target/ppc: Add helper for fsqrts

Use float64r32_sqrt. Fixes a double-rounding issue with performing the compuation in float64 and then rounding afterward. Signed-off-by: Richard Henderson <richard.henderson@linaro.org> Message-Id: <20211119160502.17432-30-richard.henderson@linaro.org> Signed-off-by: Cédric Le Goater <clg@kaod.org>
qemu · Dec 16, 2021 · f76ee2b · f76ee2b
1 parent 224e49c
commit f76ee2b
Show file tree

Hide file tree

Showing 3 changed files with 14 additions and 2 deletions.
diff --git a/target/ppc/fpu_helper.c b/target/ppc/fpu_helper.c
@@ -775,6 +775,18 @@ float64 helper_fsqrt(CPUPPCState *env, float64 arg)
     return ret;
 }
 
+/* fsqrts - fsqrts. */
+float64 helper_fsqrts(CPUPPCState *env, float64 arg)
+{
+    float64 ret = float64r32_sqrt(arg, &env->fp_status);
+    int flags = get_float_exception_flags(&env->fp_status);
+
+    if (unlikely(flags & float_flag_invalid)) {
+        float_invalid_op_sqrt(env, flags, 1, GETPC());
+    }
+    return ret;
+}
+
 /* fre - fre. */
 float64 helper_fre(CPUPPCState *env, float64 arg)
 {

diff --git a/target/ppc/helper.h b/target/ppc/helper.h
@@ -106,6 +106,7 @@ DEF_HELPER_4(fmsubs, i64, env, i64, i64, i64)
 DEF_HELPER_4(fnmadds, i64, env, i64, i64, i64)
 DEF_HELPER_4(fnmsubs, i64, env, i64, i64, i64)
 DEF_HELPER_2(fsqrt, f64, env, f64)
+DEF_HELPER_2(fsqrts, f64, env, f64)
 DEF_HELPER_2(fre, i64, env, i64)
 DEF_HELPER_2(fres, i64, env, i64)
 DEF_HELPER_2(frsqrte, i64, env, i64)

diff --git a/target/ppc/translate/fp-impl.c.inc b/target/ppc/translate/fp-impl.c.inc
@@ -270,8 +270,7 @@ static void gen_fsqrts(DisasContext *ctx)
     t1 = tcg_temp_new_i64();
     gen_reset_fpstatus();
     get_fpr(t0, rB(ctx->opcode));
-    gen_helper_fsqrt(t1, cpu_env, t0);
-    gen_helper_frsp(t1, cpu_env, t1);
+    gen_helper_fsqrts(t1, cpu_env, t0);
     set_fpr(rD(ctx->opcode), t1);
     gen_compute_fprf_float64(t1);
     if (unlikely(Rc(ctx->opcode) != 0)) {