rs6000: Enable vector mode for by pieces equality compare

This patch adds a new expand pattern - cbranchv16qi4 to enable vector
mode by pieces equality compare on rs6000.  The macro MOVE_MAX_PIECES
(COMPARE_MAX_PIECES) is set to 16 bytes when EFFICIENT_UNALIGNED_VSX
is enabled, otherwise keeps unchanged.  The macro STORE_MAX_PIECES is
set to the same value as MOVE_MAX_PIECES by default, so now it's
explicitly defined and keeps unchanged.

gcc/
	PR target/111449
	* config/rs6000/altivec.md (cbranchv16qi4): New expand pattern.
	* config/rs6000/rs6000.cc (rs6000_generate_compare): Generate
	insn sequence for V16QImode equality compare.
	* config/rs6000/rs6000.h (MOVE_MAX_PIECES): Define.
	(STORE_MAX_PIECES): Define.

gcc/testsuite/
	PR target/111449
	* gcc.target/powerpc/pr111449-1.c: New.
	* gcc.dg/tree-ssa/sra-17.c: Add additional options for 32-bit powerpc.
	* gcc.dg/tree-ssa/sra-18.c: Likewise.

6 files changed, 77 insertions, 0 deletions

diff --git a/gcc/config/rs6000/altivec.md b/gcc/config/rs6000/altivec.md
index e8a596f..8a4998c 100644
--- a/gcc/config/rs6000/altivec.md
+++ b/gcc/config/rs6000/altivec.md
@@ -2605,6 +2605,48 @@
 }
   [(set_attr "type" "vecperm")])
 
+/* The cbranch_optab doesn't allow FAIL, so old cpus which are
+   inefficient on unaligned vsx are disabled as the cost is high
+   for unaligned load/store.  */
+(define_expand "cbranchv16qi4"
+  [(use (match_operator 0 "equality_operator"
+	[(match_operand:V16QI 1 "reg_or_mem_operand")
+	 (match_operand:V16QI 2 "reg_or_mem_operand")]))
+   (use (match_operand 3))]
+  "VECTOR_MEM_VSX_P (V16QImode)
+   && TARGET_EFFICIENT_UNALIGNED_VSX"
+{
+  /* Use direct move for P8 LE to skip doubleword swap, as the byte
+     order doesn't matter for equality compare.  If any operands are
+     altivec indexed or indirect operands, the load can be implemented
+     directly by altivec aligned load instruction and swap is no
+     need.  */
+  if (!TARGET_P9_VECTOR
+      && !BYTES_BIG_ENDIAN
+      && MEM_P (operands[1])
+      && !altivec_indexed_or_indirect_operand (operands[1], V16QImode)
+      && MEM_P (operands[2])
+      && !altivec_indexed_or_indirect_operand (operands[2], V16QImode))
+    {
+      rtx reg_op1 = gen_reg_rtx (V16QImode);
+      rtx reg_op2 = gen_reg_rtx (V16QImode);
+      rs6000_emit_le_vsx_permute (reg_op1, operands[1], V16QImode);
+      rs6000_emit_le_vsx_permute (reg_op2, operands[2], V16QImode);
+      operands[1] = reg_op1;
+      operands[2] = reg_op2;
+    }
+  else
+    {
+      operands[1] = force_reg (V16QImode, operands[1]);
+      operands[2] = force_reg (V16QImode, operands[2]);
+    }
+
+  rtx_code code = GET_CODE (operands[0]);
+  operands[0] = gen_rtx_fmt_ee (code, V16QImode, operands[1], operands[2]);
+  rs6000_emit_cbranch (V16QImode, operands);
+  DONE;
+})
+
 ;; Compare vectors producing a vector result and a predicate, setting CR6 to
 ;; indicate a combined status
 (define_insn "altivec_vcmpequ<VI_char>_p"
diff --git a/gcc/config/rs6000/rs6000.cc b/gcc/config/rs6000/rs6000.cc
index 5f56c3e..3dfd79c 100644
--- a/gcc/config/rs6000/rs6000.cc
+++ b/gcc/config/rs6000/rs6000.cc
@@ -15472,6 +15472,18 @@ rs6000_generate_compare (rtx cmp, machine_mode mode)
 	  else
 	    emit_insn (gen_stack_protect_testsi (compare_result, op0, op1b));
 	}
+      else if (mode == V16QImode)
+	{
+	  gcc_assert (code == EQ || code == NE);
+
+	  rtx result_vector = gen_reg_rtx (V16QImode);
+	  rtx cc_bit = gen_reg_rtx (SImode);
+	  emit_insn (gen_altivec_vcmpequb_p (result_vector, op0, op1));
+	  emit_insn (gen_cr6_test_for_lt (cc_bit));
+	  emit_insn (gen_rtx_SET (compare_result,
+				  gen_rtx_COMPARE (comp_mode, cc_bit,
+						   const1_rtx)));
+	}
       else
 	emit_insn (gen_rtx_SET (compare_result,
 				gen_rtx_COMPARE (comp_mode, op0, op1)));
diff --git a/gcc/config/rs6000/rs6000.h b/gcc/config/rs6000/rs6000.h
index 22595f6..326c452 100644
--- a/gcc/config/rs6000/rs6000.h
+++ b/gcc/config/rs6000/rs6000.h
@@ -1730,6 +1730,9 @@ typedef struct rs6000_args
    in one reasonably fast instruction.  */
 #define MOVE_MAX (! TARGET_POWERPC64 ? 4 : 8)
 #define MAX_MOVE_MAX 8
+#define MOVE_MAX_PIECES (TARGET_EFFICIENT_UNALIGNED_VSX \
+			 ? 16 : (TARGET_POWERPC64 ? 8 : 4))
+#define STORE_MAX_PIECES (TARGET_POWERPC64 ? 8 : 4)
 
