Changeset 180098 in webkit for trunk/Source/JavaScriptCore/jit/JITOperations.cpp

Timestamp:

Feb 13, 2015, 8:20:21 PM (11 years ago)

Author:

[email protected]

Message:

Add a DFG node for the Pow Intrinsics
​https://bugs.webkit.org/show_bug.cgi?id=141540

Patch by Benjamin Poulain <​[email protected]> on 2015-02-13
Reviewed by Filip Pizlo.

Add a DFG Node for PowIntrinsic. This patch covers the basic cases
need to avoid massive regression. I will iterate over the node to cover
the missing types.

With this patch I get the following progressions on benchmarks:
-LongSpider's math-partial-sums: +5%.
-Kraken's imaging-darkroom: +17%
-AsmBench's cray.c: +6.6%
-CompressionBench: +2.2% globally.

• dfg/DFGAbstractInterpreterInlines.h:

(JSC::DFG::AbstractInterpreter<AbstractStateType>::executeEffects):
Cover a couple of trivial cases:
-If the exponent is zero, the result is always one, regardless of the base.
-If both arguments are constants, compute the result at compile time.

• dfg/DFGByteCodeParser.cpp:

(JSC::DFG::ByteCodeParser::handleIntrinsic):

• dfg/DFGClobberize.h:

(JSC::DFG::clobberize):

• dfg/DFGDoesGC.cpp:

(JSC::DFG::doesGC):

• dfg/DFGFixupPhase.cpp:

(JSC::DFG::FixupPhase::fixupNode):
We only support 2 basic cases at this time:
-Math.pow(double, int)
-Math.pow(double, double).

I'll cover Math.pow(int, int) in a follow up.

• dfg/DFGNode.h:

(JSC::DFG::Node::convertToArithSqrt):
(JSC::DFG::Node::arithNodeFlags):

• dfg/DFGNodeType.h:
• dfg/DFGPredictionPropagationPhase.cpp:

(JSC::DFG::PredictionPropagationPhase::propagate):
(JSC::DFG::PredictionPropagationPhase::doDoubleVoting):

• dfg/DFGSafeToExecute.h:

(JSC::DFG::safeToExecute):

• dfg/DFGSpeculativeJIT.cpp:

(JSC::DFG::compileArithPowIntegerFastPath):
(JSC::DFG::SpeculativeJIT::compileArithPow):

• dfg/DFGSpeculativeJIT.h:
• dfg/DFGSpeculativeJIT32_64.cpp:

(JSC::DFG::SpeculativeJIT::compile):

• dfg/DFGSpeculativeJIT64.cpp:

(JSC::DFG::SpeculativeJIT::compile):

• dfg/DFGStrengthReductionPhase.cpp:

(JSC::DFG::StrengthReductionPhase::handleNode):

• dfg/DFGValidate.cpp:

(JSC::DFG::Validate::validate):

• ftl/FTLCapabilities.cpp:

(JSC::FTL::canCompile):

• ftl/FTLIntrinsicRepository.h:
• ftl/FTLLowerDFGToLLVM.cpp:

(JSC::FTL::LowerDFGToLLVM::compileNode):
(JSC::FTL::LowerDFGToLLVM::compileArithPow):

• ftl/FTLOutput.h:

(JSC::FTL::Output::doublePow):
(JSC::FTL::Output::doublePowi):

• jit/JITOperations.cpp:
• jit/JITOperations.h:
• runtime/MathObject.cpp:

(JSC::mathProtoFuncPow):
(JSC::isDenormal): Deleted.
(JSC::isEdgeCase): Deleted.
(JSC::mathPow): Deleted.

• tests/stress/math-pow-basics.js: Added.
• tests/stress/math-pow-integer-exponent-fastpath.js: Added.
• tests/stress/math-pow-nan-behaviors.js: Added.
• tests/stress/math-pow-with-constants.js: Added.

