c41a212712
I found that when I enable ThinLTO, a miscompilation triggers that had
been hidden all the time previously. The bug appears to happen as
follows:
1. TinyGo generates a function with a runtime.trackPointer call, but
without an alloca (or the alloca gets optimized away).
2. LLVM sees that no alloca needs to be kept alive across the
runtime.trackPointer call, and therefore it adds the 'tail' flag.
One of the effects of this flag is that it makes it undefined
behavior to keep allocas alive across the call (which is still safe
at that point).
3. The GC lowering pass adds a stack slot alloca and converts
runtime.trackPointer calls into alloca stores.
The last step triggers the bug: the compiler inserts an alloca where
there was none before but that's not valid as long as the 'tail' flag is
present.
This patch fixes the bug in a somewhat dirty way, by always creating a
dummy alloca so that LLVM won't do the optimization in step 2 (and
possibly other optimizations that rely on there being no alloca
instruction).
139 строки
7,5 КиБ
LLVM
139 строки
7,5 КиБ
LLVM
; ModuleID = 'gc.go'
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source_filename = "gc.go"
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target datalayout = "e-m:e-p:32:32-p10:8:8-p20:8:8-i64:64-n32:64-S128-ni:1:10:20"
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target triple = "wasm32-unknown-wasi"
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%runtime.typecodeID = type { ptr, i32, ptr, ptr, i32 }
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%runtime._interface = type { i32, ptr }
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@main.scalar1 = hidden global ptr null, align 4
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@main.scalar2 = hidden global ptr null, align 4
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@main.scalar3 = hidden global ptr null, align 4
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@main.scalar4 = hidden global ptr null, align 4
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@main.array1 = hidden global ptr null, align 4
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@main.array2 = hidden global ptr null, align 4
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@main.array3 = hidden global ptr null, align 4
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@main.struct1 = hidden global ptr null, align 4
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@main.struct2 = hidden global ptr null, align 4
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@main.struct3 = hidden global ptr null, align 4
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@main.struct4 = hidden global ptr null, align 4
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@main.slice1 = hidden global { ptr, i32, i32 } zeroinitializer, align 8
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@main.slice2 = hidden global { ptr, i32, i32 } zeroinitializer, align 8
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@main.slice3 = hidden global { ptr, i32, i32 } zeroinitializer, align 8
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@"runtime/gc.layout:62-2000000000000001" = linkonce_odr unnamed_addr constant { i32, [8 x i8] } { i32 62, [8 x i8] c"\01\00\00\00\00\00\00 " }
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@"runtime/gc.layout:62-0001" = linkonce_odr unnamed_addr constant { i32, [8 x i8] } { i32 62, [8 x i8] c"\01\00\00\00\00\00\00\00" }
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@"reflect/types.type:basic:complex128" = linkonce_odr constant %runtime.typecodeID { ptr null, i32 0, ptr null, ptr @"reflect/types.type:pointer:basic:complex128", i32 0 }
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@"reflect/types.type:pointer:basic:complex128" = linkonce_odr constant %runtime.typecodeID { ptr @"reflect/types.type:basic:complex128", i32 0, ptr null, ptr null, i32 0 }
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declare noalias nonnull ptr @runtime.alloc(i32, ptr, ptr) #0
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declare void @runtime.trackPointer(ptr nocapture readonly, ptr, ptr) #0
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; Function Attrs: nounwind
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define hidden void @main.init(ptr %context) unnamed_addr #1 {
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entry:
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ret void
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}
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; Function Attrs: nounwind
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define hidden void @main.newScalar(ptr %context) unnamed_addr #1 {
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entry:
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%stackalloc = alloca i8, align 1
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%new = call ptr @runtime.alloc(i32 1, ptr nonnull inttoptr (i32 3 to ptr), ptr undef) #2
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call void @runtime.trackPointer(ptr nonnull %new, ptr nonnull %stackalloc, ptr undef) #2
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store ptr %new, ptr @main.scalar1, align 4
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%new1 = call ptr @runtime.alloc(i32 4, ptr nonnull inttoptr (i32 3 to ptr), ptr undef) #2
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call void @runtime.trackPointer(ptr nonnull %new1, ptr nonnull %stackalloc, ptr undef) #2
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store ptr %new1, ptr @main.scalar2, align 4
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%new2 = call ptr @runtime.alloc(i32 8, ptr nonnull inttoptr (i32 3 to ptr), ptr undef) #2
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call void @runtime.trackPointer(ptr nonnull %new2, ptr nonnull %stackalloc, ptr undef) #2
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store ptr %new2, ptr @main.scalar3, align 4
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%new3 = call ptr @runtime.alloc(i32 4, ptr nonnull inttoptr (i32 3 to ptr), ptr undef) #2
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call void @runtime.trackPointer(ptr nonnull %new3, ptr nonnull %stackalloc, ptr undef) #2
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store ptr %new3, ptr @main.scalar4, align 4
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ret void
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}
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; Function Attrs: nounwind
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define hidden void @main.newArray(ptr %context) unnamed_addr #1 {
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entry:
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%stackalloc = alloca i8, align 1
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%new = call ptr @runtime.alloc(i32 3, ptr nonnull inttoptr (i32 3 to ptr), ptr undef) #2
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call void @runtime.trackPointer(ptr nonnull %new, ptr nonnull %stackalloc, ptr undef) #2
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store ptr %new, ptr @main.array1, align 4
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%new1 = call ptr @runtime.alloc(i32 71, ptr nonnull inttoptr (i32 3 to ptr), ptr undef) #2
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call void @runtime.trackPointer(ptr nonnull %new1, ptr nonnull %stackalloc, ptr undef) #2
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store ptr %new1, ptr @main.array2, align 4
