x86: allow to request ModR/M encoding

Several insns have a (typically shorter) non-ModR/M and a (typically
longer) ModR/M encoding. In most cases the former is used by default.
This isn't too dissimilar from register-only insns sometimes having two
encoding forms. In those cases {load} or {store} can be used to control
the encoding used. Extend this to ModR/M-less encodings which have a
ModR/M counterpart (note that BSWAP hasn't). For insn reading and
writing their (explicit) memory operand, both prefixes are honored;
otherwise only the applicable one is.

Note that for some forms of XCHG, {store} has already been performing
this function, apparently as an unnoticed side effect of adding D to
the template.

5 files changed, 296 insertions, 9 deletions

diff --git a/gas/config/tc-i386.c b/gas/config/tc-i386.c
index 3df0a47..a9314f5 100644
--- a/gas/config/tc-i386.c
+++ b/gas/config/tc-i386.c
@@ -6883,19 +6883,40 @@ match_template (char mnem_suffix)
 	case 1:
 	  if (!operand_type_match (overlap0, i.types[0]))
 	    continue;
+
+	  /* Allow the ModR/M encoding to be requested by using the {load} or
+	     {store} pseudo prefix on an applicable insn.  */
+	  if (!t->opcode_modifier.modrm
+	      && i.reg_operands == 1
+	      && ((i.dir_encoding == dir_encoding_load
+		   && t->mnem_off != MN_pop)
+		  || (i.dir_encoding == dir_encoding_store
+		      && t->mnem_off != MN_push))
+	      /* Avoid BSWAP.  */
+	      && t->mnem_off != MN_bswap)
+	    continue;
 	  break;
+
 	case 2:
 	  /* xchg %eax, %eax is a special case. It is an alias for nop
 	     only in 32bit mode and we can use opcode 0x90.  In 64bit
 	     mode, we can't use 0x90 for xchg %eax, %eax since it should
 	     zero-extend %eax to %rax.  */
-	  if (flag_code == CODE_64BIT
-	      && t->base_opcode == 0x90
-	      && t->opcode_space == SPACE_BASE
-	      && i.types[0].bitfield.instance == Accum
-	      && i.types[0].bitfield.dword
-	      && i.types[1].bitfield.instance == Accum)
-	    continue;
+	  if (t->base_opcode == 0x90
+	      && t->opcode_space == SPACE_BASE)
+	    {
+	      if (flag_code == CODE_64BIT
+		  && i.types[0].bitfield.instance == Accum
+		  && i.types[0].bitfield.dword
+		  && i.types[1].bitfield.instance == Accum)
+		continue;
+
+	      /* Allow the ModR/M encoding to be requested by using the
+		 {load} or {store} pseudo prefix.  */
+	      if (i.dir_encoding == dir_encoding_load
+		  || i.dir_encoding == dir_encoding_store)
+		continue;
+	    }
 
 	  if (t->base_opcode == MOV_AX_DISP32
 	      && t->opcode_space == SPACE_BASE
@@ -6909,6 +6930,38 @@ match_template (char mnem_suffix)
 		 match the accumulator-only encoding of mov.  */
 	      if (i.hle_prefix)
 		continue;
+
+	      /* Allow the ModR/M encoding to be requested by using a suitable
+		 {load} or {store} pseudo prefix.  */
+	      if (i.dir_encoding == (i.types[0].bitfield.instance == Accum
