fpu: Add overflow_raises_invalid to FloatFmt
ARM Alt HP raises different exceptions on overflow than is standard for IEEE when saturating a value. Add a flag to control this effect. Reviewed-by: Chao Liu <chao.liu.zevorn@gmail.com> Signed-off-by: Max Chou <max.chou@sifive.com> [rth: Split out of a larger patch] Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Max Chou committed
Feb 5, 2026 at 15:37 UTC
2c2e54428b3e4c4921e4c83ccc8b43b1ff7158d0
2 files changed
+8
-2
fpu/softfloat-parts.c.inc
+3
-1
@@ -348,7 +348,9 @@ static void partsN(uncanon_normal)(FloatPartsN *p, float_status *s,
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case float_expmax_normal:
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if (unlikely(exp > exp_max)) {
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/* Overflow. Return the maximum normal. */
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- flags = float_flag_invalid;
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+ flags = (fmt->overflow_raises_invalid
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+ ? float_flag_invalid
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+ : float_flag_overflow | float_flag_inexact);
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exp = exp_max;
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frac_allones(p);
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p->frac_lo &= ~round_mask;
fpu/softfloat.c
+5
-1
@@ -542,7 +542,9 @@ typedef enum __attribute__((__packed__)) {
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* The following optional modifiers are available:
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* exp_max_kind: affects how exp == exp_max is interpreted
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* has_explicit_bit: has an explicit integer bit; this affects whether
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- * the float_status floatx80_behaviour handling applies
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+ * the float_status floatx80_behaviour handling applies
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+ * overflow_raises_invalid: for float_expmax_normal, raise invalid
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+ * instead of overflow.
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*/
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typedef struct {
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int exp_size;
@@ -553,6 +555,7 @@ typedef struct {
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int frac_shift;
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FloatFmtExpMaxKind exp_max_kind;
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bool has_explicit_bit;
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+ bool overflow_raises_invalid;
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uint64_t round_mask;
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} FloatFmt;
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@@ -576,6 +579,7 @@ static const FloatFmt float16_params = {
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static const FloatFmt float16_params_ahp = {
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FLOAT_PARAMS(5, 10),
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.exp_max_kind = float_expmax_normal,
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+ .overflow_raises_invalid = true,
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};
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static const FloatFmt bfloat16_params = {