ispc/builtins/target-sse2-common.ll

;;  Copyright (c) 2010-2011, Intel Corporation
;;  All rights reserved.
;;
;;  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.
;;
;;    * Neither the name of Intel Corporation nor the names of its
;;      contributors may 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 THE COPYRIGHT OWNER
;;   OR 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.  

ctlztz()
define_prefetches()

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;; rcp

declare <4 x float> @llvm.x86.sse.rcp.ss(<4 x float>) nounwind readnone

define float @__rcp_uniform_float(float) nounwind readonly alwaysinline {
  ; do the rcpss call
  %vecval = insertelement <4 x float> undef, float %0, i32 0
  %call = call <4 x float> @llvm.x86.sse.rcp.ss(<4 x float> %vecval)
  %scall = extractelement <4 x float> %call, i32 0

  ; do one N-R iteration to improve precision, as above
  %v_iv = fmul float %0, %scall
  %two_minus = fsub float 2., %v_iv  
  %iv_mul = fmul float %scall, %two_minus
  ret float %iv_mul
}


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; rsqrt

declare <4 x float> @llvm.x86.sse.rsqrt.ss(<4 x float>) nounwind readnone

define float @__rsqrt_uniform_float(float) nounwind readonly alwaysinline {
  ;  uniform float is = extract(__rsqrt_u(v), 0);
  %v = insertelement <4 x float> undef, float %0, i32 0
  %vis = call <4 x float> @llvm.x86.sse.rsqrt.ss(<4 x float> %v)
  %is = extractelement <4 x float> %vis, i32 0

  ; Newton-Raphson iteration to improve precision
  ;  return 0.5 * is * (3. - (v * is) * is);
  %v_is = fmul float %0, %is
  %v_is_is = fmul float %v_is, %is
  %three_sub = fsub float 3., %v_is_is
  %is_mul = fmul float %is, %three_sub
  %half_scale = fmul float 0.5, %is_mul
  ret float %half_scale
}


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; sqrt

declare <4 x float> @llvm.x86.sse.sqrt.ss(<4 x float>) nounwind readnone


define float @__sqrt_uniform_float(float) nounwind readonly alwaysinline {
  sse_unary_scalar(ret, 4, float, @llvm.x86.sse.sqrt.ss, %0)
  ret float %ret
}

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;; fast math mode

declare void @llvm.x86.sse.stmxcsr(i8 *) nounwind
declare void @llvm.x86.sse.ldmxcsr(i8 *) nounwind

define void @__fastmath() nounwind alwaysinline {
  %ptr = alloca i32
  %ptr8 = bitcast i32 * %ptr to i8 *
  call void @llvm.x86.sse.stmxcsr(i8 * %ptr8)
  %oldval = load i32 *%ptr

  ; turn on DAZ (64)/FTZ (32768) -> 32832
  %update = or i32 %oldval, 32832
  store i32 %update, i32 *%ptr
  call void @llvm.x86.sse.ldmxcsr(i8 * %ptr8)
  ret void
}

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;; float min/max

declare <4 x float> @llvm.x86.sse.max.ss(<4 x float>, <4 x float>) nounwind readnone
declare <4 x float> @llvm.x86.sse.min.ss(<4 x float>, <4 x float>) nounwind readnone

define float @__max_uniform_float(float, float) nounwind readonly alwaysinline {
  sse_binary_scalar(ret, 4, float, @llvm.x86.sse.max.ss, %0, %1)
  ret float %ret
}


define float @__min_uniform_float(float, float) nounwind readonly alwaysinline {
  sse_binary_scalar(ret, 4, float, @llvm.x86.sse.min.ss, %0, %1)
  ret float %ret
}

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;; double precision sqrt

declare <2 x double> @llvm.x86.sse2.sqrt.sd(<2 x double>) nounwind readnone

define double @__sqrt_uniform_double(double) nounwind alwaysinline {
  sse_unary_scalar(ret, 2, double, @llvm.x86.sse2.sqrt.sd, %0)
  ret double %ret
}


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;; double precision min/max

declare <2 x double> @llvm.x86.sse2.max.sd(<2 x double>, <2 x double>) nounwind readnone
declare <2 x double> @llvm.x86.sse2.min.sd(<2 x double>, <2 x double>) nounwind readnone

define double @__min_uniform_double(double, double) nounwind readnone {
  sse_binary_scalar(ret, 2, double, @llvm.x86.sse2.min.sd, %0, %1)
  ret double %ret
}

define double @__max_uniform_double(double, double) nounwind readnone {
  sse_binary_scalar(ret, 2, double, @llvm.x86.sse2.max.sd, %0, %1)
  ret double %ret
}

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;; rounding
;;
;; There are not any rounding instructions in SSE2, so we have to emulate
;; the functionality with multiple instructions...

