From 3e9325f1e99fc737093a178ea88b9fd21ebb1325 Mon Sep 17 00:00:00 2001
From: Aleksandar Markovic <aleksandar.markovic@imgtec.com>
Date: Sat, 24 Feb 2018 20:40:07 -0500
Subject: [PATCH] softfloat: Handle snan_bit_is_one == 0 in MIPS
 pickNaNMulAdd()

Only for Mips platform, and only for cases when snan_bit_is_one is 0,
correct the order of argument comparisons in pickNaNMulAdd().

For more info, see [1], page 53, section "3.5.3 NaN Propagation".

[1] "MIPS Architecture for Programmers Volume IV-j:
The MIPS32 SIMD Architecture Module",
Imagination Technologies LTD, Revision 1.12, February 3, 2016

Backports commit c27644f0e9659471e1c9355da5b667960d311937 from qemu
---
 qemu/fpu/softfloat-specialize.h | 41 +++++++++++++++++++++++----------
 1 file changed, 29 insertions(+), 12 deletions(-)

diff --git a/qemu/fpu/softfloat-specialize.h b/qemu/fpu/softfloat-specialize.h
index 3e3a4d98..570af1e2 100644
--- a/qemu/fpu/softfloat-specialize.h
+++ b/qemu/fpu/softfloat-specialize.h
@@ -569,19 +569,36 @@ static int pickNaNMulAdd(flag aIsQNaN, flag aIsSNaN, flag bIsQNaN, flag bIsSNaN,
         return 3;
     }
 
-    /* Prefer sNaN over qNaN, in the a, b, c order. */
-    if (aIsSNaN) {
-        return 0;
-    } else if (bIsSNaN) {
-        return 1;
-    } else if (cIsSNaN) {
-        return 2;
-    } else if (aIsQNaN) {
-        return 0;
-    } else if (bIsQNaN) {
-        return 1;
+    if (status->snan_bit_is_one) {
+        /* Prefer sNaN over qNaN, in the a, b, c order. */
+        if (aIsSNaN) {
+            return 0;
+        } else if (bIsSNaN) {
+            return 1;
+        } else if (cIsSNaN) {
+            return 2;
+        } else if (aIsQNaN) {
+            return 0;
+        } else if (bIsQNaN) {
+            return 1;
+        } else {
+            return 2;
+        }
     } else {
-        return 2;
+        /* Prefer sNaN over qNaN, in the c, a, b order. */
+        if (cIsSNaN) {
+            return 2;
+        } else if (aIsSNaN) {
+            return 0;
+        } else if (bIsSNaN) {
+            return 1;
+        } else if (cIsQNaN) {
+            return 2;
+        } else if (aIsQNaN) {
+            return 0;
+        } else {
+            return 1;
+        }
     }
 }
 #elif defined(TARGET_PPC)