[PULL 20/45] softfpu: Add float_round_to_odd_inf

Maintainers: "Michael S. Tsirkin" <mst@redhat.com>, Laurent Vivier <laurent@vivier.eu>, Igor Mammedov <imammedo@redhat.com>, Thomas Huth <thuth@redhat.com>, Cameron Esfahani <dirty@apple.com>, Laurent Vivier <lvivier@redhat.com>, Roman Bolshakov <r.bolshakov@yadro.com>, Paolo Bonzini <pbonzini@redhat.com>, Peter Maydell <peter.maydell@linaro.org>
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[PULL 20/45] softfpu: Add float_round_to_odd_inf
Posted by Peter Maydell 3 years, 11 months ago
From: Richard Henderson <richard.henderson@linaro.org>

For Arm BFDOT and BFMMLA, we need a version of round-to-odd
that overflows to infinity, instead of the max normal number.

Cc: Alex Bennée <alex.bennee@linaro.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Message-id: 20210525225817.400336-6-richard.henderson@linaro.org
Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
---
 include/fpu/softfloat-types.h | 4 +++-
 fpu/softfloat-parts.c.inc     | 6 ++++--
 2 files changed, 7 insertions(+), 3 deletions(-)

diff --git a/include/fpu/softfloat-types.h b/include/fpu/softfloat-types.h
index 8a3f20fae9e..3b757c3d6a6 100644
--- a/include/fpu/softfloat-types.h
+++ b/include/fpu/softfloat-types.h
@@ -134,8 +134,10 @@ typedef enum __attribute__((__packed__)) {
     float_round_up           = 2,
     float_round_to_zero      = 3,
     float_round_ties_away    = 4,
-    /* Not an IEEE rounding mode: round to the closest odd mantissa value */
+    /* Not an IEEE rounding mode: round to closest odd, overflow to max */
     float_round_to_odd       = 5,
+    /* Not an IEEE rounding mode: round to closest odd, overflow to inf */
+    float_round_to_odd_inf   = 6,
 } FloatRoundMode;
 
 /*
diff --git a/fpu/softfloat-parts.c.inc b/fpu/softfloat-parts.c.inc
index a897a5a743d..7f69da1d8fa 100644
--- a/fpu/softfloat-parts.c.inc
+++ b/fpu/softfloat-parts.c.inc
@@ -176,13 +176,12 @@ static void partsN(uncanon)(FloatPartsN *p, float_status *s,
         g_assert_not_reached();
     }
 
+    overflow_norm = false;
     switch (s->float_rounding_mode) {
     case float_round_nearest_even:
-        overflow_norm = false;
         inc = ((p->frac_lo & roundeven_mask) != frac_lsbm1 ? frac_lsbm1 : 0);
         break;
     case float_round_ties_away:
-        overflow_norm = false;
         inc = frac_lsbm1;
         break;
     case float_round_to_zero:
@@ -199,6 +198,8 @@ static void partsN(uncanon)(FloatPartsN *p, float_status *s,
         break;
     case float_round_to_odd:
         overflow_norm = true;
+        /* fall through */
+    case float_round_to_odd_inf:
         inc = p->frac_lo & frac_lsb ? 0 : round_mask;
         break;
     default:
@@ -259,6 +260,7 @@ static void partsN(uncanon)(FloatPartsN *p, float_status *s,
                        ? frac_lsbm1 : 0);
                 break;
             case float_round_to_odd:
+            case float_round_to_odd_inf:
                 inc = p->frac_lo & frac_lsb ? 0 : round_mask;
                 break;
             default:
-- 
2.20.1