Refactor muldf3 and mulsf3.

Patch from: GuanHong Liu
Differential Revision: http://reviews.llvm.org/D3886


git-svn-id: https://llvm.org/svn/llvm-project/compiler-rt/trunk@209741 91177308-0d34-0410-b5e6-96231b3b80d8

3 files changed, 122 insertions, 196 deletions

diff --git a/lib/builtins/fp_mul_impl.inc b/lib/builtins/fp_mul_impl.inc
new file mode 100644
index 000000000..ca8a0bb98
--- /dev/null
+++ b/lib/builtins/fp_mul_impl.inc
@@ -0,0 +1,116 @@
+//===---- lib/fp_mul_impl.inc - floating point multiplication -----*- C -*-===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is dual licensed under the MIT and the University of Illinois Open
+// Source Licenses. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// This file implements soft-float multiplication with the IEEE-754 default
+// rounding (to nearest, ties to even).
+//
+//===----------------------------------------------------------------------===//
+
+#include "fp_lib.h"
+
+static inline fp_t __mulXf3__(fp_t a, fp_t b) {
+    const unsigned int aExponent = toRep(a) >> significandBits & maxExponent;
+    const unsigned int bExponent = toRep(b) >> significandBits & maxExponent;
+    const rep_t productSign = (toRep(a) ^ toRep(b)) & signBit;
+
+    rep_t aSignificand = toRep(a) & significandMask;
+    rep_t bSignificand = toRep(b) & significandMask;
+    int scale = 0;
+
+    // Detect if a or b is zero, denormal, infinity, or NaN.
+    if (aExponent-1U >= maxExponent-1U || bExponent-1U >= maxExponent-1U) {
+
+        const rep_t aAbs = toRep(a) & absMask;
+        const rep_t bAbs = toRep(b) & absMask;
+
+        // NaN * anything = qNaN
+        if (aAbs > infRep) return fromRep(toRep(a) | quietBit);
+        // anything * NaN = qNaN
+        if (bAbs > infRep) return fromRep(toRep(b) | quietBit);
+
+        if (aAbs == infRep) {
+            // infinity * non-zero = +/- infinity
+            if (bAbs) return fromRep(aAbs | productSign);
+            // infinity * zero = NaN
+            else return fromRep(qnanRep);
+        }
+
+        if (bAbs == infRep) {
+            //? non-zero * infinity = +/- infinity
+            if (aAbs) return fromRep(bAbs | productSign);
+            // zero * infinity = NaN
+            else return fromRep(qnanRep);
+        }
+
+        // zero * anything = +/- zero
+        if (!aAbs) return fromRep(productSign);
+        // anything * zero = +/- zero
+        if (!bAbs) return fromRep(productSign);
+
+        // one or both of a or b is denormal, the other (if applicable) is a
+        // normal number.  Renormalize one or both of a and b, and set scale to
+        // include the necessary exponent adjustment.
+        if (aAbs < implicitBit) scale += normalize(&aSignificand);
+        if (bAbs < implicitBit) scale += normalize(&bSignificand);
+    }
+
+    // Or in the implicit significand bit.  (If we fell through from the
+    // denormal path it was already set by normalize( ), but setting it twice
+    // won't hurt anything.)
+    aSignificand |= implicitBit;
+    bSignificand |= implicitBit;
+
+    // Get the significand of a*b.  Before multiplying the significands, shift
+    // one of them left to left-align it in the field.  Thus, the product will
+    // have (exponentBits + 2) integral digits, all but two of which must be
+    // zero.  Normalizing this result is just a conditional left-shift by one
+    // and bumping the exponent accordingly.
+    rep_t productHi, productLo;
+    wideMultiply(aSignificand, bSignificand << exponentBits,
+                 &productHi, &productLo);
+
+    int productExponent = aExponent + bExponent - exponentBias + scale;
+
+    // Normalize the significand, adjust exponent if needed.
+    if (productHi & implicitBit) productExponent++;
+    else wideLeftShift(&productHi, &productLo, 1);
+
+    // If we have overflowed the type, return +/- infinity.
+    if (productExponent >= maxExponent) return fromRep(infRep | productSign);
+
+    if (productExponent <= 0) {
+        // Result is denormal before rounding
+        //
+        // If the result is so small that it just underflows to zero, return
+        // a zero of the appropriate sign.  Mathematically there is no need to
+        // handle this case separately, but we make it a special case to
+        // simplify the shift logic.
+        const unsigned int shift = REP_C(1) - (unsigned int)productExponent;
+        if (shift >= typeWidth) return fromRep(productSign);
+
+        // Otherwise, shift the significand of the result so that the round
+        // bit is the high bit of productLo.
+        wideRightShiftWithSticky(&productHi, &productLo, shift);
+    }
+    else {
+        // Result is normal before rounding; insert the exponent.
+        productHi &= significandMask;
+        productHi |= (rep_t)productExponent << significandBits;
+    }
+
+    // Insert the sign of the result:
+    productHi |= productSign;
+
+    // Final rounding.  The final result may overflow to infinity, or underflow
+    // to zero, but those are the correct results in those cases.  We use the
+    // default IEEE-754 round-to-nearest, ties-to-even rounding mode.
+    if (productLo > signBit) productHi++;
+    if (productLo == signBit) productHi += productHi & 1;
+    return fromRep(productHi);
+}
diff --git a/lib/builtins/muldf3.c b/lib/builtins/muldf3.c
index c38edba90..1eb733849 100644
--- a/lib/builtins/muldf3.c
+++ b/lib/builtins/muldf3.c
@@ -13,110 +13,10 @@
 //===----------------------------------------------------------------------===//
 
