vendor/compiler-rt/compiler-rt-r224034

1 files changed, 76 insertions, 0 deletions

diff --git a/lib/builtins/ppc/gcc_qadd.c b/lib/builtins/ppc/gcc_qadd.c
new file mode 100644
index 000000000000..32e16e9d1d11
--- /dev/null
+++ b/lib/builtins/ppc/gcc_qadd.c
@@ -0,0 +1,76 @@
+/* This file is distributed under the University of Illinois Open Source
+ *  License. See LICENSE.TXT for details.
+ */
+
+/* long double __gcc_qadd(long double x, long double y);
+ * This file implements the PowerPC 128-bit double-double add operation.
+ * This implementation is shamelessly cribbed from Apple's DDRT, circa 1993(!)
+ */
+
+#include "DD.h"
+
+long double __gcc_qadd(long double x, long double y)
+{
+	static const uint32_t infinityHi = UINT32_C(0x7ff00000);
+	
+	DD dst = { .ld = x }, src = { .ld = y };
+	
+	register double A = dst.s.hi, a = dst.s.lo,
+					B = src.s.hi, b = src.s.lo;
+	
+	/* If both operands are zero: */
+	if ((A == 0.0) && (B == 0.0)) {
+		dst.s.hi = A + B;
+		dst.s.lo = 0.0;
+		return dst.ld;
+	}
+	
+	/* If either operand is NaN or infinity: */
+	const doublebits abits = { .d = A };
+	const doublebits bbits = { .d = B };
+	if ((((uint32_t)(abits.x >> 32) & infinityHi) == infinityHi) ||
+		(((uint32_t)(bbits.x >> 32) & infinityHi) == infinityHi)) {
+		dst.s.hi = A + B;
+		dst.s.lo = 0.0;
+		return dst.ld;
+	}
+	
+	/* If the computation overflows: */
+	/* This may be playing things a little bit fast and loose, but it will do for a start. */
+	const double testForOverflow = A + (B + (a + b));
+	const doublebits testbits = { .d = testForOverflow };
+	if (((uint32_t)(testbits.x >> 32) & infinityHi) == infinityHi) {
+		dst.s.hi = testForOverflow;
+		dst.s.lo = 0.0;
+		return dst.ld;
+	}
+	
+	double H, h;
+	double T, t;
+	double W, w;
+	double Y;
+	
+	H = B + (A - (A + B));
+	T = b + (a - (a + b));
+	h = A + (B - (A + B));
+	t = a + (b - (a + b));
+	
+	if (local_fabs(A) <= local_fabs(B))
+		w = (a + b) + h;
+	else
+		w = (a + b) + H;
+	
+	W = (A + B) + w;
+	Y = (A + B) - W;
+	Y += w;
+	
+	if (local_fabs(a) <= local_fabs(b))
+		w = t + Y;
+	else
+		w = T + Y;
+	
+	dst.s.hi = Y = W + w;
+	dst.s.lo = (W - Y) + w;
+	
+	return dst.ld;
+}