diff --git a/config.h b/config.h
index 73af8e27..accbe06f 100644
--- a/config.h
+++ b/config.h
@@ -492,7 +492,7 @@ NAMESPACE_END
 # endif
 #endif
 
-// Requires ARMv8 and ACLE 2.0.
+// Requires ARMv8 and ACLE 2.0. For GCC, requires 4.8 and above.
 // Microsoft plans to support ARM-64, but its not clear how to detect it.
 // TODO: Add MSC_VER and ARM-64 platform define when available
 #if !defined(CRYPTOPP_BOOL_ARM_CRC32_INTRINSICS_AVAILABLE) && !defined(CRYPTOPP_DISABLE_ASM)
@@ -501,7 +501,7 @@ NAMESPACE_END
 # endif
 #endif
 
-// Requires ARMv8 and ACLE 2.0.
+// Requires ARMv8 and ACLE 2.0. For GCC, requires 4.8 and above.
 // Microsoft plans to support ARM-64, but its not clear how to detect it.
 // TODO: Add MSC_VER and ARM-64 platform define when available
 #if !defined(CRYPTOPP_BOOL_ARM_CRYPTO_INTRINSICS_AVAILABLE) && !defined(CRYPTOPP_DISABLE_ASM)
diff --git a/config.recommend b/config.recommend
index 19c32822..815cd184 100644
--- a/config.recommend
+++ b/config.recommend
@@ -492,7 +492,7 @@ NAMESPACE_END
 # endif
 #endif
 
-// Requires ARMv8 and ACLE 2.0.
+// Requires ARMv8 and ACLE 2.0. For GCC, requires 4.8 and above.
 // Microsoft plans to support ARM-64, but its not clear how to detect it.
 // TODO: Add MSC_VER and ARM-64 platform define when available
 #if !defined(CRYPTOPP_BOOL_ARM_CRC32_INTRINSICS_AVAILABLE) && !defined(CRYPTOPP_DISABLE_ASM)
@@ -501,7 +501,7 @@ NAMESPACE_END
 # endif
 #endif
 
-// Requires ARMv8 and ACLE 2.0.
+// Requires ARMv8 and ACLE 2.0. For GCC, requires 4.8 and above.
 // Microsoft plans to support ARM-64, but its not clear how to detect it.
 // TODO: Add MSC_VER and ARM-64 platform define when available
 #if !defined(CRYPTOPP_BOOL_ARM_CRYPTO_INTRINSICS_AVAILABLE) && !defined(CRYPTOPP_DISABLE_ASM)
diff --git a/cpu.cpp b/cpu.cpp
index 532c5a14..ce9fc2ee 100644
--- a/cpu.cpp
+++ b/cpu.cpp
@@ -101,9 +101,11 @@ bool CpuId(word32 input, word32 output[4])
 	if (oldHandler == SIG_ERR)
 		return false;
 
+# ifndef __MINGW32__
 	volatile sigset_t oldMask;
 	if (sigprocmask(0, NULL, (sigset_t*)&oldMask))
 		return false;
+# endif
 
 	if (setjmp(s_jmpNoCPUID))
 		result = false;
@@ -123,7 +125,10 @@ bool CpuId(word32 input, word32 output[4])
 		);
 	}
 
+# ifndef __MINGW32__
 	sigprocmask(SIG_SETMASK, (sigset_t*)&oldMask, NULL);
+# endif
+
 	signal(SIGILL, oldHandler);
 	return result;
 #endif
@@ -160,9 +165,11 @@ static bool TrySSE2()
 	if (oldHandler == SIG_ERR)
 		return false;
 
+# ifndef __MINGW32__
 	volatile sigset_t oldMask;
 	if (sigprocmask(0, NULL, (sigset_t*)&oldMask))
 		return false;
+# endif
 
 	if (setjmp(s_jmpNoSSE2))
 		result = false;
@@ -176,7 +183,10 @@ static bool TrySSE2()
 #endif
 	}
 
+# ifndef __MINGW32__
 	sigprocmask(SIG_SETMASK, (sigset_t*)&oldMask, NULL);
+# endif
+
 	signal(SIGILL, oldHandler);
 	return result;
 #endif
diff --git a/cpu.h b/cpu.h
index 7e7cca43..8398e37d 100644
--- a/cpu.h
+++ b/cpu.h
@@ -10,22 +10,47 @@
 #include "config.h"
 
