90ba33099c
This patch canonicalizes getelementptr instructions with constant indices to use the `i8` source element type. This makes it easier for optimizations to recognize that two GEPs are identical, because they don't need to see past many different ways to express the same offset. This is a first step towards https://discourse.llvm.org/t/rfc-replacing-getelementptr-with-ptradd/68699. This is limited to constant GEPs only for now, as they have a clear canonical form, while we're not yet sure how exactly to deal with variable indices. The test llvm/test/Transforms/PhaseOrdering/switch_with_geps.ll gives two representative examples of the kind of optimization improvement we expect from this change. In the first test SimplifyCFG can now realize that all switch branches are actually the same. In the second test it can convert it into simple arithmetic. These are representative of common optimization failures we see in Rust. Fixes https://github.com/llvm/llvm-project/issues/69841.
187 lines
6.0 KiB
LLVM
187 lines
6.0 KiB
LLVM
; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
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; RUN: opt -passes=instcombine -S < %s | FileCheck %s
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target datalayout = "e-m:e-p:64:64:64-i64:64-f80:128-n8:16:32:64-S128"
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define i32 @test_load_cast_combine_tbaa(ptr %ptr) {
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; Ensure (cast (load (...))) -> (load (cast (...))) preserves TBAA.
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; CHECK-LABEL: @test_load_cast_combine_tbaa(
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; CHECK-NEXT: entry:
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; CHECK-NEXT: [[L1:%.*]] = load i32, ptr [[PTR:%.*]], align 4, !tbaa [[TBAA0:![0-9]+]]
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; CHECK-NEXT: ret i32 [[L1]]
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;
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entry:
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%l = load float, ptr %ptr, !tbaa !0
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%c = bitcast float %l to i32
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ret i32 %c
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}
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define i32 @test_load_cast_combine_noalias(ptr %ptr) {
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; Ensure (cast (load (...))) -> (load (cast (...))) preserves no-alias metadata.
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; CHECK-LABEL: @test_load_cast_combine_noalias(
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; CHECK-NEXT: entry:
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; CHECK-NEXT: [[L1:%.*]] = load i32, ptr [[PTR:%.*]], align 4, !alias.scope !3, !noalias !3
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; CHECK-NEXT: ret i32 [[L1]]
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;
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entry:
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%l = load float, ptr %ptr, !alias.scope !3, !noalias !3
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%c = bitcast float %l to i32
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ret i32 %c
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}
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define float @test_load_cast_combine_range(ptr %ptr) {
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; Ensure (cast (load (...))) -> (load (cast (...))) drops range metadata. It
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; would be nice to preserve or update it somehow but this is hard when moving
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; between types.
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; CHECK-LABEL: @test_load_cast_combine_range(
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; CHECK-NEXT: entry:
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; CHECK-NEXT: [[L1:%.*]] = load float, ptr [[PTR:%.*]], align 4
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; CHECK-NEXT: ret float [[L1]]
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;
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entry:
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%l = load i32, ptr %ptr, !range !6
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%c = bitcast i32 %l to float
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ret float %c
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}
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define i32 @test_load_cast_combine_invariant(ptr %ptr) {
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; Ensure (cast (load (...))) -> (load (cast (...))) preserves invariant metadata.
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; CHECK-LABEL: @test_load_cast_combine_invariant(
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; CHECK-NEXT: entry:
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; CHECK-NEXT: [[L1:%.*]] = load i32, ptr [[PTR:%.*]], align 4, !invariant.load !6
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; CHECK-NEXT: ret i32 [[L1]]
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;
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entry:
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%l = load float, ptr %ptr, !invariant.load !7
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%c = bitcast float %l to i32
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ret i32 %c
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}
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define i32 @test_load_cast_combine_nontemporal(ptr %ptr) {
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; Ensure (cast (load (...))) -> (load (cast (...))) preserves nontemporal
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; metadata.
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; CHECK-LABEL: @test_load_cast_combine_nontemporal(
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; CHECK-NEXT: entry:
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; CHECK-NEXT: [[L1:%.*]] = load i32, ptr [[PTR:%.*]], align 4, !nontemporal !7
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; CHECK-NEXT: ret i32 [[L1]]
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;
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entry:
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%l = load float, ptr %ptr, !nontemporal !8
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%c = bitcast float %l to i32
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ret i32 %c
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}
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define ptr @test_load_cast_combine_align(ptr %ptr) {
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; Ensure (cast (load (...))) -> (load (cast (...))) preserves align
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; metadata.
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; CHECK-LABEL: @test_load_cast_combine_align(
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; CHECK-NEXT: entry:
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; CHECK-NEXT: [[L:%.*]] = load ptr, ptr [[PTR:%.*]], align 8, !align !8
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; CHECK-NEXT: ret ptr [[L]]
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;
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entry:
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%l = load ptr, ptr %ptr, !align !9
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ret ptr %l
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}
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define ptr @test_load_cast_combine_deref(ptr %ptr) {
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; Ensure (cast (load (...))) -> (load (cast (...))) preserves dereferenceable
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; metadata.
