjt@tls.msk.ru>

diff --git a/target/m68k/cpu.c b/target/m68k/cpu.c
index 11c7e0a790203ed71662e85d6cdb312cc46af3e2..d95deaafcd31d05f164a0671f9d6e28c8e6e2c9d 100644 (file)
--- a/target/m68k/cpu.c
+++ b/target/m68k/cpu.c
@@ -396,12 +396,19 @@ static const VMStateDescription vmstate_freg = {
     }
 };
 
-static int fpu_post_load(void *opaque, int version)
+static int fpu_pre_save(void *opaque)
 {
     M68kCPU *s = opaque;
 
-    cpu_m68k_restore_fp_status(&s->env);
+    s->env.fpsr = cpu_m68k_get_fpsr(&s->env);
+    return 0;
+}
+
+static int fpu_post_load(void *opaque, int version)
+{
+    M68kCPU *s = opaque;
 
+    cpu_m68k_set_fpsr(&s->env, s->env.fpsr);
     return 0;
 }
 
@@ -410,6 +417,7 @@ const VMStateDescription vmmstate_fpu = {
     .version_id = 1,
     .minimum_version_id = 1,
     .needed = fpu_needed,
+    .pre_save = fpu_pre_save,
     .post_load = fpu_post_load,
     .fields = (VMStateField[]) {
         VMSTATE_UINT32(env.fpcr, M68kCPU),

diff --git a/target/m68k/cpu.h b/target/m68k/cpu.h
index 6cfc696d2ba81e06c367b70678eb8585931e8d20..4d78da9d5fc3135ba0d0f95743a8782ae314e18a 100644 (file)
--- a/target/m68k/cpu.h
+++ b/target/m68k/cpu.h
@@ -199,7 +199,8 @@ void cpu_m68k_set_ccr(CPUM68KState *env, uint32_t);
 void cpu_m68k_set_sr(CPUM68KState *env, uint32_t);
 void cpu_m68k_restore_fp_status(CPUM68KState *env);
 void cpu_m68k_set_fpcr(CPUM68KState *env, uint32_t val);
-
+uint32_t cpu_m68k_get_fpsr(CPUM68KState *env);
+void cpu_m68k_set_fpsr(CPUM68KState *env, uint32_t val);
 
 /*
  * Instead of computing the condition codes after each m68k instruction,

diff --git a/target/m68k/fpu_helper.c b/target/m68k/fpu_helper.c
index ab120b5f59b1f349af12a781fa10539d82769fc6..8314791f50428a5d32d6d1c81e8755be43f37ada 100644 (file)
--- a/target/m68k/fpu_helper.c
+++ b/target/m68k/fpu_helper.c
@@ -164,6 +164,78 @@ void HELPER(set_fpcr)(CPUM68KState *env, uint32_t val)
     cpu_m68k_set_fpcr(env, val);
 }
 
+/* Convert host exception flags to cpu_m68k form.  */
+static int cpu_m68k_exceptbits_from_host(int host_bits)
+{
+    int target_bits = 0;
+
+    if (host_bits & float_flag_invalid) {
+        target_bits |= 0x80;
+    }
+    if (host_bits & float_flag_overflow) {
+        target_bits |= 0x40;
+    }
+    if (host_bits & (float_flag_underflow | float_flag_output_denormal)) {
+        target_bits |= 0x20;
+    }
+    if (host_bits & float_flag_divbyzero) {
+        target_bits |= 0x10;
+    }
+    if (host_bits & float_flag_inexact) {
+        target_bits |= 0x08;
+    }
+    return target_bits;
+}
+
+/* Convert cpu_m68k exception flags to target form.  */
+static int cpu_m68k_exceptbits_to_host(int target_bits)
+{
+    int host_bits = 0;
+
+    if (target_bits & 0x80) {
+        host_bits |= float_flag_invalid;
+    }
+    if (target_bits & 0x40) {
+        host_bits |= float_flag_overflow;
+    }
+    if (target_bits & 0x20) {
+        host_bits |= float_flag_underflow;
+    }
+    if (target_bits & 0x10) {
+        host_bits |= float_flag_divbyzero;
+    }
+    if (target_bits & 0x08) {
+        host_bits |= float_flag_inexact;
+    }
+    return host_bits;
+}
+
+uint32_t cpu_m68k_get_fpsr(CPUM68KState *env)
+{
+    int host_flags = get_float_exception_flags(&env->fp_status);
+    int target_flags = cpu_m68k_exceptbits_from_host(host_flags);
+    int except = (env->fpsr & ~(0xf8)) | target_flags;
+    return except;
+}
+
+uint32_t HELPER(get_fpsr)(CPUM68KState *env)
+{
+    return cpu_m68k_get_fpsr(env);
+}
+
+void cpu_m68k_set_fpsr(CPUM68KState *env, uint32_t val)
+{
+    env->fpsr = val;
+
+    int host_flags = cpu_m68k_exceptbits_to_host((int) env->fpsr);
+    set_float_exception_flags(host_flags, &env->fp_status);
+}
+
+void HELPER(set_fpsr)(CPUM68KState *env, uint32_t val)
+{
+    cpu_m68k_set_fpsr(env, val);
+}
+
 #define PREC_BEGIN(prec)                                        \
     do {                                                        \
         FloatX80RoundPrec old =                                 \