+				     ? dir_encoding_store
+				     : dir_encoding_load)
+		  && !i.types[0].bitfield.disp64
+		  && !i.types[1].bitfield.disp64)
+		continue;
+	    }
+
+	  /* Allow the ModR/M encoding to be requested by using the {load} or
+	     {store} pseudo prefix on an applicable insn.  */
+	  if (!t->opcode_modifier.modrm
+	      && i.reg_operands == 1
+	      && i.imm_operands == 1
+	      && (i.dir_encoding == dir_encoding_load
+		  || i.dir_encoding == dir_encoding_store)
+	      && t->opcode_space == SPACE_BASE)
+	    {
+	      if (t->base_opcode == 0xb0 /* mov $imm, %reg */
+		  && i.dir_encoding == dir_encoding_store)
+		continue;
+
+	      if ((t->base_opcode | 0x38) == 0x3c /* <alu> $imm, %acc */
+		  && (t->base_opcode != 0x3c /* cmp $imm, %acc */
+		      || i.dir_encoding == dir_encoding_load))
+		continue;
+
+	      if (t->base_opcode == 0xa8 /* test $imm, %acc */
+		  && i.dir_encoding == dir_encoding_load)
+		continue;
 	    }
 	  /* Fall through.  */
 
diff --git a/gas/testsuite/gas/i386/pseudos.d b/gas/testsuite/gas/i386/pseudos.d
index 0df9b72..98e1149 100644
--- a/gas/testsuite/gas/i386/pseudos.d
+++ b/gas/testsuite/gas/i386/pseudos.d
@@ -54,10 +54,10 @@ Disassembly of section .text:
  +[a-f0-9]+:	31 c8                	xor    %ecx,%eax
  +[a-f0-9]+:	33 c1                	xor    %ecx,%eax
  +[a-f0-9]+:	31 c8                	xor    %ecx,%eax
- +[a-f0-9]+:	a1 78 56 34 12       	mov    0x12345678,%eax
+ +[a-f0-9]+:	8b 05 78 56 34 12    	mov    0x12345678,%eax
  +[a-f0-9]+:	a3 78 56 34 12       	mov    %eax,0x12345678
  +[a-f0-9]+:	a1 78 56 34 12       	mov    0x12345678,%eax
- +[a-f0-9]+:	a3 78 56 34 12       	mov    %eax,0x12345678
+ +[a-f0-9]+:	89 05 78 56 34 12    	mov    %eax,0x12345678
  +[a-f0-9]+:	89 07                	mov    %eax,\(%edi\)
  +[a-f0-9]+:	8b 07                	mov    \(%edi\),%eax
  +[a-f0-9]+:	89 07                	mov    %eax,\(%edi\)
@@ -126,6 +126,91 @@ Disassembly of section .text:
  +[a-f0-9]+:	33 07                	xor    \(%edi\),%eax
  +[a-f0-9]+:	31 07                	xor    %eax,\(%edi\)
  +[a-f0-9]+:	33 07                	xor    \(%edi\),%eax
+ +[a-f0-9]+:	b0 12                	mov    \$0x12,%al
+ +[a-f0-9]+:	b8 45 03 00 00       	mov    \$0x345,%eax
+ +[a-f0-9]+:	b0 12                	mov    \$0x12,%al
+ +[a-f0-9]+:	b8 45 03 00 00       	mov    \$0x345,%eax
+ +[a-f0-9]+:	c6 c0 12             	mov    \$0x12,%al
+ +[a-f0-9]+:	c7 c0 45 03 00 00    	mov    \$0x345,%eax
+ +[a-f0-9]+:	14 12                	adc    \$0x12,%al
+ +[a-f0-9]+:	15 45 03 00 00       	adc    \$0x345,%eax
+ +[a-f0-9]+:	80 d0 12             	adc    \$0x12,%al
+ +[a-f0-9]+:	81 d0 45 03 00 00    	adc    \$0x345,%eax
+ +[a-f0-9]+:	80 d0 12             	adc    \$0x12,%al
+ +[a-f0-9]+:	81 d0 45 03 00 00    	adc    \$0x345,%eax
+ +[a-f0-9]+:	04 12                	add    \$0x12,%al
