From 987e16820cc02ac29d29ca37229963ce84e0405f Mon Sep 17 00:00:00 2001
From: Federico Busato <fbusato@nvidia.com>
Date: Thu, 14 Jul 2022 12:04:32 -0700
Subject: [PATCH] Fixes IBM XLC behavior with uint128 fallback

---
 include/fmt/core.h   | 12 ++++++++++++
 include/fmt/format.h |  7 +++++--
 2 files changed, 17 insertions(+), 2 deletions(-)

diff --git a/include/fmt/core.h b/include/fmt/core.h
index 1e8ecad1..fbde339f 100644
--- a/include/fmt/core.h
+++ b/include/fmt/core.h
@@ -49,6 +49,18 @@
 #  define FMT_ICC_VERSION 0
 #endif
 
+#ifdef __xlC_ver__
+#  define FMT_XLC_VERSION __xlC_ver__
+#elif defined(__xlC__)
+#  define FMT_XLC_VERSION __xlC__
+#elif defined(__IBMC__)
+#  define FMT_XLC_VERSION __IBMC__
+#elif defined(__IBMCPP__)
+#  define FMT_XLC_VERSION __IBMCPP__
+#else
+#  define FMT_XLC_VERSION 0
+#endif
+
 #ifdef _MSC_VER
 #  define FMT_MSC_VERSION _MSC_VER
 #  define FMT_MSC_WARNING(...) __pragma(warning(__VA_ARGS__))
diff --git a/include/fmt/format.h b/include/fmt/format.h
index 6516975e..d6bf02ee 100644
--- a/include/fmt/format.h
+++ b/include/fmt/format.h
@@ -391,11 +391,14 @@ class uint128_fallback {
       hi_ += (lo_ < n ? 1 : 0);
       return *this;
     }
-#if FMT_HAS_BUILTIN(__builtin_addcll)
+#if FMT_XLC_VERSION && defined(_ARCH_PWR9) && defined(_ARCH_PPC64)
+    lo_ = __addex(lo_, n, 0, &carry);
+    hi_ += carry;
+#elif FMT_HAS_BUILTIN(__builtin_addcll) && !FMT_XLC_VERSION
     unsigned long long carry;
     lo_ = __builtin_addcll(lo_, n, 0, &carry);
     hi_ += carry;
-#elif FMT_HAS_BUILTIN(__builtin_ia32_addcarryx_u64)
+#elif FMT_HAS_BUILTIN(__builtin_ia32_addcarryx_u64) && !FMT_XLC_VERSION
     unsigned long long result;
     auto carry = __builtin_ia32_addcarryx_u64(0, lo_, n, &result);
     lo_ = result;