Add another FP recoding test case

1 files changed, 20 insertions, 6 deletions

diff --git a/isa/rv64uf/recoding.S b/isa/rv64uf/recoding.S
index dee7f6d..6397143 100644
--- a/isa/rv64uf/recoding.S
+++ b/isa/rv64uf/recoding.S
@@ -5,6 +5,9 @@
 #-----------------------------------------------------------------------------
 #
 # Test corner cases of John Hauser's microarchitectural recoding scheme.
+# There are twice as many recoded values as IEEE-754 values; some of these
+# extras are redundant (e.g. Inf) and others are illegal (subnormals with
+# too many bits set).
 #
 
 #include "riscv_test.h"
@@ -13,15 +16,23 @@
 RVTEST_RV64UF
 RVTEST_CODE_BEGIN
 
-  # Infinity has a redundant internal form in Rocket.
-  # Make sure two different internal infinities compare as equal.
-  li TESTNUM, 8
+  # Make sure infinities with different mantissas compare as equal.
   flw f0, minf, a0
   flw f1, three, a0
   fmul.s f1, f1, f0
-  TEST_CASE( 8, a0, 1, feq.s a0, f0, f1)
-  TEST_CASE( 9, a0, 1, fle.s a0, f0, f1)
-  TEST_CASE(10, a0, 0, flt.s a0, f0, f1)
+  TEST_CASE( 2, a0, 1, feq.s a0, f0, f1)
+  TEST_CASE( 3, a0, 1, fle.s a0, f0, f1)
+  TEST_CASE( 4, a0, 0, flt.s a0, f0, f1)
+
+  # When converting small doubles to single-precision subnormals,
+  # ensure that the extra precision is discarded.
+  flw f0, big, a0
+  fld f1, tiny, a0
+  fcvt.s.d f1, f1
+  fmul.s f0, f0, f1
+  fmv.x.s a0, f0
+  lw a1, small
+  TEST_CASE(10, a0, 0, sub a0, a0, a1)
 
   TEST_PASSFAIL
 
@@ -32,5 +43,8 @@ RVTEST_DATA_BEGIN
 
 minf: .float -Inf
 three: .float 3.0
+big: .float 1221
+small: .float 2.9133121e-37
+tiny: .double 2.3860049081905093e-40
 
 RVTEST_DATA_END