+ +[a-f0-9]+:	05 45 03 00 00       	add    \$0x345,%eax
+ +[a-f0-9]+:	80 c0 12             	add    \$0x12,%al
+ +[a-f0-9]+:	81 c0 45 03 00 00    	add    \$0x345,%eax
+ +[a-f0-9]+:	80 c0 12             	add    \$0x12,%al
+ +[a-f0-9]+:	81 c0 45 03 00 00    	add    \$0x345,%eax
+ +[a-f0-9]+:	24 12                	and    \$0x12,%al
+ +[a-f0-9]+:	25 45 03 00 00       	and    \$0x345,%eax
+ +[a-f0-9]+:	80 e0 12             	and    \$0x12,%al
+ +[a-f0-9]+:	81 e0 45 03 00 00    	and    \$0x345,%eax
+ +[a-f0-9]+:	80 e0 12             	and    \$0x12,%al
+ +[a-f0-9]+:	81 e0 45 03 00 00    	and    \$0x345,%eax
+ +[a-f0-9]+:	3c 12                	cmp    \$0x12,%al
+ +[a-f0-9]+:	3d 45 03 00 00       	cmp    \$0x345,%eax
+ +[a-f0-9]+:	80 f8 12             	cmp    \$0x12,%al
+ +[a-f0-9]+:	81 f8 45 03 00 00    	cmp    \$0x345,%eax
+ +[a-f0-9]+:	3c 12                	cmp    \$0x12,%al
+ +[a-f0-9]+:	3d 45 03 00 00       	cmp    \$0x345,%eax
+ +[a-f0-9]+:	0c 12                	or     \$0x12,%al
+ +[a-f0-9]+:	0d 45 03 00 00       	or     \$0x345,%eax
+ +[a-f0-9]+:	80 c8 12             	or     \$0x12,%al
+ +[a-f0-9]+:	81 c8 45 03 00 00    	or     \$0x345,%eax
+ +[a-f0-9]+:	80 c8 12             	or     \$0x12,%al
+ +[a-f0-9]+:	81 c8 45 03 00 00    	or     \$0x345,%eax
+ +[a-f0-9]+:	1c 12                	sbb    \$0x12,%al
+ +[a-f0-9]+:	1d 45 03 00 00       	sbb    \$0x345,%eax
+ +[a-f0-9]+:	80 d8 12             	sbb    \$0x12,%al
+ +[a-f0-9]+:	81 d8 45 03 00 00    	sbb    \$0x345,%eax
+ +[a-f0-9]+:	80 d8 12             	sbb    \$0x12,%al
+ +[a-f0-9]+:	81 d8 45 03 00 00    	sbb    \$0x345,%eax
+ +[a-f0-9]+:	2c 12                	sub    \$0x12,%al
+ +[a-f0-9]+:	2d 45 03 00 00       	sub    \$0x345,%eax
+ +[a-f0-9]+:	80 e8 12             	sub    \$0x12,%al
+ +[a-f0-9]+:	81 e8 45 03 00 00    	sub    \$0x345,%eax
+ +[a-f0-9]+:	80 e8 12             	sub    \$0x12,%al
+ +[a-f0-9]+:	81 e8 45 03 00 00    	sub    \$0x345,%eax
+ +[a-f0-9]+:	a8 12                	test   \$0x12,%al
+ +[a-f0-9]+:	a9 45 03 00 00       	test   \$0x345,%eax
+ +[a-f0-9]+:	f6 c0 12             	test   \$0x12,%al
+ +[a-f0-9]+:	f7 c0 45 03 00 00    	test   \$0x345,%eax
+ +[a-f0-9]+:	a8 12                	test   \$0x12,%al
+ +[a-f0-9]+:	a9 45 03 00 00       	test   \$0x345,%eax
+ +[a-f0-9]+:	34 12                	xor    \$0x12,%al
+ +[a-f0-9]+:	35 45 03 00 00       	xor    \$0x345,%eax
+ +[a-f0-9]+:	80 f0 12             	xor    \$0x12,%al
+ +[a-f0-9]+:	81 f0 45 03 00 00    	xor    \$0x345,%eax
+ +[a-f0-9]+:	80 f0 12             	xor    \$0x12,%al
+ +[a-f0-9]+:	81 f0 45 03 00 00    	xor    \$0x345,%eax
+ +[a-f0-9]+:	41                   	inc    %ecx
+ +[a-f0-9]+:	ff c1                	inc    %ecx
+ +[a-f0-9]+:	ff c1                	inc    %ecx
+ +[a-f0-9]+:	49                   	dec    %ecx
+ +[a-f0-9]+:	ff c9                	dec    %ecx
+ +[a-f0-9]+:	ff c9                	dec    %ecx
