mmx.md (unspec): Move from config/i386/i386.md (unspecv) <UNSPECV_EMMS, UNSPECV_FEMMS>: Ditto.

	* config/i386/mmx.md (unspec) <UNSPEC_MOVNTQ, UNSPEC_PFRCP,
	UNSPEC_PFRCPIT1, UNSPEC_PFRCPIT2, UNSPEC_PFRSQRT, UNSPEC_PFRSQIT1>:
	Move from config/i386/i386.md
	(unspecv) <UNSPECV_EMMS, UNSPECV_FEMMS>: Ditto.
	* config/i386/sse.md (unspec) <UNSPEC_MOVNT,UNSPEC_MOVU, UNSPEC_LDDQU,
	UNSPEC_PSHUFB, UNSPEC_PSIGN, UNSPEC_PALIGNR, UNSPEC_EXTRQI,
	UNSPEC_EXTRQ, UNSPEC_INSERTQI, UNSPEC_INSERTQ, UNSPEC_BLENDV,
	UNSPEC_INSERTPS, UNSPEC_DP, UNSPEC_MOVNTDQA, UNSPEC_MPSADBW,
	UNSPEC_PHMINPOSUW, UNSPEC_PTEST, UNSPEC_PCMPESTR, UNSPEC_PCMPISTR,
	UNSPEC_FMADDSUB, UNSPEC_XOP_UNSIGNED_CMP, UNSPEC_XOP_TRUEFALSE,
	UNSPEC_XOP_PERMUTE, UNSPEC_FRCZ, UNSPEC_AESENC, UNSPEC_AESENCLAST,
	UNSPEC_AESDEC, UNSPEC_AESDECLAST, UNSPEC_AESIMC,
	UNSPEC_AESKEYGENASSIST, UNSPEC_PCLMUL, UNSPEC_PCMP, UNSPEC_VPERMIL,
	UNSPEC_VPERMIL2, UNSPEC_VPERMIL2F128, UNSPEC_CAST, UNSPEC_VTESTP,
	UNSPEC_VCVTPH2PS, UNSPEC_VCVTPS2PH, UNSPEC_VPERMSI, UNSPEC_VPERMDF,
	UNSPEC_VPERMSF, UNSPEC_VPERMTI, UNSPEC_GATHER, UNSPEC_VSIBADDR>: Ditto.
	(unspecv) <UNSPECV_LDMXCSR, UNSPECV_STMXCSR, UNSPECV_CLFLUSH,
	UNSPECV_MONITOR, UNSPECV_MWAIT, UNSPECV_VZEROALL, UNSPECV_VZEROUPPER>:
	Ditto.
	* config/i386/sync.md (unspec) <UNSPEC_LFENCE, UNSPEC_SFENCE,
	UNSPEC_MFENCE, UNSPEC_MOVA>: Ditto.
	(unspecv) <UNSPECV_CMPXCHG_1, UNSPECV_CMPXCHG_2, UNSPECV_CMPXCHG_3,
	UNSPECV_CMPXCHG_4, UNSPECV_XCHG, UNSPECV_LOCK>: Ditto.
	(sse2_lfence): Move from config/i386/sse.md.
	(*sse2_lfence): Ditto.
	(sse_sfence): Ditto.
	(*sse_sfence): Ditto.
	(sse2_mfence): Ditto.
	(mfence_sse2): Ditto.  Rename from *sse2_mfence.  Enable also
	for TARGET_64BIT.
	(mem_thread_fence): Use mfence_sse2.

