diff --git a/include/ck_pr.h b/include/ck_pr.h
index c66f95b..ee886f7 100644
--- a/include/ck_pr.h
+++ b/include/ck_pr.h
@@ -35,8 +35,6 @@
 
 #if defined(__x86_64__)
 #include "gcc/x86_64/ck_pr.h"
-#elif defined(__x86__)
-#include "gcc/x86/ck_pr.h"
 #elif defined(__sparcv9__)
 #include "gcc/sparcv9/ck_pr.h"
 #elif defined(__GNUC__)
diff --git a/include/gcc/x86/ck_f_pr.h b/include/gcc/x86/ck_f_pr.h
index 0f0ce4b..8894c74 100644
--- a/include/gcc/x86/ck_f_pr.h
+++ b/include/gcc/x86/ck_f_pr.h
@@ -37,6 +37,8 @@
 #define CK_F_PR_CAS_32_2_VALUE
 #define CK_F_PR_CAS_32_VALUE
 #define CK_F_PR_CAS_64
+#define CK_F_PR_CAS_64_1
+#define CK_F_PR_CAS_64_1_VALUE
 #define CK_F_PR_CAS_64_VALUE
 #define CK_F_PR_CAS_8
 #define CK_F_PR_CAS_8_8
@@ -86,6 +88,14 @@
 #define CK_F_PR_FAS_INT
 #define CK_F_PR_FAS_PTR
 #define CK_F_PR_FAS_UINT
+#define CK_F_PR_FENCE_LOAD
+#define CK_F_PR_FENCE_LOAD_DEPENDS
+#define CK_F_PR_FENCE_MEMORY
+#define CK_F_PR_FENCE_STORE
+#define CK_F_PR_FENCE_STRICT_LOAD
+#define CK_F_PR_FENCE_STRICT_LOAD_DEPENDS
+#define CK_F_PR_FENCE_STRICT_MEMORY
+#define CK_F_PR_FENCE_STRICT_STORE
 #define CK_F_PR_INC_16
 #define CK_F_PR_INC_16_ZERO
 #define CK_F_PR_INC_32
@@ -142,9 +152,9 @@
 #define CK_F_PR_OR_INT
 #define CK_F_PR_OR_PTR
 #define CK_F_PR_OR_UINT
+#define CK_F_PR_STALL
 #define CK_F_PR_STORE_16
 #define CK_F_PR_STORE_32
-#define CK_F_PR_STORE_64
 #define CK_F_PR_STORE_8
 #define CK_F_PR_STORE_CHAR
 #define CK_F_PR_STORE_INT
diff --git a/include/gcc/x86/ck_pr.h b/include/gcc/x86/ck_pr.h
index 2bb0dd7..eb8df18 100644
--- a/include/gcc/x86/ck_pr.h
+++ b/include/gcc/x86/ck_pr.h
@@ -52,6 +52,42 @@
 #define CK_PR_LOCK_PREFIX "lock "
 #endif
 
+/*
+ * Prevent speculative execution in busy-wait loops (P4 <=)
+ * or "predefined delay".
+ */
+CK_CC_INLINE static void
+ck_pr_stall(void)
+{
+	__asm__ __volatile__("pause" ::: "memory");
+	return;
+}
+
+/*
+ * IA32 has strong memory ordering guarantees, so memory
+ * fences are enabled if and only if the user specifies that
+ * that the program will be using non-temporal instructions.
+ * Otherwise, an optimization barrier is used in order to prevent
+ * compiler re-ordering of loads and stores across the barrier.
+ */
+#define CK_PR_FENCE(T, I)				\
+	CK_CC_INLINE static void			\
+	ck_pr_fence_strict_##T(void)			\
+	{						\
+		__asm__ __volatile__(I ::: "memory");	\
+	}						\
+	CK_CC_INLINE static void ck_pr_fence_##T(void)	\
+	{						\
+		__asm__ __volatile__("" ::: "memory");	\
+	}
+
+CK_PR_FENCE(load, "lfence")
+CK_PR_FENCE(load_depends, "")
+CK_PR_FENCE(store, "sfence")
+CK_PR_FENCE(memory, "mfence")
+
+#undef CK_PR_FENCE
+
 /*
  * Atomic fetch-and-store operations.
  */
@@ -517,9 +553,12 @@ ck_pr_cas_##S##_##W##_value(T *t, T c[W], T s[W], T *v)	\
 CK_PR_CAS_V(char, 8, char)
 CK_PR_CAS_V(int, 2, int)
 CK_PR_CAS_V(uint, 2, unsigned int)
+CK_PR_CAS_V(64, 1, uint64_t)
 CK_PR_CAS_V(16, 4, uint16_t)
 CK_PR_CAS_V(8, 8, uint8_t)
 
+#define ck_pr_cas_64_value(A, B, C, D) ck_pr_cas_64_1_value((A), &(B), &(C), (D))
+
 #undef CK_PR_CAS_V
 
 /*
diff --git a/regressions/common.h b/regressions/common.h
index 669fe30..d316580 100644
--- a/regressions/common.h
+++ b/regressions/common.h
@@ -78,7 +78,7 @@ aff_iterate(struct affinity *acb CK_CC_UNUSED)
 CK_CC_INLINE static uint64_t
 rdtsc(void)
 {
-#if defined(__x86__) || defined(__x86_64__)
+#if defined(__x86_64__)
         uint32_t eax = 0, edx;
 
         __asm__ __volatile__("cpuid;"