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| author | Chris Lattner <sabre@nondot.org> | 2010-08-27 20:32:06 +0000 |
|---|---|---|
| committer | Chris Lattner <sabre@nondot.org> | 2010-08-27 20:32:06 +0000 |
| commit | f9d05ab007d4764a78e820aecfcf8de179d178a7 (patch) | |
| tree | 4b52d50bad0f775cb0f752343f51638d09b6eb76 /lib | |
| parent | e8ac3f3be4b4df619368bf46aa4ed91557b5f76e (diff) | |
| download | llvm-f9d05ab007d4764a78e820aecfcf8de179d178a7.tar.gz llvm-f9d05ab007d4764a78e820aecfcf8de179d178a7.tar.bz2 llvm-f9d05ab007d4764a78e820aecfcf8de179d178a7.tar.xz | |
teach the truncation optimization that an entire chain of
computation can be truncated if it is fed by a sext/zext that doesn't
have to be exactly equal to the truncation result type.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@112285 91177308-0d34-0410-b5e6-96231b3b80d8
Diffstat (limited to 'lib')
| -rw-r--r-- | lib/Transforms/InstCombine/InstCombineCasts.cpp | 5 |
1 files changed, 5 insertions, 0 deletions
diff --git a/lib/Transforms/InstCombine/InstCombineCasts.cpp b/lib/Transforms/InstCombine/InstCombineCasts.cpp index 1372a1891f..89719bef09 100644 --- a/lib/Transforms/InstCombine/InstCombineCasts.cpp +++ b/lib/Transforms/InstCombine/InstCombineCasts.cpp @@ -396,6 +396,11 @@ static bool CanEvaluateTruncated(Value *V, const Type *Ty) { case Instruction::Trunc: // trunc(trunc(x)) -> trunc(x) return true; + case Instruction::ZExt: + case Instruction::SExt: + // trunc(ext(x)) -> ext(x) if the source type is smaller than the new dest + // trunc(ext(x)) -> trunc(x) if the source type is larger than the new dest + return true; case Instruction::Select: { SelectInst *SI = cast<SelectInst>(I); return CanEvaluateTruncated(SI->getTrueValue(), Ty) && |