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Florian Hahn
36c8eeeaef
Summary: This updates the SCCP solver to use of the ValueElement lattice for parameters, which provides integer range information. The range information is used to remove unneeded icmp instructions. For the following function, f() can be optimized to `ret i32 2` with this change source_filename = "sccp.c" target datalayout = "e-m:e-i64:64-f80:128-n8:16:32:64-S128" target triple = "x86_64-unknown-linux-gnu" ; Function Attrs: norecurse nounwind readnone uwtable define i32 @main() local_unnamed_addr #0 { entry: %call = tail call fastcc i32 @f(i32 1) %call1 = tail call fastcc i32 @f(i32 47) %add3 = add nsw i32 %call, %call1 ret i32 %add3 } ; Function Attrs: noinline norecurse nounwind readnone uwtable define internal fastcc i32 @f(i32 %x) unnamed_addr #1 { entry: %c1 = icmp sle i32 %x, 100 %cmp = icmp sgt i32 %x, 300 %. = select i1 %cmp, i32 1, i32 2 ret i32 %. } attributes #1 = { noinline } Reviewers: davide, sanjoy, efriedma, dberlin Reviewed By: davide, dberlin Subscribers: mcrosier, gberry, mssimpso, dberlin, llvm-commits Differential Revision: https://reviews.llvm.org/D36656 git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@315288 91177308-0d34-0410-b5e6-96231b3b80d8
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