From-SVN: r181590

5 files changed, 227 insertions, 167 deletions

diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index ad20f69..8966e42 100644
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,37 @@
+2011-11-21  Uros Bizjak  <ubizjak@gmail.com>
+
+	* config/i386/mmx.md (unspec) <UNSPEC_MOVNTQ, UNSPEC_PFRCP,
+	UNSPEC_PFRCPIT1, UNSPEC_PFRCPIT2, UNSPEC_PFRSQRT, UNSPEC_PFRSQIT1>:
+	Move from config/i386/i386.md
+	(unspecv) <UNSPECV_EMMS, UNSPECV_FEMMS>: Ditto.
+	* config/i386/sse.md (unspec) <UNSPEC_MOVNT,UNSPEC_MOVU, UNSPEC_LDDQU,
+	UNSPEC_PSHUFB, UNSPEC_PSIGN, UNSPEC_PALIGNR, UNSPEC_EXTRQI,
+	UNSPEC_EXTRQ, UNSPEC_INSERTQI, UNSPEC_INSERTQ, UNSPEC_BLENDV,
+	UNSPEC_INSERTPS, UNSPEC_DP, UNSPEC_MOVNTDQA, UNSPEC_MPSADBW,
+	UNSPEC_PHMINPOSUW, UNSPEC_PTEST, UNSPEC_PCMPESTR, UNSPEC_PCMPISTR,
+	UNSPEC_FMADDSUB, UNSPEC_XOP_UNSIGNED_CMP, UNSPEC_XOP_TRUEFALSE,
+	UNSPEC_XOP_PERMUTE, UNSPEC_FRCZ, UNSPEC_AESENC, UNSPEC_AESENCLAST,
+	UNSPEC_AESDEC, UNSPEC_AESDECLAST, UNSPEC_AESIMC,
+	UNSPEC_AESKEYGENASSIST, UNSPEC_PCLMUL, UNSPEC_PCMP, UNSPEC_VPERMIL,
+	UNSPEC_VPERMIL2, UNSPEC_VPERMIL2F128, UNSPEC_CAST, UNSPEC_VTESTP,
+	UNSPEC_VCVTPH2PS, UNSPEC_VCVTPS2PH, UNSPEC_VPERMSI, UNSPEC_VPERMDF,
+	UNSPEC_VPERMSF, UNSPEC_VPERMTI, UNSPEC_GATHER, UNSPEC_VSIBADDR>: Ditto.
+	(unspecv) <UNSPECV_LDMXCSR, UNSPECV_STMXCSR, UNSPECV_CLFLUSH,
+	UNSPECV_MONITOR, UNSPECV_MWAIT, UNSPECV_VZEROALL, UNSPECV_VZEROUPPER>:
+	Ditto.
+	* config/i386/sync.md (unspec) <UNSPEC_LFENCE, UNSPEC_SFENCE,
+	UNSPEC_MFENCE, UNSPEC_MOVA>: Ditto.
+	(unspecv) <UNSPECV_CMPXCHG_1, UNSPECV_CMPXCHG_2, UNSPECV_CMPXCHG_3,
+	UNSPECV_CMPXCHG_4, UNSPECV_XCHG, UNSPECV_LOCK>: Ditto.
+	(sse2_lfence): Move from config/i386/sse.md.
+	(*sse2_lfence): Ditto.
+	(sse_sfence): Ditto.
+	(*sse_sfence): Ditto.
+	(sse2_mfence): Ditto.
+	(mfence_sse2): Ditto.  Rename from *sse2_mfence.  Enable also
+	for TARGET_64BIT.
+	(mem_thread_fence): Use mfence_sse2.
+
 2011-11-21  Georg-Johann Lay  <avr@gjlay.de>
 
 	* config/avr/avr.h (struct base_arch_s): Add field sfr_offset.
diff --git a/gcc/config/i386/i386.md b/gcc/config/i386/i386.md
index 912c172..fa306ba 100644
--- a/gcc/config/i386/i386.md
+++ b/gcc/config/i386/i386.md
@@ -62,8 +62,6 @@
 ;; ; -- print a semicolon (after prefixes due to bug in older gas).
 ;; @ -- print a segment register of thread base pointer load
 
-;; UNSPEC usage:
-
 (define_c_enum "unspec" [
   ;; Relocation specifiers
   UNSPEC_GOT
@@ -108,6 +106,7 @@
   UNSPEC_LD_MPIC	; load_macho_picbase
   UNSPEC_TRUNC_NOOP
   UNSPEC_DIV_ALREADY_SPLIT
+  UNSPEC_MS_TO_SYSV_CALL
   UNSPEC_CALL_NEEDS_VZEROUPPER
   UNSPEC_PAUSE
 
@@ -115,22 +114,9 @@
   UNSPEC_FIX_NOTRUNC
   UNSPEC_MASKMOV
   UNSPEC_MOVMSK
-  UNSPEC_MOVNTQ
-  UNSPEC_MOVNT
-  UNSPEC_MOVU
   UNSPEC_RCP
   UNSPEC_RSQRT
-  UNSPEC_SFENCE
-  UNSPEC_PFRCP
-  UNSPEC_PFRCPIT1
-  UNSPEC_PFRCPIT2
-  UNSPEC_PFRSQRT
-  UNSPEC_PFRSQIT1
-  UNSPEC_MFENCE
-  UNSPEC_LFENCE
   UNSPEC_PSADBW
-  UNSPEC_LDDQU
-  UNSPEC_MS_TO_SYSV_CALL
 
