summaryrefslogtreecommitdiff
path: root/ports/sysdeps/ia64/fpu/e_exp.S
diff options
context:
space:
mode:
Diffstat (limited to 'ports/sysdeps/ia64/fpu/e_exp.S')
-rw-r--r--ports/sysdeps/ia64/fpu/e_exp.S793
1 files changed, 793 insertions, 0 deletions
diff --git a/ports/sysdeps/ia64/fpu/e_exp.S b/ports/sysdeps/ia64/fpu/e_exp.S
new file mode 100644
index 0000000000..f17bc26081
--- /dev/null
+++ b/ports/sysdeps/ia64/fpu/e_exp.S
@@ -0,0 +1,793 @@
+.file "exp.s"
+
+
+// Copyright (c) 2000 - 2005, Intel Corporation
+// All rights reserved.
+//
+// Contributed 2000 by the Intel Numerics Group, Intel Corporation
+//
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions are
+// met:
+//
+// * Redistributions of source code must retain the above copyright
+// notice, this list of conditions and the following disclaimer.
+//
+// * Redistributions in binary form must reproduce the above copyright
+// notice, this list of conditions and the following disclaimer in the
+// documentation and/or other materials provided with the distribution.
+//
+// * The name of Intel Corporation may not be used to endorse or promote
+// products derived from this software without specific prior written
+// permission.
+
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL INTEL OR ITS
+// CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
+// EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
+// PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
+// PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY
+// OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY OR TORT (INCLUDING
+// NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
+// SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+//
+// Intel Corporation is the author of this code, and requests that all
+// problem reports or change requests be submitted to it directly at
+// http://www.intel.com/software/products/opensource/libraries/num.htm.
+//
+// History
+//==============================================================
+// 2/02/00 Initial version
+// 3/07/00 exp(inf) = inf but now does NOT call error support
+// exp(-inf) = 0 but now does NOT call error support
+// 4/04/00 Unwind support added
+// 8/15/00 Bundle added after call to __libm_error_support to properly
+// set [the previously overwritten] GR_Parameter_RESULT.
+// 11/30/00 Reworked to shorten main path, widen main path to include all
+// args in normal range, and add quick exit for 0, nan, inf.
+// 12/05/00 Loaded constants earlier with setf to save 2 cycles.
+// 02/05/02 Corrected uninitialize predicate in POSSIBLE_UNDERFLOW path
+// 05/20/02 Cleaned up namespace and sf0 syntax
+// 09/07/02 Force inexact flag
+// 11/15/02 Split underflow path into zero/nonzero; eliminated fma in main path
+// 05/30/03 Set inexact flag on unmasked overflow/underflow
+// 03/31/05 Reformatted delimiters between data tables
+
+// API
+//==============================================================
+// double exp(double)
+
+// Overview of operation
+//==============================================================
+// Take the input x. w is "how many log2/128 in x?"
