This patch is the main part of PR85694.  The aim is to recognise at least:

  signed char *a, *b, *c;
  ...
  for (int i = 0; i < 2048; i++)
    c[i] = (a[i] + b[i]) >> 1;

as an over-widening pattern, since the addition and shift can be done
on shorts rather than ints.  However, it ended up being a lot more
general than that.

The current over-widening pattern detection is limited to a few simple
cases: logical ops with immediate second operands, and shifts by a
constant.  These cases are enough for common pixel-format conversion
and can be detected in a peephole way.

The loop above requires two generalisations of the current code: support
for addition as well as logical ops, and support for non-constant second
operands.  These are harder to detect in the same peephole way, so the
patch tries to take a more global approach.

The idea is to get information about the minimum operation width
in two ways:

(1) by using the range information attached to the SSA_NAMEs
    (effectively a forward walk, since the range info is
    context-independent).

(2) by back-propagating the number of output bits required by
    users of the result.

As explained in the comments, there's a balance to be struck between
narrowing an individual operation and fitting in with the surrounding
code.  The approach is pretty conservative: if we could narrow an
operation to N bits without changing its semantics, it's OK to do that if:

- no operations later in the chain require more than N bits; or

- all internally-defined inputs are extended from N bits or fewer,
  and at least one of them is single-use.

See the comments for the rationale.

I didn't bother adding STMT_VINFO_* wrappers for the new fields
since the code seemed more readable without.

2018-06-20  Richard Sandiford  <richard.sandiford@arm.com>

gcc/
	* poly-int.h (print_hex): New function.
	* dumpfile.h (dump_dec, dump_hex): Declare.
	* dumpfile.c (dump_dec, dump_hex): New poly_wide_int functions.
	* tree-vectorizer.h (_stmt_vec_info): Add min_output_precision,
	min_input_precision, operation_precision and operation_sign.
	* tree-vect-patterns.c (vect_get_range_info): New function.
	(vect_same_loop_or_bb_p, vect_single_imm_use)
	(vect_operation_fits_smaller_type): Delete.
	(vect_look_through_possible_promotion): Add an optional
	single_use_p parameter.
	(vect_recog_over_widening_pattern): Rewrite to use new
	stmt_vec_info infomration.  Handle one operation at a time.
	(vect_recog_cast_forwprop_pattern, vect_narrowable_type_p)
	(vect_truncatable_operation_p, vect_set_operation_type)
	(vect_set_min_input_precision): New functions.
	(vect_determine_min_output_precision_1): Likewise.
	(vect_determine_min_output_precision): Likewise.
	(vect_determine_precisions_from_range): Likewise.
	(vect_determine_precisions_from_users): Likewise.
	(vect_determine_stmt_precisions, vect_determine_precisions): Likewise.
	(vect_vect_recog_func_ptrs): Put over_widening first.
	Add cast_forwprop.
	(vect_pattern_recog): Call vect_determine_precisions.