 /* Nonzero if access to memory by bytes is no faster than for words.
    Also nonzero if doing byte operations (specifically shifts) in registers
diff --git a/gcc/testsuite/gcc.dg/tree-ssa/sra-17.c b/gcc/testsuite/gcc.dg/tree-ssa/sra-17.c
index 221d96b..b0d4811 100644
--- a/gcc/testsuite/gcc.dg/tree-ssa/sra-17.c
+++ b/gcc/testsuite/gcc.dg/tree-ssa/sra-17.c
@@ -1,6 +1,7 @@
 /* { dg-do run { target { aarch64*-*-* alpha*-*-* arm*-*-* hppa*-*-* powerpc*-*-* s390*-*-* } } } */
 /* { dg-options "-O2 -fdump-tree-esra --param sra-max-scalarization-size-Ospeed=32" } */
 /* { dg-additional-options "-mcpu=ev4" { target alpha*-*-* } } */
+/* { dg-additional-options "-mno-vsx" { target { powerpc*-*-* && ilp32 } } } */
 
 extern void abort (void);
 
diff --git a/gcc/testsuite/gcc.dg/tree-ssa/sra-18.c b/gcc/testsuite/gcc.dg/tree-ssa/sra-18.c
index f5e6a21..2cdeae6 100644
--- a/gcc/testsuite/gcc.dg/tree-ssa/sra-18.c
+++ b/gcc/testsuite/gcc.dg/tree-ssa/sra-18.c
@@ -1,6 +1,7 @@
 /* { dg-do run { target { aarch64*-*-* alpha*-*-* arm*-*-* hppa*-*-* powerpc*-*-* s390*-*-* } } } */
 /* { dg-options "-O2 -fdump-tree-esra --param sra-max-scalarization-size-Ospeed=32" } */
 /* { dg-additional-options "-mcpu=ev4" { target alpha*-*-* } } */
+/* { dg-additional-options "-mno-vsx" { target { powerpc*-*-* && ilp32 } } } */
 
 extern void abort (void);
 struct foo { long x; };
diff --git a/gcc/testsuite/gcc.target/powerpc/pr111449-1.c b/gcc/testsuite/gcc.target/powerpc/pr111449-1.c
new file mode 100644
index 0000000..0c9e176
--- /dev/null
+++ b/gcc/testsuite/gcc.target/powerpc/pr111449-1.c
@@ -0,0 +1,18 @@
+/* { dg-do compile } */
+/* { dg-require-effective-target powerpc_p8vector_ok } */
+/* { dg-options "-mdejagnu-cpu=power8 -mvsx -O2" } */
+
+/* Ensure vector mode is used for 16-byte by pieces equality compare.  */
+
+int compare1 (const char* s1, const char* s2)
+{
+  return __builtin_memcmp (s1, s2, 16) == 0;
+}
+
+int compare2 (const char* s1)
+{
+  return __builtin_memcmp (s1, "0123456789012345", 16) == 0;
+}
+
+/* { dg-final { scan-assembler-times {\mvcmpequb\.} 2 } } */
+/* { dg-final { scan-assembler-not {\mcmpd\M} } } */