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r262332 - in /trunk/gcc: ChangeLog testsuite/Ch...


Author: rsandifo
Date: Tue Jul  3 09:58:47 2018
New Revision: 262332

URL: https://gcc.gnu.org/viewcvs?rev=262332&root=gcc&view=rev
Log:
Avoid matching the same pattern statement twice

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	statements that have been replaced by further pattern statements.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.

Added:
    trunk/gcc/testsuite/gcc.dg/vect/vect-mixed-size-cond-1.c
Modified:
    trunk/gcc/ChangeLog
    trunk/gcc/testsuite/ChangeLog
    trunk/gcc/tree-vect-patterns.c


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