gcc/testsuite/
	* gcc.dg/vect/vect-widen-mult-u8-u32.c: Check specifically for a
	widen_mult pattern.
	* gcc.dg/vect/vect-over-widen-1.c: Update the scan tests for new
	over-widening messages.
	* gcc.dg/vect/vect-over-widen-1-big-array.c: Likewise.
	* gcc.dg/vect/vect-over-widen-2.c: Likewise.
	* gcc.dg/vect/vect-over-widen-2-big-array.c: Likewise.
	* gcc.dg/vect/vect-over-widen-3.c: Likewise.
	* gcc.dg/vect/vect-over-widen-3-big-array.c: Likewise.
	* gcc.dg/vect/vect-over-widen-4.c: Likewise.
	* gcc.dg/vect/vect-over-widen-4-big-array.c: Likewise.
	* gcc.dg/vect/bb-slp-over-widen-1.c: New test.
	* gcc.dg/vect/bb-slp-over-widen-2.c: Likewise.
	* gcc.dg/vect/vect-over-widen-5.c: Likewise.
	* gcc.dg/vect/vect-over-widen-6.c: Likewise.
	* gcc.dg/vect/vect-over-widen-7.c: Likewise.
	* gcc.dg/vect/vect-over-widen-8.c: Likewise.
	* gcc.dg/vect/vect-over-widen-9.c: Likewise.
	* gcc.dg/vect/vect-over-widen-10.c: Likewise.
	* gcc.dg/vect/vect-over-widen-11.c: Likewise.
	* gcc.dg/vect/vect-over-widen-12.c: Likewise.
	* gcc.dg/vect/vect-over-widen-13.c: Likewise.
	* gcc.dg/vect/vect-over-widen-14.c: Likewise.
	* gcc.dg/vect/vect-over-widen-15.c: Likewise.
	* gcc.dg/vect/vect-over-widen-16.c: Likewise.
	* gcc.dg/vect/vect-over-widen-17.c: Likewise.
	* gcc.dg/vect/vect-over-widen-18.c: Likewise.
	* gcc.dg/vect/vect-over-widen-19.c: Likewise.
	* gcc.dg/vect/vect-over-widen-20.c: Likewise.
	* gcc.dg/vect/vect-over-widen-21.c: Likewise.

From-SVN: r262333

r262275 allowed pattern matching on pattern statements.  Testing for
SVE on more benchmarks showed a case where this interacted badly
with 14/n.

The new over-widening detection could narrow a COND_EXPR A to another
COND_EXPR B, which mixed_size_cond could then match.  This was working
as expected.  However, we left B (now dead) in the pattern definition
sequence with a non-null PATTERN_DEF_SEQ.  mask_conversion also
matched B, and unlike most recognisers, didn't clear PATTERN_DEF_SEQ
before adding statements to it.  This meant that the statements
created by mixed_size_cond appeared in two supposedy separate
sequences, causing much confusion.

This patch removes pattern statements that are replaced by further
pattern statements.  As a belt-and-braces fix, it also nullifies
PATTERN_DEF_SEQ on failure, in the same way Richard B. did recently
for RELATED_STMT.

I have patches to clean up the PATTERN_DEF_SEQ handling, but they
only apply after the complete PR85694 sequence, whereas this needs
to go in before 14/n.

2018-07-03  Richard Sandiford  <richard.sandiford@arm.com>

gcc/
	* tree-vect-patterns.c (vect_mark_pattern_stmts): Remove pattern
	statements that have been replaced by further pattern statements.
	(vect_pattern_recog_1): Clear STMT_VINFO_PATTERN_DEF_SEQ on failure.

gcc/testsuite/
	* gcc.dg/vect/vect-mixed-size-cond-1.c: New test.

From-SVN: r262332

2018-07-03  Richard Biener  <rguenther@suse.de>

	* tree-vect-stmts.c (vect_is_simple_use): Consolidate dumping,
	always set *dt.  Dump vectype in vectype overload.
	* dumpfile.h (dump_gimple_expr): New function.
	(dump_gimple_expr_loc): Likewise.
	* dumpfile.c (dump_gimple_expr): New function.
	(dump_gimple_expr_loc): Likewise.

From-SVN: r262330

h8300.md (movqi_h8300, [...]): Consolidate the H8/300, H8/300H and H8/S variants into a single pattern.

	* config/h8300/h8300.md (movqi_h8300, movqi_h8300hs): Consolidate
	the H8/300, H8/300H and H8/S variants into a single pattern.
	(movhi_h8300, movqi_h8300hs): Similarly.
	(pushqi_h8300hs, pushhi_h8300hs): Consolidate into a single pattern.
	(QHI mode iterator): New.

