i386: Don't add 0x66 prefix to IRET for .code16gcc

The .code16gcc directive supports 16bit mode with 32-bit address.  Since
IRET (opcode 0xcf) in 16bit mode returns from an interrupt in 16bit mode,
we shouldn't add 0x66 prefix for IRET.

	PR gas/24485
	* config/tc-i386.c (process_suffix): Don't add DATA_PREFIX_OPCODE
	to IRET for .code16gcc.
	* testsuite/gas/i386/jump16.s: Add IRET tests.
	* testsuite/gas/i386/jump16.d: Updated.

diff --git a/gas/ChangeLog b/gas/ChangeLog
index 8558ecd7b488d6cff6f6b6ed03569e9df3baef1d..c94ffdda0b32ccb456d3710c4d90ad1360e3a533 100644 (file)
--- a/gas/ChangeLog
+++ b/gas/ChangeLog
@@ -1,3 +1,11 @@
+2019-04-26  H.J. Lu  <hongjiu.lu@intel.com>
+
+       PR gas/24485
+       * config/tc-i386.c (process_suffix): Don't add DATA_PREFIX_OPCODE
+       to IRET for .code16gcc.
+       * testsuite/gas/i386/jump16.s: Add IRET tests.
+       * testsuite/gas/i386/jump16.d: Updated.
+
 2019-04-25  Alexandre Oliva  <aoliva@redhat.com>
            Alan Modra  <amodra@gmail.com>
 

diff --git a/gas/config/tc-i386.c b/gas/config/tc-i386.c
index 5eb6c4c2692d4aafdd495db3294ef065fecf43a5..032b1d308115d3f8a95b0d1f8ba169011292a8e3 100644 (file)
--- a/gas/config/tc-i386.c
+++ b/gas/config/tc-i386.c
@@ -6352,7 +6352,13 @@ process_suffix (void)
            if (!add_prefix (ADDR_PREFIX_OPCODE))
              return 0;
        }
+      /* stackop_size is set to LONG_MNEM_SUFFIX for the .code16gcc
+        directive to support 16bit mode with 32-bit address.  Since
+        IRET (opcode 0xcf) in 16bit mode returns from an interrupt
+        in 16bit mode, we shouldn't add DATA_PREFIX_OPCODE here.  */
       else if (i.suffix != QWORD_MNEM_SUFFIX
+              && (stackop_size != LONG_MNEM_SUFFIX
+                  || i.tm.base_opcode != 0xcf)
               && !i.tm.opcode_modifier.ignoresize
               && !i.tm.opcode_modifier.floatmf
               && !i.tm.opcode_modifier.vex

diff --git a/gas/testsuite/gas/i386/jump16.d b/gas/testsuite/gas/i386/jump16.d
index a83bad615704229e4db1269d9d35e9a1ce416da3..7a1dc7661ee332cde5c8773cc9bb933bcedd7b87 100644 (file)
--- a/gas/testsuite/gas/i386/jump16.d
+++ b/gas/testsuite/gas/i386/jump16.d
@@ -67,4 +67,6 @@ Disassembly of section .text:
 [      ]*[a-f0-9]+:    ea 10 10 90 90          ljmp   \$0x9090,\$0x1010
 [      ]*[a-f0-9]+:    ea 00 00 90 90          ljmp   \$0x9090,\$0x0   ed: (R_386_)?16 xxx
 [      ]*[a-f0-9]+:    ea 00 00 90 90          ljmp   \$0x9090,\$0x0   f2: (R_386_)?16 xxx
+[      ]*[a-f0-9]+:    cf                      iret   
+[      ]*[a-f0-9]+:    cf                      iret   
 #pass

diff --git a/gas/testsuite/gas/i386/jump16.s b/gas/testsuite/gas/i386/jump16.s
index f8bc0ea5b47c034226d846ee2f071b25efef3a5a..aff5665720179579984c3a33efa35ee3eb85f4f7 100644 (file)
--- a/gas/testsuite/gas/i386/jump16.s
+++ b/gas/testsuite/gas/i386/jump16.s
@@ -71,3 +71,9 @@
        jmp     0x9090:0x1010
        jmp     0x9090,xxx
        jmp     0x9090:xxx
+
+.code16gcc
+       iret
+
+.code16
+       iret