commit be53fa785ab766d2722628403edee75b3e6ab599
author Joseph Myers <joseph@codesourcery.com> Mon May 04 23:39:39 2020 +0000
committer Richard Henderson <richard.henderson@linaro.org> Fri May 15 11:04:50 2020 -0700
tree 17bd6e1126e4ce4005f5f70b005f25d6092d1a7c
parent 41602807766e253ccb6fb761f3ff12767f786e2c

softfloat: fix floatx80 pseudo-denormal comparisons

The softfloat floatx80 comparisons fail to allow for pseudo-denormals,
which should compare equal to corresponding values with biased
exponent 1 rather than 0.  Add an adjustment for that case when
comparing numbers with the same sign.

Signed-off-by: Joseph Myers <joseph@codesourcery.com>
Message-Id: <alpine.DEB.2.21.2005042338470.22972@digraph.polyomino.org.uk>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>

fpu/softfloat.c

diff --git a/fpu/softfloat.c b/fpu/softfloat.c
index 6094d26..c57f72e 100644
--- a/fpu/softfloat.c
+++ b/fpu/softfloat.c
@@ -7966,6 +7966,13 @@
             return 1 - (2 * aSign);
         }
     } else {
+        /* Normalize pseudo-denormals before comparison.  */
+        if ((a.high & 0x7fff) == 0 && a.low & UINT64_C(0x8000000000000000)) {
+            ++a.high;
+        }
+        if ((b.high & 0x7fff) == 0 && b.low & UINT64_C(0x8000000000000000)) {
+            ++b.high;
+        }
         if (a.low == b.low && a.high == b.high) {
             return float_relation_equal;
         } else {

tests/tcg/i386/test-i386-pseudo-denormal.c

diff --git a/tests/tcg/i386/test-i386-pseudo-denormal.c b/tests/tcg/i386/test-i386-pseudo-denormal.c
index cfa2a50..acf2b9c 100644
--- a/tests/tcg/i386/test-i386-pseudo-denormal.c
+++ b/tests/tcg/i386/test-i386-pseudo-denormal.c
@@ -20,5 +20,9 @@
         printf("FAIL: pseudo-denormal add\n");
         ret = 1;
     }
+    if (ld_pseudo_m16382.ld != 0x1p-16382L) {
+        printf("FAIL: pseudo-denormal compare\n");
+        ret = 1;
+    }
     return ret;
 }