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Merged
merged 1 commit into from
Jun 4, 2024
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@jaidTw jaidTw commented Jun 3, 2024

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@jaidTw jaidTw requested review from kito-cheng and monkchiang June 3, 2024 12:40
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LGTM

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LGTM, thanks :)

@kito-cheng kito-cheng merged commit fe7602b into riscv-gcc-13.3-cfi Jun 4, 2024
@kito-cheng kito-cheng deleted the jesse/cfi-rv32 branch June 4, 2024 02:38
yulong18 pushed a commit that referenced this pull request Sep 27, 2024
…o_debug_section [PR116614]

cat abc.C
  #define A(n) struct T##n {} t##n;
  #define B(n) A(n##0) A(n##1) A(n##2) A(n##3) A(n##4) A(n##5) A(n##6) A(n##7) A(n#riscvarchive#8) A(n#riscvarchive#9)
  #define C(n) B(n##0) B(n##1) B(n##2) B(n##3) B(n##4) B(n##5) B(n##6) B(n##7) B(n#riscvarchive#8) B(n#riscvarchive#9)
  #define D(n) C(n##0) C(n##1) C(n##2) C(n##3) C(n##4) C(n##5) C(n##6) C(n##7) C(n#riscvarchive#8) C(n#riscvarchive#9)
  #define E(n) D(n##0) D(n##1) D(n##2) D(n##3) D(n##4) D(n##5) D(n##6) D(n##7) D(n#riscvarchive#8) D(n#riscvarchive#9)
  E(1) E(2) E(3)
  int main () { return 0; }
./xg++ -B ./ -o abc{.o,.C} -flto -flto-partition=1to1 -O2 -g -fdebug-types-section -c
./xgcc -B ./ -o abc{,.o} -flto -flto-partition=1to1 -O2
(not included in testsuite as it takes a while to compile) FAILs with
lto-wrapper: fatal error: Too many copied sections: Operation not supported
compilation terminated.
/usr/bin/ld: error: lto-wrapper failed
collect2: error: ld returned 1 exit status

The following patch fixes that.  Most of the 64K+ section support for
reading and writing was already there years ago (and especially reading used
quite often already) and a further bug fixed in it in the PR104617 fix.

Yet, the fix isn't solely about removing the
  if (new_i - 1 >= SHN_LORESERVE)
    {
      *err = ENOTSUP;
      return "Too many copied sections";
    }
5 lines, the missing part was that the function only handled reading of
the .symtab_shndx section but not copying/updating of it.
If the result has less than 64K-epsilon sections, that actually wasn't
needed, but e.g. with -fdebug-types-section one can exceed that pretty
easily (reported to us on WebKitGtk build on ppc64le).
Updating the section is slightly more complicated, because it basically
needs to be done in lock step with updating the .symtab section, if one
doesn't need to use SHN_XINDEX in there, the section should (or should be
updated to) contain SHN_UNDEF entry, otherwise needs to have whatever would
be overwise stored but couldn't fit.  But repeating due to that all the
symtab decisions what to discard and how to rewrite it would be ugly.

So, the patch instead emits the .symtab_shndx section (or sections) last
and prepares the content during the .symtab processing and in a second
pass when going just through .symtab_shndx sections just uses the saved
content.

2024-09-07  Jakub Jelinek  <[email protected]>

	PR lto/116614
	* simple-object-elf.c (SHN_COMMON): Align comment with neighbouring
	comments.
	(SHN_HIRESERVE): Use uppercase hex digits instead of lowercase for
	consistency.
	(simple_object_elf_find_sections): Formatting fixes.
	(simple_object_elf_fetch_attributes): Likewise.
	(simple_object_elf_attributes_merge): Likewise.
	(simple_object_elf_start_write): Likewise.
	(simple_object_elf_write_ehdr): Likewise.
	(simple_object_elf_write_shdr): Likewise.
	(simple_object_elf_write_to_file): Likewise.
	(simple_object_elf_copy_lto_debug_section): Likewise.  Don't fail for
	new_i - 1 >= SHN_LORESERVE, instead arrange in that case to copy
	over .symtab_shndx sections, though emit those last and compute their
	section content when processing associated .symtab sections.  Handle
	simple_object_internal_read failure even in the .symtab_shndx reading
	case.
yulong18 pushed a commit that referenced this pull request Nov 4, 2024
Whenever C1 and C2 are integer constants, X is of a wrapping type, and
cmp is a relational operator, the expression X +- C1 cmp C2 can be
simplified in the following cases:

