[libc-commits] [libc] [libc] Workaround for gcc complaining about implicit conversions with the ternary ?: operator. (PR #124820)

[via libc-commits]

https://github.com/lntue updated https://github.com/llvm/llvm-project/pull/124820

>From c433cfc88ee09d1101b283d341f88f0ac50e9890 Mon Sep 17 00:00:00 2001
From: Tue Ly <lntue.h at gmail.com>
Date: Tue, 28 Jan 2025 18:52:08 +0000
Subject: [PATCH 1/2] [libc] Workaround for gcc complaining about implicit
 conversions with the ternary ?: operator.

---
 libc/src/__support/FPUtil/except_value_utils.h | 12 ++++++++----
 1 file changed, 8 insertions(+), 4 deletions(-)

diff --git a/libc/src/__support/FPUtil/except_value_utils.h b/libc/src/__support/FPUtil/except_value_utils.h
index f8e4e92d3e1fb3..2e58bf2b287fdf 100644
--- a/libc/src/__support/FPUtil/except_value_utils.h
+++ b/libc/src/__support/FPUtil/except_value_utils.h
@@ -81,12 +81,16 @@ template <typename T, size_t N> struct ExceptValues {
         StorageType out_bits = values[i].rnd_towardzero_result;
         switch (fputil::quick_get_round()) {
         case FE_UPWARD:
-          out_bits += sign ? values[i].rnd_downward_offset
-                           : values[i].rnd_upward_offset;
+          if (sign)
+            out_bits += values[i].rnd_downward_offset;
+          else
+            out_bits += values[i].rnd_upward_offset;
           break;
         case FE_DOWNWARD:
-          out_bits += sign ? values[i].rnd_upward_offset
-                           : values[i].rnd_downward_offset;
+          if (sign)
+            out_bits += values[i].rnd_upward_offset;
+          else
+            out_bits += values[i].rnd_downward_offset;
           break;
         case FE_TONEAREST:
           out_bits += values[i].rnd_tonearest_offset;

>From 48a667c2bfb028802e663e9529b4bf582c3ec3f6 Mon Sep 17 00:00:00 2001
From: Tue Ly <lntue.h at gmail.com>
Date: Tue, 28 Jan 2025 21:02:58 +0000
Subject: [PATCH 2/2] Add comment about the root cause.

---
 libc/src/__support/FPUtil/except_value_utils.h | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/libc/src/__support/FPUtil/except_value_utils.h b/libc/src/__support/FPUtil/except_value_utils.h
index 2e58bf2b287fdf..5f767769974d29 100644
--- a/libc/src/__support/FPUtil/except_value_utils.h
+++ b/libc/src/__support/FPUtil/except_value_utils.h
@@ -87,6 +87,9 @@ template <typename T, size_t N> struct ExceptValues {
             out_bits += values[i].rnd_upward_offset;
           break;
         case FE_DOWNWARD:
+          // Use conditionals instead of ternary operator to work around gcc's
+          // -Wconversion false positive bug:
+          // https://gcc.gnu.org/bugzilla/show_bug.cgi?id=101537
           if (sign)
             out_bits += values[i].rnd_upward_offset;
           else