+ +[a-f0-9]+:	51                   	push   %ecx
+ +[a-f0-9]+:	ff f1                	push   %ecx
+ +[a-f0-9]+:	51                   	push   %ecx
+ +[a-f0-9]+:	59                   	pop    %ecx
+ +[a-f0-9]+:	59                   	pop    %ecx
+ +[a-f0-9]+:	8f c1                	pop    %ecx
+ +[a-f0-9]+:	0f c9                	bswap  %ecx
+ +[a-f0-9]+:	0f c9                	bswap  %ecx
+ +[a-f0-9]+:	0f c9                	bswap  %ecx
+ +[a-f0-9]+:	87 ce                	xchg   %ecx,%esi
+ +[a-f0-9]+:	87 f1                	xchg   %esi,%ecx
+ +[a-f0-9]+:	87 f1                	xchg   %esi,%ecx
+ +[a-f0-9]+:	87 ce                	xchg   %ecx,%esi
+ +[a-f0-9]+:	96                   	xchg   %eax,%esi
+ +[a-f0-9]+:	87 f0                	xchg   %esi,%eax
+ +[a-f0-9]+:	87 c6                	xchg   %eax,%esi
+ +[a-f0-9]+:	91                   	xchg   %eax,%ecx
+ +[a-f0-9]+:	87 c1                	xchg   %eax,%ecx
+ +[a-f0-9]+:	87 c8                	xchg   %ecx,%eax
  +[a-f0-9]+:	d8 c0                	fadd   %st\(0\),%st
  +[a-f0-9]+:	d8 c0                	fadd   %st\(0\),%st
  +[a-f0-9]+:	dc c0                	fadd   %st,%st\(0\)
diff --git a/gas/testsuite/gas/i386/pseudos.s b/gas/testsuite/gas/i386/pseudos.s
index 34a461c..7e3600e 100644
--- a/gas/testsuite/gas/i386/pseudos.s
+++ b/gas/testsuite/gas/i386/pseudos.s
@@ -124,6 +124,34 @@ _start:
 	{store} xor %eax, (%edi)
 	{store} xor (%edi), %eax
 
+	.irp m, mov, adc, add, and, cmp, or, sbb, sub, test, xor
+	\m	$0x12, %al
+	\m	$0x345, %eax
+	{load} \m $0x12, %al		# bogus for MOV
+	{load} \m $0x345, %eax		# bogus for MOV
+	{store} \m $0x12, %al
+	{store} \m $0x345, %eax
+	.endr
+
+	.irp m, inc, dec, push, pop, bswap
+	\m	%ecx
+	{load} \m %ecx			# bogus for POP
+	{store} \m %ecx			# bogus for PUSH
+	.endr
+
+	xchg	%ecx, %esi
+	xchg	%esi, %ecx
+	{load} xchg %ecx, %esi
+	{store} xchg %ecx, %esi
+
+	xchg	%eax, %esi
+	{load} xchg %eax, %esi
+	{store} xchg %eax, %esi
+
+	xchg	%ecx, %eax
+	{load} xchg %ecx, %eax
+	{store} xchg %ecx, %eax
+
 	fadd %st, %st
 	{load} fadd %st, %st
 	{store} fadd %st, %st
diff --git a/gas/testsuite/gas/i386/x86-64-pseudos.d b/gas/testsuite/gas/i386/x86-64-pseudos.d
index fb71942..0cc75ef 100644
--- a/gas/testsuite/gas/i386/x86-64-pseudos.d
+++ b/gas/testsuite/gas/i386/x86-64-pseudos.d
@@ -137,6 +137,91 @@ Disassembly of section .text:
  +[a-f0-9]+:	33 07                	xor    \(%rdi\),%eax
  +[a-f0-9]+:	31 07                	xor    %eax,\(%rdi\)
  +[a-f0-9]+:	33 07                	xor    \(%rdi\),%eax
+ +[a-f0-9]+:	b0 12                	mov    \$0x12,%al
+ +[a-f0-9]+:	b8 45 03 00 00       	mov    \$0x345,%eax
+ +[a-f0-9]+:	b0 12                	mov    \$0x12,%al
+ +[a-f0-9]+:	b8 45 03 00 00       	mov    \$0x345,%eax
+ +[a-f0-9]+:	c6 c0 12             	mov    \$0x12,%al
+ +[a-f0-9]+:	c7 c0 45 03 00 00    	mov    \$0x345,%eax