From-SVN: r262329

From-SVN: r262328

	gcc/
	* config/riscv/riscv.c (riscv_expand_epilogue): Use emit_jump_insn
	instead of emit_insn for interrupt returns.
	* config/riscv/riscv.md (riscv_met): Add (return) to rtl.
	(riscv_sret, riscv_uret): Likewise.

	gcc/testsuite/
	* gcc.target/riscv/interrupt-debug.c: New.

From-SVN: r262327

From-SVN: r262326

Extend __is_convertible_helper to also detect whether the conversion is
non-throwing, for std::is_nothrow_convertible in C++2a,

	* include/std/type_traits [__cplusplus > 201703]
	(__is_convertible_helper::__is_nothrow_type): Define new member.
	(__is_convertible_helper<_From, _To, false>::__test_aux1): Add
	noexcept.
	(__is_convertible_helper<_From, _To, false>::__test_nothrow)
	(__is_convertible_helper<_From, _To, false>::__is_nothrow_type): Add
	new members.
	(is_nothrow_convertible, is_nothrow_convertible_v): Define for C++2a.
	* testsuite/20_util/is_nothrow_convertible/value.cc: New.
	* testsuite/20_util/is_nothrow_convertible/requirements/
	explicit_instantiation.cc: New.
	* testsuite/20_util/is_nothrow_convertible/requirements/typedefs.cc:
	New.

From-SVN: r262322

parser.c (set_and_check_decl_spec_loc): Use rich_location::add_range in error message about __thread and thread_local...

/cp
2018-07-02  Paolo Carlini  <paolo.carlini@oracle.com>

	* parser.c (set_and_check_decl_spec_loc): Use rich_location::add_range
	in error message about __thread and thread_local at the same time.

/testsuite
2018-07-02  Paolo Carlini  <paolo.carlini@oracle.com>

	* g++.dg/diagnostic/thread-thread_local.C: New.

From-SVN: r262321

	* include/std/type_traits (type_identity, type_identity_t): Define
        for C++2a.
	* testsuite/20_util/type_identity/requirements/alias_decl.cc: New.
	* testsuite/20_util/type_identity/requirements/
	explicit_instantiation.cc:New.
	* testsuite/20_util/type_identity/requirements/typedefs.cc: New.

From-SVN: r262319

Avoid creation of unnecessary basic_string objects by using a simplified
string_view type and performing comparisons on that type instead. A
temporary basic_string object is still used when the sub_match's
iterators are not contiguous, in order to get an object that the
__string_view can reference.

	* include/bits/regex.h (sub_match::operator string_type): Call str().
	(sub_match::compare): Use _M_str() instead of str().
	(sub_match::_M_compare): New public function.
	(sub_match::__string_view): New helper type.
	(sub_match::_M_str): New overloaded functions to avoid creating a
	string_type object when not needed.
	(operator==, operator!=, operator<, operator>, operator<=, operator>=):
	Use sub_match::_M_compare instead of creating string_type objects.
	Fix Doxygen comments.
	* include/bits/regex_compiler.h (__has_contiguous_iter): Remove.
	(__is_contiguous_normal_iter): Rename to __is_contiguous_iter and
	simplify.
	(__enable_if_contiguous_iter, __disable_if_contiguous_iter): Use
	__enable_if_t.
	* include/std/type_traits (__enable_if_t): Define for C++11.
	* testsuite/28_regex/sub_match/compare.cc: New.
	* testsuite/util/testsuite_iterators.h (remove_cv): Add transformation
	trait.
	(input_iterator_wrapper): Use remove_cv for value_type argument of
	std::iterator base class.

From-SVN: r262318

This patch moves a workaround for locale differences from a
selftest in pretty-print.c to selftest.h/c to make it reusable; I need
this for a selftest in a followup patch.

gcc/ChangeLog:
	* pretty-print.c (selftest::test_pp_format): Move save and restore
	of quotes to class auto_fix_quotes, and add an instance.
	* selftest.c: Include "intl.h".
	(selftest::auto_fix_quotes::auto_fix_quotes): New ctor.
	(selftest::auto_fix_quotes::~auto_fix_quotes): New dtor.
	* selftest.h (selftest::auto_fix_quotes): New class.

