[PATCH 02/11] Arm - add speculation_barrier pattern

[Richard Earnshaw <Richard.Earnshaw@arm.com>]

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This patch defines a speculation barrier for AArch32.

	* config/arm/unspecs.md (unspecv): Add VUNSPEC_SPECULATION_BARRIER.
	* config/arm/arm.md (speculation_barrier): New expand.
	(speculation_barrier_insn): New pattern.
---
 gcc/config/arm/arm.md     | 21 +++++++++++++++++++++
 gcc/config/arm/unspecs.md |  1 +
 2 files changed, 22 insertions(+)


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diff --git a/gcc/config/arm/arm.md b/gcc/config/arm/arm.md
index 361a026..ca2a2f5 100644
--- a/gcc/config/arm/arm.md
+++ b/gcc/config/arm/arm.md
@@ -12012,6 +12012,27 @@ (define_insn "<mrrc>"
   [(set_attr "length" "4")
    (set_attr "type" "coproc")])
 
+(define_expand "speculation_barrier"
+  [(unspec_volatile [(const_int 0)] VUNSPEC_SPECULATION_BARRIER)]
+  "TARGET_EITHER"
+  "
+    /* Don't emit anything for Thumb1 and suppress the warning from the
+       generic expansion.  */
+    if (!TARGET_32BIT)
+       DONE;
+  "
+)
+
+;; Generate a hard speculation barrier when we have not enabled speculation
+;; tracking.
+(define_insn "*speculation_barrier_insn"
+  [(unspec_volatile [(const_int 0)] VUNSPEC_SPECULATION_BARRIER)]
+  "TARGET_32BIT"
+  "isb\;dsb\\tsy"
+  [(set_attr "type" "block")
+   (set_attr "length" "8")]
+)
+
 ;; Vector bits common to IWMMXT and Neon
 (include "vec-common.md")
 ;; Load the Intel Wireless Multimedia Extension patterns
diff --git a/gcc/config/arm/unspecs.md b/gcc/config/arm/unspecs.md
index b05f85e..1941673 100644
--- a/gcc/config/arm/unspecs.md
+++ b/gcc/config/arm/unspecs.md
@@ -168,6 +168,7 @@ (define_c_enum "unspecv" [
   VUNSPEC_MCRR2		; Represent the coprocessor mcrr2 instruction.
   VUNSPEC_MRRC		; Represent the coprocessor mrrc instruction.
   VUNSPEC_MRRC2		; Represent the coprocessor mrrc2 instruction.
+  VUNSPEC_SPECULATION_BARRIER ; Represents an unconditional speculation barrier.
 ])
 
 ;; Enumerators for NEON unspecs.