+// w = x * 128/log2
+// n = int(w)
+// x = n log2/128 + r + delta
+
+// n = 128M + index_1 + 2^4 index_2
+// x = M log2 + (log2/128) index_1 + (log2/8) index_2 + r + delta
+
+// exp(x) = 2^M 2^(index_1/128) 2^(index_2/8) exp(r) exp(delta)
+// Construct 2^M
+// Get 2^(index_1/128) from table_1;
+// Get 2^(index_2/8) from table_2;
+// Calculate exp(r) by 5th order polynomial
+// r = x - n (log2/128)_high
+// delta = - n (log2/128)_low
+// Calculate exp(delta) as 1 + delta
+
+
+// Special values
+//==============================================================
+// exp(+0) = 1.0
+// exp(-0) = 1.0
+
+// exp(+qnan) = +qnan
+// exp(-qnan) = -qnan
+// exp(+snan) = +qnan
+// exp(-snan) = -qnan
+
+// exp(-inf) = +0
+// exp(+inf) = +inf
+
+// Overflow and Underflow
+//=======================
+// exp(x) = largest double normal when
+// x = 709.7827 = 0x40862e42fefa39ef
+
+// exp(x) = smallest double normal when
+// x = -708.396 = 0xc086232bdd7abcd2
+
+// exp(x) = largest round-to-nearest single zero when
+// x = -745.1332 = 0xc0874910d52d3052
+
+
+// Registers used
+//==============================================================
+// Floating Point registers used:
+// f8, input, output
+// f6 -> f15, f32 -> f49
+
+// General registers used:
+// r14 -> r40
+
+// Predicate registers used:
+// p6 -> p15
+
+// Assembly macros
+//==============================================================
+
+rRshf = r14
+rAD_TB1 = r15
+rAD_T1 = r15
+rAD_TB2 = r16
+rAD_T2 = r16
+rAD_P = r17
+rN = r18
+rIndex_1 = r19
+rIndex_2_16 = r20
+rM = r21
+rBiased_M = r21
+rIndex_1_16 = r21
+rSig_inv_ln2 = r22
+rExp_bias = r23
+rExp_mask = r24
+rTmp = r25
+rRshf_2to56 = r26
+rGt_ln = r27
+rExp_2tom56 = r28
+
+
+GR_SAVE_B0 = r33
+GR_SAVE_PFS = r34
+GR_SAVE_GP = r35
+GR_SAVE_SP = r36
+
+GR_Parameter_X = r37
+GR_Parameter_Y = r38
+GR_Parameter_RESULT = r39
+GR_Parameter_TAG = r40
+
+
+FR_X = f10
+FR_Y = f1
+FR_RESULT = f8
+
+fRSHF_2TO56 = f6
+fINV_LN2_2TO63 = f7
+fW_2TO56_RSH = f9
+f2TOM56 = f11
+fP5 = f12
+fP54 = f12
+fP5432 = f12
+fP4 = f13
+fP3 = f14
+fP32 = f14
+fP2 = f15
+fP = f15
+
+fLn2_by_128_hi = f33
+fLn2_by_128_lo = f34
+
+fRSHF = f35
+fNfloat = f36
+fNormX = f37
+fR = f38
+fF = f39
+
+fRsq = f40
+f2M = f41
+fS1 = f42
+fT1 = f42
+fS2 = f43
+fT2 = f43
+fS = f43
+fWre_urm_f8 = f44
+fFtz_urm_f8 = f44
+
+fMIN_DBL_OFLOW_ARG = f45
+fMAX_DBL_ZERO_ARG = f46
+fMAX_DBL_NORM_ARG = f47
+fMIN_DBL_NORM_ARG = f48
+fGt_pln = f49
+fTmp = f49
+
+
+// Data tables
+//==============================================================
+
+RODATA
+.align 16
+
+// ************* DO NOT CHANGE ORDER OF THESE TABLES ********************
+
+// double-extended 1/ln(2)
+// 3fff b8aa 3b29 5c17 f0bb be87fed0691d3e88
+// 3fff b8aa 3b29 5c17 f0bc
+// For speed the significand will be loaded directly with a movl and setf.sig
+// and the exponent will be bias+63 instead of bias+0. Thus subsequent
+// computations need to scale appropriately.
+// The constant 128/ln(2) is needed for the computation of w. This is also
+// obtained by scaling the computations.
+//
+// Two shifting constants are loaded directly with movl and setf.d.
+// 1. fRSHF_2TO56 = 1.1000..00 * 2^(63-7)
+// This constant is added to x*1/ln2 to shift the integer part of
+// x*128/ln2 into the rightmost bits of the significand.
+// The result of this fma is fW_2TO56_RSH.
+// 2. fRSHF = 1.1000..00 * 2^(63)
+// This constant is subtracted from fW_2TO56_RSH * 2^(-56) to give
+// the integer part of w, n, as a floating-point number.
+// The result of this fms is fNfloat.
