aboutsummaryrefslogtreecommitdiff
diff options
context:
space:
mode:
authorHans-Peter Nilsson <hp@axis.com>2023-03-14 02:06:34 +0100
committerHans-Peter Nilsson <hp@bitrange.com>2023-04-04 02:19:14 +0200
commit59b4a555c3f1c3dba376da1c4886a9ea18ad208d (patch)
treede63abd7d342df646c0e6e7a25f777fe487a126e
parent10bdf6968e29cc3a2fcd5df95e93c6cbd500cc02 (diff)
downloadgcc-59b4a555c3f1c3dba376da1c4886a9ea18ad208d.zip
gcc-59b4a555c3f1c3dba376da1c4886a9ea18ad208d.tar.gz
gcc-59b4a555c3f1c3dba376da1c4886a9ea18ad208d.tar.bz2
doc: md.texi (Insn Splitting): Tweak wording for readability.
I needed to check what was allowed in a define_split, but had problems understanding what was meant by "Splitting of jump instruction into sequence that over by another jump instruction". * doc/md.texi (Insn Splitting): Tweak wording for readability. Co-Authored-By: Sandra Loosemore <sandra@codesourcery.com>
-rw-r--r--gcc/doc/md.texi30
1 files changed, 15 insertions, 15 deletions
diff --git a/gcc/doc/md.texi b/gcc/doc/md.texi
index edfa51e..970af5e 100644
--- a/gcc/doc/md.texi
+++ b/gcc/doc/md.texi
@@ -8767,21 +8767,21 @@ insns that don't. Instead, write two separate @code{define_split}
definitions, one for the insns that are valid and one for the insns that
are not valid.
-The splitter is allowed to split jump instructions into sequence of
-jumps or create new jumps in while splitting non-jump instructions. As
-the control flow graph and branch prediction information needs to be updated,
-several restriction apply.
-
-Splitting of jump instruction into sequence that over by another jump
-instruction is always valid, as compiler expect identical behavior of new
-jump. When new sequence contains multiple jump instructions or new labels,
-more assistance is needed. Splitter is required to create only unconditional
-jumps, or simple conditional jump instructions. Additionally it must attach a
-@code{REG_BR_PROB} note to each conditional jump. A global variable
-@code{split_branch_probability} holds the probability of the original branch in case
-it was a simple conditional jump, @minus{}1 otherwise. To simplify
-recomputing of edge frequencies, the new sequence is required to have only
-forward jumps to the newly created labels.
+The splitter is allowed to split jump instructions into a sequence of jumps or
+create new jumps while splitting non-jump instructions. As the control flow
+graph and branch prediction information needs to be updated after the splitter
+runs, several restrictions apply.
+
+Splitting of a jump instruction into a sequence that has another jump
+instruction to the same label is always valid, as the compiler expects
+identical behavior of the new jump. When the new sequence contains multiple
+jump instructions or new labels, more assistance is needed. The splitter is
+permitted to create only unconditional jumps, or simple conditional jump
+instructions. Additionally it must attach a @code{REG_BR_PROB} note to each
+conditional jump. A global variable @code{split_branch_probability} holds the
+probability of the original branch in case it was a simple conditional jump,
+@minus{}1 otherwise. To simplify recomputing of edge frequencies, the new
+sequence is permitted to have only forward jumps to the newly-created labels.
@findex define_insn_and_split
For the common case where the pattern of a define_split exactly matches the