From-SVN: r262317

	PR go/86331
    os: check return value as well as error from waitid
    
    https://gcc.gnu.org/PR86331 indicates that if a signal handler runs it
    is possible for syscall.Syscall6 to return a non-zero errno value even
    if no error occurs. That is a problem in general, but this fix will
    let us work around the general problem for the specific case of
    calling waitid.
    
    Reviewed-on: https://go-review.googlesource.com/121595

From-SVN: r262313

    * config/aarch64/aarch64-protos.h, config/aarch64/aarch64.c
    (aarch64_sve_prepare_conditional_op): Remove.
    * config/aarch64/aarch64-sve.md (cond_<SVE_INT_BINARY><SVE_I>):
    Allow aarch64_simd_reg_or_zero as select operand; remove
    the aarch64_sve_prepare_conditional_op call.
    (cond_<SVE_INT_BINARY_SD><SVE_SDI>): Likewise.
    (cond_<SVE_COND_FP_BINARY><SVE_F>): Likewise.
    (*cond_<SVE_INT_BINARY><SVE_I>_z): New pattern.
    (*cond_<SVE_INT_BINARY_SD><SVE_SDI>_z): New pattern.
    (*cond_<SVE_COND_FP_BINARY><SVE_F>_z): New pattern.
    (*cond_<SVE_INT_BINARY><SVE_I>_any): New pattern.
    (*cond_<SVE_INT_BINARY_SD><SVE_SDI>_any): New pattern.
    (*cond_<SVE_COND_FP_BINARY><SVE_F>_any): New pattern
    and a splitters to match all of the *_any patterns.
    * config/aarch64/predicates.md (aarch64_sve_any_binary_operator): New.

    * config/aarch64/iterators.md (SVE_INT_BINARY_REV): Remove.
    (SVE_COND_FP_BINARY_REV): Remove.
    (sve_int_op_rev, sve_fp_op_rev): New.
    * config/aarch64/aarch64-sve.md (*cond_<SVE_INT_BINARY><SVE_I>_0): New.
    (*cond_<SVE_INT_BINARY_SD><SVE_SDI>_0): New.
    (*cond_<SVE_COND_FP_BINARY><SVE_F>_0): New.
    (*cond_<SVE_INT_BINARY><SVE_I>_2): Rename, add movprfx alternative.
    (*cond_<SVE_INT_BINARY_SD><SVE_SDI>_2): Similarly.
    (*cond_<SVE_COND_FP_BINARY><SVE_F>_2): Similarly.
    (*cond_<SVE_INT_BINARY><SVE_I>_3): Similarly; use sve_int_op_rev.
    (*cond_<SVE_INT_BINARY_SD><SVE_SDI>_3): Similarly.
    (*cond_<SVE_COND_FP_BINARY><SVE_F>_3): Similarly; use sve_fp_op_rev.

    * config/aarch64/aarch64-sve.md (cond_<SVE_COND_FP_BINARY><SVE_F>):
    Remove match_dup 1 from the inner unspec.
    (*cond_<SVE_COND_FP_BINARY><SVE_F>): Likewise.

    * config/aarch64/aarch64.md (movprfx): New attr.
    (length): Default movprfx to 8.
    * config/aarch64/aarch64-sve.md (*mul<SVE_I>3): Add movprfx alt.
    (*madd<SVE_I>, *msub<SVE_I): Likewise.
    (*<su>mul<SVE_I>3_highpart): Likewise.
    (*<SVE_INT_BINARY_SD><SVE_SDI>3): Likewise.
    (*v<ASHIFT><SVE_I>3): Likewise.
    (*<su><MAXMIN><SVE_I>3): Likewise.
    (*<su><MAXMIN><SVE_F>3): Likewise.
    (*fma<SVE_F>4, *fnma<SVE_F>4): Likewise.
    (*fms<SVE_F>4, *fnms<SVE_F>4): Likewise.
    (*div<SVE_F>4): Likewise.