+
+
+LOCAL_OBJECT_START(exp_table_1)
+data8 0x40862e42fefa39f0 // smallest dbl overflow arg, +709.7827
+data8 0xc0874910d52d3052 // largest arg for rnd-to-nearest 0 result, -745.133
+data8 0x40862e42fefa39ef // largest dbl arg to give normal dbl result, +709.7827
+data8 0xc086232bdd7abcd2 // smallest dbl arg to give normal dbl result, -708.396
+data8 0xb17217f7d1cf79ab , 0x00003ff7 // ln2/128 hi
+data8 0xc9e3b39803f2f6af , 0x00003fb7 // ln2/128 lo
+//
+// Table 1 is 2^(index_1/128) where
+// index_1 goes from 0 to 15
+//
+data8 0x8000000000000000 , 0x00003FFF
+data8 0x80B1ED4FD999AB6C , 0x00003FFF
+data8 0x8164D1F3BC030773 , 0x00003FFF
+data8 0x8218AF4373FC25EC , 0x00003FFF
+data8 0x82CD8698AC2BA1D7 , 0x00003FFF
+data8 0x8383594EEFB6EE37 , 0x00003FFF
+data8 0x843A28C3ACDE4046 , 0x00003FFF
+data8 0x84F1F656379C1A29 , 0x00003FFF
+data8 0x85AAC367CC487B15 , 0x00003FFF
+data8 0x8664915B923FBA04 , 0x00003FFF
+data8 0x871F61969E8D1010 , 0x00003FFF
+data8 0x87DB357FF698D792 , 0x00003FFF
+data8 0x88980E8092DA8527 , 0x00003FFF
+data8 0x8955EE03618E5FDD , 0x00003FFF
+data8 0x8A14D575496EFD9A , 0x00003FFF
+data8 0x8AD4C6452C728924 , 0x00003FFF
+LOCAL_OBJECT_END(exp_table_1)
+
+// Table 2 is 2^(index_1/8) where
+// index_2 goes from 0 to 7
+LOCAL_OBJECT_START(exp_table_2)
+data8 0x8000000000000000 , 0x00003FFF
+data8 0x8B95C1E3EA8BD6E7 , 0x00003FFF
+data8 0x9837F0518DB8A96F , 0x00003FFF
+data8 0xA5FED6A9B15138EA , 0x00003FFF
+data8 0xB504F333F9DE6484 , 0x00003FFF
+data8 0xC5672A115506DADD , 0x00003FFF
+data8 0xD744FCCAD69D6AF4 , 0x00003FFF
+data8 0xEAC0C6E7DD24392F , 0x00003FFF
+LOCAL_OBJECT_END(exp_table_2)
+
+
+LOCAL_OBJECT_START(exp_p_table)
+data8 0x3f8111116da21757 //P5
+data8 0x3fa55555d787761c //P4
+data8 0x3fc5555555555414 //P3
+data8 0x3fdffffffffffd6a //P2
+LOCAL_OBJECT_END(exp_p_table)
+
+
+.section .text
+GLOBAL_IEEE754_ENTRY(exp)
+
+{ .mlx
+ nop.m 0
+ movl rSig_inv_ln2 = 0xb8aa3b295c17f0bc // significand of 1/ln2
+}
+{ .mlx
+ addl rAD_TB1 = @ltoff(exp_table_1), gp
+ movl rRshf_2to56 = 0x4768000000000000 // 1.10000 2^(63+56)
+}
+;;
+
+{ .mfi
+ ld8 rAD_TB1 = [rAD_TB1]
+ fclass.m p8,p0 = f8,0x07 // Test for x=0
+ mov rExp_mask = 0x1ffff
+}
+{ .mfi
+ mov rExp_bias = 0xffff
+ fnorm.s1 fNormX = f8
+ mov rExp_2tom56 = 0xffff-56
+}
+;;
+
+// Form two constants we need
+// 1/ln2 * 2^63 to compute w = x * 1/ln2 * 128
+// 1.1000..000 * 2^(63+63-7) to right shift int(w) into the significand
+
+{ .mfi
+ setf.sig fINV_LN2_2TO63 = rSig_inv_ln2 // form 1/ln2 * 2^63
+ fclass.m p9,p0 = f8,0x22 // Test for x=-inf
