From 8e7767542cfde43f16c142f05dce06cadb7f7f84 Mon Sep 17 00:00:00 2001
From: sandeepgupta12 <sandeep.gupta12@ibm.com>
Date: Wed, 13 Aug 2025 07:57:46 -0700
Subject: [PATCH] PR #1918: base: add musl + ppc64le fallback for
 UnscaledCycleClock::Frequency

Imported from GitHub PR https://github.com/abseil/abseil-cpp/pull/1918

Fixes build failures on ppc64le with musl libc, where UnscaledCycleClock::Frequency() had no implementation.

This patch adds a fallback for __linux__ + __powerpc64__ when glibc is not present, using a constant 512 MHz timebase frequency. This matches the existing AIX implementation and unblocks projects like Node.js/V8 from building on Alpine Linux (musl).

Tested by building Node.js 24.x on ppc64le + musl.

Issue- https://github.com/abseil/abseil-cpp/issues/1917

Merge aa7e63a4ffe62cf7787260bdda20d0793bc4ef68 into 274c81389f97afc612d76dc7cb5d38144cd9647f

Merging this change closes #1918

COPYBARA_INTEGRATE_REVIEW=https://github.com/abseil/abseil-cpp/pull/1918 from sandeepgupta12:master aa7e63a4ffe62cf7787260bdda20d0793bc4ef68
PiperOrigin-RevId: 794579241
Change-Id: I16b9bcb48dc9ff7c1f1fcf9b31ceb5f20dadf3ec
---
 absl/base/internal/unscaledcycleclock.cc | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/absl/base/internal/unscaledcycleclock.cc b/absl/base/internal/unscaledcycleclock.cc
index 68f92730..dca7cbaa 100644
--- a/absl/base/internal/unscaledcycleclock.cc
+++ b/absl/base/internal/unscaledcycleclock.cc
@@ -85,6 +85,10 @@ int64_t UnscaledCycleClock::Now() {
 double UnscaledCycleClock::Frequency() {
 #ifdef __GLIBC__
   return __ppc_get_timebase_freq();
+#elif defined(__linux__)
+  // Fallback for musl + ppc64le: use constant timebase frequency (512 MHz)
+  // Must come after __GLIBC__.
+  return static_cast<double>(512000000);
 #elif defined(_AIX)
   // This is the same constant value as returned by
   // __ppc_get_timebase_freq().