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https://github.com/RPCS3/llvm-mirror.git
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080898a0f3
This patches teaches LVI to recognize clamp idioms (e.g. select(a > 5, a, 5) will always produce something greater than 5. The tests end up being somewhat simplistic because trying to exercise the case I actually care about (a loop with a range check on a clamped secondary induction variable) ends up tripping across a couple of other imprecisions in the analysis. Ah, the joys of LVI... Differential Revision: http://reviews.llvm.org/D16827 llvm-svn: 260627
219 lines
4.6 KiB
LLVM
219 lines
4.6 KiB
LLVM
; RUN: opt < %s -correlated-propagation -S | FileCheck %s
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; CHECK-LABEL: @simple(
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define i8 @simple(i1) {
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entry:
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%s = select i1 %0, i8 0, i8 1
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br i1 %0, label %then, label %else
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then:
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; CHECK: ret i8 0
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%a = phi i8 [ %s, %entry ]
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ret i8 %a
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else:
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; CHECK: ret i8 1
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%b = phi i8 [ %s, %entry ]
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ret i8 %b
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}
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; CHECK-LABEL: @loop(
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define void @loop(i32) {
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entry:
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br label %loop
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loop:
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%idx = phi i32 [ %0, %entry ], [ %sel, %loop ]
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; CHECK: %idx = phi i32 [ %0, %entry ], [ %2, %loop ]
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%1 = icmp eq i32 %idx, 0
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%2 = add i32 %idx, -1
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%sel = select i1 %1, i32 0, i32 %2
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br i1 %1, label %out, label %loop
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out:
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ret void
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}
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; CHECK-LABEL: @not_correlated(
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define i8 @not_correlated(i1, i1) {
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entry:
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%s = select i1 %0, i8 0, i8 1
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br i1 %1, label %then, label %else
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then:
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; CHECK: ret i8 %s
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%a = phi i8 [ %s, %entry ]
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ret i8 %a
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else:
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; CHECK: ret i8 %s
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%b = phi i8 [ %s, %entry ]
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ret i8 %b
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}
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@c = global i32 0, align 4
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@b = global i32 0, align 4
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; CHECK-LABEL: @PR23752(
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define i32 @PR23752() {
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entry:
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br label %for.body
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for.body:
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%phi = phi i32 [ 0, %entry ], [ %sel, %for.body ]
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%sel = select i1 icmp sgt (i32* @b, i32* @c), i32 %phi, i32 1
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%cmp = icmp ne i32 %sel, 1
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br i1 %cmp, label %for.body, label %if.end
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; CHECK: %[[sel:.*]] = select i1 icmp sgt (i32* @b, i32* @c), i32 0, i32 1
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; CHECK-NEXT: %[[cmp:.*]] = icmp ne i32 %[[sel]], 1
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; CHECK-NEXT: br i1 %[[cmp]]
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if.end:
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ret i32 %sel
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; CHECK: ret i32 1
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}
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define i1 @test1(i32* %p, i1 %unknown) {
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; CHECK-LABEL: @test1
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%pval = load i32, i32* %p
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%cmp1 = icmp slt i32 %pval, 255
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br i1 %cmp1, label %next, label %exit
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next:
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%min = select i1 %unknown, i32 %pval, i32 5
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;; TODO: This pointless branch shouldn't be neccessary
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br label %next2
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next2:
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; CHECK-LABEL: next2:
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; CHECK: ret i1 false
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%res = icmp eq i32 %min, 255
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ret i1 %res
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exit:
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; CHECK-LABEL: exit:
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; CHECK: ret i1 true
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ret i1 true
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}
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; Check that we take a conservative meet
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define i1 @test2(i32* %p, i32 %qval, i1 %unknown) {
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; CHECK-LABEL: test2
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%pval = load i32, i32* %p
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%cmp1 = icmp slt i32 %pval, 255
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br i1 %cmp1, label %next, label %exit
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next:
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%min = select i1 %unknown, i32 %pval, i32 %qval
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;; TODO: This pointless branch shouldn't be neccessary
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br label %next2
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next2:
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; CHECK-LABEL: next2
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; CHECK: ret i1 %res
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%res = icmp eq i32 %min, 255
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ret i1 %res
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exit:
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; CHECK-LABEL: exit:
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; CHECK: ret i1 true
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ret i1 true
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}
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; Same as @test2, but for the opposite select input
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define i1 @test3(i32* %p, i32 %qval, i1 %unknown) {
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; CHECK-LABEL: test3
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%pval = load i32, i32* %p
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%cmp1 = icmp slt i32 %pval, 255
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br i1 %cmp1, label %next, label %exit
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next:
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%min = select i1 %unknown, i32 %qval, i32 %pval
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;; TODO: This pointless branch shouldn't be neccessary
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br label %next2
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next2:
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; CHECK-LABEL: next2
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; CHECK: ret i1 %res
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%res = icmp eq i32 %min, 255
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ret i1 %res
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exit:
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; CHECK-LABEL: exit:
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; CHECK: ret i1 true
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ret i1 true
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}
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; Conflicting constants (i.e. isOverdefined result)
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; NOTE: Using doubles in this version is a bit of a hack. This
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; is to get around the fact that all integers (including constants
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; and non-constants) are actually represented as constant-ranges.
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define i1 @test4(i32* %p, i32 %qval, i1 %unknown) {
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; CHECK-LABEL: test4
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%pval = load i32, i32* %p
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%cmp1 = icmp slt i32 %pval, 255
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br i1 %cmp1, label %next, label %exit
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next:
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%min = select i1 %unknown, double 1.0, double 0.0
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;; TODO: This pointless branch shouldn't be neccessary
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br label %next2
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next2:
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; CHECK-LABEL: next2
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; CHECK: ret i1 %res
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%res = fcmp oeq double %min, 300.0
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ret i1 %res
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exit:
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; CHECK-LABEL: exit:
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; CHECK: ret i1 true
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ret i1 true
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}
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;; Using the condition to clamp the result
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;;
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define i1 @test5(i32* %p, i1 %unknown) {
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; CHECK-LABEL: @test5
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%pval = load i32, i32* %p
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%cmp1 = icmp slt i32 %pval, 255
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br i1 %cmp1, label %next, label %exit
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next:
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%cond = icmp sgt i32 %pval, 0
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%min = select i1 %cond, i32 %pval, i32 5
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;; TODO: This pointless branch shouldn't be neccessary
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br label %next2
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next2:
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; CHECK-LABEL: next2:
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; CHECK: ret i1 false
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%res = icmp eq i32 %min, -1
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ret i1 %res
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exit:
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; CHECK-LABEL: exit:
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; CHECK: ret i1 true
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ret i1 true
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}
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define i1 @test6(i32* %p, i1 %unknown) {
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; CHECK-LABEL: @test6
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%pval = load i32, i32* %p
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%cmp1 = icmp ult i32 %pval, 255
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br i1 %cmp1, label %next, label %exit
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next:
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%cond = icmp ne i32 %pval, 254
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%sel = select i1 %cond, i32 %pval, i32 1
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;; TODO: This pointless branch shouldn't be neccessary
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br label %next2
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next2:
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; CHECK-LABEL: next2:
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; CHECK: ret i1 true
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%res = icmp slt i32 %sel, 254
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ret i1 %res
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exit:
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; CHECK-LABEL: exit:
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; CHECK: ret i1 true
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ret i1 true
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}
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