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Fold (iszero(A&K1) | iszero(A&K2)) -> (A&(K1|K2)) != (K1|K2) if we know that K1 and K2 are 'one-hot' (only one bit is on).

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git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@194525 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Nadav Rotem
2013-11-12 22:38:59 +00:00
parent f3bd3ea3fe
commit 6c84f7ad2d
2 changed files with 85 additions and 3 deletions
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test/Transforms/InstCombine/onehot_merge.ll
+35
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; RUN: opt < %s -instcombine -S | FileCheck %s
;CHECK: @and_consts
;CHECK: and i32 %k, 12
;CHECK: icmp ne i32 %0, 12
;CHECK: ret
define i1 @and_consts(i32 %k, i32 %c1, i32 %c2) {
bb:
%tmp1 = and i32 4, %k
%tmp2 = icmp eq i32 %tmp1, 0
%tmp5 = and i32 8, %k
%tmp6 = icmp eq i32 %tmp5, 0
%or = or i1 %tmp2, %tmp6
ret i1 %or
}
;CHECK: @foo1_and
;CHECK: shl i32 1, %c1
;CHECK-NEXT: shl i32 1, %c2
;CHECK-NEXT: or i32
;CHECK-NEXT: and i32
;CHECK-NEXT: icmp ne i32 %1, %0
;CHECK: ret
define i1 @foo1_and(i32 %k, i32 %c1, i32 %c2) {
bb:
%tmp = shl i32 1, %c1
%tmp4 = shl i32 1, %c2
%tmp1 = and i32 %tmp, %k
%tmp2 = icmp eq i32 %tmp1, 0
%tmp5 = and i32 %tmp4, %k
%tmp6 = icmp eq i32 %tmp5, 0
%or = or i1 %tmp2, %tmp6
ret i1 %or
}