x86[_64]cpuid.pl: harmonize usage of reserved bits #20 and #30.

crypto/rc4/asm/rc4-x86_64.pl

@@ -159,8 +159,8 @@ $code.=<<___;
 	movl	($dat,$XX[0],4),$TX[0]#d
 	test	\$-16,$len
 	jz	.Lloop1
-	bt	\$30,%r8d	# Intel CPU Family 6
-	jc	.L16x
+	bt	\$30,%r8d	# Intel CPU?
+	jc	.Lintel
 	and	\$7,$TX[1]
 	lea	1($XX[0]),$XX[1]
 	jz	.Loop8
@@ -217,7 +217,7 @@ $code.=<<___;
 	jmp	.Lexit
 
 .align	16
-.L16x:
+.Lintel:
 	test	\$-32,$len
 	jz	.Lloop1
 	and	\$15,$TX[1]
@@ -438,10 +438,8 @@ RC4_set_key:
 	xor	%r11,%r11
 
 	mov	OPENSSL_ia32cap_P(%rip),$idx#d
-	bt	\$20,$idx#d	# Intel CPU
-	jnc	.Lw1stloop
-	bt	\$30,$idx#d	# Intel CPU Family 6
-	jnc	.Lc1stloop
+	bt	\$20,$idx#d	# RC4_CHAR?
+	jc	.Lc1stloop
 	jmp	.Lw1stloop
 
 .align	16

crypto/x86_64cpuid.pl

@@ -124,13 +124,14 @@ OPENSSL_ia32_cpuid:
 .Lnocacheinfo:
 	mov	\$1,%eax
 	cpuid
+	and	\$0xbfefffff,%edx	# force reserved bits to 0
 	cmp	\$0,%r9d
 	jne	.Lnotintel
-	or	\$0x00100000,%edx	# use reserved 20th bit to engage RC4_CHAR
+	or	\$0x40000000,%edx	# set reserved bit#30 on Intel CPUs
 	and	\$15,%ah
 	cmp	\$15,%ah		# examine Family ID
-	je	.Lnotintel
-	or	\$0x40000000,%edx	# use reserved bit to skip unrolled loop
+	jne	.Lnotintel
+	or	\$0x00100000,%edx	# set reserved bit#20 to engage RC4_CHAR
 .Lnotintel:
 	bt	\$28,%edx		# test hyper-threading bit
 	jnc	.Lgeneric

crypto/x86cpuid.pl

@@ -92,13 +92,15 @@ for (@ARGV) { $sse2=1 if (/-DOPENSSL_IA32_SSE2/); }
 &set_label("nocacheinfo");
 	&mov	("eax",1);
 	&cpuid	();
+	&and	("edx",~(1<<20|1<<30));	# force reserved bits to 0
 	&cmp	("ebp",0);
-	&jne	(&label("notP4"));
+	&jne	(&label("notintel"));
+	&or	("edx",1<<30);		# set reserved bit#30 on Intel CPUs
 	&and	(&HB("eax"),15);	# familiy ID
 	&cmp	(&HB("eax"),15);	# P4?
-	&jne	(&label("notP4"));
-	&or	("edx",1<<20);		# use reserved bit to engage RC4_CHAR
-&set_label("notP4");
+	&jne	(&label("notintel"));
+	&or	("edx",1<<20);		# set reserved bit#20 to engage RC4_CHAR
+&set_label("notintel");
 	&bt	("edx",28);		# test hyper-threading bit
 	&jnc	(&label("generic"));
 	&and	("edx",0xefffffff);

doc/crypto/OPENSSL_ia32cap.pod

@@ -37,14 +37,13 @@ moment of this writing following bits are significant:
 =item bit #28 denoting Hyperthreading, which is used to distiguish
       cores with shared cache;
 
-=item bit #30, reserved by Intel, is used to choose among RC4 code
-      paths;
+=item bit #30, reserved by Intel, denotes specifically Intel CPUs;
 
 =item bit #33 denoting availability of PCLMULQDQ instruction;
 
 =item bit #41 denoting SSSE3, Supplemental SSE3, support;
 
-=item bit #43 denoting AMD XOP support (forced to zero on Intel);
+=item bit #43 denoting AMD XOP support (forced to zero on non-AMD CPUs);
 
 =item bit #57 denoting AES-NI instruction set extension;