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[LLVM 21] fix calls to llvm.lifetime.start #4979

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[LLVM 21] fix calls to llvm.lifetime.start #4979

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@thewilsonator thewilsonator commented Sep 6, 2025 •
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This mostly fixes compilation for LLVM21, except for some breakage with regards to moving llvm.lifetime.start to taking only and AllocaInst (or a Poison).

; Function Attrs: uwtable(sync)
define void @_D3std3uni15decomposeHangulFNaNbNfwZSQBjQBi8Grapheme(ptr noalias sret(%std.uni.Grapheme) align 8 %0, i32 %1) #0 {
  %3 = alloca i32, align 4
  %4 = alloca i32, align 4
  %5 = alloca %std.uni.Grapheme, align 8
  %6 = alloca [1 x i32], align 4
  %7 = alloca i32, align 4
  %8 = alloca i32, align 4
  %9 = alloca i32, align 4
  %10 = alloca i32, align 4
  %11 = alloca i32, align 4
  %12 = alloca %std.uni.Grapheme, align 8
  %13 = alloca [3 x i32], align 4
  %14 = alloca %std.uni.Grapheme, align 8
  %15 = alloca [2 x i32], align 4
  store i32 %1, ptr %3, align 4
  %16 = load i32, ptr %3, align 4
  %17 = sub i32 %16, 44032
  store i32 %17, ptr %4, align 4
  %18 = load i32, ptr %4, align 4
  %19 = icmp slt i32 %18, 0
  br i1 %19, label %23, label %20

20:                                               ; preds = %2
  %21 = load i32, ptr %4, align 4
  %22 = icmp sge i32 %21, 11172
  br label %23

23:                                               ; preds = %20, %2
  %24 = phi i1 [ true, %2 ], [ %22, %20 ]
  br i1 %24, label %25, label %35

25:                                               ; preds = %23
  call void @llvm.lifetime.start.p0(ptr captures(none) %0) #4 ; <<<<<<<<
  %26 = getelementptr inbounds %std.uni.Grapheme, ptr %0, i32 0, i32 0
  store ptr null, ptr %26, align 8
  %27 = getelementptr inbounds %std.uni.Grapheme, ptr %0, i32 0, i32 1
  store i64 0, ptr %27, align 8
  %28 = getelementptr inbounds %std.uni.Grapheme, ptr %0, i32 0, i32 2
  store i64 0, ptr %28, align 8
  %29 = getelementptr inbounds %std.uni.Grapheme, ptr %0, i32 0, i32 3
  store i64 0, ptr %29, align 8
  %30 = getelementptr inbounds [1 x i32], ptr %6, i32 0, i32 0
  %31 = load i32, ptr %3, align 4
  store i32 %31, ptr %30, align 4
  %32 = insertvalue { i64, ptr } { i64 1, ptr undef }, ptr %6, 1
  %33 = call ptr @_D3std3uni8Grapheme__T6__ctorTwZQkMFNaNbNcNiNfxAwXSQBxQBwQBv(ptr nonnull returned %0, { i64, ptr } %32) #3
  ret void

34:                                               ; No predecessors!
  br label %35

35:                                               ; preds = %34, %23
  call void @llvm.lifetime.end.p0(ptr captures(none) %5) #4
  %36 = load i32, ptr %4, align 4
  %37 = sdiv i32 %36, 588
  store i32 %37, ptr %7, align 4
  %38 = load i32, ptr %4, align 4
  %39 = srem i32 %38, 588
  %40 = sdiv i32 %39, 28
  store i32 %40, ptr %8, align 4
  %41 = load i32, ptr %4, align 4
  %42 = srem i32 %41, 28
  store i32 %42, ptr %9, align 4
  %43 = load i32, ptr %7, align 4
  %44 = add i32 4352, %43
  store i32 %44, ptr %10, align 4
  %45 = load i32, ptr %8, align 4
  %46 = add i32 4449, %45
  store i32 %46, ptr %11, align 4
  %47 = load i32, ptr %9, align 4
  %48 = icmp sgt i32 %47, 0
  br i1 %48, label %49, label %64

