From: Jakub Jelinek <jakub@redhat.com>
Date: Wed, 11 Mar 2020 08:33:52 +0000 (+0100)
Subject: dfp: Fix decimal_to_binary [PR94111]
X-Git-Url: https://git.libre-soc.org/?a=commitdiff_plain;h=312992f5a07ca25f94d538b08401789c2c764293;p=gcc.git

dfp: Fix decimal_to_binary [PR94111]

As e.g. decimal_from_decnumber shows, the REAL_VALUE_TYPE representation
contains a decimal128 embedded in ->sig only if it is rvc_normal, for
other kinds like rvc_inf or rvc_nan, ->sig is ignored and everything is
contained in the REAL_VALUE_TYPE flags (cl, sign, signalling and decimal).
decimal_to_binary which is used when folding a decimal{32,64,128} constant
to a binary floating point type ignores this and thus folds infinities and
NaNs into +0.0.
The following patch fixes that by only doing that for rvc_normal.
Similarly to the binary to decimal folding, it goes through a string, in
order to e.g. deal with canonical NaN mantissas, or binary float formats
that don't support infinities and/or NaNs.

2020-03-11  Jakub Jelinek  <jakub@redhat.com>

	PR middle-end/94111
	* dfp.c (decimal_to_binary): Only use decimal128ToString if from->cl
	is rvc_normal, otherwise use real_to_decimal to print the number to
	string.

	* gcc.dg/dfp/pr94111.c: New test.
---

diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index 6630a20a625..b2d8ee1c830 100644
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,5 +1,10 @@
 2020-03-11  Jakub Jelinek  <jakub@redhat.com>
 
+	PR middle-end/94111
+	* dfp.c (decimal_to_binary): Only use decimal128ToString if from->cl
+	is rvc_normal, otherwise use real_to_decimal to print the number to
+	string.
+
 	PR tree-optimization/94114
 	* tree-loop-distribution.c (generate_memset_builtin): Call
 	rewrite_to_non_trapping_overflow even on mem.
diff --git a/gcc/dfp.c b/gcc/dfp.c
index 688fab490e7..fef39a5ce39 100644
--- a/gcc/dfp.c
+++ b/gcc/dfp.c
@@ -342,9 +342,13 @@ decimal_to_binary (REAL_VALUE_TYPE *to, const REAL_VALUE_TYPE *from,
 		   const real_format *fmt)
 {
   char string[256];
-  const decimal128 *const d128 = (const decimal128 *) from->sig;
-
-  decimal128ToString (d128, string);
+  if (from->cl == rvc_normal)
+    {
+      const decimal128 *const d128 = (const decimal128 *) from->sig;
+      decimal128ToString (d128, string);
+    }
+  else
+    real_to_decimal (string, from, sizeof (string), 0, 1);
   real_from_string3 (to, string, fmt);
 }
 
diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog
index 954c4511816..3a4acce6746 100644
--- a/gcc/testsuite/ChangeLog
+++ b/gcc/testsuite/ChangeLog
@@ -1,5 +1,8 @@
 2020-03-11  Jakub Jelinek  <jakub@redhat.com>
 
+	PR middle-end/94111
+	* gcc.dg/dfp/pr94111.c: New test.
+
 	PR tree-optimization/94114
 	* gcc.dg/pr94114.c: New test.
 
diff --git a/gcc/testsuite/gcc.dg/dfp/pr94111.c b/gcc/testsuite/gcc.dg/dfp/pr94111.c
new file mode 100644
index 00000000000..ea3a132270a
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/dfp/pr94111.c
@@ -0,0 +1,12 @@
+/* PR middle-end/94111 */
+/* { dg-do run } */
+/* { dg-options "-O2" } */
+
+int
+main ()
+{
+  _Decimal32 d = (_Decimal32) __builtin_inff ();
+  if (!__builtin_isinf ((double) d))
+    __builtin_abort ();
+  return 0;
+}