Orkuncakilkaya
0998cb5a18
A slice has carried { ptr, len, cap } since it existed and nothing ever read
the len: every index emitted a bare getelementptr. Running off the end of one
wrote into whatever the allocator had put next, and the program died somewhere
else entirely - a maroon-lake crash took a day to find because the stack named
a texture upload and the write was in a telemetry buffer five frames earlier.
Now each index loads the length and compares unsigned, which rejects a negative
index in the same instruction, and a failure aborts with the location the other
located errors use:
oob.ludic:9: index out of range: 7, len 3
`words` and the other raw buffers are unchanged - they are a bare malloc with no
length to check, which is the argument for moving off them.
The SPIR-V variants are regenerated in the same commit: shaders --check was
failing against the edited GLSL.
Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
87 lines
4.2 KiB
Text
87 lines
4.2 KiB
Text
# emit_addr.ludic — addresses of lvalues (struct fields and slice elements),
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# shared by expression loads and assignment stores. Each returns the address
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# register; the element/field type is written into g_addr_ty.
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var g_addr_ty: pointer # out-param: the type at the computed address
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# address of `base.field`
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function emit_member_addr(e: Node) -> pointer {
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let base = emit_expr(e.a)
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let s = layout_node(base.ty)
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if (s == null) { perr(`member access on non-aggregate {base.ty}`) }
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let fidx = field_index(s, e.s)
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if fidx < 0 { perr(`no such field {e.s}`) }
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g_addr_ty = field_type(s, e.s)
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let r = nreg()
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emit(" "); emit(r); emit(" = getelementptr inbounds "); emit(layout_ty(base.ty))
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emit(", ptr "); emit(base.code); emit(", i32 0, i32 "); emit(itoa(fidx)); emit("\n")
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return r
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}
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# address of `base[index]` (slices only in this subset)
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function emit_index_addr(e: Node) -> pointer {
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let base = emit_expr(e.a)
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if not is_slice_ty(base.ty) { # a raw pointer: address of element i
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let bi = emit_expr(e.b) # (evaluate index first — it may set g_addr_ty)
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if (base.ty == "words") { # a `words` buffer: 32-bit int elements
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let rw = emit_bind(`getelementptr inbounds i32, ptr {base.code}, i32 {bi.code}`)
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g_addr_ty = "int"
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return rw
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}
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if (base.ty == "fixeds") { # a `fixeds` buffer: 32-bit fixed elements
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let rf = emit_bind(`getelementptr inbounds i32, ptr {base.code}, i32 {bi.code}`)
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g_addr_ty = "fixed"
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return rf
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}
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if (base.ty == "floats") or (base.ty == "doubles") { # IEEE float / double elements
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var et = "float"
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if (base.ty == "doubles") { et = "double" }
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let rd = emit_bind(`getelementptr inbounds {et}, ptr {base.code}, i32 {bi.code}`)
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g_addr_ty = et
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return rd
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}
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if (base.ty == "pointers") { # a `pointers` buffer: pointer elements
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let rp = emit_bind(`getelementptr inbounds ptr, ptr {base.code}, i32 {bi.code}`)
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g_addr_ty = "ptr"
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return rp
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}
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let r = emit_bind(`getelementptr inbounds i8, ptr {base.code}, i32 {bi.code}`) # a ptr/str: bytes
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g_addr_ty = "byte" # set last so the caller sees it
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return r
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}
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let el = slice_elem(base.ty)
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# load the data pointer from the slice header (field 0)
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let dp = nreg()
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emit(" "); emit(dp); emit(" = getelementptr inbounds %LSlice, ptr ")
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emit(base.code); emit(", i32 0, i32 0\n")
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let data = nreg()
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emit(" "); emit(data); emit(" = load ptr, ptr "); emit(dp); emit("\n")
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let ix = emit_expr(e.b) # (evaluate index BEFORE setting
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# THE INDEX IS CHECKED AGAINST THE LENGTH. A slice has carried { ptr, len, cap } since it
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# existed, and nothing ever read the len: every index was a bare getelementptr, so running
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# off the end of one wrote into whatever the allocator had put next and the program died
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# somewhere else entirely, minutes later, with a stack that named an innocent function.
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# The comparison is UNSIGNED, which rejects a negative index in the same instruction.
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if g_bounds {
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g_uses_bounds = true
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let lnp = nreg()
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emit(" "); emit(lnp); emit(" = getelementptr inbounds %LSlice, ptr ")
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emit(base.code); emit(", i32 0, i32 1\n")
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let lnv = emit_bind(`load i32, ptr {lnp}`)
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let okc = emit_bind(`icmp ult i32 {ix.code}, {lnv}`)
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let lok = lbl("ixok")
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let lbad = lbl("ixbad")
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emit(` br i1 {okc}, label %{lok}, label %{lbad}\n`)
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emit(`{lbad}:\n`)
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let bmsg = emit_str_const(`{g_src_name}:{itoa(e.line)}: index out of range: `)
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let bse = emit_bind(stdstream_rhs(2))
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emit(` call i32 (ptr, ptr, ...) @fprintf(ptr {bse}, ptr @.fmt_bounds, ptr {bmsg}, i32 {ix.code}, i32 {lnv})\n`)
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emit(" call void @exit(i32 1)\n unreachable\n")
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emit(`{lok}:\n`)
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}
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let r = nreg() # g_addr_ty — a member-access index
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emit(" "); emit(r); emit(" = getelementptr inbounds "); emit(llty(el)) # overwrites it)
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emit(", ptr "); emit(data); emit(", i32 "); emit(ix.code); emit("\n")
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g_addr_ty = el # set last so the caller sees the element type
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return r
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}
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