49:                                               ; preds = %35
  call void @llvm.lifetime.start.p0(ptr captures(none) %0) #4
  %50 = getelementptr inbounds %std.uni.Grapheme, ptr %0, i32 0, i32 0
  store ptr null, ptr %50, align 8
  %51 = getelementptr inbounds %std.uni.Grapheme, ptr %0, i32 0, i32 1
  store i64 0, ptr %51, align 8
  %52 = getelementptr inbounds %std.uni.Grapheme, ptr %0, i32 0, i32 2
  store i64 0, ptr %52, align 8
  %53 = getelementptr inbounds %std.uni.Grapheme, ptr %0, i32 0, i32 3
  store i64 0, ptr %53, align 8
  %54 = getelementptr inbounds [3 x i32], ptr %13, i32 0, i32 0
  %55 = load i32, ptr %10, align 4
  store i32 %55, ptr %54, align 4
  %56 = getelementptr inbounds [3 x i32], ptr %13, i32 0, i32 1
  %57 = load i32, ptr %11, align 4
  store i32 %57, ptr %56, align 4
  %58 = getelementptr inbounds [3 x i32], ptr %13, i32 0, i32 2
  %59 = load i32, ptr %9, align 4
  %60 = add i32 4519, %59
  store i32 %60, ptr %58, align 4
  %61 = insertvalue { i64, ptr } { i64 3, ptr undef }, ptr %13, 1
  %62 = call ptr @_D3std3uni8Grapheme__T6__ctorTiZQkMFNaNbNcNiNfxAiXSQBxQBwQBv(ptr nonnull returned %0, { i64, ptr } %61) #3
  ret void

63:                                               ; No predecessors!
  br label %76

64:                                               ; preds = %35
  call void @llvm.lifetime.start.p0(ptr captures(none) %0) #4
  %65 = getelementptr inbounds %std.uni.Grapheme, ptr %0, i32 0, i32 0
  store ptr null, ptr %65, align 8
  %66 = getelementptr inbounds %std.uni.Grapheme, ptr %0, i32 0, i32 1
  store i64 0, ptr %66, align 8
  %67 = getelementptr inbounds %std.uni.Grapheme, ptr %0, i32 0, i32 2
  store i64 0, ptr %67, align 8
  %68 = getelementptr inbounds %std.uni.Grapheme, ptr %0, i32 0, i32 3
  store i64 0, ptr %68, align 8
  %69 = getelementptr inbounds [2 x i32], ptr %15, i32 0, i32 0
  %70 = load i32, ptr %10, align 4
  store i32 %70, ptr %69, align 4
  %71 = getelementptr inbounds [2 x i32], ptr %15, i32 0, i32 1
  %72 = load i32, ptr %11, align 4
  store i32 %72, ptr %71, align 4
  %73 = insertvalue { i64, ptr } { i64 2, ptr undef }, ptr %15, 1
  %74 = call ptr @_D3std3uni8Grapheme__T6__ctorTiZQkMFNaNbNcNiNfxAiXSQBxQBwQBv(ptr nonnull returned %0, { i64, ptr } %73) #3
  ret void

75:                                               ; No predecessors!
  br label %76

76:                                               ; preds = %75, %63
  call void @llvm.lifetime.end.p0(ptr captures(none) %12) #4
  call void @llvm.lifetime.end.p0(ptr captures(none) %14) #4
  ret void
}

