From 35bb3f3a8d608f92a1bfffc27a04b6bb178c33ae Mon Sep 17 00:00:00 2001
From: Rowan Goemans <goemansrowan@gmail.com>
Date: Wed, 18 Sep 2024 00:33:33 +0200
Subject: [PATCH] timing: Add safe zero check function for delay_t

---
 common/kernel/nextpnr_types.h | 10 ++++++++++
 common/kernel/timing.cc       |  4 ++--
 2 files changed, 12 insertions(+), 2 deletions(-)

diff --git a/common/kernel/nextpnr_types.h b/common/kernel/nextpnr_types.h
index c806c186..095329c7 100644
--- a/common/kernel/nextpnr_types.h
+++ b/common/kernel/nextpnr_types.h
@@ -78,6 +78,16 @@ struct PortRef
     IdString port;
 };
 
+// Zero checking which works regardless if delay_t is floating or integer
+inline bool is_zero_delay(delay_t delay)
+{
+    if constexpr (std::is_floating_point<delay_t>::value) {
+        return std::fpclassify(delay) == FP_ZERO;
+    } else {
+        return delay == 0;
+    }
+}
+
 // minimum and maximum delay
 struct DelayPair
 {
diff --git a/common/kernel/timing.cc b/common/kernel/timing.cc
index 7504ead2..ce4ef9a0 100644
--- a/common/kernel/timing.cc
+++ b/common/kernel/timing.cc
@@ -985,7 +985,7 @@ CriticalPath TimingAnalyser::build_critical_path_report(domain_id_t domain_pair,
 
     if (related_clock) {
         delay_t clock_delay = clock_delays.at(clock_pair);
-        if (clock_delay != 0) {
+        if (!is_zero_delay(clock_delay)) {
             CriticalPath::Segment seg_c2c;
             seg_c2c.type = CriticalPath::Segment::Type::CLK_TO_CLK;
             seg_c2c.delay = DelayPair(clock_delay);
@@ -1005,7 +1005,7 @@ CriticalPath TimingAnalyser::build_critical_path_report(domain_id_t domain_pair,
 
         delay_t clock_skew = clock_delay_launch - clock_delay_capture;
 
-        if (clock_skew != 0) {
+        if (!is_zero_delay(clock_skew)) {
             CriticalPath::Segment seg_skew;
             seg_skew.type = CriticalPath::Segment::Type::CLK_SKEW;
             seg_skew.delay = DelayPair(clock_skew);