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| author | Sanjoy Das <sanjoy@playingwithpointers.com> | 2015-09-16 20:41:29 +0000 |
|---|---|---|
| committer | Sanjoy Das <sanjoy@playingwithpointers.com> | 2015-09-16 20:41:29 +0000 |
| commit | e5f4889ba9468dea349ea36417ceab28444fb52a (patch) | |
| tree | aa08aafec669671cf67679275bf97c34fcc80b43 /llvm/lib/CodeGen/MachineBasicBlock.cpp | |
| parent | 3e9d733e687828a79027403b9ad3da97e8074c44 (diff) | |
| download | llvm-e5f4889ba9468dea349ea36417ceab28444fb52a.zip llvm-e5f4889ba9468dea349ea36417ceab28444fb52a.tar.gz llvm-e5f4889ba9468dea349ea36417ceab28444fb52a.tar.bz2 | |
[InstCombine] Optimize icmp slt signum(x), 1 --> icmp slt x, 1
Summary:
`signum(x)` is sometimes implemented as `(x >> 63) | (-x >>> 63)` (for
an `i64` `x`). This change adds a matcher for that pattern, and an
instcombine rule to optimize `signum(x) s< 1`.
Later, we can also consider optimizing:
icmp slt signum(x), 0 --> icmp slt x, 0
icmp sle signum(x), 1 --> true
etc.
Reviewers: majnemer
Subscribers: llvm-commits
Differential Revision: http://reviews.llvm.org/D12703
llvm-svn: 247846
Diffstat (limited to 'llvm/lib/CodeGen/MachineBasicBlock.cpp')
0 files changed, 0 insertions, 0 deletions