and

; Function Attrs: uwtable(sync)
define weak_odr void @_D3std3uni__T11memoizeExprVAyaa91_756e69636f64652e416c7068616265746963207c20756e69636f64652e4d6e207c20756e69636f64652e4d630a20202020202020207c20756e69636f64652e4d65207c20756e69636f64652e4e64207c20756e69636f64652e5063ZQHwFNfZSQIpQIo__T13InversionListTSQJpQJo8GcPolicyZQBh(ptr noalias sret(%"std.uni.InversionList!(GcPolicy).InversionList") align 8 %0) #0 personality ptr @_d_eh_personality {
  %2 = alloca %"std.uni.InversionList!(GcPolicy).InversionList", align 8
  %3 = alloca %"std.uni.InversionList!(GcPolicy).InversionList", align 8
  %4 = alloca %"std.uni.InversionList!(GcPolicy).InversionList", align 8
  %5 = alloca %"std.uni.InversionList!(GcPolicy).InversionList", align 8
  %6 = alloca %"std.uni.InversionList!(GcPolicy).InversionList", align 8
  %7 = alloca %"std.uni.InversionList!(GcPolicy).InversionList", align 8
  %8 = alloca ptr, align 8
  %9 = alloca i32, align 4
  %10 = alloca %"std.uni.InversionList!(GcPolicy).InversionList", align 8
  %11 = alloca %"std.uni.InversionList!(GcPolicy).InversionList", align 8
  %12 = alloca %"std.uni.InversionList!(GcPolicy).InversionList", align 8
  %13 = alloca %"std.uni.InversionList!(GcPolicy).InversionList", align 8
  %14 = alloca %"std.uni.InversionList!(GcPolicy).InversionList", align 8
  %15 = alloca ptr, align 8
  %16 = alloca i32, align 4
  %17 = alloca %"std.uni.InversionList!(GcPolicy).InversionList", align 8
  %18 = load i8, ptr @_D3std3uni__T11memoizeExprVAyaa91_756e69636f64652e416c7068616265746963207c20756e69636f64652e4d6e207c20756e69636f64652e4d630a20202020202020207c20756e69636f64652e4d65207c20756e69636f64652e4e64207c20756e69636f64652e5063ZQHwFZ11initializedb, align 1, !range !44
  %19 = trunc i8 %18 to i1
  %20 = xor i1 %19, true
  br i1 %20, label %21, label %35

21:                                               ; preds = %1
  call void @llvm.lifetime.start.p0(ptr captures(none) %2) #4
  call void @llvm.lifetime.start.p0(ptr captures(none) %3) #4
  call void @llvm.lifetime.start.p0(ptr captures(none) %4) #4
  call void @llvm.lifetime.start.p0(ptr captures(none) %5) #4
  call void @llvm.lifetime.start.p0(ptr captures(none) %6) #4
  call void @_D3std3uni7unicode__T10opDispatchVAyaa10_416c7068616265746963ZQBpFNaNdNfZSQCuQCt__T13InversionListTSQDuQDt8GcPolicyZQBh(ptr noalias sret(%"std.uni.InversionList!(GcPolicy).InversionList") align 8 %6) #3
  invoke void @_D3std3uni7unicode__T10opDispatchVAyaa2_4d6eZQyFNaNdNfZSQCcQCb__T13InversionListTSQDcQDb8GcPolicyZQBh(ptr noalias sret(%"std.uni.InversionList!(GcPolicy).InversionList") align 8 %7) #3
          to label %22 unwind label %36

22:                                               ; preds = %21
  call void @_D3std3uni__T13InversionListTSQBcQBb8GcPolicyZQBh__T8opBinaryVAyaa1_7cTSQCsQCr__TQCqTQCeZQCyZQBpMFNaNbNfQBhZQBl(ptr noalias sret(%"std.uni.InversionList!(GcPolicy).InversionList") align 8 %5, ptr nonnull %6, ptr noalias align 8 captures(none) %7) #3
  invoke void @_D3std3uni7unicode__T10opDispatchVAyaa2_4d63ZQyFNaNdNfZSQCcQCb__T13InversionListTSQDcQDb8GcPolicyZQBh(ptr noalias sret(%"std.uni.InversionList!(GcPolicy).InversionList") align 8 %10) #3
          to label %23 unwind label %42

23:                                               ; preds = %22
  call void @_D3std3uni__T13InversionListTSQBcQBb8GcPolicyZQBh__T8opBinaryVAyaa1_7cTSQCsQCr__TQCqTQCeZQCyZQBpMFNaNbNfQBhZQBl(ptr noalias sret(%"std.uni.InversionList!(GcPolicy).InversionList") align 8 %4, ptr nonnull %5, ptr noalias align 8 captures(none) %10) #3
  invoke void @_D3std3uni7unicode__T10opDispatchVAyaa2_4d65ZQyFNaNdNfZSQCcQCb__T13InversionListTSQDcQDb8GcPolicyZQBh(ptr noalias sret(%"std.uni.InversionList!(GcPolicy).InversionList") align 8 %11) #3
          to label %24 unwind label %46

