From e0ca05b1ec5ef4abbfed5f70623ed3e5ea77dd6b Mon Sep 17 00:00:00 2001
From: Jean-Marc Valin <jmvalin@amazon.com>
Date: Thu, 30 Jun 2022 16:25:03 -0400
Subject: Adds fuzzing to CPU detection

Makes ti possible to randomize (with --enable-fuzzing) the CPU flags
so we can better test all the intrinsics implementations.
---
 celt/arm/armcpu.c |  9 ++++++++-
 celt/x86/x86cpu.c | 11 ++++++++++-
 2 files changed, 18 insertions(+), 2 deletions(-)

diff --git a/celt/arm/armcpu.c b/celt/arm/armcpu.c
index cce3ae3a..c7d16e6d 100644
--- a/celt/arm/armcpu.c
+++ b/celt/arm/armcpu.c
@@ -156,7 +156,7 @@ opus_uint32 opus_cpu_capabilities(void)
    "your platform.  Reconfigure with --disable-rtcd (or send patches)."
 #endif
 
-int opus_select_arch(void)
+static int opus_select_arch_impl(void)
 {
   opus_uint32 flags = opus_cpu_capabilities();
   int arch = 0;
@@ -184,4 +184,11 @@ int opus_select_arch(void)
   return arch;
 }
 
+int opus_select_arch(void) {
+  int arch = opus_select_arch_impl();
+#ifdef FUZZING
+  arch = rand()%(arch+1);
+#endif
+  return arch;
+}
 #endif
diff --git a/celt/x86/x86cpu.c b/celt/x86/x86cpu.c
index d95a9b94..7cfc8db5 100644
--- a/celt/x86/x86cpu.c
+++ b/celt/x86/x86cpu.c
@@ -128,7 +128,7 @@ static void opus_cpu_feature_check(CPU_Feature *cpu_feature)
     }
 }
 
-int opus_select_arch(void)
+static int opus_select_arch_impl(void)
 {
     CPU_Feature cpu_feature;
     int arch;
@@ -163,4 +163,13 @@ int opus_select_arch(void)
     return arch;
 }
 
+int opus_select_arch(void) {
+    int arch = opus_select_arch_impl();
+#ifdef FUZZING
+    /* Randomly downgrade the architecture. */
+    arch = rand()%(arch+1);
+#endif
+    return arch;
+}
+
 #endif
-- 
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