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authorMagnus Lång <[email protected]>2016-05-11 13:39:53 +0200
committerMagnus Lång <[email protected]>2016-05-11 13:39:53 +0200
commit7814ec18b095d40af95f362ff668a68915982e45 (patch)
tree50f16b9f246275c12843bbc8270cb0529aa86bd6 /lib/hipe/llvm
parent0f489445070cf65d96db7938f80ad118921c1f6a (diff)
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hipe_llvm: Allow LLVM-generated constants
Since 3.7, LLVM sometimes generates SSE constants in a special constant section with the requisite alignment (".rodata.cst16"). This broke hipe_llvm since it assumed that all constants that were linked from the text section were constants generated by hipe_llvm. As this is the first time alignments larger than 8 have been required, some small changes were required to hipe_consttab and hipe_bifs:alloc_data/2. Note that hipe_bifs:alloc_data/2 still assumes that erl_alloc will provide the requisite alignment.
Diffstat (limited to 'lib/hipe/llvm')
-rw-r--r--lib/hipe/llvm/elf_format.erl7
-rw-r--r--lib/hipe/llvm/hipe_llvm_main.erl31
2 files changed, 35 insertions, 3 deletions
diff --git a/lib/hipe/llvm/elf_format.erl b/lib/hipe/llvm/elf_format.erl
index 4155dff7c4..b3c5ecddab 100644
--- a/lib/hipe/llvm/elf_format.erl
+++ b/lib/hipe/llvm/elf_format.erl
@@ -23,6 +23,8 @@
get_exn_handlers/1,
%% Symbols
elf_symbols/1,
+ %% Sections
+ section_contents/2,
%% Main interface
read/1
]).
@@ -312,6 +314,11 @@ elf_section(?SHN_ABS, #elf{}) -> abs;
elf_section(Index, #elf{sec_idx=SecIdx}) when Index =< tuple_size(SecIdx) ->
element(Index, SecIdx).
+%% Reads the contents of a section from an object
+-spec section_contents(elf_shdr(), elf()) -> binary().
+section_contents(#elf_shdr{offset=Offset, size=Size}, #elf{file=ElfBin}) ->
+ get_binary_segment(ElfBin, Offset, Size).
+
%%------------------------------------------------------------------------------
%% Functions to manipulate Symbol Table
%%------------------------------------------------------------------------------
diff --git a/lib/hipe/llvm/hipe_llvm_main.erl b/lib/hipe/llvm/hipe_llvm_main.erl
index 3ab213f94c..476d6fb49c 100644
--- a/lib/hipe/llvm/hipe_llvm_main.erl
+++ b/lib/hipe/llvm/hipe_llvm_main.erl
@@ -13,7 +13,7 @@
%% chain is invoked in order to produce an object file.
rtl_to_native(MFA, RTL, Roots, Options) ->
%% Compile to LLVM and get Instruction List (along with infos)
- {LLVMCode, RelocsDict, ConstTab} =
+ {LLVMCode, RelocsDict0, ConstTab0} =
hipe_rtl_to_llvm:translate(RTL, Roots),
%% Fix function name to an acceptable LLVM identifier (needed for closures)
{_Module, Fun, Arity} = hipe_rtl_to_llvm:fix_mfa_name(MFA),
@@ -32,10 +32,11 @@ rtl_to_native(MFA, RTL, Roots, Options) ->
{SwitchInfos, ExposedClosures} = correlate_labels(Tables, Labels),
%% SwitchInfos: [{"table_50", [Labels]}]
%% ExposedClosures: [{"table_closures", [Labels]}]
-
+
%% Labelmap contains the offsets of the labels in the code that are
%% used for switch's jump tables
- LabelMap = create_labelmap(MFA, SwitchInfos, RelocsDict),
+ LabelMap = create_labelmap(MFA, SwitchInfos, RelocsDict0),
+ {RelocsDict, ConstTab} = extract_constants(RelocsDict0, ConstTab0, Obj),
%% Get relocation info
TextRelocs = elf_format:extract_rela(Obj, ?TEXT),
%% AccRefs contains the offsets of all references to relocatable symbols in
@@ -219,6 +220,25 @@ insert_to_labelmap([{Key, Value}|Rest], LabelMap) ->
insert_to_labelmap(Rest, LabelMap)
end.
+%% Find any LLVM-generated constants and add them to the constant table
+extract_constants(RelocsDict0, ConstTab0, Obj) ->
+ TextRelocs = elf_format:extract_rela(Obj, ?TEXT),
+ AnonConstSections =
+ lists:usort([{Sec, Offset}
+ || #elf_rel{symbol=#elf_sym{type=section, section=Sec},
+ addend=Offset} <- TextRelocs]),
+ lists:foldl(
+ fun({#elf_shdr{name=Name, type=progbits, addralign=Align, entsize=EntSize,
+ size=Size} = Section, Offset}, {RelocsDict1, ConstTab1})
+ when EntSize > 0, 0 =:= Size rem EntSize, 0 =:= Offset rem EntSize ->
+ SectionBin = elf_format:section_contents(Section, Obj),
+ Constant = binary:part(SectionBin, Offset, EntSize),
+ {ConstTab, ConstLbl} =
+ hipe_consttab:insert_binary_const(ConstTab1, Align, Constant),
+ {dict:store({anon, Name, Offset}, {constant, ConstLbl}, RelocsDict1),
+ ConstTab}
+ end, {RelocsDict0, ConstTab0}, AnonConstSections).
+
%% @doc Correlate object file relocation symbols with info from translation to
%% llvm code.
fix_relocations(Relocs, RelocsDict, MFA) ->
@@ -269,6 +289,11 @@ fix_reloc(#elf_rel{symbol=#elf_sym{name=Name, section=#elf_shdr{name=?RODATA},
case dict:fetch(Name, RelocsDict) of
{switch, _, JTabLab} -> %% Treat switch exactly as constant
{?LOAD_ADDRESS, Offset, {constant, JTabLab}}
+ end;
+fix_reloc(#elf_rel{symbol=#elf_sym{type=section, section=#elf_shdr{name=Name}},
+ offset=Offset, type=?ABS_T, addend=Addend}, RelocsDict, _) ->
+ case dict:fetch({anon, Name, Addend}, RelocsDict) of
+ {constant, Label} -> {?LOAD_ADDRESS, Offset, {constant, Label}}
end.
%%------------------------------------------------------------------------------