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Commitb30cc0f

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Further portability tweaks for float4/float8 hash functions.
Attempting to make hashfloat4() look as much as possible likehashfloat8(), I'd figured I could replace NaNs with get_float4_nan()before widening to float8. However, results from protosciurusand topminnow show that on some platforms that produces a differentbit-pattern from get_float8_nan(), breaking the intent ofce773f2.Rearrange so that we use the result of get_float8_nan() for all NaNcases. As before, back-patch.
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‎src/backend/access/hash/hashfunc.c

Lines changed: 12 additions & 10 deletions
Original file line numberDiff line numberDiff line change
@@ -151,14 +151,6 @@ hashfloat4(PG_FUNCTION_ARGS)
151151
if (key== (float4)0)
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PG_RETURN_UINT32(0);
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154-
/*
155-
* Similarly, NaNs can have different bit patterns but they should all
156-
* compare as equal. For backwards-compatibility reasons we force them to
157-
* have the hash value of a standard NaN.
158-
*/
159-
if (isnan(key))
160-
key=get_float4_nan();
161-
162154
/*
163155
* To support cross-type hashing of float8 and float4, we want to return
164156
* the same hash value hashfloat8 would produce for an equal float8 value.
@@ -168,6 +160,16 @@ hashfloat4(PG_FUNCTION_ARGS)
168160
*/
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key8=key;
170162

163+
/*
164+
* Similarly, NaNs can have different bit patterns but they should all
165+
* compare as equal. For backwards-compatibility reasons we force them to
166+
* have the hash value of a standard float8 NaN. (You'd think we could
167+
* replace key with a float4 NaN and then widen it; but on some old
168+
* platforms, that way produces a different bit pattern.)
169+
*/
170+
if (isnan(key8))
171+
key8=get_float8_nan();
172+
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returnhash_any((unsignedchar*)&key8,sizeof(key8));
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}
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@@ -181,9 +183,9 @@ hashfloat4extended(PG_FUNCTION_ARGS)
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/* Same approach as hashfloat4 */
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if (key== (float4)0)
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PG_RETURN_UINT64(seed);
184-
if (isnan(key))
185-
key=get_float4_nan();
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key8=key;
187+
if (isnan(key8))
188+
key8=get_float8_nan();
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returnhash_any_extended((unsignedchar*)&key8,sizeof(key8),seed);
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}

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