Replace FMA_EXPR with one internal fn per optab

There are four optabs for various forms of fused multiply-add:
fma, fms, fnma and fnms.  Of these, only fma had a direct gimple
representation.  For the other three we relied on special pattern-
matching during expand, although tree-ssa-math-opts.c did have
some code to try to second-guess what expand would do.

This patch removes the old FMA_EXPR representation of fma and
introduces four new internal functions, one for each optab.
IFN_FMA is tied to BUILT_IN_FMA* while the other three are
independent directly-mapped internal functions.  It's then
possible to do the pattern-matching in match.pd and
tree-ssa-math-opts.c (via folding) can select the exact
FMA-based operation.

The BRIG & HSA parts are a best guess, but seem relatively simple.

2018-05-18  Richard Sandiford  <richard.sandiford@linaro.org>

gcc/
	* doc/sourcebuild.texi (scalar_all_fma): Document.
	* tree.def (FMA_EXPR): Delete.
	* internal-fn.def (FMA, FMS, FNMA, FNMS): New internal functions.
	* internal-fn.c (ternary_direct): New macro.
	(expand_ternary_optab_fn): Likewise.
	(direct_ternary_optab_supported_p): Likewise.
	* Makefile.in (build/genmatch.o): Depend on case-fn-macros.h.
	* builtins.c (fold_builtin_fma): Delete.
	(fold_builtin_3): Don't call it.
	* cfgexpand.c (expand_debug_expr): Remove FMA_EXPR handling.
	* expr.c (expand_expr_real_2): Likewise.
	* fold-const.c (operand_equal_p): Likewise.
	(fold_ternary_loc): Likewise.
	* gimple-pretty-print.c (dump_ternary_rhs): Likewise.
	* gimple.c (DEFTREECODE): Likewise.
	* gimplify.c (gimplify_expr): Likewise.
	* optabs-tree.c (optab_for_tree_code): Likewise.
	* tree-cfg.c (verify_gimple_assign_ternary): Likewise.
	* tree-eh.c (operation_could_trap_p): Likewise.
	(stmt_could_throw_1_p): Likewise.
	* tree-inline.c (estimate_operator_cost): Likewise.
	* tree-pretty-print.c (dump_generic_node): Likewise.
	(op_code_prio): Likewise.
	* tree-ssa-loop-im.c (stmt_cost): Likewise.
	* tree-ssa-operands.c (get_expr_operands): Likewise.
	* tree.c (commutative_ternary_tree_code, add_expr): Likewise.
	* fold-const-call.h (fold_fma): Delete.
	* fold-const-call.c (fold_const_call_ssss): Handle CFN_FMS,
	CFN_FNMA and CFN_FNMS.
	(fold_fma): Delete.
	* genmatch.c (combined_fn): New enum.
	(commutative_ternary_tree_code): Remove FMA_EXPR handling.
	(commutative_op): New function.
	(commutate): Use it.  Handle more than 2 operands.
	(dt_operand::gen_gimple_expr): Use commutative_op.
	(parser::parse_expr): Allow :c to be used with non-binary
	operators if the commutative operand is known.
	* gimple-ssa-backprop.c (backprop::process_builtin_call_use): Handle
	CFN_FMS, CFN_FNMA and CFN_FNMS.
	(backprop::process_assign_use): Remove FMA_EXPR handling.
	* hsa-gen.c (gen_hsa_insns_for_operation_assignment): Likewise.
	(gen_hsa_fma): New function.
	(gen_hsa_insn_for_internal_fn_call): Use it for IFN_FMA, IFN_FMS,
	IFN_FNMA and IFN_FNMS.
	* match.pd: Add folds for IFN_FMS, IFN_FNMA and IFN_FNMS.
	* gimple-fold.h (follow_all_ssa_edges): Declare.
	* gimple-fold.c (follow_all_ssa_edges): New function.
	* tree-ssa-math-opts.c (convert_mult_to_fma_1): Use the
	gimple_build interface and use follow_all_ssa_edges to fold the result.
	(convert_mult_to_fma): Use direct_internal_fn_suppoerted_p
	instead of checking for optabs directly.
	* config/i386/i386.c (ix86_add_stmt_cost): Recognize FMAs as calls
	rather than FMA_EXPRs.
	* config/rs6000/rs6000.c (rs6000_gimple_fold_builtin): Create a
	call to IFN_FMA instead of an FMA_EXPR.

gcc/brig/
	* brigfrontend/brig-function.cc
	(brig_function::get_builtin_for_hsa_opcode): Use BUILT_IN_FMA
	for BRIG_OPCODE_FMA.
	(brig_function::get_tree_code_for_hsa_opcode): Treat BUILT_IN_FMA
	as a call.

gcc/c/
	* gimple-parser.c (c_parser_gimple_postfix_expression): Remove
	__FMA_EXPR handlng.

gcc/cp/
	* constexpr.c (cxx_eval_constant_expression): Remove FMA_EXPR handling.
	(potential_constant_expression_1): Likewise.

gcc/testsuite/
	* lib/target-supports.exp (check_effective_target_scalar_all_fma):
	New proc.
	* gcc.dg/fma-1.c: New test.
	* gcc.dg/fma-2.c: Likewise.
	* gcc.dg/fma-3.c: Likewise.
	* gcc.dg/fma-4.c: Likewise.
	* gcc.dg/fma-5.c: Likewise.
	* gcc.dg/fma-6.c: Likewise.
	* gcc.dg/fma-7.c: Likewise.
	* gcc.dg/gimplefe-26.c: Use .FMA instead of __FMA and require
	scalar_all_fma.
	* gfortran.dg/reassoc_7.f: Pass -ffp-contract=off.
	* gfortran.dg/reassoc_8.f: Likewise.
	* gfortran.dg/reassoc_9.f: Likewise.
	* gfortran.dg/reassoc_10.f: Likewise.