diff --git a/target/m68k/helper.c b/target/m68k/helper.c
index 0a1544cd68d9dc7cff8983283d07c83d773c32d6..beab4b96bc3be62372a17c7c44e4291586f8e504 100644 (file)
--- a/target/m68k/helper.c
+++ b/target/m68k/helper.c
@@ -118,7 +118,7 @@ static int m68k_fpu_gdb_get_reg(CPUM68KState *env, GByteArray *mem_buf, int n)
     case 8: /* fpcontrol */
         return gdb_get_reg32(mem_buf, env->fpcr);
     case 9: /* fpstatus */
-        return gdb_get_reg32(mem_buf, env->fpsr);
+        return gdb_get_reg32(mem_buf, cpu_m68k_get_fpsr(env));
     case 10: /* fpiar, not implemented */
         return gdb_get_reg32(mem_buf, 0);
     }
@@ -137,7 +137,7 @@ static int m68k_fpu_gdb_set_reg(CPUM68KState *env, uint8_t *mem_buf, int n)
         cpu_m68k_set_fpcr(env, ldl_p(mem_buf));
         return 4;
     case 9: /* fpstatus */
-        env->fpsr = ldl_p(mem_buf);
+        cpu_m68k_set_fpsr(env, ldl_p(mem_buf));
         return 4;
     case 10: /* fpiar, not implemented */
         return 4;

diff --git a/target/m68k/helper.h b/target/m68k/helper.h
index 2bbe0dc03253d323078994f8a102f825b386a365..95aa5e53bb97b38084588d52cc90222b5c141851 100644 (file)
--- a/target/m68k/helper.h
+++ b/target/m68k/helper.h
@@ -54,6 +54,8 @@ DEF_HELPER_4(fsdiv, void, env, fp, fp, fp)
 DEF_HELPER_4(fddiv, void, env, fp, fp, fp)
 DEF_HELPER_4(fsgldiv, void, env, fp, fp, fp)
 DEF_HELPER_FLAGS_3(fcmp, TCG_CALL_NO_RWG, void, env, fp, fp)
+DEF_HELPER_2(set_fpsr, void, env, i32)
+DEF_HELPER_1(get_fpsr, i32, env)
 DEF_HELPER_FLAGS_2(set_fpcr, TCG_CALL_NO_RWG, void, env, i32)
 DEF_HELPER_FLAGS_2(ftst, TCG_CALL_NO_RWG, void, env, fp)
 DEF_HELPER_3(fconst, void, env, fp, i32)

diff --git a/target/m68k/translate.c b/target/m68k/translate.c
index 4a0b0b270364f2d91e7cdb91ecfc167d32ef4308..f8eeb70379853723f932978e0088a839357a7936 100644 (file)
--- a/target/m68k/translate.c
+++ b/target/m68k/translate.c
@@ -4686,7 +4686,7 @@ static void gen_load_fcr(DisasContext *s, TCGv res, int reg)
         tcg_gen_movi_i32(res, 0);
         break;
     case M68K_FPSR:
-        tcg_gen_ld_i32(res, tcg_env, offsetof(CPUM68KState, fpsr));
+        gen_helper_get_fpsr(res, tcg_env);
         break;
     case M68K_FPCR:
         tcg_gen_ld_i32(res, tcg_env, offsetof(CPUM68KState, fpcr));
@@ -4700,7 +4700,7 @@ static void gen_store_fcr(DisasContext *s, TCGv val, int reg)
     case M68K_FPIAR:
         break;
     case M68K_FPSR:
-        tcg_gen_st_i32(val, tcg_env, offsetof(CPUM68KState, fpsr));
+        gen_helper_set_fpsr(tcg_env, val);
         break;
     case M68K_FPCR:
         gen_helper_set_fpcr(tcg_env, val);