[PATCH][AArch64] Add combine pattern to fuse AESE/AESMC instructions

[Kyrill Tkachov <kyrylo.tkachov@foss.arm.com>]

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Hi all,

When the AESE,AESD and AESMC, AESMC instructions are generated through the appropriate arm_neon.h intrinsics
we really want to keep them together when the AESE feeds into an AESMC and fusion is supported by the target CPU.
We have macro-fusion hooks and scheduling model forwarding paths defined to facilitate that.
It is, however, not always enough.

This patch adds another mechanism for doing that.
When we can detect during combine that the required dependency is exists (AESE -> AESMC, AESD -> AESIMC)
just keep them together with a combine pattern throughout the rest of compilation.
We won't ever want to split them.

The testcases generate 4 AESE(D) instructions in a block followed by 4 AES(I)MC instructions that
consume the corresponding results and it also adds a bunch of computations in-between so that the
AESE and AESMC instructions are not trivially back-to-back, thus exercising the compiler's ability
to bring them together.

With this patch all 4 pairs are fused whereas before a couple of fusions would be missed due to intervening
arithmetic and memory instructions.

Bootstrapped and tested on aarch64-none-linux-gnu.

Ok for trunk?

Thanks,
Kyrill

2018-05-11  Kyrylo Tkachov  <kyrylo.tkachov@arm.com>

     * config/aarch64/aarch64-simd.md (*aarch64_crypto_aese_fused):
     New pattern.
     (aarch64_crypto_aesd_fused): Likewise.

2018-05-11  Kyrylo Tkachov  <kyrylo.tkachov@arm.com>

     * gcc.target/aarch64/crypto-fuse-1.c: New test.
     * gcc.target/aarch64/crypto-fuse-2.c: Likewise.

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diff --git a/gcc/config/aarch64/aarch64-simd.md b/gcc/config/aarch64/aarch64-simd.md
index 7c166b6c8ec40475d1e01561b613b590b6690ad5..9a6ed304432af0ca23ec7d3797783a3128776a6e 100644
--- a/gcc/config/aarch64/aarch64-simd.md
+++ b/gcc/config/aarch64/aarch64-simd.md
@@ -5790,6 +5790,44 @@ (define_insn "aarch64_crypto_aes<aesmc_op>v16qi"
       (const_string "yes")])]
 )
 
+;; When AESE/AESMC fusion is enabled we really want to keep the two together
+;; and enforce the register dependency without scheduling or register
+;; allocation messing up the order or introducing moves inbetween.
+;;  Mash the two together during combine.
+
+(define_insn "*aarch64_crypto_aese_fused"
+  [(set (match_operand:V16QI 0 "register_operand" "=&w")
+	(unspec:V16QI
+	  [(unspec:V16QI
+	    [(match_operand:V16QI 1 "register_operand" "0")
+	     (match_operand:V16QI 2 "register_operand" "w")] UNSPEC_AESE)
+	  ] UNSPEC_AESMC))]
+  "TARGET_SIMD && TARGET_AES
+   && aarch64_fusion_enabled_p (AARCH64_FUSE_AES_AESMC)"
+  "aese\\t%0.16b, %2.16b\;aesmc\\t%0.16b, %0.16b"
+  [(set_attr "type" "crypto_aese")
+   (set_attr "length" "8")]
+)
+
+;; When AESD/AESIMC fusion is enabled we really want to keep the two together
+;; and enforce the register dependency without scheduling or register
+;; allocation messing up the order or introducing moves inbetween.
+;;  Mash the two together during combine.
+
+(define_insn "*aarch64_crypto_aesd_fused"
+  [(set (match_operand:V16QI 0 "register_operand" "=&w")
+	(unspec:V16QI
+	  [(unspec:V16QI
+	    [(match_operand:V16QI 1 "register_operand" "0")
+	     (match_operand:V16QI 2 "register_operand" "w")] UNSPEC_AESD)
+	  ] UNSPEC_AESIMC))]
+  "TARGET_SIMD && TARGET_AES
+   && aarch64_fusion_enabled_p (AARCH64_FUSE_AES_AESMC)"
+  "aesd\\t%0.16b, %2.16b\;aesimc\\t%0.16b, %0.16b"
+  [(set_attr "type" "crypto_aese")
+   (set_attr "length" "8")]
+)
+
 ;; sha1
 