Start some basic testing of Math.pow().
Due to the various transform, the value change when the code tiers up,
I covered this by checking for approximate values.

File:

• trunk/Source/JavaScriptCore/jit/JITOperations.cpp (modified) (1 diff)

trunk/Source/JavaScriptCore/jit/JITOperations.cpp

@@ -1214 +1214 @@
 #endif
 
+#if PLATFORM(IOS) && CPU(ARM_THUMB2)
+
+// The following code is taken from netlib.org:
+//   http://www.netlib.org/fdlibm/fdlibm.h
+//   http://www.netlib.org/fdlibm/e_pow.c
+//   http://www.netlib.org/fdlibm/s_scalbn.c
+//
+// And was originally distributed under the following license:
+
+/*
+ * ====================================================
+ * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved.
+ *
+ * Developed at SunSoft, a Sun Microsystems, Inc. business.
+ * Permission to use, copy, modify, and distribute this
+ * software is freely granted, provided that this notice 
+ * is preserved.
+ * ====================================================
+ */
+/*
+ * ====================================================
+ * Copyright (C) 2004 by Sun Microsystems, Inc. All rights reserved.
+ *
+ * Permission to use, copy, modify, and distribute this
+ * software is freely granted, provided that this notice 
+ * is preserved.
+ * ====================================================
+ */
+
+/* __ieee754_pow(x,y) return x**y
+ *
+ *              n
+ * Method:  Let x =  2   * (1+f)
+ *    1. Compute and return log2(x) in two pieces:
+ *        log2(x) = w1 + w2,
+ *       where w1 has 53-24 = 29 bit trailing zeros.
+ *    2. Perform y*log2(x) = n+y' by simulating muti-precision 
+ *       arithmetic, where |y'|<=0.5.
+ *    3. Return x**y = 2**n*exp(y'*log2)
+ *
+ * Special cases:
+ *    1.  (anything) ** 0  is 1
+ *    2.  (anything) ** 1  is itself
+ *    3.  (anything) ** NAN is NAN
+ *    4.  NAN ** (anything except 0) is NAN
+ *    5.  +-(|x| > 1) **  +INF is +INF
+ *    6.  +-(|x| > 1) **  -INF is +0
+ *    7.  +-(|x| < 1) **  +INF is +0
+ *    8.  +-(|x| < 1) **  -INF is +INF
+ *    9.  +-1         ** +-INF is NAN
+ *    10. +0 ** (+anything except 0, NAN)               is +0
+ *    11. -0 ** (+anything except 0, NAN, odd integer)  is +0
+ *    12. +0 ** (-anything except 0, NAN)               is +INF
+ *    13. -0 ** (-anything except 0, NAN, odd integer)  is +INF
+ *    14. -0 ** (odd integer) = -( +0 ** (odd integer) )
+ *    15. +INF ** (+anything except 0,NAN) is +INF
+ *    16. +INF ** (-anything except 0,NAN) is +0
+ *    17. -INF ** (anything)  = -0 ** (-anything)
+ *    18. (-anything) ** (integer) is (-1)**(integer)*(+anything**integer)
+ *    19. (-anything except 0 and inf) ** (non-integer) is NAN
+ *
+ * Accuracy:
+ *    pow(x,y) returns x**y nearly rounded. In particular
+ *            pow(integer,integer)
+ *    always returns the correct integer provided it is 