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%new2 = call ptr @runtime.alloc(i32 12, ptr nonnull inttoptr (i32 67 to ptr), ptr undef) #2
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call void @runtime.trackPointer(ptr nonnull %new2, ptr nonnull %stackalloc, ptr undef) #2
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store ptr %new2, ptr @main.array3, align 4
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ret void
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}
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; Function Attrs: nounwind
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define hidden void @main.newStruct(ptr %context) unnamed_addr #1 {
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entry:
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%stackalloc = alloca i8, align 1
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%new = call ptr @runtime.alloc(i32 0, ptr nonnull inttoptr (i32 3 to ptr), ptr undef) #2
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call void @runtime.trackPointer(ptr nonnull %new, ptr nonnull %stackalloc, ptr undef) #2
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store ptr %new, ptr @main.struct1, align 4
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%new1 = call ptr @runtime.alloc(i32 8, ptr nonnull inttoptr (i32 3 to ptr), ptr undef) #2
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call void @runtime.trackPointer(ptr nonnull %new1, ptr nonnull %stackalloc, ptr undef) #2
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store ptr %new1, ptr @main.struct2, align 4
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%new2 = call ptr @runtime.alloc(i32 248, ptr nonnull @"runtime/gc.layout:62-2000000000000001", ptr undef) #2
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call void @runtime.trackPointer(ptr nonnull %new2, ptr nonnull %stackalloc, ptr undef) #2
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store ptr %new2, ptr @main.struct3, align 4
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%new3 = call ptr @runtime.alloc(i32 248, ptr nonnull @"runtime/gc.layout:62-0001", ptr undef) #2
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call void @runtime.trackPointer(ptr nonnull %new3, ptr nonnull %stackalloc, ptr undef) #2
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store ptr %new3, ptr @main.struct4, align 4
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ret void
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}
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; Function Attrs: nounwind
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define hidden ptr @main.newFuncValue(ptr %context) unnamed_addr #1 {
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entry:
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%stackalloc = alloca i8, align 1
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%new = call ptr @runtime.alloc(i32 8, ptr nonnull inttoptr (i32 197 to ptr), ptr undef) #2
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call void @runtime.trackPointer(ptr nonnull %new, ptr nonnull %stackalloc, ptr undef) #2
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ret ptr %new
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}
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; Function Attrs: nounwind
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define hidden void @main.makeSlice(ptr %context) unnamed_addr #1 {
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entry:
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%stackalloc = alloca i8, align 1
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%makeslice = call ptr @runtime.alloc(i32 5, ptr nonnull inttoptr (i32 3 to ptr), ptr undef) #2
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call void @runtime.trackPointer(ptr nonnull %makeslice, ptr nonnull %stackalloc, ptr undef) #2
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store ptr %makeslice, ptr @main.slice1, align 8
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store i32 5, ptr getelementptr inbounds ({ ptr, i32, i32 }, ptr @main.slice1, i32 0, i32 1), align 4
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store i32 5, ptr getelementptr inbounds ({ ptr, i32, i32 }, ptr @main.slice1, i32 0, i32 2), align 8
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%makeslice1 = call ptr @runtime.alloc(i32 20, ptr nonnull inttoptr (i32 67 to ptr), ptr undef) #2
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call void @runtime.trackPointer(ptr nonnull %makeslice1, ptr nonnull %stackalloc, ptr undef) #2
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store ptr %makeslice1, ptr @main.slice2, align 8
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store i32 5, ptr getelementptr inbounds ({ ptr, i32, i32 }, ptr @main.slice2, i32 0, i32 1), align 4
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store i32 5, ptr getelementptr inbounds ({ ptr, i32, i32 }, ptr @main.slice2, i32 0, i32 2), align 8
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%makeslice3 = call ptr @runtime.alloc(i32 60, ptr nonnull inttoptr (i32 71 to ptr), ptr undef) #2
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call void @runtime.trackPointer(ptr nonnull %makeslice3, ptr nonnull %stackalloc, ptr undef) #2
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store ptr %makeslice3, ptr @main.slice3, align 8
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store i32 5, ptr getelementptr inbounds ({ ptr, i32, i32 }, ptr @main.slice3, i32 0, i32 1), align 4
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store i32 5, ptr getelementptr inbounds ({ ptr, i32, i32 }, ptr @main.slice3, i32 0, i32 2), align 8
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ret void
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}
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; Function Attrs: nounwind
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define hidden %runtime._interface @main.makeInterface(double %v.r, double %v.i, ptr %context) unnamed_addr #1 {
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entry:
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%stackalloc = alloca i8, align 1
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%0 = call ptr @runtime.alloc(i32 16, ptr null, ptr undef) #2
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call void @runtime.trackPointer(ptr nonnull %0, ptr nonnull %stackalloc, ptr undef) #2
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store double %v.r, ptr %0, align 8
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%.repack1 = getelementptr inbounds { double, double }, ptr %0, i32 0, i32 1
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store double %v.i, ptr %.repack1, align 8
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%1 = insertvalue %runtime._interface { i32 ptrtoint (ptr @"reflect/types.type:basic:complex128" to i32), ptr undef }, ptr %0, 1
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call void @runtime.trackPointer(ptr nonnull %0, ptr nonnull %stackalloc, ptr undef) #2
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ret %runtime._interface %1
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}
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attributes #0 = { "target-features"="+bulk-memory,+nontrapping-fptoint,+sign-ext" }
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attributes #1 = { nounwind "target-features"="+bulk-memory,+nontrapping-fptoint,+sign-ext" }
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attributes #2 = { nounwind }
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