Refactor extendsfdf2.

Patch by: GuanHong Liu
Differential Revision: http://reviews.llvm.org/D3887


git-svn-id: https://llvm.org/svn/llvm-project/compiler-rt/trunk@209781 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 5 insertions, 124 deletions

diff --git a/lib/builtins/extendsfdf2.c b/lib/builtins/extendsfdf2.c
index 9e4c77b49..7a267c2f4 100644
--- a/lib/builtins/extendsfdf2.c
+++ b/lib/builtins/extendsfdf2.c
@@ -7,132 +7,13 @@
 //
 //===----------------------------------------------------------------------===//
 //
-// This file implements a fairly generic conversion from a narrower to a wider
-// IEEE-754 floating-point type.  The constants and types defined following the
-// includes below parameterize the conversion.
-//
-// This routine can be trivially adapted to support conversions from 
-// half-precision or to quad-precision. It does not support types that don't
-// use the usual IEEE-754 interchange formats; specifically, some work would be
-// needed to adapt it to (for example) the Intel 80-bit format or PowerPC
-// double-double format.
-//
-// Note please, however, that this implementation is only intended to support
-// *widening* operations; if you need to convert to a *narrower* floating-point
-// type (e.g. double -> float), then this routine will not do what you want it
-// to.
-//
-// It also requires that integer types at least as large as both formats
-// are available on the target platform; this may pose a problem when trying
-// to add support for quad on some 32-bit systems, for example.  You also may
-// run into trouble finding an appropriate CLZ function for wide source types;
-// you will likely need to roll your own on some platforms.
-//
-// Finally, the following assumptions are made:
-//
-// 1. floating-point types and integer types have the same endianness on the
-//    target platform
-//
-// 2. quiet NaNs, if supported, are indicated by the leading bit of the
-//    significand field being set
-//
-//===----------------------------------------------------------------------===//
-
-#include "int_lib.h"
 
-typedef float src_t;
-typedef uint32_t src_rep_t;
-#define SRC_REP_C UINT32_C
-static const int srcSigBits = 23;
-#define src_rep_t_clz __builtin_clz
-
-typedef double dst_t;
-typedef uint64_t dst_rep_t;
-#define DST_REP_C UINT64_C
-static const int dstSigBits = 52;
-
-// End of specialization parameters.  Two helper routines for conversion to and
-// from the representation of floating-point data as integer values follow.
-
-static inline src_rep_t srcToRep(src_t x) {
-    const union { src_t f; src_rep_t i; } rep = {.f = x};
-    return rep.i;
-}
-
-static inline dst_t dstFromRep(dst_rep_t x) {
-    const union { dst_t f; dst_rep_t i; } rep = {.i = x};
-    return rep.f;
-}
-
-// End helper routines.  Conversion implementation follows.
+#define SRC_SINGLE
+#define DST_DOUBLE
+#include "fp_extend_impl.inc"
 
 ARM_EABI_FNALIAS(f2d, extendsfdf2)
 
-COMPILER_RT_ABI dst_t
-__extendsfdf2(src_t a) {
-    
-    // Various constants whose values follow from the type parameters.
-    // Any reasonable optimizer will fold and propagate all of these.
-    const int srcBits = sizeof(src_t)*CHAR_BIT;
-    const int srcExpBits = srcBits - srcSigBits - 1;
-    const int srcInfExp = (1 << srcExpBits) - 1;
-    const int srcExpBias = srcInfExp >> 1;
-    
-    const src_rep_t srcMinNormal = SRC_REP_C(1) << srcSigBits;
-    const src_rep_t srcInfinity = (src_rep_t)srcInfExp << srcSigBits;
-    const src_rep_t srcSignMask = SRC_REP_C(1) << (srcSigBits + srcExpBits);
-    const src_rep_t srcAbsMask = srcSignMask - 1;
-    const src_rep_t srcQNaN = SRC_REP_C(1) << (srcSigBits - 1);
-    const src_rep_t srcNaNCode = srcQNaN - 1;
-    
-    const int dstBits = sizeof(dst_t)*CHAR_BIT;
-    const int dstExpBits = dstBits - dstSigBits - 1;
-    const int dstInfExp = (1 << dstExpBits) - 1;
-    const int dstExpBias = dstInfExp >> 1;
-    
-    const dst_rep_t dstMinNormal = DST_REP_C(1) << dstSigBits;
-    
-    // Break a into a sign and representation of the absolute value
-    const src_rep_t aRep = srcToRep(a);
-    const src_rep_t aAbs = aRep & srcAbsMask;
-    const src_rep_t sign = aRep & srcSignMask;
-    dst_rep_t absResult;
-    
-    if (aAbs - srcMinNormal < srcInfinity - srcMinNormal) {
-        // a is a normal number.
-        // Extend to the destination type by shifting the significand and
-        // exponent into the proper position and rebiasing the exponent.
-        absResult = (dst_rep_t)aAbs << (dstSigBits - srcSigBits);
-        absResult += (dst_rep_t)(dstExpBias - srcExpBias) << dstSigBits;
-    }
-    
-    else if (aAbs >= srcInfinity) {
-        // a is NaN or infinity.
-        // Conjure the result by beginning with infinity, then setting the qNaN
-        // bit (if needed) and right-aligning the rest of the trailing NaN
-        // payload field.
-        absResult = (dst_rep_t)dstInfExp << dstSigBits;
-        absResult |= (dst_rep_t)(aAbs & srcQNaN) << (dstSigBits - srcSigBits);
-        absResult |= aAbs & srcNaNCode;
-    }
-    
-    else if (aAbs) {
-        // a is denormal.
-        // renormalize the significand and clear the leading bit, then insert
-        // the correct adjusted exponent in the destination type.
-        const int scale = src_rep_t_clz(aAbs) - src_rep_t_clz(srcMinNormal);
-        absResult = (dst_rep_t)aAbs << (dstSigBits - srcSigBits + scale);
-        absResult ^= dstMinNormal;
-        const int resultExponent = dstExpBias - srcExpBias - scale + 1;
-        absResult |= (dst_rep_t)resultExponent << dstSigBits;
-    }
-
-    else {
-        // a is zero.
-        absResult = 0;
-    }
-    
-    // Apply the signbit to (dst_t)abs(a).
-    const dst_rep_t result = absResult | (dst_rep_t)sign << (dstBits - srcBits);
-    return dstFromRep(result);
+COMPILER_RT_ABI double __extendsfdf2(float a) {
+    return __extendXfYf2__(a);
 }