X-Git-Url: http://nsz.repo.hu/git/?a=blobdiff_plain;ds=sidebyside;f=src%2Fmath%2Ffma.c;h=02f5c865519d7c0e251b66242ad9930c930aec2e;hb=6a25313c1122629b43b990ada70af1c209f03a54;hp=1b1c13217698767125dd6814ea307b240dbb7af6;hpb=34660d73bd0db29469d2758e1b48d2360edf3a2f;p=musl

diff --git a/src/math/fma.c b/src/math/fma.c
index 1b1c1321..02f5c865 100644
--- a/src/math/fma.c
+++ b/src/math/fma.c
@@ -232,16 +232,16 @@ static inline struct dd dd_add(double a, double b)
 static inline double add_adjusted(double a, double b)
 {
 	struct dd sum;
-	uint64_t hibits, lobits;
+	union {double f; uint64_t i;} uhi, ulo;
 
 	sum = dd_add(a, b);
 	if (sum.lo != 0) {
-		EXTRACT_WORD64(hibits, sum.hi);
-		if ((hibits & 1) == 0) {
+		uhi.f = sum.hi;
+		if ((uhi.i & 1) == 0) {
 			/* hibits += (int)copysign(1.0, sum.hi * sum.lo) */
-			EXTRACT_WORD64(lobits, sum.lo);
-			hibits += 1 - ((hibits ^ lobits) >> 62);
-			INSERT_WORD64(sum.hi, hibits);
+			ulo.f = sum.lo;
+			uhi.i += 1 - ((uhi.i ^ ulo.i) >> 62);
+			sum.hi = uhi.f;
 		}
 	}
 	return (sum.hi);
@@ -255,7 +255,7 @@ static inline double add_adjusted(double a, double b)
 static inline double add_and_denormalize(double a, double b, int scale)
 {
 	struct dd sum;
-	uint64_t hibits, lobits;
+	union {double f; uint64_t i;} uhi, ulo;
 	int bits_lost;
 
 	sum = dd_add(a, b);
@@ -271,13 +271,13 @@ static inline double add_and_denormalize(double a, double b, int scale)
 	 * break the ties manually.
 	 */
 	if (sum.lo != 0) {
-		EXTRACT_WORD64(hibits, sum.hi);
-		bits_lost = -((int)(hibits >> 52) & 0x7ff) - scale + 1;
-		if (bits_lost != 1 ^ (int)(hibits & 1)) {
+		uhi.f = sum.hi;
+		bits_lost = -((int)(uhi.i >> 52) & 0x7ff) - scale + 1;
+		if (bits_lost != 1 ^ (int)(uhi.i & 1)) {
 			/* hibits += (int)copysign(1.0, sum.hi * sum.lo) */
-			EXTRACT_WORD64(lobits, sum.lo);
-			hibits += 1 - (((hibits ^ lobits) >> 62) & 2);
-			INSERT_WORD64(sum.hi, hibits);
+			ulo.f = sum.lo;
+			uhi.i += 1 - (((uhi.i ^ ulo.i) >> 62) & 2);
+			sum.hi = uhi.f;
 		}
 	}
 	return scalbn(sum.hi, scale);
@@ -431,12 +431,24 @@ double fma(double x, double y, double z)
 		/*
 		 * There is no need to worry about double rounding in directed
 		 * rounding modes.
-		 * TODO: underflow is not raised properly, example in downward rounding:
+		 * But underflow may not be raised properly, example in downward rounding:
 		 * fma(0x1.000000001p-1000, 0x1.000000001p-30, -0x1p-1066)
 		 */
+		double ret;
+#if defined(FE_INEXACT) && defined(FE_UNDERFLOW)
+		int e = fetestexcept(FE_INEXACT);
+		feclearexcept(FE_INEXACT);
+#endif
 		fesetround(oround);
 		adj = r.lo + xy.lo;
-		return scalbn(r.hi + adj, spread);
+		ret = scalbn(r.hi + adj, spread);
+#if defined(FE_INEXACT) && defined(FE_UNDERFLOW)
+		if (ilogb(ret) < -1022 && fetestexcept(FE_INEXACT))
+			feraiseexcept(FE_UNDERFLOW);
+		else if (e)
+			feraiseexcept(FE_INEXACT);
+#endif
+		return ret;
 	}
 
 	adj = add_adjusted(r.lo, xy.lo);