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| author | Daniel Dunbar <daniel@zuster.org> | 2009-02-24 06:34:04 +0000 |
|---|---|---|
| committer | Daniel Dunbar <daniel@zuster.org> | 2009-02-24 06:34:04 +0000 |
| commit | 6eba1438ae905ca2a863dc32480712c8a6411aa3 (patch) | |
| tree | 0379bdc0b8b4b1634a2152ac2916dbf5b0bc083c | |
| parent | f0b26b1d9dee57c84e55f05200802658a7312683 (diff) | |
Add a note about an IRgen optimization opportunity.
git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@65376 91177308-0d34-0410-b5e6-96231b3b80d8
| -rw-r--r-- | lib/CodeGen/README.txt | 8 |
1 files changed, 7 insertions, 1 deletions
diff --git a/lib/CodeGen/README.txt b/lib/CodeGen/README.txt index ea2cf8cf0e..e4508c7b82 100644 --- a/lib/CodeGen/README.txt +++ b/lib/CodeGen/README.txt @@ -28,6 +28,12 @@ In theory, the same optimization could be a win for block local variables as long as the declaration dominates all statements in the block. +NOTE: The main case we care about this for is for -O0 -g compile time +performance, and in that scenario we will need to emit the alloca +anyway currently to emit proper debug info. So this is blocked by +being able to emit debug information which refers to an LLVM +temporary, not an alloca. + //===---------------------------------------------------------------------===// We should try and avoid generating basic blocks which only contain @@ -36,7 +42,7 @@ instruction overhead), all the way down through code generation and assembly time. On 176.gcc:expr.ll, it looks like over 12% of basic blocks are just -direct branches. +direct branches! //===---------------------------------------------------------------------===// |