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| author | Roger Sayle <roger@nextmovesoftware.com> | 2020-07-16 11:47:47 +0100 |
|---|---|---|
| committer | Roger Sayle <roger@nextmovesoftware.com> | 2020-07-16 11:47:47 +0100 |
| commit | 5abe0d81db068c06ae57b011e1a9d4fd7976ac56 (patch) | |
| tree | a212d4eb01f60556fccb4f49e34077c37663b2e1 | |
| parent | 135c02769b9ec625a55a0beba63415c1484f8951 (diff) | |
| download | gcc-5abe0d81db068c06ae57b011e1a9d4fd7976ac56.zip gcc-5abe0d81db068c06ae57b011e1a9d4fd7976ac56.tar.gz gcc-5abe0d81db068c06ae57b011e1a9d4fd7976ac56.tar.bz2 | |
doc: Document TARGET_TRULY_NOOP_TRUNCATION requires trunc?i?i2 patterns.
2020-07-16 Roger Sayle <roger@nextmovesoftware.com>
gcc/ChangeLog:
* target.def (TARGET_TRULY_NOOP_TRUNCATION): Clarify that
targets that return false, indicating SUBREGs shouldn't be
used, also need to provide a trunc?i?i2 optab that performs this
truncation.
* doc/tm.texi: Regenerate.
| -rw-r--r-- | gcc/doc/tm.texi | 4 | ||||
| -rw-r--r-- | gcc/target.def | 4 |
2 files changed, 6 insertions, 2 deletions
diff --git a/gcc/doc/tm.texi b/gcc/doc/tm.texi index 6e7d9dc..41b9e10 100644 --- a/gcc/doc/tm.texi +++ b/gcc/doc/tm.texi @@ -11122,7 +11122,9 @@ This hook returns true if it is safe to ``convert'' a value of @var{inprec} bits to one of @var{outprec} bits (where @var{outprec} is smaller than @var{inprec}) by merely operating on it as if it had only @var{outprec} bits. The default returns true unconditionally, which -is correct for most machines. +is correct for most machines. When @code{TARGET_TRULY_NOOP_TRUNCATION} +returns false, the machine description should provide a @code{trunc} +optab to specify the RTL that performs the required truncation. If @code{TARGET_MODES_TIEABLE_P} returns false for a pair of modes, suboptimal code can result if this hook returns true for the corresponding diff --git a/gcc/target.def b/gcc/target.def index 07059a8..f2f314e 100644 --- a/gcc/target.def +++ b/gcc/target.def @@ -3148,7 +3148,9 @@ DEFHOOK @var{inprec} bits to one of @var{outprec} bits (where @var{outprec} is\n\ smaller than @var{inprec}) by merely operating on it as if it had only\n\ @var{outprec} bits. The default returns true unconditionally, which\n\ -is correct for most machines.\n\ +is correct for most machines. When @code{TARGET_TRULY_NOOP_TRUNCATION}\n\ +returns false, the machine description should provide a @code{trunc}\n\ +optab to specify the RTL that performs the required truncation.\n\ \n\ If @code{TARGET_MODES_TIEABLE_P} returns false for a pair of modes,\n\ suboptimal code can result if this hook returns true for the corresponding\n\ |