re-apply commit

Author: perazz

example_packages/features_demo/fpm.toml

@@ -19,7 +19,7 @@ release.preprocess.cpp.macros = "RELEASE"
 
 # Compiler-specific features
 debug.gfortran.flags = "-Wall -fcheck=bounds"
-release.gfortran.flags = "-march=native"
+release.gfortran.flags = "-mtune=generic -funroll-loops"
 
 # Platform-specific features
 linux.preprocess.cpp.macros = "LINUX_BUILD"

example_packages/features_per_compiler/app/main.f90

@@ -126,17 +126,8 @@ function check_gfortran_flags(options, debug_on, release_on, fast_on, strict_on)
     end if
 
     if (release_on) then
-      ! Check for either -march or -mcpu (Apple Silicon uses -mcpu; -match=native may be re-resolved by gcc)
-      if (.not. (index(options, '-march') > 0 .or. index(options, '-mcpu') > 0)) then
-        print '(a)', '  ✗ Release: neither -march=native nor -mcpu found'
-        failed_count = failed_count + 1
-      else
-        if (index(options, '-march=native') > 0) then
-          print '(a)', '  ✓ Release: -march found'
-        else
-          print '(a)', '  ✓ Release: -mcpu found'
-        end if
-      end if
+      ! Check for -mtune flag (portable tuning flag that works on all platforms)
+      if (.not. check_flag(options, '-mtune', 'Release', '-mtune')) failed_count = failed_count + 1
       if (.not. check_flag(options, '-funroll-loops', 'Release', '-funroll-loops')) failed_count = failed_count + 1
     end if
 

example_packages/features_per_compiler/fpm.toml

@@ -34,7 +34,7 @@ debug.preprocess.cpp.macros = "DEBUG"
 
 # Release feature with base optimization, then per-compiler extensions
 release.flags = "-O3"  # Base optimization for ALL compilers (applied first)
-release.gfortran.flags = "-march=native -funroll-loops"
+release.gfortran.flags = "-mtune=generic -funroll-loops"
 release.ifort.flags = "-unroll"     # Unix/Linux/macOS Intel
 release.ifx.flags = "-unroll"       # Intel oneAPI
 

example_packages/features_with_dependency/fpm.toml

@@ -30,7 +30,7 @@ linux_specific.preprocess.cpp.macros = ["WITH_DEMO","LINUX_FEATURES"]
 
 # Feature combining compiler and dependency features
 gfortran_optimized.gfortran.dependencies.features_demo = { path = "../features_demo", features = ["release", "gfortran"] }
-gfortran_optimized.gfortran.flags = "-O3 -march=native"
+gfortran_optimized.gfortran.flags = "-O3 -mtune=generic -funroll-loops"
 gfortran_optimized.preprocess.cpp.macros = ["WITH_DEMO"]