+ *    representable.
+ *
+ * Constants :
+ * The hexadecimal values are the intended ones for the following 
+ * constants. The decimal values may be used, provided that the 
+ * compiler will convert from decimal to binary accurately enough 
+ * to produce the hexadecimal values shown.
+ */
+
+#define __HI(x) *(1+(int*)&x)
+#define __LO(x) *(int*)&x
+
+static const double
+bp[] = {1.0, 1.5,},
+dp_h[] = { 0.0, 5.84962487220764160156e-01,}, /* 0x3FE2B803, 0x40000000 */
+dp_l[] = { 0.0, 1.35003920212974897128e-08,}, /* 0x3E4CFDEB, 0x43CFD006 */
+zero    =  0.0,
+one    =  1.0,
+two    =  2.0,
+two53    =  9007199254740992.0,    /* 0x43400000, 0x00000000 */
+huge    =  1.0e300,
+tiny    =  1.0e-300,
+        /* for scalbn */
+two54   =  1.80143985094819840000e+16, /* 0x43500000, 0x00000000 */
+twom54  =  5.55111512312578270212e-17, /* 0x3C900000, 0x00000000 */
+    /* poly coefs for (3/2)*(log(x)-2s-2/3*s**3 */
+L1  =  5.99999999999994648725e-01, /* 0x3FE33333, 0x33333303 */
+L2  =  4.28571428578550184252e-01, /* 0x3FDB6DB6, 0xDB6FABFF */
+L3  =  3.33333329818377432918e-01, /* 0x3FD55555, 0x518F264D */
+L4  =  2.72728123808534006489e-01, /* 0x3FD17460, 0xA91D4101 */
+L5  =  2.30660745775561754067e-01, /* 0x3FCD864A, 0x93C9DB65 */
+L6  =  2.06975017800338417784e-01, /* 0x3FCA7E28, 0x4A454EEF */
+P1   =  1.66666666666666019037e-01, /* 0x3FC55555, 0x5555553E */
+P2   = -2.77777777770155933842e-03, /* 0xBF66C16C, 0x16BEBD93 */
+P3   =  6.61375632143793436117e-05, /* 0x3F11566A, 0xAF25DE2C */
+P4   = -1.65339022054652515390e-06, /* 0xBEBBBD41, 0xC5D26BF1 */
+P5   =  4.13813679705723846039e-08, /* 0x3E663769, 0x72BEA4D0 */
+lg2  =  6.93147180559945286227e-01, /* 0x3FE62E42, 0xFEFA39EF */
+lg2_h  =  6.93147182464599609375e-01, /* 0x3FE62E43, 0x00000000 */
+lg2_l  = -1.90465429995776804525e-09, /* 0xBE205C61, 0x0CA86C39 */
+ovt =  8.0085662595372944372e-0017, /* -(1024-log2(ovfl+.5ulp)) */
+cp    =  9.61796693925975554329e-01, /* 0x3FEEC709, 0xDC3A03FD =2/(3ln2) */
+cp_h  =  9.61796700954437255859e-01, /* 0x3FEEC709, 0xE0000000 =(float)cp */
+cp_l  = -7.02846165095275826516e-09, /* 0xBE3E2FE0, 0x145B01F5 =tail of cp_h*/
+ivln2    =  1.44269504088896338700e+00, /* 0x3FF71547, 0x652B82FE =1/ln2 */
+ivln2_h  =  1.44269502162933349609e+00, /* 0x3FF71547, 0x60000000 =24b 1/ln2*/
+ivln2_l  =  1.92596299112661746887e-08; /* 0x3E54AE0B, 0xF85DDF44 =1/ln2 tail*/
+
+inline double fdlibmScalbn (double x, int n)
+{
+    int  k,hx,lx;
+    hx = __HI(x);
+    lx = __LO(x);
+        k = (hx&0x7ff00000)>>20;        /* extract exponent */
+        if (k==0) {                /* 0 or subnormal x */
+            if ((lx|(hx&0x7fffffff))==0) return x; /* +-0 */
+        x *= two54; 
+        hx = __HI(x);
+        k = ((hx&0x7ff00000)>>20) - 54; 
+            if (n< -50000) return tiny*x;     /*underflow*/
+        }