 #define DOUBLE_PRECISION
-#include "fp_lib.h"
+#include "fp_mul_impl.inc"
 
 ARM_EABI_FNALIAS(dmul, muldf3)
 
-COMPILER_RT_ABI fp_t
-__muldf3(fp_t a, fp_t b) {
-    
-    const unsigned int aExponent = toRep(a) >> significandBits & maxExponent;
-    const unsigned int bExponent = toRep(b) >> significandBits & maxExponent;
-    const rep_t productSign = (toRep(a) ^ toRep(b)) & signBit;
-    
-    rep_t aSignificand = toRep(a) & significandMask;
-    rep_t bSignificand = toRep(b) & significandMask;
-    int scale = 0;
-    
-    // Detect if a or b is zero, denormal, infinity, or NaN.
-    if (aExponent-1U >= maxExponent-1U || bExponent-1U >= maxExponent-1U) {
-        
-        const rep_t aAbs = toRep(a) & absMask;
-        const rep_t bAbs = toRep(b) & absMask;
-        
-        // NaN * anything = qNaN
-        if (aAbs > infRep) return fromRep(toRep(a) | quietBit);
-        // anything * NaN = qNaN
-        if (bAbs > infRep) return fromRep(toRep(b) | quietBit);
-        
-        if (aAbs == infRep) {
-            // infinity * non-zero = +/- infinity
-            if (bAbs) return fromRep(aAbs | productSign);
-            // infinity * zero = NaN
-            else return fromRep(qnanRep);
-        }
-        
-        if (bAbs == infRep) {
-            // non-zero * infinity = +/- infinity
-            if (aAbs) return fromRep(bAbs | productSign);
-            // zero * infinity = NaN
-            else return fromRep(qnanRep);
-        }
-        
-        // zero * anything = +/- zero
-        if (!aAbs) return fromRep(productSign);
-        // anything * zero = +/- zero
-        if (!bAbs) return fromRep(productSign);
-        
-        // one or both of a or b is denormal, the other (if applicable) is a
-        // normal number.  Renormalize one or both of a and b, and set scale to
-        // include the necessary exponent adjustment.
-        if (aAbs < implicitBit) scale += normalize(&aSignificand);
-        if (bAbs < implicitBit) scale += normalize(&bSignificand);
-    }
-    
-    // Or in the implicit significand bit.  (If we fell through from the
-    // denormal path it was already set by normalize( ), but setting it twice
-    // won't hurt anything.)
-    aSignificand |= implicitBit;
-    bSignificand |= implicitBit;
-    
-    // Get the significand of a*b.  Before multiplying the significands, shift
-    // one of them left to left-align it in the field.  Thus, the product will
-    // have (exponentBits + 2) integral digits, all but two of which must be
-    // zero.  Normalizing this result is just a conditional left-shift by one
-    // and bumping the exponent accordingly.
-    rep_t productHi, productLo;
-    wideMultiply(aSignificand, bSignificand << exponentBits,
-                 &productHi, &productLo);
-    
-    int productExponent = aExponent + bExponent - exponentBias + scale;
-    
-    // Normalize the significand, adjust exponent if needed.
-    if (productHi & implicitBit) productExponent++;
-    else wideLeftShift(&productHi, &productLo, 1);
-    
-    // If we have overflowed the type, return +/- infinity.
-    if (productExponent >= maxExponent) return fromRep(infRep | productSign);
-    
-    if (productExponent <= 0) {
-        // Result is denormal before rounding
-        //
-        // If the result is so small that it just underflows to zero, return
-        // a zero of the appropriate sign.  Mathematically there is no need to
-        // handle this case separately, but we make it a special case to
-        // simplify the shift logic.
-        const unsigned int shift = 1U - (unsigned int)productExponent;
-        if (shift >= typeWidth) return fromRep(productSign);
-        
-        // Otherwise, shift the significand of the result so that the round
-        // bit is the high bit of productLo.
-        wideRightShiftWithSticky(&productHi, &productLo, shift);
-    }
-    
-    else {
-        // Result is normal before rounding; insert the exponent.
-        productHi &= significandMask;
-        productHi |= (rep_t)productExponent << significandBits;
-    }
-    
-    // Insert the sign of the result:
-    productHi |= productSign;
-    
-    // Final rounding.  The final result may overflow to infinity, or underflow
-    // to zero, but those are the correct results in those cases.  We use the
-    // default IEEE-754 round-to-nearest, ties-to-even rounding mode.
-    if (productLo > signBit) productHi++;
-    if (productLo == signBit) productHi += productHi & 1;
-    return fromRep(productHi);
+COMPILER_RT_ABI fp_t __muldf3(fp_t a, fp_t b) {
+    return __mulXf3__(a, b);
 }
diff --git a/lib/builtins/mulsf3.c b/lib/builtins/mulsf3.c
index 861a9ba5f..478b3bc0e 100644
--- a/lib/builtins/mulsf3.c
+++ b/lib/builtins/mulsf3.c
@@ -13,100 +13,10 @@
 //===----------------------------------------------------------------------===//
 
