[Qemu-devel] [V2 PATCH 15/18] target-ppc: Add ISA 2.06 ftdiv Instruction

[Tom Musta <tommusta@gmail.com>]

This patch adds the Floating Point Test for Divide instruction which
was introduced in Power ISA 2.06.

Signed-off-by: Tom Musta <tommusta@gmail.com>
---
 target-ppc/fpu_helper.c |   56 ++++++++++++++++++++++++++++++++++++++--------
 target-ppc/helper.h     |    2 +
 target-ppc/translate.c  |   17 ++++++++++++++
 3 files changed, 65 insertions(+), 10 deletions(-)

diff --git a/target-ppc/fpu_helper.c b/target-ppc/fpu_helper.c
index 981f002..82ff0db 100644
--- a/target-ppc/fpu_helper.c
+++ b/target-ppc/fpu_helper.c
@@ -50,6 +50,16 @@ static inline int isden(float64 d)
     return ((u.ll >> 52) & 0x7FF) == 0;
 }
 
+static inline int ppc_float32_get_unbiased_exp(float32 f)
+{
+    return ((f >> 23) & 0xFF) - 127;
+}
+
+static inline int ppc_float64_get_unbiased_exp(float64 f)
+{
+    return ((f >> 52) & 0x7FF) - 1023;
+}
+
 uint32_t helper_compute_fprf(CPUPPCState *env, uint64_t arg, uint32_t set_fprf)
 {
     CPU_DoubleU farg;
@@ -988,6 +998,42 @@ uint64_t helper_fsel(CPUPPCState *env, uint64_t arg1, uint64_t arg2,
     }
 }
 
+void helper_ftdiv(CPUPPCState *env, uint32_t bf, uint64_t fra, uint64_t frb)
+{
+    int fe_flag = 0;
+    int fg_flag = 0;
+
+    if (unlikely(float64_is_infinity(fra) ||
+                 float64_is_infinity(frb) ||
+                 float64_is_zero(frb))) {
+        fe_flag = 1;
+        fg_flag = 1;
+    } else {
+        int e_a = ppc_float64_get_unbiased_exp(fra);
+        int e_b = ppc_float64_get_unbiased_exp(frb);
+
+        if (unlikely(float64_is_any_nan(fra) ||
+                     float64_is_any_nan(frb))) {
+            fe_flag = 1;
+        } else if ((e_b <= -1022) || (e_b >= 1021)) {
+            fe_flag = 1;
+        } else if (!float64_is_zero(fra) &&
+                   (((e_a - e_b) >= 1023) ||
+                    ((e_a - e_b) <= -1021) ||
+                    (e_a <= -970))) {
+            fe_flag = 1;
+        }
+
+        if (unlikely(float64_is_zero_or_denormal(frb))) {
+            /* XB is not zero because of the above check and */
+            /* so must be denormalized.                      */
+            fg_flag = 1;
+        }
+    }
+
+    env->crf[bf] = 0x8 | (fg_flag ? 4 : 0) | (fe_flag ? 2 : 0);
+}
+
 void helper_fcmpu(CPUPPCState *env, uint64_t arg1, uint64_t arg2,
                   uint32_t crfD)
 {
@@ -2016,16 +2062,6 @@ VSX_RSQRTE(xsrsqrtesp, 1, float64, f64, 1, 1)
 VSX_RSQRTE(xvrsqrtedp, 2, float64, f64, 0, 0)
 VSX_RSQRTE(xvrsqrtesp, 4, float32, f32, 0, 0)
 
-static inline int ppc_float32_get_unbiased_exp(float32 f)
-{
-    return ((f >> 23) & 0xFF) - 127;
-}
-
-static inline int ppc_float64_get_unbiased_exp(float64 f)
-{
-    return ((f >> 52) & 0x7FF) - 1023;
-}
-
 /* VSX_TDIV - VSX floating point test for divide
  *   op    - instruction mnemonic
  *   nels  - number of elements (1, 2 or 4)
diff --git a/target-ppc/helper.h b/target-ppc/helper.h
index 19b2f6b..5f5d3f6 100644
--- a/target-ppc/helper.h
+++ b/target-ppc/helper.h
@@ -97,6 +97,8 @@ DEF_HELPER_2(fres, i64, env, i64)
 DEF_HELPER_2(frsqrte, i64, env, i64)
 DEF_HELPER_4(fsel, i64, env, i64, i64, i64)
 
+DEF_HELPER_4(ftdiv, void, env, i32, i64, i64)
+
 #define dh_alias_avr ptr
 #define dh_ctype_avr ppc_avr_t *
 #define dh_is_signed_avr dh_is_signed_ptr
diff --git a/target-ppc/translate.c b/target-ppc/translate.c
index 9f0c682..403e274 100644
--- a/target-ppc/translate.c
+++ b/target-ppc/translate.c
@@ -2299,6 +2299,22 @@ GEN_FLOAT_B(rip, 0x08, 0x0E, 1, PPC_FLOAT_EXT);
 /* frim */
 GEN_FLOAT_B(rim, 0x08, 0x0F, 1, PPC_FLOAT_EXT);
 
+static void gen_ftdiv(DisasContext *ctx)
+{
+    TCGv_i32 bf;
+    if (unlikely(!ctx->fpu_enabled)) {
+        gen_exception(ctx, POWERPC_EXCP_FPU);
+        return;
+    }
+    /* NIP cannot be restored if the memory exception comes from an helper */
+    gen_update_nip(ctx, ctx->nip - 4);
+    bf = tcg_const_i32(crfD(ctx->opcode));
+    gen_helper_ftdiv(cpu_env, bf, cpu_fpr[rA(ctx->opcode)],
+                     cpu_fpr[rB(ctx->opcode)]);
+}
+
+
+
 /***                         Floating-Point compare                        ***/
 
 /* fcmpo */
@@ -9801,6 +9817,7 @@ GEN_FLOAT_ACB(madd, 0x1D, 1, PPC_FLOAT),
 GEN_FLOAT_ACB(msub, 0x1C, 1, PPC_FLOAT),
 GEN_FLOAT_ACB(nmadd, 0x1F, 1, PPC_FLOAT),
 GEN_FLOAT_ACB(nmsub, 0x1E, 1, PPC_FLOAT),
+GEN_HANDLER_E(ftdiv, 0x3F, 0x00, 0x04, 1, PPC_NONE, PPC2_ISA206),
 GEN_FLOAT_B(ctiw, 0x0E, 0x00, 0, PPC_FLOAT),
 GEN_HANDLER_E(fctiwu, 0x3F, 0x0E, 0x04, 0x00000000, PPC_NONE, PPC2_ISA206),
 GEN_FLOAT_B(ctiwz, 0x0F, 0x00, 0, PPC_FLOAT),
-- 
1.7.1