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7b5862ed32
If SCEV can prove that the backedge taken count for a loop is zero, it does not need to "understand" a recursive PHI to compute its exiting value. This should fix PR33885. llvm-svn: 309758
75 lines
2.7 KiB
LLVM
75 lines
2.7 KiB
LLVM
; PR23538
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; RUN: opt < %s -indvars -loop-deletion -S | FileCheck %s
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; Check IndVarSimplify should not replace exit value because or else
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; udiv will be introduced by expand and the cost will be high.
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declare void @_Z3mixRjj(i32* dereferenceable(4), i32)
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declare void @llvm.lifetime.start.p0i8(i64, i8* nocapture)
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declare void @llvm.lifetime.end.p0i8(i64, i8* nocapture)
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define i32 @_Z3fooPKcjj(i8* nocapture readonly %s, i32 %len, i32 %c) {
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; CHECK-LABEL: @_Z3fooPKcjj(
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; CHECK-NOT: udiv
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entry:
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%a = alloca i32, align 4
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%tmp = bitcast i32* %a to i8*
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call void @llvm.lifetime.start.p0i8(i64 4, i8* %tmp)
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store i32 -1640531527, i32* %a, align 4
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%cmp8 = icmp ugt i32 %len, 11
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br i1 %cmp8, label %while.body.lr.ph, label %while.end
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while.body.lr.ph: ; preds = %entry
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br label %while.body
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while.body: ; preds = %while.body, %while.body.lr.ph
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%keylen.010 = phi i32 [ %len, %while.body.lr.ph ], [ %sub, %while.body ]
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%s.addr.09 = phi i8* [ %s, %while.body.lr.ph ], [ %add.ptr, %while.body ]
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%tmp1 = bitcast i8* %s.addr.09 to i32*
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%tmp2 = load i32, i32* %tmp1, align 4
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%shl.i = shl i32 %tmp2, 1
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%and.i = and i32 %shl.i, 16843008
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%tmp3 = load i32, i32* %a, align 4
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%sub.i = add i32 %tmp3, %tmp2
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%add = sub i32 %sub.i, %and.i
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store i32 %add, i32* %a, align 4
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%add.ptr = getelementptr inbounds i8, i8* %s.addr.09, i64 12
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%sub = add i32 %keylen.010, -12
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%cmp = icmp ugt i32 %sub, 11
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br i1 %cmp, label %while.body, label %while.cond.while.end_crit_edge
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while.cond.while.end_crit_edge: ; preds = %while.body
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%sub.lcssa = phi i32 [ %sub, %while.body ]
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br label %while.end
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while.end: ; preds = %while.cond.while.end_crit_edge, %entry
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%keylen.0.lcssa = phi i32 [ %sub.lcssa, %while.cond.while.end_crit_edge ], [ %len, %entry ]
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call void @_Z3mixRjj(i32* dereferenceable(4) %a, i32 %keylen.0.lcssa)
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%tmp4 = load i32, i32* %a, align 4
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call void @llvm.lifetime.end.p0i8(i64 4, i8* %tmp)
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ret i32 %tmp4
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}
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define i32 @zero_backedge_count_test(i32 %unknown_init, i32* %unknown_mem) {
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; CHECK-LABEL: @zero_backedge_count_test(
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entry:
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br label %loop
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loop:
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%iv = phi i32 [ 0, %entry], [ %iv.inc, %loop ]
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%unknown_phi = phi i32 [ %unknown_init, %entry ], [ %unknown_next, %loop ]
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%iv.inc = add i32 %iv, 1
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%be_taken = icmp ne i32 %iv.inc, 1
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%unknown_next = load volatile i32, i32* %unknown_mem
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br i1 %be_taken, label %loop, label %leave
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leave:
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; We can fold %unknown_phi even though the backedge value for it is completely
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; unknown, since we can prove that the loop's backedge taken count is 0.
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; CHECK: leave:
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; CHECK: ret i32 %unknown_init
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%exit_val = phi i32 [ %unknown_phi, %loop ]
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ret i32 %exit_val
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}
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