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; CHECK-LABEL: @test_load_cast_combine_deref(
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; CHECK-NEXT: entry:
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; CHECK-NEXT: [[L:%.*]] = load ptr, ptr [[PTR:%.*]], align 8, !dereferenceable !8
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; CHECK-NEXT: ret ptr [[L]]
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;
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entry:
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%l = load ptr, ptr %ptr, !dereferenceable !9
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ret ptr %l
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}
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define ptr @test_load_cast_combine_deref_or_null(ptr %ptr) {
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; Ensure (cast (load (...))) -> (load (cast (...))) preserves
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; dereferenceable_or_null metadata.
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; CHECK-LABEL: @test_load_cast_combine_deref_or_null(
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; CHECK-NEXT: entry:
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; CHECK-NEXT: [[L:%.*]] = load ptr, ptr [[PTR:%.*]], align 8, !dereferenceable_or_null !8
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; CHECK-NEXT: ret ptr [[L]]
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;
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entry:
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%l = load ptr, ptr %ptr, !dereferenceable_or_null !9
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ret ptr %l
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}
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define void @test_load_cast_combine_loop(ptr %src, ptr %dst, i32 %n) {
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; Ensure (cast (load (...))) -> (load (cast (...))) preserves loop access
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; metadata.
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; CHECK-LABEL: @test_load_cast_combine_loop(
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; CHECK-NEXT: entry:
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; CHECK-NEXT: br label [[LOOP:%.*]]
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; CHECK: loop:
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; CHECK-NEXT: [[I:%.*]] = phi i32 [ 0, [[ENTRY:%.*]] ], [ [[I_NEXT:%.*]], [[LOOP]] ]
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; CHECK-NEXT: [[TMP0:%.*]] = sext i32 [[I]] to i64
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; CHECK-NEXT: [[SRC_GEP:%.*]] = getelementptr inbounds float, ptr [[SRC:%.*]], i64 [[TMP0]]
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; CHECK-NEXT: [[TMP1:%.*]] = sext i32 [[I]] to i64
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; CHECK-NEXT: [[DST_GEP:%.*]] = getelementptr inbounds i32, ptr [[DST:%.*]], i64 [[TMP1]]
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; CHECK-NEXT: [[L1:%.*]] = load i32, ptr [[SRC_GEP]], align 4, !llvm.access.group [[ACC_GRP9:![0-9]+]]
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; CHECK-NEXT: store i32 [[L1]], ptr [[DST_GEP]], align 4
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; CHECK-NEXT: [[I_NEXT]] = add i32 [[I]], 1
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; CHECK-NEXT: [[CMP:%.*]] = icmp slt i32 [[I_NEXT]], [[N:%.*]]
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; CHECK-NEXT: br i1 [[CMP]], label [[LOOP]], label [[EXIT:%.*]], !llvm.loop [[LOOP1:![0-9]+]]
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; CHECK: exit:
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; CHECK-NEXT: ret void
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;
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entry:
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br label %loop
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loop:
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%i = phi i32 [ 0, %entry ], [ %i.next, %loop ]
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%src.gep = getelementptr inbounds float, ptr %src, i32 %i
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%dst.gep = getelementptr inbounds i32, ptr %dst, i32 %i
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%l = load float, ptr %src.gep, !llvm.access.group !10
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%c = bitcast float %l to i32
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store i32 %c, ptr %dst.gep
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%i.next = add i32 %i, 1
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%cmp = icmp slt i32 %i.next, %n
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br i1 %cmp, label %loop, label %exit, !llvm.loop !1
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exit:
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ret void
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}
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define void @test_load_cast_combine_nonnull(ptr %ptr) {
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; CHECK-LABEL: @test_load_cast_combine_nonnull(
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; CHECK-NEXT: entry:
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; CHECK-NEXT: [[P:%.*]] = load ptr, ptr [[PTR:%.*]], align 8, !nonnull !6
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; CHECK-NEXT: [[GEP:%.*]] = getelementptr i8, ptr [[PTR]], i64 336
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; CHECK-NEXT: store ptr [[P]], ptr [[GEP]], align 8
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; CHECK-NEXT: ret void
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;
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entry:
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%p = load ptr, ptr %ptr, !nonnull !{}
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%gep = getelementptr ptr, ptr %ptr, i32 42
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store ptr %p, ptr %gep
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ret void
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}
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define i32 @test_load_cast_combine_noundef(ptr %ptr) {
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; CHECK-LABEL: @test_load_cast_combine_noundef(
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; CHECK-NEXT: [[L1:%.*]] = load i32, ptr [[PTR:%.*]], align 4, !noundef !6
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; CHECK-NEXT: ret i32 [[L1]]
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;
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%l = load float, ptr %ptr, !noundef !{}
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%c = bitcast float %l to i32
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ret i32 %c
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}
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!0 = !{!1, !1, i64 0}
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!1 = !{!"scalar type", !2}
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!2 = !{!"root"}
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!3 = !{!4}
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!4 = distinct !{!4, !5}
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!5 = distinct !{!5}
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!6 = !{i32 0, i32 42}
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!7 = !{}
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!8 = !{i32 1}
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!9 = !{i64 8}
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!10 = distinct !{}
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