target/ppc: overhauled and moved logic of storing fpscr

Followed the suggested overhaul to store_fpscr logic, and moved it to
cpu.c where it can be accessed in !TCG builds.

The overhaul was suggested because storing a value to fpscr should
never raise an exception, so we could remove all the mess that happened
with POWERPC_EXCP_FP.

We also moved fpscr_set_rounding_mode into cpu.c as it could now be moved
there, and it is needed when a value for the fpscr is being stored
directly.

Suggested-by: Richard Henderson <richard.henderson@linaro.org>
Signed-off-by: Bruno Larsen (billionai) <bruno.larsen@eldorado.org.br>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Message-Id: <20210527163522.23019-1-bruno.larsen@eldorado.org.br>
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>

1 files changed, 43 insertions, 0 deletions

diff --git a/target/ppc/cpu.c b/target/ppc/cpu.c
index c8e87e3..19d67b5 100644
--- a/target/ppc/cpu.c
+++ b/target/ppc/cpu.c
@@ -25,6 +25,7 @@
 #include "fpu/softfloat-helpers.h"
 #include "mmu-hash64.h"
 #include "helper_regs.h"
+#include "sysemu/tcg.h"
 
 target_ulong cpu_read_xer(CPUPPCState *env)
 {
@@ -109,3 +110,45 @@ void ppc_store_lpcr(PowerPCCPU *cpu, target_ulong val)
     /* The gtse bit affects hflags */
     hreg_compute_hflags(env);
 }
+
+static inline void fpscr_set_rounding_mode(CPUPPCState *env)
+{
+    int rnd_type;
+
+    /* Set rounding mode */
+    switch (fpscr_rn) {
+    case 0:
+        /* Best approximation (round to nearest) */
+        rnd_type = float_round_nearest_even;
+        break;
+    case 1:
+        /* Smaller magnitude (round toward zero) */
+        rnd_type = float_round_to_zero;
+        break;
+    case 2:
+        /* Round toward +infinite */
+        rnd_type = float_round_up;
+        break;
+    default:
+    case 3:
+        /* Round toward -infinite */
+        rnd_type = float_round_down;
+        break;
+    }
+    set_float_rounding_mode(rnd_type, &env->fp_status);
+}
+
+void ppc_store_fpscr(CPUPPCState *env, target_ulong val)
+{
+    val &= ~(FP_VX | FP_FEX);
+    if (val & FPSCR_IX) {
+        val |= FP_VX;
+    }
+    if ((val >> FPSCR_XX) & (val >> FPSCR_XE) & 0x1f) {
+        val |= FP_FEX;
+    }
+    env->fpscr = val;
+    if (tcg_enabled()) {
+        fpscr_set_rounding_mode(env);
+    }
+}