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author | Daniel Dunbar <daniel@zuster.org> | 2009-02-20 19:34:45 +0000 |
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committer | Daniel Dunbar <daniel@zuster.org> | 2009-02-20 19:34:45 +0000 |
commit | 2f3a3d9f7af82e8b6588f7a9afa71e7357bae21e (patch) | |
tree | 0159438d902a7cefe1b4a6ab7a54b3555744cb46 /clang/lib/CodeGen/README.txt | |
parent | 27032de34b0d57f00f0ade9f83b51fa0461a6471 (diff) | |
download | bcm5719-llvm-2f3a3d9f7af82e8b6588f7a9afa71e7357bae21e.tar.gz bcm5719-llvm-2f3a3d9f7af82e8b6588f7a9afa71e7357bae21e.zip |
Add some IRgen improvement notes.
llvm-svn: 65146
Diffstat (limited to 'clang/lib/CodeGen/README.txt')
-rw-r--r-- | clang/lib/CodeGen/README.txt | 17 |
1 files changed, 17 insertions, 0 deletions
diff --git a/clang/lib/CodeGen/README.txt b/clang/lib/CodeGen/README.txt index 56069dd99d2..ea2cf8cf0ee 100644 --- a/clang/lib/CodeGen/README.txt +++ b/clang/lib/CodeGen/README.txt @@ -30,3 +30,20 @@ block. //===---------------------------------------------------------------------===// +We should try and avoid generating basic blocks which only contain +jumps. At -O0, this penalizes us all the way from IRgen (malloc & +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. + +//===---------------------------------------------------------------------===// + +There are some more places where we could avoid generating unreachable code. For +example: + void f0(int a) { abort(); if (a) printf("hi"); } +still generates a call to printf. This doesn't occur much in real +code, but would still be nice to clean up. + +//===---------------------------------------------------------------------===// |