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diff --git a/src/math/hypot_amd64.s b/src/math/hypot_amd64.s
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+// Copyright 2010 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+#include "textflag.h"
+
+#define PosInf 0x7FF0000000000000
+#define NaN 0x7FF8000000000001
+
+// func archHypot(p, q float64) float64
+TEXT ·archHypot(SB),NOSPLIT,$0
+ // test bits for special cases
+ MOVQ p+0(FP), BX
+ MOVQ $~(1<<63), AX
+ ANDQ AX, BX // p = |p|
+ MOVQ q+8(FP), CX
+ ANDQ AX, CX // q = |q|
+ MOVQ $PosInf, AX
+ CMPQ AX, BX
+ JLE isInfOrNaN
+ CMPQ AX, CX
+ JLE isInfOrNaN
+ // hypot = max * sqrt(1 + (min/max)**2)
+ MOVQ BX, X0
+ MOVQ CX, X1
+ ORQ CX, BX
+ JEQ isZero
+ MOVAPD X0, X2
+ MAXSD X1, X0
+ MINSD X2, X1
+ DIVSD X0, X1
+ MULSD X1, X1
+ ADDSD $1.0, X1
+ SQRTSD X1, X1
+ MULSD X1, X0
+ MOVSD X0, ret+16(FP)
+ RET
+isInfOrNaN:
+ CMPQ AX, BX
+ JEQ isInf
+ CMPQ AX, CX
+ JEQ isInf
+ MOVQ $NaN, AX
+ MOVQ AX, ret+16(FP) // return NaN
+ RET
+isInf:
+ MOVQ AX, ret+16(FP) // return +Inf
+ RET
+isZero:
+ MOVQ $0, AX
+ MOVQ AX, ret+16(FP) // return 0
+ RET