+ +[a-f0-9]+:	14 12                	adc    \$0x12,%al
+ +[a-f0-9]+:	15 45 03 00 00       	adc    \$0x345,%eax
+ +[a-f0-9]+:	80 d0 12             	adc    \$0x12,%al
+ +[a-f0-9]+:	81 d0 45 03 00 00    	adc    \$0x345,%eax
+ +[a-f0-9]+:	80 d0 12             	adc    \$0x12,%al
+ +[a-f0-9]+:	81 d0 45 03 00 00    	adc    \$0x345,%eax
+ +[a-f0-9]+:	04 12                	add    \$0x12,%al
+ +[a-f0-9]+:	05 45 03 00 00       	add    \$0x345,%eax
+ +[a-f0-9]+:	80 c0 12             	add    \$0x12,%al
+ +[a-f0-9]+:	81 c0 45 03 00 00    	add    \$0x345,%eax
+ +[a-f0-9]+:	80 c0 12             	add    \$0x12,%al
+ +[a-f0-9]+:	81 c0 45 03 00 00    	add    \$0x345,%eax
+ +[a-f0-9]+:	24 12                	and    \$0x12,%al
+ +[a-f0-9]+:	25 45 03 00 00       	and    \$0x345,%eax
+ +[a-f0-9]+:	80 e0 12             	and    \$0x12,%al
+ +[a-f0-9]+:	81 e0 45 03 00 00    	and    \$0x345,%eax
+ +[a-f0-9]+:	80 e0 12             	and    \$0x12,%al
+ +[a-f0-9]+:	81 e0 45 03 00 00    	and    \$0x345,%eax
+ +[a-f0-9]+:	3c 12                	cmp    \$0x12,%al
+ +[a-f0-9]+:	3d 45 03 00 00       	cmp    \$0x345,%eax
+ +[a-f0-9]+:	80 f8 12             	cmp    \$0x12,%al
+ +[a-f0-9]+:	81 f8 45 03 00 00    	cmp    \$0x345,%eax
+ +[a-f0-9]+:	3c 12                	cmp    \$0x12,%al
+ +[a-f0-9]+:	3d 45 03 00 00       	cmp    \$0x345,%eax
+ +[a-f0-9]+:	0c 12                	or     \$0x12,%al
+ +[a-f0-9]+:	0d 45 03 00 00       	or     \$0x345,%eax
+ +[a-f0-9]+:	80 c8 12             	or     \$0x12,%al
+ +[a-f0-9]+:	81 c8 45 03 00 00    	or     \$0x345,%eax
+ +[a-f0-9]+:	80 c8 12             	or     \$0x12,%al
+ +[a-f0-9]+:	81 c8 45 03 00 00    	or     \$0x345,%eax
+ +[a-f0-9]+:	1c 12                	sbb    \$0x12,%al
+ +[a-f0-9]+:	1d 45 03 00 00       	sbb    \$0x345,%eax
+ +[a-f0-9]+:	80 d8 12             	sbb    \$0x12,%al
+ +[a-f0-9]+:	81 d8 45 03 00 00    	sbb    \$0x345,%eax
+ +[a-f0-9]+:	80 d8 12             	sbb    \$0x12,%al
+ +[a-f0-9]+:	81 d8 45 03 00 00    	sbb    \$0x345,%eax
+ +[a-f0-9]+:	2c 12                	sub    \$0x12,%al
+ +[a-f0-9]+:	2d 45 03 00 00       	sub    \$0x345,%eax
+ +[a-f0-9]+:	80 e8 12             	sub    \$0x12,%al
+ +[a-f0-9]+:	81 e8 45 03 00 00    	sub    \$0x345,%eax
+ +[a-f0-9]+:	80 e8 12             	sub    \$0x12,%al
+ +[a-f0-9]+:	81 e8 45 03 00 00    	sub    \$0x345,%eax
+ +[a-f0-9]+:	a8 12                	test   \$0x12,%al
+ +[a-f0-9]+:	a9 45 03 00 00       	test   \$0x345,%eax
+ +[a-f0-9]+:	f6 c0 12             	test   \$0x12,%al
+ +[a-f0-9]+:	f7 c0 45 03 00 00    	test   \$0x345,%eax
+ +[a-f0-9]+:	a8 12                	test   \$0x12,%al
+ +[a-f0-9]+:	a9 45 03 00 00       	test   \$0x345,%eax
+ +[a-f0-9]+:	34 12                	xor    \$0x12,%al
+ +[a-f0-9]+:	35 45 03 00 00       	xor    \$0x345,%eax
+ +[a-f0-9]+:	80 f0 12             	xor    \$0x12,%al
+ +[a-f0-9]+:	81 f0 45 03 00 00    	xor    \$0x345,%eax