 #if (CRYPTOPP_BOOL_ARM32 || CRYPTOPP_BOOL_ARM64)
-# if defined(_MSC_VER) || defined(__BORLANDC__)
-#  define CRYPTOPP_MS_STYLE_INLINE_ASSEMBLY
-# else
-#  define CRYPTOPP_GNU_STYLE_INLINE_ASSEMBLY
+# if __GNUC__
+#  include <stdint.h>
 # endif
 # if CRYPTOPP_BOOL_NEON_INTRINSICS_AVAILABLE
 #  include <arm_neon.h>
 # endif
 # if (CRYPTOPP_BOOL_ARM_CRYPTO_INTRINSICS_AVAILABLE || CRYPTOPP_BOOL_ARM_CRC32_INTRINSICS_AVAILABLE)
-#  include <stdint.h>
-#  if (defined(__ARM_ACLE) || defined(__GNUC__)) && !defined(__APPLE__)
+#  if (defined(__ARM_ACLE))
 #   include <arm_acle.h>
 #  endif
 # endif
 #endif  // ARM-32 or ARM-64
 
+// Applies to both X86/X32/X64 and ARM32/ARM64. And we've got MIPS devices on the way.
+#if defined(_MSC_VER) || defined(__BORLANDC__)
+# define CRYPTOPP_MS_STYLE_INLINE_ASSEMBLY
+#else
+# define CRYPTOPP_GNU_STYLE_INLINE_ASSEMBLY
+#endif
+
+// Applies to both X86/X32/X64 and ARM32/ARM64
+#if defined(CRYPTOPP_LLVM_CLANG_VERSION) || defined(CRYPTOPP_APPLE_CLANG_VERSION) || defined(CRYPTOPP_CLANG_INTEGRATED_ASSEMBLER)
+	#define NEW_LINE "\n"
+	#define INTEL_PREFIX ".intel_syntax;"
+	#define INTEL_NOPREFIX ".intel_syntax;"
+	#define ATT_PREFIX ".att_syntax;"
+	#define ATT_NOPREFIX ".att_syntax;"
+#elif defined(__GNUC__)
+	#define NEW_LINE
+	#define INTEL_PREFIX ".intel_syntax prefix;"
+	#define INTEL_NOPREFIX ".intel_syntax noprefix;"
+	#define ATT_PREFIX ".att_syntax prefix;"
+	#define ATT_NOPREFIX ".att_syntax noprefix;"
+#else
+	#define NEW_LINE
+	#define INTEL_PREFIX
+	#define INTEL_NOPREFIX
+	#define ATT_PREFIX
+	#define ATT_NOPREFIX
+#endif
+
 #ifdef CRYPTOPP_GENERATE_X64_MASM
 
 #define CRYPTOPP_X86_ASM_AVAILABLE
@@ -39,12 +64,6 @@
 #  include <emmintrin.h>
 # endif
 
-// #if defined(CRYPTOPP_GCC_VERSION) && (CRYPTOPP_GCC_VERSION < 50000)
-// typedef int __v4si __attribute__ ((__vector_size__ (16)));
-// typedef long long __v2di __attribute__ ((__vector_size__ (16)));
-// typedef long long __m128i __attribute__ ((__vector_size__ (16), __may_alias__));
-// #endif
-
 #if CRYPTOPP_BOOL_AESNI_INTRINSICS_AVAILABLE
 
 // GCC 5.3/i686 fails to declare __m128 in the headers we use when compiling with -std=c++11 or -std=c++14.
@@ -650,27 +669,6 @@ inline int GetCacheLineSize()
 
 #endif  //  X86/X32/X64
 
-// Applies to both X86/X32/X64 and ARM32/ARM64
-#if defined(CRYPTOPP_LLVM_CLANG_VERSION) || defined(CRYPTOPP_APPLE_CLANG_VERSION) || defined(CRYPTOPP_CLANG_INTEGRATED_ASSEMBLER)
-	#define NEW_LINE "\n"
-	#define INTEL_PREFIX ".intel_syntax;"
-	#define INTEL_NOPREFIX ".intel_syntax;"
-	#define ATT_PREFIX ".att_syntax;"
-	#define ATT_NOPREFIX ".att_syntax;"
-#elif defined(__GNUC__)
-	#define NEW_LINE
-	#define INTEL_PREFIX ".intel_syntax prefix;"
-	#define INTEL_NOPREFIX ".intel_syntax noprefix;"
-	#define ATT_PREFIX ".att_syntax prefix;"
-	#define ATT_NOPREFIX ".att_syntax noprefix;"
-#else
-	#define NEW_LINE
-	#define INTEL_PREFIX
-	#define INTEL_NOPREFIX
-	#define ATT_PREFIX
-	#define ATT_NOPREFIX
-#endif
-
 NAMESPACE_END
 
 #endif  // CRYPTOPP_CPU_H
diff --git a/cryptest.sh b/cryptest.sh
index d2594568..bdcaff2b 100755
--- a/cryptest.sh
+++ b/cryptest.sh
@@ -331,56 +331,65 @@ else
 	fi
 fi
 