   ;; Generic math support
   UNSPEC_COPYSIGN
@@ -178,105 +164,32 @@
   UNSPEC_SP_TLS_SET
   UNSPEC_SP_TLS_TEST
 
-  ;; SSSE3
-  UNSPEC_PSHUFB
-  UNSPEC_PSIGN
-  UNSPEC_PALIGNR
-
-  ;; For SSE4A support
-  UNSPEC_EXTRQI
-  UNSPEC_EXTRQ
-  UNSPEC_INSERTQI
-  UNSPEC_INSERTQ
-
-  ;; For SSE4.1 support
-  UNSPEC_BLENDV
-  UNSPEC_INSERTPS
-  UNSPEC_DP
-  UNSPEC_MOVNTDQA
-  UNSPEC_MPSADBW
-  UNSPEC_PHMINPOSUW
-  UNSPEC_PTEST
+  ;; For ROUND support
   UNSPEC_ROUND
 
-  ;; For SSE4.2 support
+  ;; For CRC32 support
   UNSPEC_CRC32
-  UNSPEC_PCMPESTR
-  UNSPEC_PCMPISTR
-
-  ;; For FMA4 support
-  UNSPEC_FMADDSUB
-  UNSPEC_XOP_UNSIGNED_CMP
-  UNSPEC_XOP_TRUEFALSE
-  UNSPEC_XOP_PERMUTE
-  UNSPEC_FRCZ
-
-  ;; For AES support
-  UNSPEC_AESENC
-  UNSPEC_AESENCLAST
-  UNSPEC_AESDEC
-  UNSPEC_AESDECLAST
-  UNSPEC_AESIMC
-  UNSPEC_AESKEYGENASSIST
-
-  ;; For PCLMUL support
-  UNSPEC_PCLMUL
-
-  ;; For AVX support
-  UNSPEC_PCMP
-  UNSPEC_VPERMIL
-  UNSPEC_VPERMIL2
-  UNSPEC_VPERMIL2F128
-  UNSPEC_CAST
-  UNSPEC_VTESTP
-  UNSPEC_VCVTPH2PS
-  UNSPEC_VCVTPS2PH
-
-  ;; For AVX2 support
-  UNSPEC_VPERMSI
-  UNSPEC_VPERMDF
-  UNSPEC_VPERMSF
-  UNSPEC_VPERMTI
-  UNSPEC_GATHER
-  UNSPEC_VSIBADDR
-
-  ;; For BMI support
-  UNSPEC_BEXTR
 
   ;; For RDRAND support
   UNSPEC_RDRAND
 
+  ;; For BMI support
+  UNSPEC_BEXTR
+
   ;; For BMI2 support
   UNSPEC_PDEP
   UNSPEC_PEXT
-
-  ;; For __atomic support
-  UNSPEC_MOVA
 ])
 
 (define_c_enum "unspecv" [
   UNSPECV_BLOCKAGE
   UNSPECV_STACK_PROBE
   UNSPECV_PROBE_STACK_RANGE
-  UNSPECV_EMMS
-  UNSPECV_LDMXCSR
-  UNSPECV_STMXCSR
-  UNSPECV_FEMMS
-  UNSPECV_CLFLUSH
   UNSPECV_ALIGN
-  UNSPECV_MONITOR
-  UNSPECV_MWAIT
-  UNSPECV_CMPXCHG_1
-  UNSPECV_CMPXCHG_2
-  UNSPECV_CMPXCHG_3
-  UNSPECV_CMPXCHG_4
-  UNSPECV_XCHG
-  UNSPECV_LOCK
   UNSPECV_PROLOGUE_USE
+  UNSPECV_SPLIT_STACK_RETURN
   UNSPECV_CLD
   UNSPECV_NOPS
-  UNSPECV_VZEROALL
-  UNSPECV_VZEROUPPER
   UNSPECV_RDTSC
   UNSPECV_RDTSCP
   UNSPECV_RDPMC
@@ -288,7 +201,6 @@
   UNSPECV_RDGSBASE
   UNSPECV_WRFSBASE
   UNSPECV_WRGSBASE
-  UNSPECV_SPLIT_STACK_RETURN
 ])
 
 ;; Constants to represent rounding modes in the ROUND instruction
diff --git a/gcc/config/i386/mmx.md b/gcc/config/i386/mmx.md
index 7fa072e..e859b9f 100644
--- a/gcc/config/i386/mmx.md
+++ b/gcc/config/i386/mmx.md
@@ -30,6 +30,20 @@
 ;; means that we should never use any of these patterns except at the
 ;; direction of the user via a builtin.
 