From-SVN: r262312

2018-07-02  Martin Liska  <mliska@suse.cz>

        PR testsuite/86366
	* gcc.dg/profile-dir-1.c: Fix scanned pattern.
	* gcc.dg/profile-dir-2.c: Likewise.
	* gcc.dg/profile-dir-3.c: Likewise.

From-SVN: r262311

2018-07-02  Christophe Lyon  <christophe.lyon@linaro.org>

	* gcc.target/arm/arm-soft-strd-even.c: Skip if -mfloat-abi is
	overriden.

From-SVN: r262309

Noticed by Christophe on arm-none-linux-gnueabihf.

2018-07-02  Richard Sandiford  <richard.sandiford@arm.com>

gcc/
	* tree-vect-patterns.c (vect_recog_widen_shift_pattern): Fix typo
	in dump string.

From-SVN: r262308

2018-07-02  Richard Biener  <rguenther@suse.de>

	PR tree-optimization/86363
	* tree-ssa-sccvn.c (vn_reference_lookup_3): Check the
	memset argument refers to a non-variable address.

	* gcc.dg/torture/pr86363.c: New testcase.

From-SVN: r262307

extract_range_from_binary_expr_1 into separate functions.

From-SVN: r262306

	* tree-vrp.c (extract_range_from_unary_expr): Abstract ABS_EXPR
	code...
	(extract_range_from_abs_expr): ...here.

From-SVN: r262305

2018-07-02  Martin Liska  <mliska@suse.cz>

	* gcc.dg/completion-1.c: New test.
	* gcc.dg/completion-2.c: New test.
	* gcc.dg/completion-3.c: New test.

From-SVN: r262304

i386.c (ix86_finalize_stack_frame_flags): Do not overrule -fno-omit-frame-pointer when not optimizing.

	* config/i386/i386.c (ix86_finalize_stack_frame_flags): Do not overrule
	-fno-omit-frame-pointer when not optimizing.

From-SVN: r262302

re PR lto/86321 (ICE:  in splice_child_die, at dwarf2out.c:5693 for several Fortran tests with -g -flto)

2018-07-02  Richard Biener  <rguenther@suse.de>

	PR lto/86321
	* trans-types.c (gfc_get_array_type_bounds): Unshare TYPE_FIELDs
	for the distinct type copy.

From-SVN: r262301

2018-07-02  Paul Thomas  <pault@gcc.gnu.org>

	PR fortran/45305
	* expr.c : Add a prototype for scalarize_intrinsic_call.
	(gfc_simplify_expr): Use scalarize_intrinsic_call for elemental
	intrinsic function calls.
	(scalarize_intrinsic_call): Add 'init_flag' argument. Check if
	the expression or any of the actual argument expressions are
	NULL. Before calling gfc_check_init_expr, check 'init_flag'.
	Only simplify the scalarized expressions if there are no errors
	on the stack.
	(gfc_check_init_expr): Set 'init_flag' true in the call to
	scalarize_intrinsic_call.

2018-07-02  Paul Thomas  <pault@gcc.gnu.org>

	PR fortran/45305
	* gfortran.dg/scalarize_parameter_array_2.f90: New test.

From-SVN: r262300

2018-07-02  Paul Thomas  <pault@gcc.gnu.org>

	PR fortran/45305
	* expr.c : Add a prototype for scalarize_intrinsic_call.
	(gfc_simplify_expr): Use scalarize_intrinsic_call for elemental
	intrinsic function calls.
	(scalarize_intrinsic_call): Add 'init_flag' argument. Check if
	the expression or any of the actual argument expressions are
	NULL. Before calling gfc_check_init_expr, check 'init_flag'.
	Only simplify the scalarized expressions if there are no errors
	on the stack.
	(gfc_check_init_expr): Set 'init_flag' true in the call to
	scalarize_intrinsic_call.