+        if (k==0x7ff) return x+x;        /* NaN or Inf */
+        k = k+n; 
+        if (k >  0x7fe) return huge*copysign(huge,x); /* overflow  */
+        if (k > 0)                 /* normal result */
+        {__HI(x) = (hx&0x800fffff)|(k<<20); return x;}
+        if (k <= -54) {
+            if (n > 50000)     /* in case integer overflow in n+k */
+        return huge*copysign(huge,x);    /*overflow*/
+        else return tiny*copysign(tiny,x);     /*underflow*/
+        }
+        k += 54;                /* subnormal result */
+        __HI(x) = (hx&0x800fffff)|(k<<20);
+        return x*twom54;
+}
+
+static double fdlibmPow(double x, double y)
+{
+    double z,ax,z_h,z_l,p_h,p_l;
+    double y1,t1,t2,r,s,t,u,v,w;
+    int i0,i1,i,j,k,yisint,n;
+    int hx,hy,ix,iy;
+    unsigned lx,ly;
+
+    i0 = ((*(int*)&one)>>29)^1; i1=1-i0;
+    hx = __HI(x); lx = __LO(x);
+    hy = __HI(y); ly = __LO(y);
+    ix = hx&0x7fffffff;  iy = hy&0x7fffffff;
+
+    /* y==zero: x**0 = 1 */
+    if((iy|ly)==0) return one;     
+
+    /* +-NaN return x+y */
+    if(ix > 0x7ff00000 || ((ix==0x7ff00000)&&(lx!=0)) ||
+       iy > 0x7ff00000 || ((iy==0x7ff00000)&&(ly!=0))) 
+        return x+y;    
+
+    /* determine if y is an odd int when x < 0
+     * yisint = 0    ... y is not an integer
+     * yisint = 1    ... y is an odd int
+     * yisint = 2    ... y is an even int
+     */
+    yisint  = 0;
+    if(hx<0) {    
+        if(iy>=0x43400000) yisint = 2; /* even integer y */
+        else if(iy>=0x3ff00000) {
+        k = (iy>>20)-0x3ff;       /* exponent */
+        if(k>20) {
+            j = ly>>(52-k);
+            if(static_cast<unsigned>(j<<(52-k))==ly) yisint = 2-(j&1);
+        } else if(ly==0) {
+            j = iy>>(20-k);
+            if((j<<(20-k))==iy) yisint = 2-(j&1);
+        }
+        }        
+    } 
+
+    /* special value of y */
+    if(ly==0) {     
+        if (iy==0x7ff00000) {    /* y is +-inf */
+            if(((ix-0x3ff00000)|lx)==0)
+            return  y - y;    /* inf**+-1 is NaN */
+            else if (ix >= 0x3ff00000)/* (|x|>1)**+-inf = inf,0 */
+            return (hy>=0)? y: zero;
+            else            /* (|x|<1)**-,+inf = inf,0 */
+            return (hy<0)?-y: zero;
+        } 
+        if(iy==0x3ff00000) {    /* y is  +-1 */
+        if(hy<0) return one/x; else return x;
+        }
+        if(hy==0x40000000) return x*x; /* y is  2 */
+        if(hy==0x3fe00000) {    /* y is  0.5 */
+        if(hx>=0)    /* x >= +0 */
+        return sqrt(x);    
+        }
+    }
+
+    ax   = fabs(x);
+    /* special value of x */
+    if(lx==0) {
+        if(ix==0x7ff00000||ix==0||ix==0x3ff00000){
+        z = ax;            /*x is +-0,+-inf,+-1*/
+        if(hy<0) z = one/z;    /* z = (1/|x|) */
+        if(hx<0) {
+            if(((ix-0x3ff00000)|yisint)==0) {
