[PATCH] x86: %riz, %rip, and %eip don't require REX

[Jan Beulich]

While these can't be used as register operands, they can be used for
memory operand addressing. Such uses do not prevent conversion: The
RegRex64 checks in check_Rex_required() for base and index registers
were simply wrong. They specifically also aren't needed for byte
registers, as those won't pass i386_index_check() anyway.
---
I'm inclined to reduce RegRex64 use in the register table as well
(checking of the possibility of which actually made me spot the issue
addressed here): With a little bit of care in tc-i386.c it should
really only be %axl through %dil which need this attribute. All others
are sufficiently distinguishable by having RegRex / RegRex2.

--- a/gas/config/tc-i386.c
+++ b/gas/config/tc-i386.c
@@ -8668,8 +8668,8 @@ check_Rex_required (void)
 	return true;
     }
 
-  if ((i.index_reg && (i.index_reg->reg_flags & (RegRex | RegRex64)))
-      || (i.base_reg && (i.base_reg->reg_flags & (RegRex | RegRex64))))
+  if ((i.index_reg && (i.index_reg->reg_flags & RegRex))
+      || (i.base_reg && (i.base_reg->reg_flags & RegRex)))
     return true;
 
   /* Check pseudo prefix {rex} are valid.  */
--- a/gas/testsuite/gas/i386/x86-64-apx-ndd-optimize.d
+++ b/gas/testsuite/gas/i386/x86-64-apx-ndd-optimize.d
@@ -127,10 +127,12 @@ Disassembly of section .text:
 \s*[a-f0-9]+:\s*62 74 3d 18 66 c0    	adcx   %eax,%r8d,%r8d
 \s*[a-f0-9]+:\s*62 d4 7d 18 66 c7    	adcx   %r15d,%eax,%eax
 \s*[a-f0-9]+:\s*67 66 0f 38 f6 04 0a 	adcx   \(%edx,%ecx,1\),%eax
+\s*[a-f0-9]+:\s*66 0f 38 f6 04 22    	adcx   \(%rdx,%riz,1\),%eax
 \s*[a-f0-9]+:\s*f3 0f 38 f6 c3       	adox   %ebx,%eax
 \s*[a-f0-9]+:\s*f3 0f 38 f6 c3       	adox   %ebx,%eax
 \s*[a-f0-9]+:\s*62 f4 fe 18 66 c3    	adox   %rbx,%rax,%rax
 \s*[a-f0-9]+:\s*62 74 3e 18 66 c0    	adox   %eax,%r8d,%r8d
 \s*[a-f0-9]+:\s*62 d4 7e 18 66 c7    	adox   %r15d,%eax,%eax
 \s*[a-f0-9]+:\s*67 f3 0f 38 f6 04 0a 	adox   \(%edx,%ecx,1\),%eax
+\s*[a-f0-9]+:\s*f3 0f 38 f6 05 00 00 00 00 	adox   (0x)?0\(%rip\),%eax[ 	]+# .*	sym.*
 #pass
--- a/gas/testsuite/gas/i386/x86-64-apx-ndd-optimize.s
+++ b/gas/testsuite/gas/i386/x86-64-apx-ndd-optimize.s
@@ -1,5 +1,6 @@
 # Check 64bit APX NDD instructions with optimized encoding
 
+	.allow_index_reg
 	.text
 _start:
 add    %r31,%r8,%r8
@@ -120,9 +121,11 @@ adcx   %rbx,%rax,%rax
 adcx   %eax,%r8d,%r8d
 adcx   %r15d,%eax,%eax
 adcx   (%edx,%ecx,1),%eax,%eax
+adcx   (%rdx,%riz,1),%eax,%eax
 adox   %ebx,%eax,%eax
 adox   %eax,%ebx,%eax
 adox   %rbx,%rax,%rax
 adox   %eax,%r8d,%r8d
 adox   %r15d,%eax,%eax
 adox   (%edx,%ecx,1),%eax,%eax
+adox   sym(%rip),%eax,%eax