Generate offset adjusted operation for op_by_pieces operations

Add an overlap_op_by_pieces_p target hook for op_by_pieces operations
between two areas of memory to generate one offset adjusted operation
in the smallest integer mode for the remaining bytes on the last piece
operation of a memory region to avoid doing more than one smaller
operations.

Pass the RTL information from the previous iteration to m_constfn in
op_by_pieces operation so that builtin_memset_[read|gen]_str can
generate the new RTL from the previous RTL.

Tested on Linux/x86-64.

gcc/

	PR middle-end/90773
	* builtins.c (builtin_memcpy_read_str): Add a dummy argument.
	(builtin_strncpy_read_str): Likewise.
	(builtin_memset_read_str): Add an argument for the previous RTL
	information and generate the new RTL from the previous RTL info.
	(builtin_memset_gen_str): Likewise.
	* builtins.h (builtin_strncpy_read_str): Update the prototype.
	(builtin_memset_read_str): Likewise.
	* expr.c (by_pieces_ninsns): If targetm.overlap_op_by_pieces_p()
	returns true, round up size and alignment to the widest integer
	mode for maximum size.
	(pieces_addr::adjust): Add a pointer to by_pieces_prev argument
	and pass it to m_constfn.
	(op_by_pieces_d): Add m_push and m_overlap_op_by_pieces.
	(op_by_pieces_d::op_by_pieces_d): Add a bool argument to
	initialize m_push.  Initialize m_overlap_op_by_pieces with
	targetm.overlap_op_by_pieces_p ().
	(op_by_pieces_d::run): Pass the previous RTL information to
	pieces_addr::adjust and generate overlapping operations if
	m_overlap_op_by_pieces is true.
	(PUSHG_P): New.
	(move_by_pieces_d::move_by_pieces_d): Updated for op_by_pieces_d
	change.
	(store_by_pieces_d::store_by_pieces_d): Updated for op_by_pieces_d
	change.
	(can_store_by_pieces): Use by_pieces_constfn on constfun.
	(store_by_pieces): Use by_pieces_constfn on constfun.  Updated
	for op_by_pieces_d change.
	(clear_by_pieces_1): Add a dummy argument.
	(clear_by_pieces): Updated for op_by_pieces_d change.
	(compare_by_pieces_d::compare_by_pieces_d): Likewise.
	(string_cst_read_str): Add a dummy argument.
	* expr.h (by_pieces_constfn): Add a dummy argument.
	(by_pieces_prev): New.
	* target.def (overlap_op_by_pieces_p): New target hook.
	* config/i386/i386.c (TARGET_OVERLAP_OP_BY_PIECES_P): New.
	* doc/tm.texi.in: Add TARGET_OVERLAP_OP_BY_PIECES_P.
	* doc/tm.texi: Regenerated.

gcc/testsuite/

	PR middle-end/90773
	* g++.dg/pr90773-1.h: New test.
	* g++.dg/pr90773-1a.C: Likewise.
	* g++.dg/pr90773-1b.C: Likewise.
	* g++.dg/pr90773-1c.C: Likewise.
	* g++.dg/pr90773-1d.C: Likewise.
	* gcc.target/i386/pr90773-1.c: Likewise.
	* gcc.target/i386/pr90773-2.c: Likewise.
	* gcc.target/i386/pr90773-3.c: Likewise.
	* gcc.target/i386/pr90773-4.c: Likewise.
	* gcc.target/i386/pr90773-5.c: Likewise.
	* gcc.target/i386/pr90773-6.c: Likewise.
	* gcc.target/i386/pr90773-7.c: Likewise.
	* gcc.target/i386/pr90773-8.c: Likewise.
	* gcc.target/i386/pr90773-9.c: Likewise.
	* gcc.target/i386/pr90773-10.c: Likewise.
	* gcc.target/i386/pr90773-11.c: Likewise.
	* gcc.target/i386/pr90773-12.c: Likewise.
	* gcc.target/i386/pr90773-13.c: Likewise.
	* gcc.target/i386/pr90773-14.c: Likewise.

1 files changed, 2 insertions, 0 deletions

diff --git a/gcc/doc/tm.texi.in b/gcc/doc/tm.texi.in
index 2974dae..20acf36 100644
--- a/gcc/doc/tm.texi.in
+++ b/gcc/doc/tm.texi.in
@@ -4588,6 +4588,8 @@ If you don't define this, a reasonable default is used.
 
 @hook TARGET_USE_BY_PIECES_INFRASTRUCTURE_P
 
+@hook TARGET_OVERLAP_OP_BY_PIECES_P
+
 @hook TARGET_COMPARE_BY_PIECES_BRANCH_RATIO
 
 @defmac MOVE_MAX_PIECES