From a99406bbd9c01dc04e79b14681a254fe22c9d424 Mon Sep 17 00:00:00 2001 From: Bernhard Schommer Date: Thu, 28 Nov 2019 17:00:27 +0100 Subject: Fix for AArch64 alignment problem (#206) In addressing modes for load and store instructions, the offset must be a multiple of the memory size being accessed. When accessing global variables, this may not be the case if the alignment of the variable is less than its size. Errors occur at link time. This PR extends the check for a representable offset for the addressing of global variables to also check whether the variable is correctly aligned. Only if both conditions are met can we generate the short sequence Padrp / ADadr. Otherwise we go through the generic loadsymbol sequence. --- cfrontend/C2C.ml | 5 +++++ 1 file changed, 5 insertions(+) (limited to 'cfrontend/C2C.ml') diff --git a/cfrontend/C2C.ml b/cfrontend/C2C.ml index c1dfa9f4..9ae7bbd9 100644 --- a/cfrontend/C2C.ml +++ b/cfrontend/C2C.ml @@ -61,6 +61,11 @@ let atom_alignof a = with Not_found -> None +let atom_is_aligned a sz = + match atom_alignof a with + | None -> false + | Some align -> align mod (Z.to_int sz) = 0 + let atom_sections a = try (Hashtbl.find decl_atom a).a_sections -- cgit From a9eaf4897c825093aba2137ff76e56bfbf1e72d5 Mon Sep 17 00:00:00 2001 From: Bernhard Schommer Date: Thu, 20 Feb 2020 18:55:34 +0100 Subject: More precise determination of small data accesses (#220) We can get linker errors for addresses of the form "symbol + offset" where "symbol" is in the small data area and "offset" is large enough to overflow the relative displacement from the SDA base register. To avoid this, this commit enriches `C2C.atom_is_small_data`, which is the implementation of `Asm.symbol_is_small_data` in the PPC port, with a check that the offset is within the bounds of the symbol. If it is not, `Asm.symbol_is_small_data` returns `false` and Asmgen produces an absolute addressing instead of a SDA-relative addressing. To implement the check, we record the sizes of symbols in the atom table, just like we already record their alignments. --- cfrontend/C2C.ml | 18 +++++++++++++++--- 1 file changed, 15 insertions(+), 3 deletions(-) (limited to 'cfrontend/C2C.ml') diff --git a/cfrontend/C2C.ml b/cfrontend/C2C.ml index 9ae7bbd9..293e79f0 100644 --- a/cfrontend/C2C.ml +++ b/cfrontend/C2C.ml @@ -33,6 +33,7 @@ type inline_status = type atom_info = { a_storage: C.storage; (* storage class *) + a_size: int64 option; (* size in bytes *) a_alignment: int option; (* alignment *) a_sections: Sections.section_name list; (* in which section to put it *) (* 1 section for data, 3 sections (code/lit/jumptbl) for functions *) @@ -72,9 +73,14 @@ let atom_sections a = with Not_found -> [] -let atom_is_small_data a ofs = +let atom_is_small_data a ofs = try - (Hashtbl.find decl_atom a).a_access = Sections.Access_near + let info = Hashtbl.find decl_atom a in + info.a_access = Sections.Access_near + && (match info.a_size with + | None -> false + | Some sz -> + let ofs = camlint64_of_ptrofs ofs in 0L <= ofs && ofs < sz) with Not_found -> false @@ -352,6 +358,7 @@ let name_for_string_literal s = Hashtbl.add decl_atom id { a_storage = C.Storage_static; a_alignment = Some 1; + a_size = Some (Int64.of_int (String.length s + 1)); a_sections = [Sections.for_stringlit()]; a_access = Sections.Access_default; a_inline = No_specifier; @@ -379,9 +386,12 @@ let name_for_wide_string_literal s = incr stringNum; let name = Printf.sprintf "__stringlit_%d" !stringNum in let id = intern_string name in + let wchar_size = Machine.((!config).sizeof_wchar) in Hashtbl.add decl_atom id { a_storage = C.Storage_static; - a_alignment = Some Machine.((!config).sizeof_wchar); + a_alignment = Some wchar_size; + a_size = Some (Int64.(mul (of_int (List.length s + 1)) + (of_int wchar_size))); a_sections = [Sections.for_stringlit()]; a_access = Sections.Access_default; a_inline = No_specifier; @@ -1223,6 +1233,7 @@ let convertFundef loc env fd = Hashtbl.add decl_atom id' { a_storage = fd.fd_storage; a_alignment = None; + a_size = None; a_sections = Sections.for_function env id' fd.fd_attrib; a_access = Sections.Access_default; a_inline = inline; @@ -1309,6 +1320,7 @@ let convertGlobvar loc env (sto, id, ty, optinit) = Hashtbl.add decl_atom id' { a_storage = sto; a_alignment = Some (Z.to_int al); + a_size = Some (Z.to_int64 sz); a_sections = [section]; a_access = access; a_inline = No_specifier; -- cgit From 14f89bf9c397a4268d2b47418de234992b008d6c Mon Sep 17 00:00:00 2001 From: Bernhard Schommer Date: Sun, 29 Mar 2020 11:35:58 +0200 Subject: Explicit error messages for ill-formed section attributes (#232) Introduce an error message for section attributes with non string arguments,and another for multiple, ambiguous section attributes. This is more consistent with the handling of other attributes, like packed, than the old behavior of silently ignoring them. --- cfrontend/C2C.ml | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) (limited to 'cfrontend/C2C.ml') diff --git a/cfrontend/C2C.ml b/cfrontend/C2C.ml index 293e79f0..7f796fe3 100644 --- a/cfrontend/C2C.ml +++ b/cfrontend/C2C.ml @@ -1234,7 +1234,7 @@ let convertFundef loc env fd = { a_storage = fd.fd_storage; a_alignment = None; a_size = None; - a_sections = Sections.for_function env id' fd.fd_attrib; + a_sections = Sections.for_function env loc id' fd.fd_attrib; a_access = Sections.Access_default; a_inline = inline; a_loc = loc }; @@ -1311,7 +1311,7 @@ let convertGlobvar loc env (sto, id, ty, optinit) = | Some i -> convertInitializer env ty i in let (section, access) = - Sections.for_variable env id' ty (optinit <> None) in + Sections.for_variable env loc id' ty (optinit <> None) in if Z.gt sz (Z.of_uint64 0xFFFF_FFFFL) then error "'%s' is too big (%s bytes)" id.name (Z.to_string sz); -- cgit