From f14aa417f0188db905b1af26aeccccd29b71705b Mon Sep 17 00:00:00 2001
From: Hanno Schwalm <hanno@schwalm-bremen.de>
Date: Sun, 29 Jun 2025 17:28:24 +0200
Subject: [PATCH] OPENMP and __GNUC__ compiler safety and performance

As references see #18729 #18975 and
https://bugzilla.redhat.com/show_bug.cgi?id=2362561 see late comments there from Jakub Jelinek
https://bugzilla.redhat.com/show_bug.cgi?id=2368336
https://bugzilla.redhat.com/show_bug.cgi?id=2373291
---
 src/develop/openmp_maths.h | 53 ++++++++++++++++++--------------------
 src/iop/rawdenoise.c       |  4 +--
 2 files changed, 27 insertions(+), 30 deletions(-)

diff --git a/src/develop/openmp_maths.h b/src/develop/openmp_maths.h
index a3d466b841f4..fa88077e1ba9 100644
--- a/src/develop/openmp_maths.h
+++ b/src/develop/openmp_maths.h
@@ -23,44 +23,41 @@
 #pragma once
 
 
-#if defined(_OPENMP) && !defined(_WIN32) && (!defined(__GNUC__) || __GNUC__ >= 12)
+#if defined(_OPENMP) && !defined(_WIN32) && !defined(__GNUC__)
+  // GCC and CLANG have declarations in standard headers if and only if the architecture and compile options support vectorization, so
+  // don't try to override that here - causes dynamic-link errors at startup.
+  DT_OMP_DECLARE_SIMD()
+  extern float fmaxf(const float x, const float y);
 
-#ifndef __GNUC__  // GCC 12 compiles but fails at runtime due to missing library function
-DT_OMP_DECLARE_SIMD()
-extern float fmaxf(const float x, const float y);
-#endif
+  DT_OMP_DECLARE_SIMD()
+  extern float fminf(const float x, const float y);
 
-#ifndef __GNUC__  // GCC 12 compiles but fails at runtime due to missing library function
-DT_OMP_DECLARE_SIMD()
-extern float fminf(const float x, const float y);
-#endif
+  DT_OMP_DECLARE_SIMD()
+  extern float fabsf(const float x);
 
-DT_OMP_DECLARE_SIMD()
-extern float fabsf(const float x);
-
-DT_OMP_DECLARE_SIMD()
-extern float powf(const float x, const float y);
+  DT_OMP_DECLARE_SIMD()
+  extern float powf(const float x, const float y);
 
-DT_OMP_DECLARE_SIMD()
-extern float sqrtf(const float x);
+  DT_OMP_DECLARE_SIMD()
+  extern float sqrtf(const float x);
 
-DT_OMP_DECLARE_SIMD()
-extern float cbrtf(const float x);
+  DT_OMP_DECLARE_SIMD()
+  extern float cbrtf(const float x);
 
-DT_OMP_DECLARE_SIMD()
-extern float log2f(const float x);
+  DT_OMP_DECLARE_SIMD()
+  extern float log2f(const float x);
 
-DT_OMP_DECLARE_SIMD()
-extern float exp2f(const float x);
+  DT_OMP_DECLARE_SIMD()
+  extern float exp2f(const float x);
 
-DT_OMP_DECLARE_SIMD()
-extern float log10f(const float x);
+  DT_OMP_DECLARE_SIMD()
+  extern float log10f(const float x);
 
-DT_OMP_DECLARE_SIMD()
-extern float expf(const float x);
+  DT_OMP_DECLARE_SIMD()
+  extern float expf(const float x);
 
-DT_OMP_DECLARE_SIMD()
-extern float logf(const float x);
+  DT_OMP_DECLARE_SIMD()
+  extern float logf(const float x);
 
 #endif
 
diff --git a/src/iop/rawdenoise.c b/src/iop/rawdenoise.c
index 841f068dbde6..deb0db55bbd1 100644
--- a/src/iop/rawdenoise.c
+++ b/src/iop/rawdenoise.c
@@ -1,6 +1,6 @@
 /*
     This file is part of darktable,
-    Copyright (C) 2011-2024 darktable developers.
+    Copyright (C) 2011-2025 darktable developers.
 
 
     darktable is free software: you can redistribute it and/or modify
@@ -226,7 +226,7 @@ static void wavelet_denoise(const float *const restrict in, float *const restric
       const float *const restrict inp = in + (size_t)row * roi->width + offset;
       const int senselwidth = (roi->width-offset+1)/2;
       for(int col = 0; col < senselwidth; col++)
-        fimgp[col] = sqrtf(fmaxf(0.0f, inp[2*col]));
+        fimgp[col] = sqrtf(MAX(0.0f, inp[2*col]));
     }
 
     // perform the wavelet decomposition and denoising