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8f66bc28ae
Commit 0597c84b9bdb ("Cygwin: revamp TLS offsets computation")
introduced a really weird problem when building Cygwin with
optimization.
First of all, the tlsoffsets file is broken with -O2. This
can easily be fixed by running the compiler with -O0 when called
from the gentls_offsets script.
But it gets worse:
When creating sigfe.o with optimization, the generated machine code
uses incorrect offsets: For some reason the assembler codes using
_cygtls.stackptr as offset value are assembled into machine code
using _cygtls.pstackptr as offsets.
And as if that isn't already absurd enough, renaming _cygtls.pstackptr
to, say, _cygtls.blurb, fixes the assembled machine code expressions;
they use the value of _cygtls.stackptr again.
So I changed gentls_offsets and gendef to use _cygtls.foo_p rather
than _cygtls.pfoo and that fixes the assembled code in the optimized
case.
No, I can't explain that. There's no system in that behaviour.
It looks absolutely crazy.
Fixes: 0597c84b9bdb ("Cygwin: revamp TLS offsets computation")
Signed-off-by: Corinna Vinschen <corinna@vinschen.de>
84 lines
2.5 KiB
Bash
Executable File
84 lines
2.5 KiB
Bash
Executable File
#!/usr/bin/env bash
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#set -x
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input_file=$1
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output_file=$2
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# Preprocess cygtls.h and filter out only the member lines from
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# class _cygtls to generate an input file for the cross compiler
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# to generate the member offsets for tlsoffsets-$(target_cpu).h.
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${CXXCOMPILE} -E -P "${input_file}" 2> /dev/null | \
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gawk '
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BEGIN {
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# marker is used to split out the member lines from class _cygtls
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marker=0;
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# Prepare the input file for the subsequent compiler run.
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# Prepend value of __CYGTLS_PADSIZE__ so we can compute the offsets
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# up and down at the same time
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print "#include \"winsup.h\"";
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print "#include \"cygtls.h\"";
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print "extern \"C\" const uint32_t __CYGTLS__start_offset = __CYGTLS_PADSIZE__;";
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}
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/^class _cygtls$/ {
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# Ok, bump marker, next we are expecting a "public:" line
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marker=1;
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}
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/^public:/ {
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# We are only interested in the lines between the first (marker == 2)
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# and the second (marker == 3) "public:" line in class _cygtls. These
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# are where the members are defined.
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if (marker > 0) ++marker;
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if (marker > 2) exit;
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}
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{
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if (marker == 2 && $1 != "public:") {
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# Filter out function names
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$0 = gensub (/\(\*(\w+)\)\s*\([^\)]*\)/, "\\1", "g");
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# Filter out leading asterisk
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$NF = gensub (/^\**(\w+)/, "\\1", "g", $NF);
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# Filter out trailing array expression
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$NF = gensub (/(\w+)\s*\[[^\]]*\]/, "\\1", "g", $NF);
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$NF = gensub (/(\w+);/, "\\1", "g", $NF);
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print "extern \"C\" const uint32_t __CYGTLS__" $NF " = offsetof (class _cygtls, " $NF ");";
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}
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}
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' | \
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# Now run the compiler to generate an assembler file.
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${CXXCOMPILE} -x c++ -g0 -O0 -S - -o - | \
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# The assembler file consists of lines like these:
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#
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# __CYGTLS__foo
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# .long 42
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# .globl __CYGTLS__foo
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# .align 4
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#
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# From this info, generate the tlsoffsets file.
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gawk '\
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BEGIN {
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varname=""
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start_offset = 0
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}
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/^__CYGTLS__/ {
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varname = gensub (/__CYGTLS__(\w+):/, "\\1", "g");
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}
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/\s*\.space\s*4/ {
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if (length (varname) > 0) {
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printf (".equ _cygtls.%s, %d\n", varname, -start_offset);
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printf (".equ _cygtls.%s_p, 0\n", varname);
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varname = "";
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}
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}
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/\s*\.long\s+/ {
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if (length (varname) > 0) {
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if (varname == "start_offset") {
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start_offset = $2;
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printf (".equ _cygtls.%s, -%u\n", varname, start_offset);
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} else {
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value = $2;
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printf (".equ _cygtls.%s, %d\n", varname, value - start_offset);
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printf (".equ _cygtls.%s_p, %d\n", varname, value);
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}
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varname = "";
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}
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}
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' > "${output_file}"
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