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| author | Eli Friedman <eli.friedman@gmail.com> | 2011-03-22 20:49:53 +0000 |
|---|---|---|
| committer | Eli Friedman <eli.friedman@gmail.com> | 2011-03-22 20:49:53 +0000 |
| commit | 822e7bc061ec77efd38154c6011403dfa92174ac (patch) | |
| tree | cbf97c85747602585daefc467236570c6e5f76da /llvm/lib | |
| parent | 0cf62f50451a3dd16ba77c255a1bec2ee6cf533b (diff) | |
| download | bcm5719-llvm-822e7bc061ec77efd38154c6011403dfa92174ac.tar.gz bcm5719-llvm-822e7bc061ec77efd38154c6011403dfa92174ac.zip | |
A bit more analysis of a memset-related README entry.
llvm-svn: 128107
Diffstat (limited to 'llvm/lib')
| -rw-r--r-- | llvm/lib/Target/README.txt | 9 |
1 files changed, 5 insertions, 4 deletions
diff --git a/llvm/lib/Target/README.txt b/llvm/lib/Target/README.txt index 63f1f79962b..33941f451a0 100644 --- a/llvm/lib/Target/README.txt +++ b/llvm/lib/Target/README.txt @@ -2074,11 +2074,12 @@ for.end: ; preds = %entry } This shouldn't need the ((zext (%n - 1)) + 1) game, and it should ideally fold -the two memset's together. The issue with %n seems to stem from poor handling -of the original loop. +the two memset's together. -To simplify this, we need SCEV to know that "n != 0" because of the dominating -conditional. That would turn the second memset into a simple memset of 'n'. +The issue with the addition only occurs in 64-bit mode, and appears to be at +least partially caused by Scalar Evolution not keeping its cache updated: it +returns the "wrong" result immediately after indvars runs, but figures out the +expected result if it is run from scratch on IR resulting from running indvars. //===---------------------------------------------------------------------===// |
