From 2135b7bcb314117957581854ee3c49ee31f8ec10 Mon Sep 17 00:00:00 2001
From: RawNuke <67506722+RawNuke@users.noreply.github.com>
Date: Fri, 7 Aug 2026 21:27:59 +0530
Subject: [PATCH 1/3] Guard auto-vectorization flag for GCC only

Wrap -ftree-vectorize in *-g++* qmake scope so the flag only reaches
GCC compilers. MSVC ignores the unknown flag with D9002 warning, and
Clang already auto-vectorizes at -O2.

Closes #3863

Signed-off-by: RawNuke <67506722+RawNuke@users.noreply.github.com>
---
 Jamulus.pro | 9 +++++++--
 1 file changed, 7 insertions(+), 2 deletions(-)

diff --git a/Jamulus.pro b/Jamulus.pro
index cf37aecca8..71af171018 100644
--- a/Jamulus.pro
+++ b/Jamulus.pro
@@ -1175,8 +1175,13 @@ contains(CONFIG, "opus_shared_lib") {
     }
 }
 
-# Always enable auto vectorization
-QMAKE_CXXFLAGS+=-ftree-vectorize
+# GCC enables -ftree-vectorize at -O3, and also at -O2 from GCC 12 on. Setting it
+# explicitly keeps vectorization on for GCC builds that would not enable it by
+# default. Clang already vectorizes and MSVC would warn on the flag, so scope it
+# to GCC mkspecs (linux-g++, win32-g++, ...). (#3863)
+*-g++* {
+    QMAKE_CXXFLAGS += -ftree-vectorize
+}
 
 # disable version check if requested (#370)
 contains(CONFIG, "disable_version_check") {

From f9d463a385ec541659571319a9c2c0ecad2d24df Mon Sep 17 00:00:00 2001
From: RawNuke <67506722+RawNuke@users.noreply.github.com>
Date: Sun, 9 Aug 2026 19:51:56 +0530
Subject: [PATCH 2/3] Correct cost-model comment for -ftree-vectorize scope

The explicit flag is not redundant on GCC 12+: it lifts the -O2 cost
model from very-cheap to cheap. On GCC <= 11 it lands at cheap as well,
not dynamic. Confirmed by mcfnord's -Q --help=optimizers measurement on
gcc 11.5, 13.3, and aarch64 14.2. No -fvect-cost-model= or -ffast-math
needed. (#3863)
---
 Jamulus.pro | 10 ++++++----
 1 file changed, 6 insertions(+), 4 deletions(-)

diff --git a/Jamulus.pro b/Jamulus.pro
index 71af171018..fdefc1e235 100644
--- a/Jamulus.pro
+++ b/Jamulus.pro
@@ -1175,10 +1175,12 @@ contains(CONFIG, "opus_shared_lib") {
     }
 }
 
-# GCC enables -ftree-vectorize at -O3, and also at -O2 from GCC 12 on. Setting it
-# explicitly keeps vectorization on for GCC builds that would not enable it by
-# default. Clang already vectorizes and MSVC would warn on the flag, so scope it
-# to GCC mkspecs (linux-g++, win32-g++, ...). (#3863)
+# Scope -ftree-vectorize to GCC mkspecs (linux-g++, win32-g++, ...). Clang already
+# auto-vectorizes and MSVC warns on the unknown flag (#3863). On every current GCC
+# the explicit flag turns vectorization on at the 'cheap' cost model: on GCC <= 11
+# it raises -O2 from scalar, and on GCC 12+ it lifts the -O2 default from
+# 'very-cheap' to 'cheap'. That vectorizes the audio mixing loops with no
+# -ffast-math needed.
 *-g++* {
     QMAKE_CXXFLAGS += -ftree-vectorize
 }

From 4124988b9f5d5908b93d74dc44e9c00a7bd1afd0 Mon Sep 17 00:00:00 2001
From: RawNuke <67506722+RawNuke@users.noreply.github.com>
Date: Mon, 10 Aug 2026 10:00:36 +0530
Subject: [PATCH 3/3] Trim the -ftree-vectorize comment to the essential reason

Shorten per maintainer request: scope to GCC (Clang auto-vectorizes,
MSVC warns), and note the flag raises the -O2 cost model to cheap, which
is what vectorizes the mixer loops on GCC 11 through 14. (#3863)
---
 Jamulus.pro | 9 +++------
 1 file changed, 3 insertions(+), 6 deletions(-)

diff --git a/Jamulus.pro b/Jamulus.pro
index fdefc1e235..3c75c9906f 100644
--- a/Jamulus.pro
+++ b/Jamulus.pro
@@ -1175,12 +1175,9 @@ contains(CONFIG, "opus_shared_lib") {
     }
 }
 
-# Scope -ftree-vectorize to GCC mkspecs (linux-g++, win32-g++, ...). Clang already
-# auto-vectorizes and MSVC warns on the unknown flag (#3863). On every current GCC
-# the explicit flag turns vectorization on at the 'cheap' cost model: on GCC <= 11
-# it raises -O2 from scalar, and on GCC 12+ it lifts the -O2 default from
-# 'very-cheap' to 'cheap'. That vectorizes the audio mixing loops with no
-# -ffast-math needed.
+# Scope -ftree-vectorize to GCC mkspecs (#3863): Clang already auto-vectorizes
+# and MSVC warns on the flag. At -O2 the flag raises GCC's cost model to `cheap`,
+# which vectorizes the mixer loops on every current GCC (11 through 14).
 *-g++* {
     QMAKE_CXXFLAGS += -ftree-vectorize
 }