24:                                               ; preds = %23
  call void @_D3std3uni__T13InversionListTSQBcQBb8GcPolicyZQBh__T8opBinaryVAyaa1_7cTSQCsQCr__TQCqTQCeZQCyZQBpMFNaNbNfQBhZQBl(ptr noalias sret(%"std.uni.InversionList!(GcPolicy).InversionList") align 8 %3, ptr nonnull %4, ptr noalias align 8 captures(none) %11) #3
  invoke void @_D3std3uni7unicode__T10opDispatchVAyaa2_4e64ZQyFNaNdNfZSQCcQCb__T13InversionListTSQDcQDb8GcPolicyZQBh(ptr noalias sret(%"std.uni.InversionList!(GcPolicy).InversionList") align 8 %12) #3
          to label %25 unwind label %50

25:                                               ; preds = %24
  call void @_D3std3uni__T13InversionListTSQBcQBb8GcPolicyZQBh__T8opBinaryVAyaa1_7cTSQCsQCr__TQCqTQCeZQCyZQBpMFNaNbNfQBhZQBl(ptr noalias sret(%"std.uni.InversionList!(GcPolicy).InversionList") align 8 %2, ptr nonnull %3, ptr noalias align 8 captures(none) %12) #3
  invoke void @_D3std3uni7unicode__T10opDispatchVAyaa2_5063ZQyFNaNdNfZSQCcQCb__T13InversionListTSQDcQDb8GcPolicyZQBh(ptr noalias sret(%"std.uni.InversionList!(GcPolicy).InversionList") align 8 %14) #3
          to label %26 unwind label %54

26:                                               ; preds = %25
  call void @_D3std3uni__T13InversionListTSQBcQBb8GcPolicyZQBh__T8opBinaryVAyaa1_7cTSQCsQCr__TQCqTQCeZQCyZQBpMFNaNbNfQBhZQBl(ptr noalias sret(%"std.uni.InversionList!(GcPolicy).InversionList") align 8 %13, ptr nonnull %2, ptr noalias align 8 captures(none) %14) #3
  %27 = call ptr @_D3std3uni__T13InversionListTSQBcQBb8GcPolicyZQBh8opAssignMFNaNbNcNjNeSQCrQCq__TQCpTQCdZQCxZQw(ptr nonnull @_D3std3uni__T11memoizeExprVAyaa91_756e69636f64652e416c7068616265746963207c20756e69636f64652e4d6e207c20756e69636f64652e4d630a20202020202020207c20756e69636f64652e4d65207c20756e69636f64652e4e64207c20756e69636f64652e5063ZQHwFZ4slotSQIsQIr__T13InversionListTSQJsQJr8GcPolicyZQBh, ptr noalias align 8 captures(none) %13) #0
  store ptr %27, ptr %15, align 8
  store i32 1, ptr %16, align 4
  br label %29

28:                                               ; preds = %33
  store i8 1, ptr @_D3std3uni__T11memoizeExprVAyaa91_756e69636f64652e416c7068616265746963207c20756e69636f64652e4d6e207c20756e69636f64652e4d630a20202020202020207c20756e69636f64652e4d65207c20756e69636f64652e4e64207c20756e69636f64652e5063ZQHwFZ11initializedb, align 1
  call void @llvm.lifetime.end.p0(ptr captures(none) %2) #4
  call void @llvm.lifetime.end.p0(ptr captures(none) %3) #4
  call void @llvm.lifetime.end.p0(ptr captures(none) %4) #4
  call void @llvm.lifetime.end.p0(ptr captures(none) %5) #4
  call void @llvm.lifetime.end.p0(ptr captures(none) %6) #4
  br label %35

29:                                               ; preds = %26, %54
  call void @_D3std3uni__T13InversionListTSQBcQBb8GcPolicyZQBh11__fieldDtorMFNaNbNeZv(ptr nonnull %2) #0
  br label %30

30:                                               ; preds = %29, %50
  call void @_D3std3uni__T13InversionListTSQBcQBb8GcPolicyZQBh11__fieldDtorMFNaNbNeZv(ptr nonnull %3) #0
  br label %31

31:                                               ; preds = %30, %46
  call void @_D3std3uni__T13InversionListTSQBcQBb8GcPolicyZQBh11__fieldDtorMFNaNbNeZv(ptr nonnull %4) #0
  br label %32

32:                                               ; preds = %31, %42
  call void @_D3std3uni__T13InversionListTSQBcQBb8GcPolicyZQBh11__fieldDtorMFNaNbNeZv(ptr nonnull %5) #0
  br label %33