-HAVE_O3=0
-OPT_O3=
-rm -f "$TMP/adhoc.exe" > /dev/null 2>&1
-"$CXX" -DCRYPTOPP_ADHOC_MAIN -O3 adhoc.cpp -o "$TMP/adhoc.exe" > /dev/null 2>&1
-if [[ ("$?" -eq "0") ]]; then
-	HAVE_O3=1
-	OPT_O3=-O3
-else
+if [[ (-z "$HAVE_O3") ]]; then
+	HAVE_O3=0
+	OPT_O3=
 	rm -f "$TMP/adhoc.exe" > /dev/null 2>&1
-	"$CXX" -DCRYPTOPP_ADHOC_MAIN -xO3 adhoc.cpp -o "$TMP/adhoc.exe" > /dev/null 2>&1
+	"$CXX" -DCRYPTOPP_ADHOC_MAIN -O3 adhoc.cpp -o "$TMP/adhoc.exe" > /dev/null 2>&1
 	if [[ ("$?" -eq "0") ]]; then
 		HAVE_O3=1
-		OPT_O3=-xO3
+		OPT_O3=-O3
+	else
+		rm -f "$TMP/adhoc.exe" > /dev/null 2>&1
+		"$CXX" -DCRYPTOPP_ADHOC_MAIN -xO3 adhoc.cpp -o "$TMP/adhoc.exe" > /dev/null 2>&1
+		if [[ ("$?" -eq "0") ]]; then
+			HAVE_O3=1
+			OPT_O3=-xO3
+		fi
 	fi
 fi
 
 # Hit or miss, mostly hit
-HAVE_O5=0
-OPT_O5=
-rm -f "$TMP/adhoc.exe" > /dev/null 2>&1
-"$CXX" -DCRYPTOPP_ADHOC_MAIN -O5 adhoc.cpp -o "$TMP/adhoc.exe" > /dev/null 2>&1
-if [[ ("$?" -eq "0") ]]; then
-	HAVE_O5=1
-	OPT_O5=-O5
-else
+if [[ (-z "$HAVE_O5") ]]; then
+	HAVE_O5=0
+	OPT_O5=
 	rm -f "$TMP/adhoc.exe" > /dev/null 2>&1
-	"$CXX" -DCRYPTOPP_ADHOC_MAIN -xO5 adhoc.cpp -o "$TMP/adhoc.exe" > /dev/null 2>&1
+	"$CXX" -DCRYPTOPP_ADHOC_MAIN -O5 adhoc.cpp -o "$TMP/adhoc.exe" > /dev/null 2>&1
 	if [[ ("$?" -eq "0") ]]; then
 		HAVE_O5=1
-		OPT_O5=-xO5
+		OPT_O5=-O5
+	else
+		rm -f "$TMP/adhoc.exe" > /dev/null 2>&1
+		"$CXX" -DCRYPTOPP_ADHOC_MAIN -xO5 adhoc.cpp -o "$TMP/adhoc.exe" > /dev/null 2>&1
+		if [[ ("$?" -eq "0") ]]; then
+			HAVE_O5=1
+			OPT_O5=-xO5
+		fi
 	fi
 fi
 
 # Hit or miss, mostly hit
-HAVE_OS=0
-OPT_OS=
-rm -f "$TMP/adhoc.exe" > /dev/null 2>&1
-"$CXX" -DCRYPTOPP_ADHOC_MAIN -Os adhoc.cpp -o "$TMP/adhoc.exe" > /dev/null 2>&1
-if [[ ("$?" -eq "0") ]]; then
-	HAVE_OS=1
-	OPT_OS=-Os
+if [[ (-z "$HAVE_OS") ]]; then
+	HAVE_OS=0
+	OPT_OS=
+	rm -f "$TMP/adhoc.exe" > /dev/null 2>&1
+	"$CXX" -DCRYPTOPP_ADHOC_MAIN -Os adhoc.cpp -o "$TMP/adhoc.exe" > /dev/null 2>&1
+	if [[ ("$?" -eq "0") ]]; then
+		HAVE_OS=1
+		HAVE_OS=-Os
+	fi
 fi
 
-HAVE_OFAST=0
-OPT_OFAST=
-rm -f "$TMP/adhoc.exe" > /dev/null 2>&1
-"$CXX" -DCRYPTOPP_ADHOC_MAIN -Ofast adhoc.cpp -o "$TMP/adhoc.exe" > /dev/null 2>&1
-if [[ ("$?" -eq "0") ]]; then
-	HAVE_OFAST=1
-	OPT_OFAST=-Ofast
+# Hit or miss, mostly hit
+if [[ (-z "$HAVE_OFAST") ]]; then
+	HAVE_OFAST=0
+	OPT_OFAST=
+	rm -f "$TMP/adhoc.exe" > /dev/null 2>&1
+	"$CXX" -DCRYPTOPP_ADHOC_MAIN -Ofast adhoc.cpp -o "$TMP/adhoc.exe" > /dev/null 2>&1
+	if [[ ("$?" -eq "0") ]]; then
+		HAVE_OFAST=1
+		OPT_OFAST=-Ofast
+	fi
 fi
 
 # Use a fallback strategy so OPT_G2 can be used with RELEASE_CXXFLAGS