2018-07-02  Paul Thomas  <pault@gcc.gnu.org>

	PR fortran/45305
	* gfortran.dg/scalarize_parameter_array_2.f90: New test.

From-SVN: r262299

2018-07-02  Martin Liska  <mliska@suse.cz>

        PR ipa/86279
	* ipa-pure-const.c (malloc_candidate_p): Revert usage of ::get.
	(propagate_nothrow): Likewise.
2018-07-02  Martin Liska  <mliska@suse.cz>

        PR ipa/86279
	* gcc.dg/ipa/pr86279.c: New test.

From-SVN: r262298

2018-07-02  Martin Liska  <mliska@suse.cz>

        PR ipa/86323
	* ipa-inline.c (early_inliner): Revert wrongly added ::get call.
2018-07-02  Martin Liska  <mliska@suse.cz>

        PR ipa/86323
	* g++.dg/ipa/pr86323.C: New test.

From-SVN: r262297

2018-07-02  Martin Liska  <mliska@suse.cz>

	* gnatvsn.ads: Bump Library_Version to 9.

From-SVN: r262296

gcc/ChangeLog:
	* dumpfile.c (dump_generic_expr_loc): Undo removal of this
	function in r262149, changing "loc" param from source_location to
	const dump_location_t &.
	* dumpfile.h (dump_generic_expr_loc): Undo removal of this
	declaration, as above.

From-SVN: r262295

From-SVN: r262294

2018-07-01  Tom de Vries  <tdevries@suse.de>

	revert:
	2018-07-01  Tom de Vries  <tdevries@suse.de>

	* gcc.dg/guality/prevent-optimization.h (VOLATILE): Define.
	* gcc.dg/guality/vla-1.c (f1): Mark local vla a as VOLATILE.

From-SVN: r262290

        compatible output.

	* common/config/pdp11/pdp11-common.c (pdp11_handle_option): Handle
	-munit-asm, -mgnu-asm, -mdec-asm.
	* config/pdp11/pdp11-protos.h (pdp11_gen_int_label): New.
	(pdp11_output_labelref): New.
	(pdp11_output_def): New.
	(pdp11_output_addr_vec_elt): New.
	* config/pdp11/pdp11.c: Use tab between opcode and operands.  Use
	%# and %@ format codes.
	(pdp11_option_override): New.
	(TARGET_ASM_FILE_START_FILE_DIRECTIVE): Define.
	(pdp11_output_ident): New.
	(pdp11_asm_named_section): New.
	(pdp11_asm_init_sections): New.
	(pdp11_file_start): New.
	(pdp11_file_end): New.
	(output_ascii): Use .ascii/.asciz for -mdec-asm.
	(pdp11_asm_print_operand): Update %# and %$ for -mdec-asm.  Add
	%o, like %c but octal.
	(pdp11_option_override): New.
	* config/pdp11/pdp11.h (TEXT_SECTION_ASM_OP): Update for
	-mdec-asm.
	(DATA_SECTION_ASM_OP): Ditto.
	(READONLY_DATA_SECTION_ASM_OP): New.
	(IS_ASM_LOGICAL_LINE_SEPARATOR): New.
	(ASM_GENERATE_INTERNAL_LABEL): Use new function.
	(ASM_OUTPUT_LABELREF): Ditto.
	(ASM_OUTPUT_DEF): Ditto.
	(ASM_OUTPUT_EXTERNAL): New.
	(ASM_OUTPUT_SOURCE_FILENAME): New.
	(ASM_OUTPUT_ADDR_VEC_ELT): Use new function.
	(ASM_OUTPUT_SKIP): Update for -mdec-asm.
	* config/pdp11/pdp11.md: Use tab between opcode and operands.  Use
	%# and %@ format codes.
	* config/pdp11/pdp11.opt (mgnu-asm): New.
	(mdec-asm): Conflicts with -mgnu-asm and -munix-asm.
	(munix-asm): Conflicts with -mdec-asm and -mgnu-asm.
	* doc/invoke.txt (PDP-11 Options): Add -mgnu-asm.

