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Summary:
Folding patterns like:
%vec = shufflevector <4 x i8> %insvec, <4 x i8> undef, <4 x i32> zeroinitializer
%cast = bitcast <4 x i8> %vec to i32
%cond = icmp eq i32 %cast, 0
into:
%ext = extractelement <4 x i8> %insvec, i32 0
%cond = icmp eq i32 %ext, 0
Combined with existing rules, this allows us to fold patterns like:
%insvec = insertelement <4 x i8> undef, i8 %val, i32 0
%vec = shufflevector <4 x i8> %insvec, <4 x i8> undef, <4 x i32> zeroinitializer
%cast = bitcast <4 x i8> %vec to i32
%cond = icmp eq i32 %cast, 0
into:
%cond = icmp eq i8 %val, 0
When we construct a splat vector via a shuffle, and bitcast the vector into an integer type for comparison against an integer constant. Then we can simplify the the comparison to compare the splatted value against the integer constant.
Reviewers: spatel, anna, mkazantsev
Reviewed By: spatel
Subscribers: efriedma, rengolin, llvm-commits
Differential Revision: https://reviews.llvm.org/D44997
llvm-svn: 329087
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