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PATCH: Remove branches in swap_operands in x86 assembler
- From: "H. J. Lu" <hjl at lucon dot org>
- To: binutils at sources dot redhat dot com
- Date: Wed, 3 Jan 2007 20:03:54 -0800
- Subject: PATCH: Remove branches in swap_operands in x86 assembler
I am checking this patch to remove some branches in swap_operands.
H.J.
----
2007-01-03 H.J. Lu <hongjiu.lu@intel.com>
* config/tc-i386.c (swap_operands): Remove branches.
--- gas/config/tc-i386.c.swap 2007-01-03 14:49:01.000000000 -0800
+++ gas/config/tc-i386.c 2007-01-03 19:59:01.000000000 -0800
@@ -2280,16 +2280,13 @@ swap_operands (void)
union i386_op temp_op;
unsigned int temp_type;
enum bfd_reloc_code_real temp_reloc;
- int xchg1 = 0;
- int xchg2 = 0;
+ int xchg1, xchg2;
- if (i.operands == 4)
- /* There will be two exchanges in a 4 operand instruction.
- First exchange is the done inside this block.(1st and 4rth operand)
- The next exchange is done outside this block.(2nd and 3rd operand) */
+ switch (i.operands)
{
- xchg1 = 0;
- xchg2 = 3;
+ case 4:
+ xchg1 = 1;
+ xchg2 = i.operands - 2;
temp_type = i.types[xchg2];
i.types[xchg2] = i.types[xchg1];
i.types[xchg1] = temp_type;
@@ -2299,29 +2296,23 @@ swap_operands (void)
temp_reloc = i.reloc[xchg2];
i.reloc[xchg2] = i.reloc[xchg1];
i.reloc[xchg1] = temp_reloc;
- xchg1 = 1;
- xchg2 = 2;
- }
-
- if (i.operands == 2)
- {
- xchg1 = 0;
- xchg2 = 1;
- }
- else if (i.operands == 3)
- {
+ case 3:
+ case 2:
xchg1 = 0;
- xchg2 = 2;
+ xchg2 = i.operands - 1;
+ temp_type = i.types[xchg2];
+ i.types[xchg2] = i.types[xchg1];
+ i.types[xchg1] = temp_type;
+ temp_op = i.op[xchg2];
+ i.op[xchg2] = i.op[xchg1];
+ i.op[xchg1] = temp_op;
+ temp_reloc = i.reloc[xchg2];
+ i.reloc[xchg2] = i.reloc[xchg1];
+ i.reloc[xchg1] = temp_reloc;
+ break;
+ default:
+ abort ();
}
- temp_type = i.types[xchg2];
- i.types[xchg2] = i.types[xchg1];
- i.types[xchg1] = temp_type;
- temp_op = i.op[xchg2];
- i.op[xchg2] = i.op[xchg1];
- i.op[xchg1] = temp_op;
- temp_reloc = i.reloc[xchg2];
- i.reloc[xchg2] = i.reloc[xchg1];
- i.reloc[xchg1] = temp_reloc;
if (i.mem_operands == 2)
{