+(define_c_enum "unspec" [
+  UNSPEC_MOVNTQ
+  UNSPEC_PFRCP
+  UNSPEC_PFRCPIT1
+  UNSPEC_PFRCPIT2
+  UNSPEC_PFRSQRT
+  UNSPEC_PFRSQIT1
+])
+
+(define_c_enum "unspecv" [
+  UNSPECV_EMMS
+  UNSPECV_FEMMS
+])
+
 ;; 8 byte integral modes handled by MMX (and by extension, SSE)
 (define_mode_iterator MMXMODEI [V8QI V4HI V2SI])
 (define_mode_iterator MMXMODEI8 [V8QI V4HI V2SI V1DI])
diff --git a/gcc/config/i386/sse.md b/gcc/config/i386/sse.md
index 8955996..97fc333 100644
--- a/gcc/config/i386/sse.md
+++ b/gcc/config/i386/sse.md
@@ -18,6 +18,85 @@
 ;; along with GCC; see the file COPYING3.  If not see
 ;; <http://www.gnu.org/licenses/>.
 
+(define_c_enum "unspec" [
+  ;; SSE
+  UNSPEC_MOVNT
+  UNSPEC_MOVU
+
+  ;; SSE3
+  UNSPEC_LDDQU
+
+  ;; SSSE3
+  UNSPEC_PSHUFB
+  UNSPEC_PSIGN
+  UNSPEC_PALIGNR
+
+  ;; For SSE4A support
+  UNSPEC_EXTRQI
+  UNSPEC_EXTRQ
+  UNSPEC_INSERTQI
+  UNSPEC_INSERTQ
+
+  ;; For SSE4.1 support
+  UNSPEC_BLENDV
+  UNSPEC_INSERTPS
+  UNSPEC_DP
+  UNSPEC_MOVNTDQA
+  UNSPEC_MPSADBW
+  UNSPEC_PHMINPOSUW
+  UNSPEC_PTEST
+
+  ;; For SSE4.2 support
+  UNSPEC_PCMPESTR
+  UNSPEC_PCMPISTR
+
+  ;; For FMA4 support
+  UNSPEC_FMADDSUB
+  UNSPEC_XOP_UNSIGNED_CMP
+  UNSPEC_XOP_TRUEFALSE
+  UNSPEC_XOP_PERMUTE
+  UNSPEC_FRCZ
+
+  ;; For AES support
+  UNSPEC_AESENC
+  UNSPEC_AESENCLAST
+  UNSPEC_AESDEC
+  UNSPEC_AESDECLAST
+  UNSPEC_AESIMC
+  UNSPEC_AESKEYGENASSIST
+
+  ;; For PCLMUL support
+  UNSPEC_PCLMUL
+
+  ;; For AVX support
+  UNSPEC_PCMP
+  UNSPEC_VPERMIL
+  UNSPEC_VPERMIL2
+  UNSPEC_VPERMIL2F128
+  UNSPEC_CAST
+  UNSPEC_VTESTP
+  UNSPEC_VCVTPH2PS
+  UNSPEC_VCVTPS2PH
+
+  ;; For AVX2 support
+  UNSPEC_VPERMSI
+  UNSPEC_VPERMDF
+  UNSPEC_VPERMSF
+  UNSPEC_VPERMTI
+  UNSPEC_GATHER
+  UNSPEC_VSIBADDR
+])
+
+(define_c_enum "unspecv" [
+  UNSPECV_LDMXCSR
+  UNSPECV_STMXCSR
+  UNSPECV_CLFLUSH
+  UNSPECV_MONITOR
+  UNSPECV_MWAIT
+  UNSPECV_VZEROALL
+  UNSPECV_VZEROUPPER
+])
+
 ;; All vector modes including V?TImode, used in move patterns.
 (define_mode_iterator V16
   [(V32QI "TARGET_AVX") V16QI
@@ -8041,25 +8120,6 @@
    (set_attr "prefix" "maybe_vex")
    (set_attr "memory" "store")])
 
