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| author | Chris Lattner <sabre@nondot.org> | 2011-01-06 07:09:23 +0000 |
|---|---|---|
| committer | Chris Lattner <sabre@nondot.org> | 2011-01-06 07:09:23 +0000 |
| commit | c1853e4a0355a7a7d48bd314024967d462d983e1 (patch) | |
| tree | 1cd4b3aef8bab372ea5b6367bfde648b733240c4 /lib/Target/README.txt | |
| parent | 0521928ae7cc492f3f45ef0e0cedc349102489c5 (diff) | |
| download | llvm-c1853e4a0355a7a7d48bd314024967d462d983e1.tar.gz llvm-c1853e4a0355a7a7d48bd314024967d462d983e1.tar.bz2 llvm-c1853e4a0355a7a7d48bd314024967d462d983e1.tar.xz | |
add a trivial instcombine missed in Dhrystone
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@122953 91177308-0d34-0410-b5e6-96231b3b80d8
Diffstat (limited to 'lib/Target/README.txt')
| -rw-r--r-- | lib/Target/README.txt | 37 |
1 files changed, 37 insertions, 0 deletions
diff --git a/lib/Target/README.txt b/lib/Target/README.txt index fa5e6010cf..a02863c6a4 100644 --- a/lib/Target/README.txt +++ b/lib/Target/README.txt @@ -1964,4 +1964,41 @@ This occurs several times in viterbi. //===---------------------------------------------------------------------===// +This code (from Benchmarks/Dhrystone/dry.c): + +define i32 @Func1(i32, i32) nounwind readnone optsize ssp { +entry: + %sext = shl i32 %0, 24 + %conv = ashr i32 %sext, 24 + %sext6 = shl i32 %1, 24 + %conv4 = ashr i32 %sext6, 24 + %cmp = icmp eq i32 %conv, %conv4 + %. = select i1 %cmp, i32 10000, i32 0 + ret i32 %. +} + +Should be simplified into something like: + +define i32 @Func1(i32, i32) nounwind readnone optsize ssp { +entry: + %sext = shl i32 %0, 24 + %conv = and i32 %sext, 0xFF000000 + %sext6 = shl i32 %1, 24 + %conv4 = and i32 %sext6, 0xFF000000 + %cmp = icmp eq i32 %conv, %conv4 + %. = select i1 %cmp, i32 10000, i32 0 + ret i32 %. +} + +and then to: + +define i32 @Func1(i32, i32) nounwind readnone optsize ssp { +entry: + %conv = and i32 %0, 0xFF + %conv4 = and i32 %1, 0xFF + %cmp = icmp eq i32 %conv, %conv4 + %. = select i1 %cmp, i32 10000, i32 0 + ret i32 %. +} +//===---------------------------------------------------------------------===// |