; The code for __round_* is the result of compiling the following source
; code.
;
; export float Round(float x) {
;    unsigned int sign = signbits(x);
;    unsigned int ix = intbits(x);
;    ix ^= sign;
;    x = floatbits(ix);
;    x += 0x1.0p23f;
;    x -= 0x1.0p23f;
;    ix = intbits(x);
;    ix ^= sign;
;    x = floatbits(ix);
;    return x;
;}

define float @__round_uniform_float(float) nounwind readonly alwaysinline {
  %float_to_int_bitcast.i.i.i.i = bitcast float %0 to i32
  %bitop.i.i = and i32 %float_to_int_bitcast.i.i.i.i, -2147483648
  %bitop.i = xor i32 %bitop.i.i, %float_to_int_bitcast.i.i.i.i
  %int_to_float_bitcast.i.i40.i = bitcast i32 %bitop.i to float
  %binop.i = fadd float %int_to_float_bitcast.i.i40.i, 8.388608e+06
  %binop21.i = fadd float %binop.i, -8.388608e+06
  %float_to_int_bitcast.i.i.i = bitcast float %binop21.i to i32
  %bitop31.i = xor i32 %float_to_int_bitcast.i.i.i, %bitop.i.i
  %int_to_float_bitcast.i.i.i = bitcast i32 %bitop31.i to float
  ret float %int_to_float_bitcast.i.i.i
}

;; Similarly, for implementations of the __floor* functions below, we have the
;; bitcode from compiling the following source code...

;export float Floor(float x) {
;    float y = Round(x);
;    unsigned int cmp = y > x ? 0xffffffff : 0;
;    float delta = -1.f;
;    unsigned int idelta = intbits(delta);
;    idelta &= cmp;
;    delta = floatbits(idelta);
;    return y + delta;
;}

define float @__floor_uniform_float(float) nounwind readonly alwaysinline {
  %calltmp.i = tail call float @__round_uniform_float(float %0) nounwind
  %bincmp.i = fcmp ogt float %calltmp.i, %0
  %selectexpr.i = sext i1 %bincmp.i to i32
  %bitop.i = and i32 %selectexpr.i, -1082130432
  %int_to_float_bitcast.i.i.i = bitcast i32 %bitop.i to float
  %binop.i = fadd float %calltmp.i, %int_to_float_bitcast.i.i.i
  ret float %binop.i
}

;; And here is the code we compiled to get the __ceil* functions below
;
;export uniform float Ceil(uniform float x) {
;    uniform float y = Round(x);
;    uniform int yltx = y < x ? 0xffffffff : 0;
;    uniform float delta = 1.f;
;    uniform int idelta = intbits(delta);
;    idelta &= yltx;
;    delta = floatbits(idelta);
;    return y + delta;
;}

define float @__ceil_uniform_float(float) nounwind readonly alwaysinline {
  %calltmp.i = tail call float @__round_uniform_float(float %0) nounwind
  %bincmp.i = fcmp olt float %calltmp.i, %0
  %selectexpr.i = sext i1 %bincmp.i to i32
  %bitop.i = and i32 %selectexpr.i, 1065353216
  %int_to_float_bitcast.i.i.i = bitcast i32 %bitop.i to float
  %binop.i = fadd float %calltmp.i, %int_to_float_bitcast.i.i.i
  ret float %binop.i
}


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;; rounding doubles

declare double @round(double)
declare double @floor(double)
declare double @ceil(double)

define double @__round_uniform_double(double) nounwind readonly alwaysinline {
  %r = call double @round(double %0)
  ret double %r
}

define double @__floor_uniform_double(double) nounwind readonly alwaysinline {
  %r = call double @floor(double %0)
  ret double %r
}

define double @__ceil_uniform_double(double) nounwind readonly alwaysinline {
  %r = call double @ceil(double %0)
  ret double %r
}

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; horizontal ops / reductions

declare i32 @llvm.ctpop.i32(i32)
declare i64 @llvm.ctpop.i64(i64)

define i32 @__popcnt_int32(i32) nounwind readonly alwaysinline {
  %val = call i32 @llvm.ctpop.i32(i32 %0)
  ret i32 %val
}

define i64 @__popcnt_int64(i64) nounwind readnone alwaysinline {
  %val = call i64 @llvm.ctpop.i64(i64 %0)
  ret i64 %val
}