-(define_expand "sse_sfence"
-  [(set (match_dup 0)
-	(unspec:BLK [(match_dup 0)] UNSPEC_SFENCE))]
-  "TARGET_SSE || TARGET_3DNOW_A"
-{
-  operands[0] = gen_rtx_MEM (BLKmode, gen_rtx_SCRATCH (Pmode));
-  MEM_VOLATILE_P (operands[0]) = 1;
-})
-
-(define_insn "*sse_sfence"
-  [(set (match_operand:BLK 0 "" "")
-	(unspec:BLK [(match_dup 0)] UNSPEC_SFENCE))]
-  "TARGET_SSE || TARGET_3DNOW_A"
-  "sfence"
-  [(set_attr "type" "sse")
-   (set_attr "length_address" "0")
-   (set_attr "atom_sse_attr" "fence")
-   (set_attr "memory" "unknown")])
-
 (define_insn "sse2_clflush"
   [(unspec_volatile [(match_operand 0 "address_operand" "p")]
 		    UNSPECV_CLFLUSH)]
@@ -8069,43 +8129,6 @@
    (set_attr "atom_sse_attr" "fence")
    (set_attr "memory" "unknown")])
 
-(define_expand "sse2_mfence"
-  [(set (match_dup 0)
-	(unspec:BLK [(match_dup 0)] UNSPEC_MFENCE))]
-  "TARGET_SSE2"
-{
-  operands[0] = gen_rtx_MEM (BLKmode, gen_rtx_SCRATCH (Pmode));
-  MEM_VOLATILE_P (operands[0]) = 1;
-})
-
-(define_insn "*sse2_mfence"
-  [(set (match_operand:BLK 0 "" "")
-	(unspec:BLK [(match_dup 0)] UNSPEC_MFENCE))]
-  "TARGET_64BIT || TARGET_SSE2"
-  "mfence"
-  [(set_attr "type" "sse")
-   (set_attr "length_address" "0")
-   (set_attr "atom_sse_attr" "fence")
-   (set_attr "memory" "unknown")])
-
-(define_expand "sse2_lfence"
-  [(set (match_dup 0)
-	(unspec:BLK [(match_dup 0)] UNSPEC_LFENCE))]
-  "TARGET_SSE2"
-{
-  operands[0] = gen_rtx_MEM (BLKmode, gen_rtx_SCRATCH (Pmode));
-  MEM_VOLATILE_P (operands[0]) = 1;
-})
-
-(define_insn "*sse2_lfence"
-  [(set (match_operand:BLK 0 "" "")
-	(unspec:BLK [(match_dup 0)] UNSPEC_LFENCE))]
-  "TARGET_SSE2"
-  "lfence"
-  [(set_attr "type" "sse")
-   (set_attr "length_address" "0")
-   (set_attr "atom_sse_attr" "lfence")
-   (set_attr "memory" "unknown")])
 
 (define_insn "sse3_mwait"
   [(unspec_volatile [(match_operand:SI 0 "register_operand" "a")
diff --git a/gcc/config/i386/sync.md b/gcc/config/i386/sync.md
index 0ff1712..542d3b8 100644
--- a/gcc/config/i386/sync.md
+++ b/gcc/config/i386/sync.md
@@ -18,26 +18,79 @@
 ;; along with GCC; see the file COPYING3.  If not see
 ;; <http://www.gnu.org/licenses/>.
 
-(define_expand "mem_thread_fence"
-  [(match_operand:SI 0 "const_int_operand" "")]		;; model
-  ""
+(define_c_enum "unspec" [
+  UNSPEC_LFENCE
+  UNSPEC_SFENCE
+  UNSPEC_MFENCE
+  UNSPEC_MOVA	; For __atomic support
+])
+
+(define_c_enum "unspecv" [
+  UNSPECV_CMPXCHG_1
+  UNSPECV_CMPXCHG_2
+  UNSPECV_CMPXCHG_3
+  UNSPECV_CMPXCHG_4
+  UNSPECV_XCHG
+  UNSPECV_LOCK
+])
+
+(define_expand "sse2_lfence"
+  [(set (match_dup 0)
+	(unspec:BLK [(match_dup 0)] UNSPEC_LFENCE))]
+  "TARGET_SSE2"
 {
-  /* Unless this is a SEQ_CST fence, the i386 memory model is strong
-     enough not to require barriers of any kind.  */
-  if (INTVAL (operands[0]) != MEMMODEL_SEQ_CST)
-    DONE;
+  operands[0] = gen_rtx_MEM (BLKmode, gen_rtx_SCRATCH (Pmode));
+  MEM_VOLATILE_P (operands[0]) = 1;
+})
 