From-SVN: r262289

2018-07-01  Tom de Vries  <tdevries@suse.de>

	* lib/gcc-gdb-test.exp (gdb-test): Handle '@' prefix in line number
	argument.
	* gcc.dg/guality/const-volatile.c: Replace gdb-test line nrs 50 and 58
	with @main.

From-SVN: r262288

2018-07-01  Tom de Vries  <tdevries@suse.de>

	* gcc.dg/guality/prevent-optimization.h (VOLATILE): Define.
	* gcc.dg/guality/vla-1.c (f1): Mark local vla a as VOLATILE.

From-SVN: r262287

2018-07-01  Tom de Vries  <tdevries@suse.de>

	* lib/gcc-dg.exp (get-absolute-line): Handle '.'.
	* gcc.dg/guality/vla-1.c: Use relative line numbers.

From-SVN: r262286

2018-07-01  Tom de Vries  <tdevries@suse.de>

	* gcc.dg-selftests/dg-final.exp (verify_call_1): Factor out of ...
	(verify_call): ... here.  Move to toplevel.
	(verify_call_np, dg_final_directive_check_utils): New proc.
	(toplevel): Call dg_final_directive_check_utils.
	* lib/gcc-dg.exp (get-absolute-line): Fix typo in variable reference.

From-SVN: r262284

From-SVN: r262283

From-SVN: r262282

	gcc/
	* config/riscv/predicates.md (p2m1_shift_operand): New.
	(high_mask_shift_operand): New.
	* config/riscv/riscv.md (lshrsi3_zero_extend_3+1): New combiner
	pattern using p2m1_shift_operand.
	(lshsi3_zero_extend_3+2): New combiner pattern using
	high_mask_shift_operand.

	gcc/testsuite/
	* gcc.target/riscv/shift-shift-1.c: New.
	* gcc.target/riscv/shift-shift-2.c: New.
	* gcc.target/riscv/shift-shift-3.c: New.

From-SVN: r262278

vect_recog_rotate_pattern had code to prevent operations
on invariants being vectorised unnecessarily:

  if (dt == vect_external_def
      && TREE_CODE (oprnd1) == SSA_NAME
      && is_a <loop_vec_info> (vinfo))
    {
      struct loop *loop = as_a <loop_vec_info> (vinfo)->loop;
      ext_def = loop_preheader_edge (loop);
      if (!SSA_NAME_IS_DEFAULT_DEF (oprnd1))
        {
          basic_block bb = gimple_bb (SSA_NAME_DEF_STMT (oprnd1));
          if (bb == NULL
              || !dominated_by_p (CDI_DOMINATORS, ext_def->dest, bb))
            ext_def = NULL;
        }
    }
  [..]
      if (ext_def)
        {
          basic_block new_bb
            = gsi_insert_on_edge_immediate (ext_def, def_stmt);
          gcc_assert (!new_bb);
        }

This patch reuses the same idea for casts of invariants created
during widening optimisations.

One hitch was that vect_loop_versioning asserted that the vector loop
preheader was still empty, although the cfg transformation it's doing
should be correct either way.

2018-06-30  Richard Sandiford  <richard.sandiford@arm.com>

gcc/
	* tree-vect-patterns.c (vect_get_external_def_edge): New function,
	split out from...
	(vect_recog_rotate_pattern): ...here.
	(vect_convert_input): Try to insert casts of invariants in the
	preheader.
	* tree-vect-loop-manip.c (vect_loop_versioning): Don't require the
	preheader to be empty.

gcc/testsuite/
	* gcc.dg/vect/vect-widen-mult-extern-1.c: New test.

From-SVN: r262277