From-SVN: r260348

1 files changed, 19 insertions, 18 deletions

diff --git a/gcc/tree-ssa-math-opts.c b/gcc/tree-ssa-math-opts.c
index 16d9399..273396d 100644
--- a/gcc/tree-ssa-math-opts.c
+++ b/gcc/tree-ssa-math-opts.c
@@ -2650,7 +2650,7 @@ convert_mult_to_fma_1 (tree mul_result, tree op1, tree op2)
   tree type = TREE_TYPE (mul_result);
   gimple *use_stmt;
   imm_use_iterator imm_iter;
-  gassign *fma_stmt;
+  gcall *fma_stmt;
 
   FOR_EACH_IMM_USE_STMT (use_stmt, imm_iter, mul_result)
     {
@@ -2658,6 +2658,7 @@ convert_mult_to_fma_1 (tree mul_result, tree op1, tree op2)
       enum tree_code use_code;
       tree addop, mulop1 = op1, result = mul_result;
       bool negate_p = false;
+      gimple_seq seq = NULL;
 
       if (is_gimple_debug (use_stmt))
 	continue;
@@ -2683,11 +2684,7 @@ convert_mult_to_fma_1 (tree mul_result, tree op1, tree op2)
 	  addop = gimple_assign_rhs2 (use_stmt);
 	  /* a * b - c -> a * b + (-c)  */
 	  if (gimple_assign_rhs_code (use_stmt) == MINUS_EXPR)
-	    addop = force_gimple_operand_gsi (&gsi,
-					      build1 (NEGATE_EXPR,
-						      type, addop),
-					      true, NULL_TREE, true,
-					      GSI_SAME_STMT);
+	    addop = gimple_build (&seq, NEGATE_EXPR, type, addop);
 	}
       else
 	{
@@ -2698,23 +2695,26 @@ convert_mult_to_fma_1 (tree mul_result, tree op1, tree op2)
 	}
 
       if (negate_p)
-	mulop1 = force_gimple_operand_gsi (&gsi,
-					   build1 (NEGATE_EXPR,
-						   type, mulop1),
-					   true, NULL_TREE, true,
-					   GSI_SAME_STMT);
+	mulop1 = gimple_build (&seq, NEGATE_EXPR, type, mulop1);
 
-      fma_stmt = gimple_build_assign (gimple_assign_lhs (use_stmt),
-				      FMA_EXPR, mulop1, op2, addop);
+      if (seq)
+	gsi_insert_seq_before (&gsi, seq, GSI_SAME_STMT);
+      fma_stmt = gimple_build_call_internal (IFN_FMA, 3, mulop1, op2, addop);
+      gimple_call_set_lhs (fma_stmt, gimple_assign_lhs (use_stmt));
+      gimple_call_set_nothrow (fma_stmt, !stmt_can_throw_internal (use_stmt));
+      gsi_replace (&gsi, fma_stmt, true);
+      /* Follow all SSA edges so that we generate FMS, FNMA and FNMS
+	 regardless of where the negation occurs.  */
+      if (fold_stmt (&gsi, follow_all_ssa_edges))
+	update_stmt (gsi_stmt (gsi));
 
       if (dump_file && (dump_flags & TDF_DETAILS))
 	{
 	  fprintf (dump_file, "Generated FMA ");
-	  print_gimple_stmt (dump_file, fma_stmt, 0, 0);
+	  print_gimple_stmt (dump_file, gsi_stmt (gsi), 0, 0);
 	  fprintf (dump_file, "\n");
 	}
 
-      gsi_replace (&gsi, fma_stmt, true);
       widen_mul_stats.fmas_inserted++;
     }
 }
@@ -2862,7 +2862,8 @@ convert_mult_to_fma (gimple *mul_stmt, tree op1, tree op2,
 
   /* If the target doesn't support it, don't generate it.  We assume that
      if fma isn't available then fms, fnma or fnms are not either.  */
-  if (optab_handler (fma_optab, TYPE_MODE (type)) == CODE_FOR_nothing)
+  optimization_type opt_type = bb_optimization_type (gimple_bb (mul_stmt));
+  if (!direct_internal_fn_supported_p (IFN_FMA, type, opt_type))
     return false;
 
   /* If the multiplication has zero uses, it is kept around probably because
@@ -2958,8 +2959,8 @@ convert_mult_to_fma (gimple *mul_stmt, tree op1, tree op2,
 	 that a mult / subtract pair.  */
       if (use_code == MINUS_EXPR && !negate_p
 	  && gimple_assign_rhs1 (use_stmt) == result
-	  && optab_handler (fms_optab, TYPE_MODE (type)) == CODE_FOR_nothing
-	  && optab_handler (fnma_optab, TYPE_MODE (type)) != CODE_FOR_nothing)
+	  && !direct_internal_fn_supported_p (IFN_FMS, type, opt_type)
+	  && direct_internal_fn_supported_p (IFN_FNMA, type, opt_type))
 	{
 	  tree rhs2 = gimple_assign_rhs2 (use_stmt);