re PR target/86677 (popcount builtin detection is breaking some kernel build)

gcc/ChangeLog:

2018-11-13  Kugan Vivekanandarajah  <kuganv@linaro.org>

	PR middle-end/86677
	PR middle-end/87528
	* tree-scalar-evolution.c (expression_expensive_p): Make BUILTIN POPCOUNT
	as expensive when backend does not define it.

gcc/testsuite/ChangeLog:

2018-11-13  Kugan Vivekanandarajah  <kuganv@linaro.org>

	PR middle-end/86677
	PR middle-end/87528
	* g++.dg/tree-ssa/pr86544.C: Run only for target supporting popcount
	pattern.
	* gcc.dg/tree-ssa/popcount.c: Likewise.
	* gcc.dg/tree-ssa/popcount2.c: Likewise.
	* gcc.dg/tree-ssa/popcount3.c: Likewise.
	* gcc.target/aarch64/popcount4.c: New test.
	* lib/target-supports.exp (check_effective_target_popcountl): New.

From-SVN: r266039

gcc/ChangeLog

@@ -1,3 +1,10 @@
+2018-11-13  Kugan Vivekanandarajah  <kuganv@linaro.org>
+
+	PR middle-end/86677
+	PR middle-end/87528
+	* tree-scalar-evolution.c (expression_expensive_p): Make BUILTIN POPCOUNT
+	as expensive when backend does not define it.
+
 2018-11-12  Fredrik Noring  <noring@nocrew.org>
 
 	* config.gcc: Update with-llsc defaults for MIPS r5900.

gcc/testsuite/ChangeLog

@@ -1,3 +1,15 @@
+2018-11-13  Kugan Vivekanandarajah  <kuganv@linaro.org>
+
+	PR middle-end/86677
+	PR middle-end/87528
+	* g++.dg/tree-ssa/pr86544.C: Run only for target supporting popcount
+	pattern.
+	* gcc.dg/tree-ssa/popcount.c: Likewise.
+	* gcc.dg/tree-ssa/popcount2.c: Likewise.
+	* gcc.dg/tree-ssa/popcount3.c: Likewise.
+	* gcc.target/aarch64/popcount4.c: New test.
+	* lib/target-supports.exp (check_effective_target_popcountl): New.
+
 2018-11-12  Martin Liska  <mliska@suse.cz>
 
 	PR gcov-profile/87442

gcc/testsuite/g++.dg/tree-ssa/pr86544.C

@@ -1,4 +1,5 @@
 /* { dg-do compile } */
+/* { dg-require-effective-target popcountl } */
 /* { dg-options "-O2 -fdump-tree-phiopt4 -fdump-tree-optimized" } */
 
 int PopCount (long b) {

gcc/testsuite/gcc.dg/tree-ssa/popcount.c

@@ -1,4 +1,5 @@
 /* { dg-do compile } */
+/* { dg-require-effective-target popcountl } */
 /* { dg-options "-O3 -fdump-tree-optimized -fno-tree-ch" } */
 
 extern int foo (int);

gcc/testsuite/gcc.dg/tree-ssa/popcount2.c

@@ -1,4 +1,5 @@
 /* { dg-do run } */
+/* { dg-require-effective-target popcountl } */
 /* { dg-options "-O2 -fno-tree-ch -fdump-tree-optimized" } */
 
 int

gcc/testsuite/gcc.dg/tree-ssa/popcount3.c

@@ -1,4 +1,5 @@
 /* { dg-do compile } */
+/* { dg-require-effective-target popcountl } */
 /* { dg-options "-O2 -fdump-tree-phiopt4 -fdump-tree-optimized" } */
 
 int PopCount (long b) {

gcc/testsuite/gcc.target/aarch64/popcount4.c

@@ -0,0 +1,14 @@
+/* { dg-do compile } */
+/* { dg-options "-O2 -fdump-tree-optimized -mgeneral-regs-only" } */
+
+int PopCount (long b) {
+    int c = 0;
+
+    while (b) {
+	b &= b - 1;
+	c++;
+    }
+    return c;
+}
+
+/* { dg-final { scan-tree-dump-times "__builtin_popcount" 0 "optimized" } } */

gcc/testsuite/lib/target-supports.exp

@@ -6522,6 +6522,17 @@ proc check_effective_target_sync_long_long { } {
     }
 }
 
+# Return 1 if the target supports popcount on long.
+
+proc check_effective_target_popcountl { } {
+    return [check_no_messages_and_pattern popcountl "!\\(call" rtl-expand {
+	int foo (long b)
+	  {
+	    return __builtin_popcountl (b);
+	  }
+    } "" ]
+}
+
 # Return 1 if the target supports atomic operations on "long long"
 # and can execute them.
 #

gcc/tree-scalar-evolution.c

@@ -257,7 +257,9 @@ along with GCC; see the file COPYING3.  If not see
 #include "system.h"
 #include "coretypes.h"
 #include "backend.h"
+#include "target.h"
 #include "rtl.h"
+#include "optabs-query.h"
 #include "tree.h"
 #include "gimple.h"
 #include "ssa.h"
@@ -282,6 +284,7 @@ along with GCC; see the file COPYING3.  If not see
 #include "gimple-fold.h"
 #include "tree-into-ssa.h"
 #include "builtins.h"
+#include "case-cfn-macros.h"
 
 static tree analyze_scalar_evolution_1 (struct loop *, tree);
 static tree analyze_scalar_evolution_for_address_of (struct loop *loop,
@@ -3500,6 +3503,36 @@ expression_expensive_p (tree expr)
     {
       tree arg;
       call_expr_arg_iterator iter;
+      /* Even though is_inexpensive_builtin might say true, we will get a
+	 library call for popcount when backend does not have an instruction
+	 to do so.  We consider this to be expenseive and generate
+	 __builtin_popcount only when backend defines it.  */
+      combined_fn cfn = get_call_combined_fn (expr);
+      switch (cfn)
+	{
+	CASE_CFN_POPCOUNT:
+	  /* Check if opcode for popcount is available in the mode required.  */
+	  if (optab_handler (popcount_optab,
+			     TYPE_MODE (TREE_TYPE (CALL_EXPR_ARG (expr, 0))))
+	      == CODE_FOR_nothing)
+	    {
+	      machine_mode mode;
+	      mode = TYPE_MODE (TREE_TYPE (CALL_EXPR_ARG (expr, 0)));
+	      scalar_int_mode int_mode;
+
+	      /* If the mode is of 2 * UNITS_PER_WORD size, we can handle
+		 double-word popcount by emitting two single-word popcount
+		 instructions.  */
+	      if (is_a <scalar_int_mode> (mode, &int_mode)
+		  && GET_MODE_SIZE (int_mode) == 2 * UNITS_PER_WORD
+		  && (optab_handler (popcount_optab, word_mode)
+		      != CODE_FOR_nothing))
+		  break;
+	      return true;
+	    }
+	default:
+	  break;
+	}
 
       if (!is_inexpensive_builtin (get_callee_fndecl (expr)))
 	return true;