33:                                               ; preds = %32, %36
  call void @_D3std3uni__T13InversionListTSQBcQBb8GcPolicyZQBh11__fieldDtorMFNaNbNeZv(ptr nonnull %6) #0
  %34 = load i32, ptr %16, align 4
  switch i32 %34, label %40 [
    i32 1, label %28
  ]

35:                                               ; preds = %28, %1
  call void @llvm.lifetime.start.p0(ptr captures(none) %0) #4 ; <<<<<<< Here
  call void @llvm.memcpy.p0.p0.i64(ptr align 1 %0, ptr align 1 @_D3std3uni__T11memoizeExprVAyaa91_756e69636f64652e416c7068616265746963207c20756e69636f64652e4d6e207c20756e69636f64652e4d630a20202020202020207c20756e69636f64652e4d65207c20756e69636f64652e4e64207c20756e69636f64652e5063ZQHwFZ4slotSQIsQIr__T13InversionListTSQJsQJr8GcPolicyZQBh, i64 16, i1 false)
  call void @_D3std3uni__T13InversionListTSQBcQBb8GcPolicyZQBh15__fieldPostblitMFNaNbNiNlNeZv(ptr nonnull %0) #0
  ret void

36:                                               ; preds = %21
  %37 = landingpad { ptr, i32 }
          cleanup
  %38 = extractvalue { ptr, i32 } %37, 0
  store ptr %38, ptr %8, align 8
  %39 = extractvalue { ptr, i32 } %37, 1
  store i32 %39, ptr %9, align 4
  store i32 0, ptr %16, align 4
  br label %33

40:                                               ; preds = %33
  %41 = load ptr, ptr %8, align 8
  call void @_Unwind_Resume(ptr %41)
  unreachable

42:                                               ; preds = %22
  %43 = landingpad { ptr, i32 }
          cleanup
  %44 = extractvalue { ptr, i32 } %43, 0
  store ptr %44, ptr %8, align 8
  %45 = extractvalue { ptr, i32 } %43, 1
  store i32 %45, ptr %9, align 4
  store i32 0, ptr %16, align 4
  br label %32

46:                                               ; preds = %23
  %47 = landingpad { ptr, i32 }
          cleanup
  %48 = extractvalue { ptr, i32 } %47, 0
  store ptr %48, ptr %8, align 8
  %49 = extractvalue { ptr, i32 } %47, 1
  store i32 %49, ptr %9, align 4
  store i32 0, ptr %16, align 4
  br label %31

50:                                               ; preds = %24
  %51 = landingpad { ptr, i32 }
          cleanup
  %52 = extractvalue { ptr, i32 } %51, 0
  store ptr %52, ptr %8, align 8
  %53 = extractvalue { ptr, i32 } %51, 1
  store i32 %53, ptr %9, align 4
  store i32 0, ptr %16, align 4
  br label %30

54:                                               ; preds = %25
  %55 = landingpad { ptr, i32 }
          cleanup
  %56 = extractvalue { ptr, i32 } %55, 0
  store ptr %56, ptr %8, align 8
  %57 = extractvalue { ptr, i32 } %55, 1
  store i32 %57, ptr %9, align 4
  store i32 0, ptr %16, align 4
  br label %29
}

(the above ` | grep "%0")

