[Qemu-devel] [PATCH 7/9] target-sh4: implement FPU exceptions

[Aurelien Jarno]

FPU exception support where not implemented on SH4. Implement them by
clearing the softfloat exceptions flags before an FP instruction (the
SH4 FPU also clear them before an instruction), and calling a function
to update the FPSCR register after an FP instruction. This function
update the corresponding FPSCR bits (both flags and cumulative flags)
and trigger exception if enabled.

Signed-off-by: Aurelien Jarno <address@hidden>
---
 target-sh4/op_helper.c |  158 +++++++++++++++++++++++++++++++++++++++++-------
 1 files changed, 136 insertions(+), 22 deletions(-)

diff --git a/target-sh4/op_helper.c b/target-sh4/op_helper.c
index 76a40bd..6ab87d9 100644
--- a/target-sh4/op_helper.c
+++ b/target-sh4/op_helper.c
@@ -21,6 +21,22 @@
 #include "exec.h"
 #include "helper.h"
 
+static void cpu_restore_state_from_retaddr(void *retaddr)
+{
+    TranslationBlock *tb;
+    unsigned long pc;
+
+    if (retaddr) {
+        pc = (unsigned long) retaddr;
+        tb = tb_find_pc(pc);
+        if (tb) {
+            /* the PC is inside the translated code. It means that we have
+               a virtual CPU fault */
+            cpu_restore_state(tb, env, pc, NULL);
+        }
+    }
+}
+
 #ifndef CONFIG_USER_ONLY
 
 #define MMUSUFFIX _mmu
@@ -39,9 +55,7 @@
 
 void tlb_fill(target_ulong addr, int is_write, int mmu_idx, void *retaddr)
 {
-    TranslationBlock *tb;
     CPUState *saved_env;
-    unsigned long pc;
     int ret;
 
     /* XXX: hack to restore env in all cases, even if not called from
@@ -50,16 +64,8 @@ void tlb_fill(target_ulong addr, int is_write, int mmu_idx, 
void *retaddr)
     env = cpu_single_env;
     ret = cpu_sh4_handle_mmu_fault(env, addr, is_write, mmu_idx, 1);
     if (ret) {
-       if (retaddr) {
-           /* now we have a real cpu fault */
-           pc = (unsigned long) retaddr;
-           tb = tb_find_pc(pc);
-           if (tb) {
-               /* the PC is inside the translated code. It means that we have
-                  a virtual CPU fault */
-               cpu_restore_state(tb, env, pc, NULL);
-           }
-       }
+        /* now we have a real cpu fault */
+        cpu_restore_state_from_retaddr(retaddr);
        cpu_loop_exit();
     }
     env = saved_env;
@@ -437,6 +443,47 @@ void helper_ld_fpscr(uint32_t val)
     set_flush_to_zero((val & FPSCR_DN) != 0, &env->fp_status);
 }
 
+static void update_fpscr(void *retaddr)
+{
+    int xcpt, cause, enable;
+
+    xcpt = get_float_exception_flags(&env->fp_status);
+
+    /* Clear the flag entries */
+    env->fpscr &= ~FPSCR_FLAG_MASK;
+
+    if (unlikely(xcpt)) {
+        if (xcpt & float_flag_invalid) {
+            env->fpscr |= FPSCR_FLAG_V;
+        }
+        if (xcpt & float_flag_divbyzero) {
+            env->fpscr |= FPSCR_FLAG_Z;
+        }
+        if (xcpt & float_flag_overflow) {
+            env->fpscr |= FPSCR_FLAG_O;
+        }
+        if (xcpt & float_flag_underflow) {
+            env->fpscr |= FPSCR_FLAG_U;
+        }
+        if (xcpt & float_flag_inexact) {
+            env->fpscr |= FPSCR_FLAG_I;
+        }
+
+        /* Accumulate in cause entries */
+        env->fpscr |= (env->fpscr & FPSCR_FLAG_MASK)
+                      << (FPSCR_CAUSE_SHIFT - FPSCR_FLAG_SHIFT);
+
+        /* Generate an exception if enabled */
+        cause = (env->fpscr & FPSCR_CAUSE_MASK) >> FPSCR_CAUSE_SHIFT;
+        enable = (env->fpscr & FPSCR_ENABLE_MASK) >> FPSCR_ENABLE_SHIFT;
+        if (cause & enable) {
+            cpu_restore_state_from_retaddr(retaddr);
+            env->exception_index = 0x120;
+            cpu_loop_exit();
+        }
+    }
+}
+
 uint32_t helper_fabs_FT(uint32_t t0)
 {
     CPU_FloatU f;
@@ -458,7 +505,9 @@ uint32_t helper_fadd_FT(uint32_t t0, uint32_t t1)
     CPU_FloatU f0, f1;
     f0.l = t0;
     f1.l = t1;
+    set_float_exception_flags(0, &env->fp_status);
     f0.f = float32_add(f0.f, f1.f, &env->fp_status);
+    update_fpscr(GETPC());
     return f0.l;
 }
 