+            z = (z-z)/(z-z); /* (-1)**non-int is NaN */
+            } else if(yisint==1) 
+            z = -z;        /* (x<0)**odd = -(|x|**odd) */
+        }
+        return z;
+        }
+    }
+    
+    n = (hx>>31)+1;
+
+    /* (x<0)**(non-int) is NaN */
+    if((n|yisint)==0) return (x-x)/(x-x);
+
+    s = one; /* s (sign of result -ve**odd) = -1 else = 1 */
+    if((n|(yisint-1))==0) s = -one;/* (-ve)**(odd int) */
+
+    /* |y| is huge */
+    if(iy>0x41e00000) { /* if |y| > 2**31 */
+        if(iy>0x43f00000){    /* if |y| > 2**64, must o/uflow */
+        if(ix<=0x3fefffff) return (hy<0)? huge*huge:tiny*tiny;
+        if(ix>=0x3ff00000) return (hy>0)? huge*huge:tiny*tiny;
+        }
+    /* over/underflow if x is not close to one */
+        if(ix<0x3fefffff) return (hy<0)? s*huge*huge:s*tiny*tiny;
+        if(ix>0x3ff00000) return (hy>0)? s*huge*huge:s*tiny*tiny;
+    /* now |1-x| is tiny <= 2**-20, suffice to compute 
+       log(x) by x-x^2/2+x^3/3-x^4/4 */
+        t = ax-one;        /* t has 20 trailing zeros */
+        w = (t*t)*(0.5-t*(0.3333333333333333333333-t*0.25));
+        u = ivln2_h*t;    /* ivln2_h has 21 sig. bits */
+        v = t*ivln2_l-w*ivln2;
+        t1 = u+v;
+        __LO(t1) = 0;
+        t2 = v-(t1-u);
+    } else {
+        double ss,s2,s_h,s_l,t_h,t_l;
+        n = 0;
+    /* take care subnormal number */
+        if(ix<0x00100000)
+        {ax *= two53; n -= 53; ix = __HI(ax); }
+        n  += ((ix)>>20)-0x3ff;
+        j  = ix&0x000fffff;
+    /* determine interval */
+        ix = j|0x3ff00000;        /* normalize ix */
+        if(j<=0x3988E) k=0;        /* |x|<sqrt(3/2) */
+        else if(j<0xBB67A) k=1;    /* |x|<sqrt(3)   */
+        else {k=0;n+=1;ix -= 0x00100000;}
+        __HI(ax) = ix;
+
+    /* compute ss = s_h+s_l = (x-1)/(x+1) or (x-1.5)/(x+1.5) */
+        u = ax-bp[k];        /* bp[0]=1.0, bp[1]=1.5 */
+        v = one/(ax+bp[k]);
+        ss = u*v;
+        s_h = ss;
+        __LO(s_h) = 0;
+    /* t_h=ax+bp[k] High */
+        t_h = zero;
+        __HI(t_h)=((ix>>1)|0x20000000)+0x00080000+(k<<18); 
+        t_l = ax - (t_h-bp[k]);
+        s_l = v*((u-s_h*t_h)-s_h*t_l);
+    /* compute log(ax) */
+        s2 = ss*ss;
+        r = s2*s2*(L1+s2*(L2+s2*(L3+s2*(L4+s2*(L5+s2*L6)))));
+        r += s_l*(s_h+ss);
+        s2  = s_h*s_h;
+        t_h = 3.0+s2+r;
+        __LO(t_h) = 0;
+        t_l = r-((t_h-3.0)-s2);
+    /* u+v = ss*(1+...) */
+        u = s_h*t_h;
+        v = s_l*t_h+t_l*ss;
+    /* 2/(3log2)*(ss+...) */
+        p_h = u+v;
+        __LO(p_h) = 0;
+        p_l = v-(p_h-u);
+        z_h = cp_h*p_h;        /* cp_h+cp_l = 2/(3*log2) */
+        z_l = cp_l*p_h+p_l*cp+dp_l[k];
+    /* log2(ax) = (ss+..)*2/(3*log2) = n + dp_h + z_h + z_l */
+        t = (double)n;
+        t1 = (((z_h+z_l)+dp_h[k])+t);
+        __LO(t1) = 0;