 #define SINGLE_PRECISION
-#include "fp_lib.h"
+#include "fp_mul_impl.inc"
 
 ARM_EABI_FNALIAS(fmul, mulsf3)
 
-COMPILER_RT_ABI fp_t
-__mulsf3(fp_t a, fp_t b) {
-    
-    const unsigned int aExponent = toRep(a) >> significandBits & maxExponent;
-    const unsigned int bExponent = toRep(b) >> significandBits & maxExponent;
-    const rep_t productSign = (toRep(a) ^ toRep(b)) & signBit;
-    
-    rep_t aSignificand = toRep(a) & significandMask;
-    rep_t bSignificand = toRep(b) & significandMask;
-    int scale = 0;
-    
-    // Detect if a or b is zero, denormal, infinity, or NaN.
-    if (aExponent-1U >= maxExponent-1U || bExponent-1U >= maxExponent-1U) {
-        
-        const rep_t aAbs = toRep(a) & absMask;
-        const rep_t bAbs = toRep(b) & absMask;
-        
-        // NaN * anything = qNaN
-        if (aAbs > infRep) return fromRep(toRep(a) | quietBit);
-        // anything * NaN = qNaN
-        if (bAbs > infRep) return fromRep(toRep(b) | quietBit);
-        
-        if (aAbs == infRep) {
-            // infinity * non-zero = +/- infinity
-            if (bAbs) return fromRep(aAbs | productSign);
-            // infinity * zero = NaN
-            else return fromRep(qnanRep);
-        }
-        
-        if (bAbs == infRep) {
-            // non-zero * infinity = +/- infinity
-            if (aAbs) return fromRep(bAbs | productSign);
-            // zero * infinity = NaN
-            else return fromRep(qnanRep);
-        }
-        
-        // zero * anything = +/- zero
-        if (!aAbs) return fromRep(productSign);
-        // anything * zero = +/- zero
-        if (!bAbs) return fromRep(productSign);
-        
-        // one or both of a or b is denormal, the other (if applicable) is a
-        // normal number.  Renormalize one or both of a and b, and set scale to
-        // include the necessary exponent adjustment.
-        if (aAbs < implicitBit) scale += normalize(&aSignificand);
-        if (bAbs < implicitBit) scale += normalize(&bSignificand);
-    }
-    
-    // Or in the implicit significand bit.  (If we fell through from the
-    // denormal path it was already set by normalize( ), but setting it twice
-    // won't hurt anything.)
-    aSignificand |= implicitBit;
-    bSignificand |= implicitBit;
-    
-    // Get the significand of a*b.  Before multiplying the significands, shift
-    // one of them left to left-align it in the field.  Thus, the product will
-    // have (exponentBits + 2) integral digits, all but two of which must be
-    // zero.  Normalizing this result is just a conditional left-shift by one
-    // and bumping the exponent accordingly.
-    rep_t productHi, productLo;
-    wideMultiply(aSignificand, bSignificand << exponentBits,
-                 &productHi, &productLo);
-    
-    int productExponent = aExponent + bExponent - exponentBias + scale;
-    
-    // Normalize the significand, adjust exponent if needed.
-    if (productHi & implicitBit) productExponent++;
-    else wideLeftShift(&productHi, &productLo, 1);
-    
-    // If we have overflowed the type, return +/- infinity.
-    if (productExponent >= maxExponent) return fromRep(infRep | productSign);
-    
-    if (productExponent <= 0) {
-        // Result is denormal before rounding, the exponent is zero and we
-        // need to shift the significand.
-        wideRightShiftWithSticky(&productHi, &productLo, 1U - (unsigned)productExponent);
-    }
-    
-    else {
-        // Result is normal before rounding; insert the exponent.
-        productHi &= significandMask;
-        productHi |= (rep_t)productExponent << significandBits;
-    }
-    
-    // Insert the sign of the result:
-    productHi |= productSign;
-    
-    // Final rounding.  The final result may overflow to infinity, or underflow
-    // to zero, but those are the correct results in those cases.
-    if (productLo > signBit) productHi++;
-    if (productLo == signBit) productHi += productHi & 1;
-    return fromRep(productHi);
+COMPILER_RT_ABI fp_t __mulsf3(fp_t a, fp_t b) {
+    return __mulXf3__(a, b);
 }