@@ -467,56 +516,82 @@ uint64_t helper_fadd_DT(uint64_t t0, uint64_t t1)
     CPU_DoubleU d0, d1;
     d0.ll = t0;
     d1.ll = t1;
+    set_float_exception_flags(0, &env->fp_status);
     d0.d = float64_add(d0.d, d1.d, &env->fp_status);
+    update_fpscr(GETPC());
     return d0.ll;
 }
 
 void helper_fcmp_eq_FT(uint32_t t0, uint32_t t1)
 {
     CPU_FloatU f0, f1;
+    int relation;
     f0.l = t0;
     f1.l = t1;
 
-    if (float32_compare(f0.f, f1.f, &env->fp_status) == 0)
+    set_float_exception_flags(0, &env->fp_status);
+    relation = float32_compare(f0.f, f1.f, &env->fp_status);
+    if (unlikely(relation == float_relation_unordered)) {
+        update_fpscr(GETPC());
+    } else if (relation == float_relation_equal) {
        set_t();
-    else
+    } else {
        clr_t();
+    }
 }
 
 void helper_fcmp_eq_DT(uint64_t t0, uint64_t t1)
 {
     CPU_DoubleU d0, d1;
+    int relation;
     d0.ll = t0;
     d1.ll = t1;
 
-    if (float64_compare(d0.d, d1.d, &env->fp_status) == 0)
+    set_float_exception_flags(0, &env->fp_status);
+    relation = float64_compare(d0.d, d1.d, &env->fp_status);
+    if (unlikely(relation == float_relation_unordered)) {
+        update_fpscr(GETPC());
+    } else if (relation == float_relation_equal) {
        set_t();
-    else
+    } else {
        clr_t();
+    }
 }
 
 void helper_fcmp_gt_FT(uint32_t t0, uint32_t t1)
 {
     CPU_FloatU f0, f1;
+    int relation;
     f0.l = t0;
     f1.l = t1;
 
-    if (float32_compare(f0.f, f1.f, &env->fp_status) == 1)
+    set_float_exception_flags(0, &env->fp_status);
+    relation = float32_compare(f0.f, f1.f, &env->fp_status);
+    if (unlikely(relation == float_relation_unordered)) {
+        update_fpscr(GETPC());
+    } else if (relation == float_relation_greater) {
        set_t();
-    else
+    } else {
        clr_t();
+    }
 }
 
 void helper_fcmp_gt_DT(uint64_t t0, uint64_t t1)
 {
     CPU_DoubleU d0, d1;
+    int relation;
     d0.ll = t0;
     d1.ll = t1;
 
-    if (float64_compare(d0.d, d1.d, &env->fp_status) == 1)
+    set_float_exception_flags(0, &env->fp_status);
+    relation = float64_compare(d0.d, d1.d, &env->fp_status);
+    if (unlikely(relation == float_relation_unordered)) {
+        update_fpscr(GETPC());
+    } else if (relation == float_relation_greater) {
        set_t();
-    else
+    } else {
        clr_t();
+    }
 }
 
 uint64_t helper_fcnvsd_FT_DT(uint32_t t0)
@@ -524,7 +599,9 @@ uint64_t helper_fcnvsd_FT_DT(uint32_t t0)
     CPU_DoubleU d;
     CPU_FloatU f;
     f.l = t0;
+    set_float_exception_flags(0, &env->fp_status);
     d.d = float32_to_float64(f.f, &env->fp_status);
+    update_fpscr(GETPC());
     return d.ll;
 }
 
@@ -533,7 +610,9 @@ uint32_t helper_fcnvds_DT_FT(uint64_t t0)
     CPU_DoubleU d;
     CPU_FloatU f;
     d.ll = t0;
+    set_float_exception_flags(0, &env->fp_status);
     f.f = float64_to_float32(d.d, &env->fp_status);
+    update_fpscr(GETPC());
     return f.l;
 }
 
@@ -542,7 +621,9 @@ uint32_t helper_fdiv_FT(uint32_t t0, uint32_t t1)
     CPU_FloatU f0, f1;
     f0.l = t0;
     f1.l = t1;
+    set_float_exception_flags(0, &env->fp_status);
     f0.f = float32_div(f0.f, f1.f, &env->fp_status);
+    update_fpscr(GETPC());
     return f0.l;
 }
 