 (define_insn "aarch64_crypto_sha1hsi"
diff --git a/gcc/testsuite/gcc.target/aarch64/crypto-fuse-1.c b/gcc/testsuite/gcc.target/aarch64/crypto-fuse-1.c
new file mode 100644
index 0000000000000000000000000000000000000000..79fd6011ed946d746ed5f03d26c7fe661f3f8154
--- /dev/null
+++ b/gcc/testsuite/gcc.target/aarch64/crypto-fuse-1.c
@@ -0,0 +1,44 @@
+/* { dg-do compile } */
+/* { dg-options "-O3 -mcpu=cortex-a72+crypto -dp" } */
+
+#include <arm_neon.h>
+
+#define AESE(r, v, key) (r = vaeseq_u8 ((v), (key)));
+#define AESMC(r, i) (r = vaesmcq_u8 (i))
+
+uint8x16_t dummy;
+uint8x16_t a;
+uint8x16_t b;
+uint8x16_t c;
+uint8x16_t d;
+uint8x16_t e;
+
+void
+foo (void)
+{
+  AESE (a, a, e);
+  dummy = vaddq_u8 (dummy, dummy);
+  dummy = vaddq_u8 (dummy, dummy);
+  AESE (b, b, e);
+  dummy = vaddq_u8 (dummy, dummy);
+  dummy = vaddq_u8 (dummy, dummy);
+  AESE (c, c, e);
+  dummy = vaddq_u8 (dummy, dummy);
+  dummy = vaddq_u8 (dummy, dummy);
+  AESE (d, d, e);
+  dummy = vaddq_u8 (dummy, dummy);
+  dummy = vaddq_u8 (dummy, dummy);
+
+  AESMC (a, a);
+  dummy = vaddq_u8 (dummy, dummy);
+  dummy = vaddq_u8 (dummy, dummy);
+  AESMC (b, b);
+  dummy = vaddq_u8 (dummy, dummy);
+  dummy = vaddq_u8 (dummy, dummy);
+  AESMC (c, c);
+  dummy = vaddq_u8 (dummy, dummy);
+  dummy = vaddq_u8 (dummy, dummy);
+  AESMC (d, d);
+}
+
+/* { dg-final { scan-assembler-times "crypto_aese_fused" 4 } } */
\ No newline at end of file
diff --git a/gcc/testsuite/gcc.target/aarch64/crypto-fuse-2.c b/gcc/testsuite/gcc.target/aarch64/crypto-fuse-2.c
new file mode 100644
index 0000000000000000000000000000000000000000..ed9eb69e803b24ec16a72075c46a9b6e6898c2fe
--- /dev/null
+++ b/gcc/testsuite/gcc.target/aarch64/crypto-fuse-2.c
@@ -0,0 +1,44 @@
+/* { dg-do compile } */
+/* { dg-options "-O3 -mcpu=cortex-a72+crypto -dp" } */
+
+#include <arm_neon.h>
+
+#define AESE(r, v, key) (r = vaesdq_u8 ((v), (key)));
+#define AESMC(r, i) (r = vaesimcq_u8 (i))
+
+uint8x16_t dummy;
+uint8x16_t a;
+uint8x16_t b;
+uint8x16_t c;
+uint8x16_t d;
+uint8x16_t e;
+
+void
+foo (void)
+{
+  AESE (a, a, e);
+  dummy = vaddq_u8 (dummy, dummy);
+  dummy = vaddq_u8 (dummy, dummy);
+  AESE (b, b, e);
+  dummy = vaddq_u8 (dummy, dummy);
+  dummy = vaddq_u8 (dummy, dummy);
+  AESE (c, c, e);
+  dummy = vaddq_u8 (dummy, dummy);
+  dummy = vaddq_u8 (dummy, dummy);
+  AESE (d, d, e);
+  dummy = vaddq_u8 (dummy, dummy);
+  dummy = vaddq_u8 (dummy, dummy);
+
+  AESMC (a, a);
+  dummy = vaddq_u8 (dummy, dummy);
+  dummy = vaddq_u8 (dummy, dummy);
+  AESMC (b, b);
+  dummy = vaddq_u8 (dummy, dummy);
+  dummy = vaddq_u8 (dummy, dummy);
+  AESMC (c, c);
+  dummy = vaddq_u8 (dummy, dummy);
+  dummy = vaddq_u8 (dummy, dummy);
+  AESMC (d, d);
+}
+
+/* { dg-final { scan-assembler-times "crypto_aesd_fused" 4 } } */
\ No newline at end of file