+ nop.i 0
+}
+{ .mlx
+ setf.d fRSHF_2TO56 = rRshf_2to56 // Form const 1.100 * 2^(63+56)
+ movl rRshf = 0x43e8000000000000 // 1.10000 2^63 for right shift
+}
+;;
+
+{ .mfi
+ ldfpd fMIN_DBL_OFLOW_ARG, fMAX_DBL_ZERO_ARG = [rAD_TB1],16
+ fclass.m p10,p0 = f8,0x1e1 // Test for x=+inf, nan, NaT
+ nop.i 0
+}
+{ .mfb
+ setf.exp f2TOM56 = rExp_2tom56 // form 2^-56 for scaling Nfloat
+(p9) fma.d.s0 f8 = f0,f0,f0 // quick exit for x=-inf
+(p9) br.ret.spnt b0
+}
+;;
+
+{ .mfi
+ ldfpd fMAX_DBL_NORM_ARG, fMIN_DBL_NORM_ARG = [rAD_TB1],16
+ nop.f 0
+ nop.i 0
+}
+{ .mfb
+ setf.d fRSHF = rRshf // Form right shift const 1.100 * 2^63
+(p8) fma.d.s0 f8 = f1,f1,f0 // quick exit for x=0
+(p8) br.ret.spnt b0
+}
+;;
+
+{ .mfb
+ ldfe fLn2_by_128_hi = [rAD_TB1],16
+(p10) fma.d.s0 f8 = f8,f8,f0 // Result if x=+inf, nan, NaT
+(p10) br.ret.spnt b0 // quick exit for x=+inf, nan, NaT
+}
+;;
+
+{ .mfi
+ ldfe fLn2_by_128_lo = [rAD_TB1],16
+ fcmp.eq.s0 p6,p0 = f8, f0 // Dummy to set D
+ nop.i 0
+}
+;;
+
+// After that last load, rAD_TB1 points to the beginning of table 1
+
+// W = X * Inv_log2_by_128
+// By adding 1.10...0*2^63 we shift and get round_int(W) in significand.
+// We actually add 1.10...0*2^56 to X * Inv_log2 to do the same thing.
+
+{ .mfi
+ nop.m 0
+ fma.s1 fW_2TO56_RSH = fNormX, fINV_LN2_2TO63, fRSHF_2TO56
+ nop.i 0
+}
+;;
+
+// Divide arguments into the following categories:
+// Certain Underflow p11 - -inf < x <= MAX_DBL_ZERO_ARG
+// Possible Underflow p13 - MAX_DBL_ZERO_ARG < x < MIN_DBL_NORM_ARG
+// Certain Safe - MIN_DBL_NORM_ARG <= x <= MAX_DBL_NORM_ARG
+// Possible Overflow p14 - MAX_DBL_NORM_ARG < x < MIN_DBL_OFLOW_ARG
+// Certain Overflow p15 - MIN_DBL_OFLOW_ARG <= x < +inf
+//
+// If the input is really a double arg, then there will never be
+// "Possible Overflow" arguments.
+//
+
+{ .mfi
+ add rAD_TB2 = 0x100, rAD_TB1
+ fcmp.ge.s1 p15,p0 = fNormX,fMIN_DBL_OFLOW_ARG
+ nop.i 0
+}
+;;
+
+{ .mfi
+ add rAD_P = 0x80, rAD_TB2
+ fcmp.le.s1 p11,p0 = fNormX,fMAX_DBL_ZERO_ARG
+ nop.i 0
+}
+;;
+
+{ .mfb
+ ldfpd fP5, fP4 = [rAD_P] ,16
+ fcmp.gt.s1 p14,p0 = fNormX,fMAX_DBL_NORM_ARG
+(p15) br.cond.spnt EXP_CERTAIN_OVERFLOW
+}
+;;
+
+// Nfloat = round_int(W)
+// The signficand of fW_2TO56_RSH contains the rounded integer part of W,
+// as a twos complement number in the lower bits (that is, it may be negative).
+// That twos complement number (called N) is put into rN.
+
+// Since fW_2TO56_RSH is scaled by 2^56, it must be multiplied by 2^-56
+// before the shift constant 1.10000 * 2^63 is subtracted to yield fNfloat.