@@ -551,21 +632,29 @@ uint64_t helper_fdiv_DT(uint64_t t0, uint64_t t1)
     CPU_DoubleU d0, d1;
     d0.ll = t0;
     d1.ll = t1;
+    set_float_exception_flags(0, &env->fp_status);
     d0.d = float64_div(d0.d, d1.d, &env->fp_status);
+    update_fpscr(GETPC());
     return d0.ll;
 }
 
 uint32_t helper_float_FT(uint32_t t0)
 {
     CPU_FloatU f;
+
+    set_float_exception_flags(0, &env->fp_status);
     f.f = int32_to_float32(t0, &env->fp_status);
+    update_fpscr(GETPC());
+
     return f.l;
 }
 
 uint64_t helper_float_DT(uint32_t t0)
 {
     CPU_DoubleU d;
+    set_float_exception_flags(0, &env->fp_status);
     d.d = int32_to_float64(t0, &env->fp_status);
+    update_fpscr(GETPC());
     return d.ll;
 }
 
@@ -575,8 +664,11 @@ uint32_t helper_fmac_FT(uint32_t t0, uint32_t t1, uint32_t 
t2)
     f0.l = t0;
     f1.l = t1;
     f2.l = t2;
+    set_float_exception_flags(0, &env->fp_status);
     f0.f = float32_mul(f0.f, f1.f, &env->fp_status);
     f0.f = float32_add(f0.f, f2.f, &env->fp_status);
+    update_fpscr(GETPC());
+
     return f0.l;
 }
 
@@ -585,7 +677,9 @@ uint32_t helper_fmul_FT(uint32_t t0, uint32_t t1)
     CPU_FloatU f0, f1;
     f0.l = t0;
     f1.l = t1;
+    set_float_exception_flags(0, &env->fp_status);
     f0.f = float32_mul(f0.f, f1.f, &env->fp_status);
+    update_fpscr(GETPC());
     return f0.l;
 }
 
@@ -594,7 +688,10 @@ uint64_t helper_fmul_DT(uint64_t t0, uint64_t t1)
     CPU_DoubleU d0, d1;
     d0.ll = t0;
     d1.ll = t1;
+    set_float_exception_flags(0, &env->fp_status);
     d0.d = float64_mul(d0.d, d1.d, &env->fp_status);
+    update_fpscr(GETPC());
+
     return d0.ll;
 }
 
@@ -610,7 +707,9 @@ uint32_t helper_fsqrt_FT(uint32_t t0)
 {
     CPU_FloatU f;
     f.l = t0;
+    set_float_exception_flags(0, &env->fp_status);
     f.f = float32_sqrt(f.f, &env->fp_status);
+    update_fpscr(GETPC());
     return f.l;
 }
 
@@ -618,7 +717,9 @@ uint64_t helper_fsqrt_DT(uint64_t t0)
 {
     CPU_DoubleU d;
     d.ll = t0;
+    set_float_exception_flags(0, &env->fp_status);
     d.d = float64_sqrt(d.d, &env->fp_status);
+    update_fpscr(GETPC());
     return d.ll;
 }
 
@@ -627,29 +728,42 @@ uint32_t helper_fsub_FT(uint32_t t0, uint32_t t1)
     CPU_FloatU f0, f1;
     f0.l = t0;
     f1.l = t1;
+    set_float_exception_flags(0, &env->fp_status);
     f0.f = float32_sub(f0.f, f1.f, &env->fp_status);
+    update_fpscr(GETPC());
     return f0.l;
 }
 
 uint64_t helper_fsub_DT(uint64_t t0, uint64_t t1)
 {
     CPU_DoubleU d0, d1;
+
     d0.ll = t0;
     d1.ll = t1;
+    set_float_exception_flags(0, &env->fp_status);
     d0.d = float64_sub(d0.d, d1.d, &env->fp_status);
+    update_fpscr(GETPC());
     return d0.ll;
 }
 
 uint32_t helper_ftrc_FT(uint32_t t0)
 {
     CPU_FloatU f;
+    uint32_t ret;
     f.l = t0;
-    return float32_to_int32_round_to_zero(f.f, &env->fp_status);
+    set_float_exception_flags(0, &env->fp_status);
+    ret = float32_to_int32_round_to_zero(f.f, &env->fp_status);
+    update_fpscr(GETPC());
+    return ret;
 }
 
 uint32_t helper_ftrc_DT(uint64_t t0)
 {
     CPU_DoubleU d;
+    uint32_t ret;
     d.ll = t0;
-    return float64_to_int32_round_to_zero(d.d, &env->fp_status);
+    set_float_exception_flags(0, &env->fp_status);
+    ret = float64_to_int32_round_to_zero(d.d, &env->fp_status);
+    update_fpscr(GETPC());
+    return ret;
 }
-- 
1.7.2.3