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| author | Paul Koning <ni1d@arrl.net> | 2018-10-12 09:50:15 -0400 |
|---|---|---|
| committer | Paul Koning <pkoning@gcc.gnu.org> | 2018-10-12 09:50:15 -0400 |
| commit | a01abe9d08712c3cd691589ce606e30caabfdcb2 (patch) | |
| tree | b88eb616f2ee4c38900867c58ae85093d4000121 /gcc | |
| parent | e5989e71ffdee9f030f0b8ac38aef5a4ff7bd444 (diff) | |
| download | gcc-a01abe9d08712c3cd691589ce606e30caabfdcb2.zip gcc-a01abe9d08712c3cd691589ce606e30caabfdcb2.tar.gz gcc-a01abe9d08712c3cd691589ce606e30caabfdcb2.tar.bz2 | |
md.texi (doloop_end): Document that the pattern code may need to check operand mode.
* doc/md.texi (doloop_end): Document that the pattern code may
need to check operand mode.
From-SVN: r265102
Diffstat (limited to 'gcc')
| -rw-r--r-- | gcc/ChangeLog | 5 | ||||
| -rw-r--r-- | gcc/doc/md.texi | 37 |
2 files changed, 38 insertions, 4 deletions
diff --git a/gcc/ChangeLog b/gcc/ChangeLog index ecf2b80..2393367 100644 --- a/gcc/ChangeLog +++ b/gcc/ChangeLog @@ -1,3 +1,8 @@ +2018-10-12 Paul Koning <ni1d@arrl.net> + + * doc/md.texi (doloop_end): Document that the pattern code may + need to check operand mode. + 2018-10-12 Wilco Dijkstra <wdijkstr@arm.com> * config/aarch64/aarch64.md (zero_extendsidi2_aarch64): Add alternatives diff --git a/gcc/doc/md.texi b/gcc/doc/md.texi index 4801d68..360b36b 100644 --- a/gcc/doc/md.texi +++ b/gcc/doc/md.texi @@ -7619,7 +7619,23 @@ simplified) from the PDP-11 target: @smallexample @group -(define_insn "doloop_end" +(define_expand "doloop_end" + [(parallel [(set (pc) + (if_then_else + (ne (match_operand:HI 0 "nonimmediate_operand" "+r,!m") + (const_int 1)) + (label_ref (match_operand 1 "" "")) + (pc))) + (set (match_dup 0) + (plus:HI (match_dup 0) + (const_int -1)))])] + "" + "@{ + if (GET_MODE (operands[0]) != HImode) + FAIL; + @}") + +(define_insn "doloop_end_insn" [(set (pc) (if_then_else (ne (match_operand:HI 0 "nonimmediate_operand" "+r,!m") @@ -7662,9 +7678,22 @@ will be non-negative. Since the @code{doloop_end} insn is a jump insn that also has an output, the reload pass does not handle the output operand. Therefore, the constraint must allow for that operand to be in memory rather than a -register. In the example shown above, that is handled by using a loop -instruction sequence that can handle memory operands when the memory -alternative appears. +register. In the example shown above, that is handled (in the +@code{doloop_end_insn} pattern) by using a loop instruction sequence +that can handle memory operands when the memory alternative appears. + +GCC does not check the mode of the loop register operand when generating +the @code{doloop_end} pattern. If the pattern is only valid for some +modes but not others, the pattern should be a @code{define_expand} +pattern that checks the operand mode in the preparation code, and issues +@code{FAIL} if an unsupported mode is found. The example above does +this, since the machine instruction to be used only exists for +@code{HImode}. + +If the @code{doloop_end} pattern is a @code{define_expand}, there must +also be a @code{define_insn} or @code{define_insn_and_split} matching +the generated pattern. Otherwise, the compiler will fail during loop +optimization. @end ifset @ifset INTERNALS |