+// Thus, fNfloat contains the floating point version of N
+
+{ .mfb
+ ldfpd fP3, fP2 = [rAD_P]
+ fms.s1 fNfloat = fW_2TO56_RSH, f2TOM56, fRSHF
+(p11) br.cond.spnt EXP_CERTAIN_UNDERFLOW
+}
+;;
+
+{ .mfi
+ getf.sig rN = fW_2TO56_RSH
+ nop.f 0
+ nop.i 0
+}
+;;
+
+// rIndex_1 has index_1
+// rIndex_2_16 has index_2 * 16
+// rBiased_M has M
+// rIndex_1_16 has index_1 * 16
+
+// rM has true M
+// r = x - Nfloat * ln2_by_128_hi
+// f = 1 - Nfloat * ln2_by_128_lo
+{ .mfi
+ and rIndex_1 = 0x0f, rN
+ fnma.s1 fR = fNfloat, fLn2_by_128_hi, fNormX
+ shr rM = rN, 0x7
+}
+{ .mfi
+ and rIndex_2_16 = 0x70, rN
+ fnma.s1 fF = fNfloat, fLn2_by_128_lo, f1
+ nop.i 0
+}
+;;
+
+// rAD_T1 has address of T1
+// rAD_T2 has address if T2
+
+{ .mmi
+ add rBiased_M = rExp_bias, rM
+ add rAD_T2 = rAD_TB2, rIndex_2_16
+ shladd rAD_T1 = rIndex_1, 4, rAD_TB1
+}
+;;
+
+// Create Scale = 2^M
+{ .mmi
+ setf.exp f2M = rBiased_M
+ ldfe fT2 = [rAD_T2]
+ nop.i 0
+}
+;;
+
+// Load T1 and T2
+{ .mfi
+ ldfe fT1 = [rAD_T1]
+ fmpy.s0 fTmp = fLn2_by_128_lo, fLn2_by_128_lo // Force inexact
+ nop.i 0
+}
+;;
+
+{ .mfi
+ nop.m 0
+ fma.s1 fRsq = fR, fR, f0
+ nop.i 0
+}
+{ .mfi
+ nop.m 0
+ fma.s1 fP54 = fR, fP5, fP4
+ nop.i 0
+}
+;;
+
+{ .mfi
+ nop.m 0
+ fcmp.lt.s1 p13,p0 = fNormX,fMIN_DBL_NORM_ARG
+ nop.i 0
+}
+{ .mfi
+ nop.m 0
+ fma.s1 fP32 = fR, fP3, fP2
+ nop.i 0
+}
+;;
+
+{ .mfi
+ nop.m 0
+ fma.s1 fP5432 = fRsq, fP54, fP32
+ nop.i 0
+}
+;;
+
+{ .mfi
+ nop.m 0
+ fma.s1 fS1 = f2M,fT1,f0
+ nop.i 0
+}
+{ .mfi
+ nop.m 0
+ fma.s1 fS2 = fF,fT2,f0
+ nop.i 0
+}
+;;
+
+{ .mfi
+ nop.m 0
+ fma.s1 fP = fRsq, fP5432, fR
+ nop.i 0
+}
+{ .mfi
+ nop.m 0
+ fma.s1 fS = fS1,fS2,f0
+ nop.i 0
+}
+;;
+
+{ .mbb
+ nop.m 0
+(p13) br.cond.spnt EXP_POSSIBLE_UNDERFLOW
+(p14) br.cond.spnt EXP_POSSIBLE_OVERFLOW
+}
+;;
+
+{ .mfb
+ nop.m 0
+ fma.d.s0 f8 = fS, fP, fS
+ br.ret.sptk b0 // Normal path exit
+}
+;;
+
+
+EXP_POSSIBLE_OVERFLOW:
+
+// Here if fMAX_DBL_NORM_ARG < x < fMIN_DBL_OFLOW_ARG
+// This cannot happen if input is a double, only if input higher precision.
+// Overflow is a possibility, not a certainty.
