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ac54d0066c
Summary: These are good candidates for jump threading. This enables later opts (such as InstCombine) to combine instructions from the selects with instructions out of the selects. SimplifyCFG will fold the select again if unfolding wasn't worth it. Patch by James Molloy and Pablo Barrio. Reviewers: rengolin, haicheng, sebpop Subscribers: jojo, jmolloy, llvm-commits Differential Revision: https://reviews.llvm.org/D26391 git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@286236 91177308-0d34-0410-b5e6-96231b3b80d8
46 lines
1.4 KiB
LLVM
46 lines
1.4 KiB
LLVM
; RUN: opt < %s -jump-threading -instcombine -simplifycfg -S | FileCheck %s
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; The three selects are jump-threaded so that instcombine can optimize, and
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; simplifycfg should turn the result into a single select.
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define i32 @f(i32 %a, i32 %b) {
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; CHECK: select
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; CHECK-NOT: select
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entry:
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%0 = and i32 %a, 1
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%1 = and i32 %b, 1
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%xor = xor i32 %1, %a
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%shr32 = lshr i32 %a, 1
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%cmp10 = icmp eq i32 %xor, 1
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%2 = xor i32 %b, 12345
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%b.addr.1 = select i1 %cmp10, i32 %2, i32 %b
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%shr1633 = lshr i32 %b.addr.1, 1
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%3 = or i32 %shr1633, 54321
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%b.addr.2 = select i1 %cmp10, i32 %3, i32 %shr1633
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%shr1634 = lshr i32 %b.addr.2, 2
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%4 = or i32 %shr1634, 54320
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%b.addr.3 = select i1 %cmp10, i32 %4, i32 %shr1634
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ret i32 %b.addr.3
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}
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; Case where the condition is not only used as condition but also as the
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; true or false value in at least one of the selects.
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define i1 @g(i32 %a, i32 %b) {
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; CHECK: select
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; CHECK-NOT: select
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entry:
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%0 = and i32 %a, 1
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%1 = and i32 %b, 1
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%xor = xor i32 %1, %a
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%shr32 = lshr i32 %a, 1
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%cmp10 = icmp eq i32 %xor, 1
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%2 = xor i32 %b, 12345
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%b.addr.1 = select i1 %cmp10, i32 %2, i32 %b
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%shr1633 = lshr i32 %b.addr.1, 1
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%3 = or i32 %shr1633, 54321
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%b.addr.2 = select i1 %cmp10, i32 %3, i32 %shr1633
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%shr1634 = lshr i32 %b.addr.2, 2
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%4 = icmp eq i32 %shr1634, 54320
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%b.addr.3 = select i1 %cmp10, i1 %4, i1 %cmp10
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ret i1 %b.addr.3
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}
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