+ +[a-f0-9]+:	80 f0 12             	xor    \$0x12,%al
+ +[a-f0-9]+:	81 f0 45 03 00 00    	xor    \$0x345,%eax
+ +[a-f0-9]+:	48 b9 89 67 45 23 01 00 00 00 	movabs \$0x123456789,%rcx
+ +[a-f0-9]+:	48 b9 89 67 45 23 01 00 00 00 	movabs \$0x123456789,%rcx
+ +[a-f0-9]+:	48 b9 89 67 45 23 01 00 00 00 	movabs \$0x123456789,%rcx
+ +[a-f0-9]+:	48 b9 78 56 34 12 00 00 00 00 	movabs \$0x12345678,%rcx
+ +[a-f0-9]+:	48 b9 78 56 34 12 00 00 00 00 	movabs \$0x12345678,%rcx
+ +[a-f0-9]+:	48 b9 78 56 34 12 00 00 00 00 	movabs \$0x12345678,%rcx
+ +[a-f0-9]+:	51                   	push   %rcx
+ +[a-f0-9]+:	ff f1                	push   %rcx
+ +[a-f0-9]+:	51                   	push   %rcx
+ +[a-f0-9]+:	59                   	pop    %rcx
+ +[a-f0-9]+:	59                   	pop    %rcx
+ +[a-f0-9]+:	8f c1                	pop    %rcx
+ +[a-f0-9]+:	48 0f c9             	bswap  %rcx
+ +[a-f0-9]+:	48 0f c9             	bswap  %rcx
+ +[a-f0-9]+:	48 0f c9             	bswap  %rcx
+ +[a-f0-9]+:	87 ce                	xchg   %ecx,%esi
+ +[a-f0-9]+:	87 f1                	xchg   %esi,%ecx
+ +[a-f0-9]+:	87 f1                	xchg   %esi,%ecx
+ +[a-f0-9]+:	87 ce                	xchg   %ecx,%esi
+ +[a-f0-9]+:	96                   	xchg   %eax,%esi
+ +[a-f0-9]+:	87 f0                	xchg   %esi,%eax
+ +[a-f0-9]+:	87 c6                	xchg   %eax,%esi
+ +[a-f0-9]+:	91                   	xchg   %eax,%ecx
+ +[a-f0-9]+:	87 c1                	xchg   %eax,%ecx
+ +[a-f0-9]+:	87 c8                	xchg   %ecx,%eax
  +[a-f0-9]+:	d8 c0                	fadd   %st\(0\),%st
  +[a-f0-9]+:	d8 c0                	fadd   %st\(0\),%st
  +[a-f0-9]+:	dc c0                	fadd   %st,%st\(0\)
diff --git a/gas/testsuite/gas/i386/x86-64-pseudos.s b/gas/testsuite/gas/i386/x86-64-pseudos.s
index 3818df97..08fac83 100644
--- a/gas/testsuite/gas/i386/x86-64-pseudos.s
+++ b/gas/testsuite/gas/i386/x86-64-pseudos.s
@@ -135,6 +135,42 @@ _start:
 	{store} xor %eax, (%rdi)
 	{store} xor (%rdi), %eax
 
+	.irp m, mov, adc, add, and, cmp, or, sbb, sub, test, xor
+	\m	$0x12, %al
+	\m	$0x345, %eax
+	{load} \m $0x12, %al		# bogus for MOV
+	{load} \m $0x345, %eax		# bogus for MOV
+	{store} \m $0x12, %al
+	{store} \m $0x345, %eax
+	.endr
+
+	# There should be no effect of the pseudo-prefixes on any of these.
+	mov	$0x123456789, %rcx
+	{load} mov $0x123456789, %rcx
+	{store} mov $0x123456789, %rcx
+	movabs	$0x12345678, %rcx
+	{load} movabs $0x12345678, %rcx
+	{store} movabs $0x12345678, %rcx
+
+	.irp m, push, pop, bswap
+	\m	%rcx
+	{load} \m %rcx			# bogus for POP
+	{store} \m %rcx			# bogus for PUSH
+	.endr
+
+	xchg	%ecx, %esi
+	xchg	%esi, %ecx
+	{load} xchg %ecx, %esi
+	{store} xchg %ecx, %esi
+
+	xchg	%eax, %esi
+	{load} xchg %eax, %esi
+	{store} xchg %eax, %esi
+
+	xchg	%ecx, %eax
+	{load} xchg %ecx, %eax
+	{store} xchg %ecx, %eax
+
 	fadd %st, %st
 	{load} fadd %st, %st
 	{store} fadd %st, %st