+
+// Recompute result using status field 2 with user's rounding mode,
+// and wre set. If result is larger than largest double, then we have
+// overflow
+
+{ .mfi
+ mov rGt_ln = 0x103ff // Exponent for largest dbl + 1 ulp
+ fsetc.s2 0x7F,0x42 // Get user's round mode, set wre
+ nop.i 0
+}
+;;
+
+{ .mfi
+ setf.exp fGt_pln = rGt_ln // Create largest double + 1 ulp
+ fma.d.s2 fWre_urm_f8 = fS, fP, fS // Result with wre set
+ nop.i 0
+}
+;;
+
+{ .mfi
+ nop.m 0
+ fsetc.s2 0x7F,0x40 // Turn off wre in sf2
+ nop.i 0
+}
+;;
+
+{ .mfi
+ nop.m 0
+ fcmp.ge.s1 p6, p0 = fWre_urm_f8, fGt_pln // Test for overflow
+ nop.i 0
+}
+;;
+
+{ .mfb
+ nop.m 0
+ nop.f 0
+(p6) br.cond.spnt EXP_CERTAIN_OVERFLOW // Branch if overflow
+}
+;;
+
+{ .mfb
+ nop.m 0
+ fma.d.s0 f8 = fS, fP, fS
+ br.ret.sptk b0 // Exit if really no overflow
+}
+;;
+
+EXP_CERTAIN_OVERFLOW:
+{ .mmi
+ sub rTmp = rExp_mask, r0, 1
+;;
+ setf.exp fTmp = rTmp
+ nop.i 0
+}
+;;
+
+{ .mfi
+ alloc r32=ar.pfs,1,4,4,0
+ fmerge.s FR_X = f8,f8
+ nop.i 0
+}
+{ .mfb
+ mov GR_Parameter_TAG = 14
+ fma.d.s0 FR_RESULT = fTmp, fTmp, fTmp // Set I,O and +INF result
+ br.cond.sptk __libm_error_region
+}
+;;
+
+EXP_POSSIBLE_UNDERFLOW:
+
+// Here if fMAX_DBL_ZERO_ARG < x < fMIN_DBL_NORM_ARG
+// Underflow is a possibility, not a certainty
+
+// We define an underflow when the answer with
+// ftz set
+// is zero (tiny numbers become zero)
+
+// Notice (from below) that if we have an unlimited exponent range,
+// then there is an extra machine number E between the largest denormal and
+// the smallest normal.
+
+// So if with unbounded exponent we round to E or below, then we are
+// tiny and underflow has occurred.
+
+// But notice that you can be in a situation where we are tiny, namely
+// rounded to E, but when the exponent is bounded we round to smallest
+// normal. So the answer can be the smallest normal with underflow.
+
+// E
+// -----+--------------------+--------------------+-----
+// | | |
+// 1.1...10 2^-3fff 1.1...11 2^-3fff 1.0...00 2^-3ffe
+// 0.1...11 2^-3ffe (biased, 1)
+// largest dn smallest normal
+
+{ .mfi
+ nop.m 0
+ fsetc.s2 0x7F,0x41 // Get user's round mode, set ftz
+ nop.i 0
+}
+;;
+
+{ .mfi
+ nop.m 0
+ fma.d.s2 fFtz_urm_f8 = fS, fP, fS // Result with ftz set
+ nop.i 0
+}
+;;
+
+{ .mfi
+ nop.m 0
+ fsetc.s2 0x7F,0x40 // Turn off ftz in sf2
+ nop.i 0
+}
+;;
+
+{ .mfi
+ nop.m 0
+ fcmp.eq.s1 p6, p7 = fFtz_urm_f8, f0 // Test for underflow
+ nop.i 0
+}
+{ .mfi
+ nop.m 0
+ fma.d.s0 f8 = fS, fP, fS // Compute result, set I, maybe U
+ nop.i 0
+}
+;;
+
+{ .mbb
+ nop.m 0