(a) If cmp is <= and C2 -+ C1 == +INF(1), we can transform the initial
comparison in the following way:
   X +- C1 <= C2
   -INF <= X +- C1 <= C2 (add left hand side which holds for any X, C1)
   -INF -+ C1 <= X <= C2 -+ C1 (add -+C1 to all 3 expressions)
   -INF -+ C1 <= X <= +INF (due to (1))
   -INF -+ C1 <= X (eliminate the right hand side since it holds for any X)

(b) By analogy, if cmp if >= and C2 -+ C1 == -INF(1), use the following
sequence of transformations:

   X +- C1 >= C2
   +INF >= X +- C1 >= C2 (add left hand side which holds for any X, C1)
   +INF -+ C1 >= X >= C2 -+ C1 (add -+C1 to all 3 expressions)
   +INF -+ C1 >= X >= -INF (due to (1))
   +INF -+ C1 >= X (eliminate the right hand side since it holds for any X)

(c) The > and < cases are negations of (a) and (b), respectively.

This transformation allows to occasionally save add / sub instructions,
for instance the expression

3 + (uint32_t)f() < 2

compiles to

cmn     w0, #4
cset    w0, ls

instead of

add     w0, w0, 3
cmp     w0, 2
cset    w0, ls

on aarch64.

Testcases that go together with this patch have been split into two
separate files, one containing testcases for unsigned variables and the
other for wrapping signed ones (and thus compiled with -fwrapv).
Additionally, one aarch64 test has been adjusted since the patch has
caused the generated code to change from

cmn     w0, #2
csinc   w0, w1, wzr, cc   (x < -2)

to

cmn     w0, #3
csinc   w0, w1, wzr, cs   (x <= -3)

This patch has been bootstrapped and regtested on aarch64, x86_64, and
i386, and additionally regtested on riscv32.

gcc/ChangeLog:

	PR tree-optimization/116024
	* match.pd: New transformation around integer comparison.

gcc/testsuite/ChangeLog:

	* gcc.dg/tree-ssa/pr116024-2.c: New test.
	* gcc.dg/tree-ssa/pr116024-2-fwrapv.c: Ditto.
	* gcc.target/aarch64/gtu_to_ltu_cmp_1.c: Adjust.
yulong18 pushed a commit that referenced this pull request Nov 4, 2024
This patch folds svindex with constant arguments into a vector series.
We implemented this in svindex_impl::fold using the function build_vec_series.
For example,
svuint64_t f1 ()
{
  return svindex_u642 (10, 3);
}
compiled with -O2 -march=armv8.2-a+sve, is folded to {10, 13, 16, ...}
in the gimple pass lower.
This optimization benefits cases where svindex is used in combination with
other gimple-level optimizations.
For example,
svuint64_t f2 ()
{
    return svmul_x (svptrue_b64 (), svindex_u64 (10, 3), 5);
}
has previously been compiled to
f2:
        index   z0.d, riscvarchive#10, #3
        mul     z0.d, z0.d, #5
        ret
Now, it is compiled to
f2:
        mov     x0, 50
        index   z0.d, x0, riscvarchive#15
        ret

We added test cases checking
- the application of the transform during gimple for constant arguments,
- the interaction with another gimple-level optimization.

The patch was bootstrapped and regtested on aarch64-linux-gnu, no regression.
OK for mainline?

Signed-off-by: Jennifer Schmitz <[email protected]>

gcc/
	* config/aarch64/aarch64-sve-builtins-base.cc
	(svindex_impl::fold): Add constant folding.

gcc/testsuite/
	* gcc.target/aarch64/sve/index_const_fold.c: New test.
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