define weak_odr void @_D3std3uni__T11memoizeExprVAyaa91_756e69636f64652e416c7068616265746963207c20756e69636f64652e4d6e207c20756e69636f64652e4d630a20202020202020207c20756e69636f64652e4d65207c20756e69636f64652e4e64207c20756e69636f64652e5063ZQHwFNfZSQIpQIo__T13InversionListTSQJpQJo8GcPolicyZQBh(ptr noalias sret(%"std.uni.InversionList!(GcPolicy).InversionList") align 8 %0) #0 personality ptr @_d_eh_personality {
  call void @llvm.lifetime.start.p0(ptr captures(none) %0) #4
  call void @llvm.memcpy.p0.p0.i64(ptr align 1 %0, ptr align 1 @_D3std3uni__T11memoizeExprVAyaa91_756e69636f64652e416c7068616265746963207c20756e69636f64652e4d6e207c20756e69636f64652e4d630a20202020202020207c20756e69636f64652e4d65207c20756e69636f64652e4e64207c20756e69636f64652e5063ZQHwFZ4slotSQIsQIr__T13InversionListTSQJsQJr8GcPolicyZQBh, i64 16, i1 false)
  call void @_D3std3uni__T13InversionListTSQBcQBb8GcPolicyZQBh15__fieldPostblitMFNaNbNiNlNeZv(ptr nonnull %0) #0
ptr %0
  call void @llvm.lifetime.start.p0(ptr captures(none) %0) #4
define void @_D3std3uni15decomposeHangulFNaNbNfwZSQBjQBi8Grapheme(ptr noalias sret(%std.uni.Grapheme) align 8 %0, i32 %1) #0 {
  call void @llvm.lifetime.start.p0(ptr captures(none) %0) #4
  %26 = getelementptr inbounds %std.uni.Grapheme, ptr %0, i32 0, i32 0
  %27 = getelementptr inbounds %std.uni.Grapheme, ptr %0, i32 0, i32 1
  %28 = getelementptr inbounds %std.uni.Grapheme, ptr %0, i32 0, i32 2
  %29 = getelementptr inbounds %std.uni.Grapheme, ptr %0, i32 0, i32 3
  %33 = call ptr @_D3std3uni8Grapheme__T6__ctorTwZQkMFNaNbNcNiNfxAwXSQBxQBwQBv(ptr nonnull returned %0, { i64, ptr } %32) #3
  call void @llvm.lifetime.start.p0(ptr captures(none) %0) #4
  %50 = getelementptr inbounds %std.uni.Grapheme, ptr %0, i32 0, i32 0
  %51 = getelementptr inbounds %std.uni.Grapheme, ptr %0, i32 0, i32 1
  %52 = getelementptr inbounds %std.uni.Grapheme, ptr %0, i32 0, i32 2
  %53 = getelementptr inbounds %std.uni.Grapheme, ptr %0, i32 0, i32 3
  %62 = call ptr @_D3std3uni8Grapheme__T6__ctorTiZQkMFNaNbNcNiNfxAiXSQBxQBwQBv(ptr nonnull returned %0, { i64, ptr } %61) #3
  call void @llvm.lifetime.start.p0(ptr captures(none) %0) #4
  %65 = getelementptr inbounds %std.uni.Grapheme, ptr %0, i32 0, i32 0
  %66 = getelementptr inbounds %std.uni.Grapheme, ptr %0, i32 0, i32 1
  %67 = getelementptr inbounds %std.uni.Grapheme, ptr %0, i32 0, i32 2
  %68 = getelementptr inbounds %std.uni.Grapheme, ptr %0, i32 0, i32 3
  %74 = call ptr @_D3std3uni8Grapheme__T6__ctorTiZQkMFNaNbNcNiNfxAiXSQBxQBwQBv(ptr nonnull returned %0, { i64, ptr } %73) #3
define void @_D3std3uni15decomposeHangulFNaNbNfwZSQBjQBi8Grapheme(ptr noalias sret(%std.uni.Grapheme) align 8 %0, i32 %1) #0 {
  call void @llvm.lifetime.start.p0(ptr captures(none) %0) #4
  %26 = getelementptr inbounds %std.uni.Grapheme, ptr %0, i32 0, i32 0
  %27 = getelementptr inbounds %std.uni.Grapheme, ptr %0, i32 0, i32 1
  %28 = getelementptr inbounds %std.uni.Grapheme, ptr %0, i32 0, i32 2
  %29 = getelementptr inbounds %std.uni.Grapheme, ptr %0, i32 0, i32 3
  %33 = call ptr @_D3std3uni8Grapheme__T6__ctorTwZQkMFNaNbNcNiNfxAwXSQBxQBwQBv(ptr nonnull returned %0, { i64, ptr } %32) #3
  call void @llvm.lifetime.start.p0(ptr captures(none) %0) #4
  %50 = getelementptr inbounds %std.uni.Grapheme, ptr %0, i32 0, i32 0
  %51 = getelementptr inbounds %std.uni.Grapheme, ptr %0, i32 0, i32 1
