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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 | 36ae309434a7818e5fda0c6eab53b0b6be6505f9 (patch) | |
| tree | 3619c3b174aad3ea998c2d2794619fd61cb0a0fd /clang/lib/CodeGen | |
| parent | 0fb12efbc11ebe36399489ead5fc8665a1799de6 (diff) | |
| download | bcm5719-llvm-36ae309434a7818e5fda0c6eab53b0b6be6505f9.tar.gz bcm5719-llvm-36ae309434a7818e5fda0c6eab53b0b6be6505f9.zip | |
Add a note about an IRgen optimization opportunity.
llvm-svn: 65376
Diffstat (limited to 'clang/lib/CodeGen')
| -rw-r--r-- | clang/lib/CodeGen/README.txt | 8 |
1 files changed, 7 insertions, 1 deletions
diff --git a/clang/lib/CodeGen/README.txt b/clang/lib/CodeGen/README.txt index ea2cf8cf0ee..e4508c7b82a 100644 --- a/clang/lib/CodeGen/README.txt +++ b/clang/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! //===---------------------------------------------------------------------===// |