+        t2 = z_l-(((t1-t)-dp_h[k])-z_h);
+    }
+
+    /* split up y into y1+y2 and compute (y1+y2)*(t1+t2) */
+    y1  = y;
+    __LO(y1) = 0;
+    p_l = (y-y1)*t1+y*t2;
+    p_h = y1*t1;
+    z = p_l+p_h;
+    j = __HI(z);
+    i = __LO(z);
+    if (j>=0x40900000) {                /* z >= 1024 */
+        if(((j-0x40900000)|i)!=0)            /* if z > 1024 */
+        return s*huge*huge;            /* overflow */
+        else {
+        if(p_l+ovt>z-p_h) return s*huge*huge;    /* overflow */
+        }
+    } else if((j&0x7fffffff)>=0x4090cc00 ) {    /* z <= -1075 */
+        if(((j-0xc090cc00)|i)!=0)         /* z < -1075 */
+        return s*tiny*tiny;        /* underflow */
+        else {
+        if(p_l<=z-p_h) return s*tiny*tiny;    /* underflow */
+        }
+    }
+    /*
+     * compute 2**(p_h+p_l)
+     */
+    i = j&0x7fffffff;
+    k = (i>>20)-0x3ff;
+    n = 0;
+    if(i>0x3fe00000) {        /* if |z| > 0.5, set n = [z+0.5] */
+        n = j+(0x00100000>>(k+1));
+        k = ((n&0x7fffffff)>>20)-0x3ff;    /* new k for n */
+        t = zero;
+        __HI(t) = (n&~(0x000fffff>>k));
+        n = ((n&0x000fffff)|0x00100000)>>(20-k);
+        if(j<0) n = -n;
+        p_h -= t;
+    } 
+    t = p_l+p_h;
+    __LO(t) = 0;
+    u = t*lg2_h;
+    v = (p_l-(t-p_h))*lg2+t*lg2_l;
+    z = u+v;
+    w = v-(z-u);
+    t  = z*z;
+    t1  = z - t*(P1+t*(P2+t*(P3+t*(P4+t*P5))));
+    r  = (z*t1)/(t1-two)-(w+z*w);
+    z  = one-(r-z);
+    j  = __HI(z);
+    j += (n<<20);
+    if((j>>20)<=0) z = fdlibmScalbn(z,n);    /* subnormal output */
+    else __HI(z) += (n<<20);
+    return s*z;
+}
+
+static ALWAYS_INLINE bool isDenormal(double x)
+{
+    static const uint64_t signbit = 0x8000000000000000ULL;
+    static const uint64_t minNormal = 0x0001000000000000ULL;
+    return (bitwise_cast<uint64_t>(x) & ~signbit) - 1 < minNormal - 1;
+}
+
+static ALWAYS_INLINE bool isEdgeCase(double x)
+{
+    static const uint64_t signbit = 0x8000000000000000ULL;
+    static const uint64_t infinity = 0x7fffffffffffffffULL;
+    return (bitwise_cast<uint64_t>(x) & ~signbit) - 1 >= infinity - 1;
+}
+
+static ALWAYS_INLINE double mathPowInternal(double x, double y)
+{
+    if (!isDenormal(x) && !isDenormal(y)) {
+        double libmResult = pow(x, y);
+        if (libmResult || isEdgeCase(x) || isEdgeCase(y))
+            return libmResult;
+    }
+    return fdlibmPow(x, y);
+}
+
+#else
+
+ALWAYS_INLINE double mathPowInternal(double x, double y)
+{
+    return pow(x, y);
+}
+
+#endif
+
+double JSC_HOST_CALL operationMathPow(double x, double y)
+{
+    if (std::isnan(y))
+        return PNaN;
+    if (std::isinf(y) && fabs(x) == 1)
+        return PNaN;
+    return mathPowInternal(x, y);
+}
+
 void JIT_OPERATION operationPutByIndex(ExecState* exec, EncodedJSValue encodedArrayValue, int32_t index, EncodedJSValue encodedValue)
 {