-  if (TARGET_64BIT || TARGET_SSE2)
-    emit_insn (gen_sse2_mfence ());
-  else
-    {
-      rtx mem = gen_rtx_MEM (BLKmode, gen_rtx_SCRATCH (Pmode));
-      MEM_VOLATILE_P (mem) = 1;
-      emit_insn (gen_mfence_nosse (mem));
-    }
-  DONE;
+(define_insn "*sse2_lfence"
+  [(set (match_operand:BLK 0 "" "")
+	(unspec:BLK [(match_dup 0)] UNSPEC_LFENCE))]
+  "TARGET_SSE2"
+  "lfence"
+  [(set_attr "type" "sse")
+   (set_attr "length_address" "0")
+   (set_attr "atom_sse_attr" "lfence")
+   (set_attr "memory" "unknown")])
+
+(define_expand "sse_sfence"
+  [(set (match_dup 0)
+	(unspec:BLK [(match_dup 0)] UNSPEC_SFENCE))]
+  "TARGET_SSE || TARGET_3DNOW_A"
+{
+  operands[0] = gen_rtx_MEM (BLKmode, gen_rtx_SCRATCH (Pmode));
+  MEM_VOLATILE_P (operands[0]) = 1;
 })
 
+(define_insn "*sse_sfence"
+  [(set (match_operand:BLK 0 "" "")
+	(unspec:BLK [(match_dup 0)] UNSPEC_SFENCE))]
+  "TARGET_SSE || TARGET_3DNOW_A"
+  "sfence"
+  [(set_attr "type" "sse")
+   (set_attr "length_address" "0")
+   (set_attr "atom_sse_attr" "fence")
+   (set_attr "memory" "unknown")])
+
+(define_expand "sse2_mfence"
+  [(set (match_dup 0)
+	(unspec:BLK [(match_dup 0)] UNSPEC_MFENCE))]
+  "TARGET_SSE2"
+{
+  operands[0] = gen_rtx_MEM (BLKmode, gen_rtx_SCRATCH (Pmode));
+  MEM_VOLATILE_P (operands[0]) = 1;
+})
+
+(define_insn "mfence_sse2"
+  [(set (match_operand:BLK 0 "" "")
+	(unspec:BLK [(match_dup 0)] UNSPEC_MFENCE))]
+  "TARGET_64BIT || TARGET_SSE2"
+  "mfence"
+  [(set_attr "type" "sse")
+   (set_attr "length_address" "0")
+   (set_attr "atom_sse_attr" "fence")
+   (set_attr "memory" "unknown")])
+
 (define_insn "mfence_nosse"
   [(set (match_operand:BLK 0 "" "")
 	(unspec:BLK [(match_dup 0)] UNSPEC_MFENCE))
@@ -46,6 +99,30 @@
   "lock{%;} or{l}\t{$0, (%%esp)|DWORD PTR [esp], 0}"
   [(set_attr "memory" "unknown")])
 
+(define_expand "mem_thread_fence"
+  [(match_operand:SI 0 "const_int_operand" "")]		;; model
+  ""
+{
+  /* Unless this is a SEQ_CST fence, the i386 memory model is strong
+     enough not to require barriers of any kind.  */
+  if (INTVAL (operands[0]) == MEMMODEL_SEQ_CST)
+    {
+      rtx (*mfence_insn)(rtx);
+      rtx mem;
+
+      if (TARGET_64BIT || TARGET_SSE2)
+	mfence_insn = gen_mfence_sse2;
+      else
+	mfence_insn = gen_mfence_nosse;
+
+      mem = gen_rtx_MEM (BLKmode, gen_rtx_SCRATCH (Pmode));
+      MEM_VOLATILE_P (mem) = 1;
+
+      emit_insn (mfence_insn (mem));
+    }
+  DONE;
+})
+
 ;; ??? From volume 3 section 7.1.1 Guaranteed Atomic Operations,
 ;; Only beginning at Pentium family processors do we get any guarantee of
 ;; atomicity in aligned 64-bit quantities.  Beginning at P6, we get a