  %52 = getelementptr inbounds %std.uni.Grapheme, ptr %0, i32 0, i32 2
  %53 = getelementptr inbounds %std.uni.Grapheme, ptr %0, i32 0, i32 3
  %62 = call ptr @_D3std3uni8Grapheme__T6__ctorTiZQkMFNaNbNcNiNfxAiXSQBxQBwQBv(ptr nonnull returned %0, { i64, ptr } %61) #3
  call void @llvm.lifetime.start.p0(ptr captures(none) %0) #4
  %65 = getelementptr inbounds %std.uni.Grapheme, ptr %0, i32 0, i32 0
  %66 = getelementptr inbounds %std.uni.Grapheme, ptr %0, i32 0, i32 1
  %67 = getelementptr inbounds %std.uni.Grapheme, ptr %0, i32 0, i32 2
  %68 = getelementptr inbounds %std.uni.Grapheme, ptr %0, i32 0, i32 3
  %74 = call ptr @_D3std3uni8Grapheme__T6__ctorTiZQkMFNaNbNcNiNfxAiXSQBxQBwQBv(ptr nonnull returned %0, { i64, ptr } %73) #3
define void @_D3std3uni15decomposeHangulFNaNbNfwZSQBjQBi8Grapheme(ptr noalias sret(%std.uni.Grapheme) align 8 %0, i32 %1) #0 {
  call void @llvm.lifetime.start.p0(ptr captures(none) %0) #4
  %26 = getelementptr inbounds %std.uni.Grapheme, ptr %0, i32 0, i32 0
  %27 = getelementptr inbounds %std.uni.Grapheme, ptr %0, i32 0, i32 1
  %28 = getelementptr inbounds %std.uni.Grapheme, ptr %0, i32 0, i32 2
  %29 = getelementptr inbounds %std.uni.Grapheme, ptr %0, i32 0, i32 3
  %33 = call ptr @_D3std3uni8Grapheme__T6__ctorTwZQkMFNaNbNcNiNfxAwXSQBxQBwQBv(ptr nonnull returned %0, { i64, ptr } %32) #3
  call void @llvm.lifetime.start.p0(ptr captures(none) %0) #4
  %50 = getelementptr inbounds %std.uni.Grapheme, ptr %0, i32 0, i32 0
  %51 = getelementptr inbounds %std.uni.Grapheme, ptr %0, i32 0, i32 1
  %52 = getelementptr inbounds %std.uni.Grapheme, ptr %0, i32 0, i32 2
  %53 = getelementptr inbounds %std.uni.Grapheme, ptr %0, i32 0, i32 3
  %62 = call ptr @_D3std3uni8Grapheme__T6__ctorTiZQkMFNaNbNcNiNfxAiXSQBxQBwQBv(ptr nonnull returned %0, { i64, ptr } %61) #3
  call void @llvm.lifetime.start.p0(ptr captures(none) %0) #4
  %65 = getelementptr inbounds %std.uni.Grapheme, ptr %0, i32 0, i32 0
  %66 = getelementptr inbounds %std.uni.Grapheme, ptr %0, i32 0, i32 1
  %67 = getelementptr inbounds %std.uni.Grapheme, ptr %0, i32 0, i32 2
  %68 = getelementptr inbounds %std.uni.Grapheme, ptr %0, i32 0, i32 3
  %74 = call ptr @_D3std3uni8Grapheme__T6__ctorTiZQkMFNaNbNcNiNfxAiXSQBxQBwQBv(ptr nonnull returned %0, { i64, ptr } %73) #3

which both produce a call to @llvm.lifetime.start.p0(ptr captures(none) %0) and %0 in this case is an Argument not an AllocaInst.

I'm trying to figure out where those calls are coming from. Is it the ABI messing things up somehow? I don't know what is special about those functions.

% git grep getLLVMLifetimeStartFn
variable_lifetime.cpp:  irs.CreateCallOrInvoke(getLLVMLifetimeStartFn(),
variable_lifetime.cpp:llvm::Function *LocalVariableLifetimeAnnotator::getLLVMLifetimeStartFn() {
variable_lifetime.h:  llvm::Function *getLLVMLifetimeStartFn();

there is only the one use of it and

% git grep lifetime_start
variable_lifetime.cpp:      &irs.module, llvm::Intrinsic::lifetime_start, allocaType);

JohanEngelen
JohanEngelen reviewed Sep 6, 2025
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Did you check whether those lifetime calls are there for LLVM 20? (in the exact same functions?) Would help to get a standalone smaller testcase btw. Something like this: https://d.godbolt.org/z/d6f9763KE

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@thewilsonator @JohanEngelen