all: Replace if (ARCH_FOO) checks by #if ARCH_FOO

This is more spec-compliant because it does not rely
on dead-code elimination by the compiler. Especially
MSVC has problems with this, as can be seen in
https://ffmpeg.org/pipermail/ffmpeg-devel/2022-May/296373.html
or
https://ffmpeg.org/pipermail/ffmpeg-devel/2022-May/297022.html

This commit does not eliminate every instance where we rely
on dead code elimination: It only tackles branching to
the initialization of arch-specific dsp code, not e.g. all
uses of CONFIG_ and HAVE_ checks. But maybe it is already
enough to compile FFmpeg with MSVC with whole-programm-optimizations
enabled (if one does not disable too many components).

Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt@outlook.com>

1 files changed, 26 insertions, 24 deletions

diff --git a/libavutil/cpu.c b/libavutil/cpu.c
index 24b99d2554..0035e927a5 100644
--- a/libavutil/cpu.c
+++ b/libavutil/cpu.c
@@ -54,18 +54,19 @@ static atomic_int cpu_count = ATOMIC_VAR_INIT(-1);
 
 static int get_cpu_flags(void)
 {
-    if (ARCH_MIPS)
-        return ff_get_cpu_flags_mips();
-    if (ARCH_AARCH64)
-        return ff_get_cpu_flags_aarch64();
-    if (ARCH_ARM)
-        return ff_get_cpu_flags_arm();
-    if (ARCH_PPC)
-        return ff_get_cpu_flags_ppc();
-    if (ARCH_X86)
-        return ff_get_cpu_flags_x86();
-    if (ARCH_LOONGARCH)
-        return ff_get_cpu_flags_loongarch();
+#if ARCH_MIPS
+    return ff_get_cpu_flags_mips();
+#elif ARCH_AARCH64
+    return ff_get_cpu_flags_aarch64();
+#elif ARCH_ARM
+    return ff_get_cpu_flags_arm();
+#elif ARCH_PPC
+    return ff_get_cpu_flags_ppc();
+#elif ARCH_X86
+    return ff_get_cpu_flags_x86();
+#elif ARCH_LOONGARCH
+    return ff_get_cpu_flags_loongarch();
+#endif
     return 0;
 }
 
@@ -252,18 +253,19 @@ void av_cpu_force_count(int count)
 
 size_t av_cpu_max_align(void)
 {
-    if (ARCH_MIPS)
-        return ff_get_cpu_max_align_mips();
-    if (ARCH_AARCH64)
-        return ff_get_cpu_max_align_aarch64();
-    if (ARCH_ARM)
-        return ff_get_cpu_max_align_arm();
-    if (ARCH_PPC)
-        return ff_get_cpu_max_align_ppc();
-    if (ARCH_X86)
-        return ff_get_cpu_max_align_x86();
-    if (ARCH_LOONGARCH)
-        return ff_get_cpu_max_align_loongarch();
+#if ARCH_MIPS
+    return ff_get_cpu_max_align_mips();
+#elif ARCH_AARCH64
+    return ff_get_cpu_max_align_aarch64();
+#elif ARCH_ARM
+    return ff_get_cpu_max_align_arm();
+#elif ARCH_PPC
+    return ff_get_cpu_max_align_ppc();
+#elif ARCH_X86
+    return ff_get_cpu_max_align_x86();
+#elif ARCH_LOONGARCH
+    return ff_get_cpu_max_align_loongarch();
+#endif
 
     return 8;
 }