+(p6) br.cond.spnt EXP_UNDERFLOW_COMMON // Branch if really underflow
+(p7) br.ret.sptk b0 // Exit if really no underflow
+}
+;;
+
+EXP_CERTAIN_UNDERFLOW:
+// Here if x < fMAX_DBL_ZERO_ARG
+// Result will be zero (or smallest denorm if round to +inf) with I, U set
+{ .mmi
+ mov rTmp = 1
+;;
+ setf.exp fTmp = rTmp // Form small normal
+ nop.i 0
+}
+;;
+
+{ .mfi
+ nop.m 0
+ fmerge.se fTmp = fTmp, fLn2_by_128_lo // Small with signif lsb 1
+ nop.i 0
+}
+;;
+
+{ .mfb
+ nop.m 0
+ fma.d.s0 f8 = fTmp, fTmp, f0 // Set I,U, tiny (+0.0) result
+ br.cond.sptk EXP_UNDERFLOW_COMMON
+}
+;;
+
+EXP_UNDERFLOW_COMMON:
+// Determine if underflow result is zero or nonzero
+{ .mfi
+ alloc r32=ar.pfs,1,4,4,0
+ fcmp.eq.s1 p6, p0 = f8, f0
+ nop.i 0
+}
+;;
+
+{ .mfb
+ nop.m 0
+ fmerge.s FR_X = fNormX,fNormX
+(p6) br.cond.spnt EXP_UNDERFLOW_ZERO
+}
+;;
+
+EXP_UNDERFLOW_NONZERO:
+// Here if x < fMIN_DBL_NORM_ARG and result nonzero;
+// I, U are set
+{ .mfb
+ mov GR_Parameter_TAG = 15
+ nop.f 0 // FR_RESULT already set
+ br.cond.sptk __libm_error_region
+}
+;;
+
+EXP_UNDERFLOW_ZERO:
+// Here if x < fMIN_DBL_NORM_ARG and result zero;
+// I, U are set
+{ .mfb
+ mov GR_Parameter_TAG = 15
+ nop.f 0 // FR_RESULT already set
+ br.cond.sptk __libm_error_region
+}
+;;
+
+GLOBAL_IEEE754_END(exp)
+
+
+LOCAL_LIBM_ENTRY(__libm_error_region)
+.prologue
+{ .mfi
+ add GR_Parameter_Y=-32,sp // Parameter 2 value
+ nop.f 0
+.save ar.pfs,GR_SAVE_PFS
+ mov GR_SAVE_PFS=ar.pfs // Save ar.pfs
+}
+{ .mfi
+.fframe 64
+ add sp=-64,sp // Create new stack
+ nop.f 0
+ mov GR_SAVE_GP=gp // Save gp
+};;
+{ .mmi
+ stfd [GR_Parameter_Y] = FR_Y,16 // STORE Parameter 2 on stack
+ add GR_Parameter_X = 16,sp // Parameter 1 address
+.save b0, GR_SAVE_B0
+ mov GR_SAVE_B0=b0 // Save b0
+};;
+.body
+{ .mib
+ stfd [GR_Parameter_X] = FR_X // STORE Parameter 1 on stack
+ add GR_Parameter_RESULT = 0,GR_Parameter_Y // Parameter 3 address
+ nop.b 0
+}
+{ .mib
+ stfd [GR_Parameter_Y] = FR_RESULT // STORE Parameter 3 on stack
+ add GR_Parameter_Y = -16,GR_Parameter_Y
+ br.call.sptk b0=__libm_error_support# // Call error handling function
+};;
+{ .mmi
+ add GR_Parameter_RESULT = 48,sp
+ nop.m 0
+ nop.i 0
+};;
+{ .mmi
+ ldfd f8 = [GR_Parameter_RESULT] // Get return result off stack
+.restore sp
+ add sp = 64,sp // Restore stack pointer
+ mov b0 = GR_SAVE_B0 // Restore return address
+};;
+{ .mib
+ mov gp = GR_SAVE_GP // Restore gp
+ mov ar.pfs = GR_SAVE_PFS // Restore ar.pfs
+ br.ret.sptk b0 // Return
+};;
+
+LOCAL_LIBM_END(__libm_error_region)
+.type __libm_error_support#,@function
+.global __libm_error_support#