Re: [GCC 13 PATCH] LoongArch: Don't default to -mno-explicit-relocs if -mno-relax

[chenglulu]

在 2024/2/22 下午6:20, Xi Ruoyao 写道:

To improve Binutils compatibility we've had to backported relaxation
support.  But if a user just updates to GCC 13.3 and sticks with
Binutils 2.41, there is no reason to use -mno-explicit-relocs as the
default because we are turning off relaxation for Binutils 2.41 (it
lacks conditional branch relaxation support) anyway.

So like GCC 14, make the default of -m[no-]explicit-relocs depend on
-m[no-]relax instead of HAVE_AS_MRELAX_OPTION.  Also update the doc to
reflect the behavior change.

gcc/ChangeLog:

        * config/loongarch/genopts/loongarch.opt.in
        (TARGET_EXPLICIT_RELOCS): Init to M_OPTION_NOT_SEEN.
        * config/loongarch/loongarch.opt: Regenerate.
        * config/loongarch/loongarch.cc
        (loongarch_option_override_internal): Set the default of
        TARGET_EXPLICIT_RELOCS to HAVE_AS_EXPLICIT_RELOCS
        && !loongarch_mrelax.
        * doc/invoke.texi (-m[no-]explicit-relocs): Update for
        LoongArch.
---

Ok for releases/gcc-13?

LGTM!

Thanks!

  gcc/config/loongarch/genopts/loongarch.opt.in |  2 +-
  gcc/config/loongarch/loongarch.cc             |  4 ++++
  gcc/config/loongarch/loongarch.opt            |  2 +-
  gcc/doc/invoke.texi                           | 11 +++++------
  4 files changed, 11 insertions(+), 8 deletions(-)

diff --git a/gcc/config/loongarch/genopts/loongarch.opt.in 
b/gcc/config/loongarch/genopts/loongarch.opt.in
index da6fedd153e..76acd35d39c 100644
--- a/gcc/config/loongarch/genopts/loongarch.opt.in
+++ b/gcc/config/loongarch/genopts/loongarch.opt.in
@@ -155,7 +155,7 @@ Target Joined RejectNegative UInteger 
Var(loongarch_max_inline_memcpy_size) Init
  -mmax-inline-memcpy-size=SIZE Set the max size of memcpy to inline, default 
is 1024.

mexplicit-relocs

-Target Var(TARGET_EXPLICIT_RELOCS) Init(HAVE_AS_EXPLICIT_RELOCS & 
!HAVE_AS_MRELAX_OPTION)
+Target Var(TARGET_EXPLICIT_RELOCS) Init(M_OPTION_NOT_SEEN)
  Use %reloc() assembly operators.

; The code model option names for -mcmodel.

diff --git a/gcc/config/loongarch/loongarch.cc 
b/gcc/config/loongarch/loongarch.cc
index 768e2427285..e78b81cd8fc 100644
--- a/gcc/config/loongarch/loongarch.cc
+++ b/gcc/config/loongarch/loongarch.cc
@@ -6222,6 +6222,10 @@ loongarch_option_override_internal (struct gcc_options 
*opts)
        gcc_unreachable ();
      }

+ if (TARGET_EXPLICIT_RELOCS == M_OPTION_NOT_SEEN)

+    TARGET_EXPLICIT_RELOCS = (HAVE_AS_EXPLICIT_RELOCS
+                             && !loongarch_mrelax);
+
    /* Validate the guard size.  */
    int guard_size = param_stack_clash_protection_guard_size;

diff --git a/gcc/config/loongarch/loongarch.opt b/gcc/config/loongarch/loongarch.opt

index 59b1e06d3f2..e61fbaed2c1 100644
--- a/gcc/config/loongarch/loongarch.opt
+++ b/gcc/config/loongarch/loongarch.opt
@@ -162,7 +162,7 @@ Target Joined RejectNegative UInteger 
Var(loongarch_max_inline_memcpy_size) Init
  -mmax-inline-memcpy-size=SIZE Set the max size of memcpy to inline, default 
is 1024.

mexplicit-relocs

-Target Var(TARGET_EXPLICIT_RELOCS) Init(HAVE_AS_EXPLICIT_RELOCS & 
!HAVE_AS_MRELAX_OPTION)
+Target Var(TARGET_EXPLICIT_RELOCS) Init(M_OPTION_NOT_SEEN)
  Use %reloc() assembly operators.

; The code model option names for -mcmodel.

diff --git a/gcc/doc/invoke.texi b/gcc/doc/invoke.texi
index 99657fb44d8..792ce283bb9 100644
--- a/gcc/doc/invoke.texi
+++ b/gcc/doc/invoke.texi
@@ -25830,12 +25830,11 @@ The default code model is @code{normal}.
  @itemx -mno-explicit-relocs
  Use or do not use assembler relocation operators when dealing with symbolic
  addresses.  The alternative is to use assembler macros instead, which may
-limit optimization.  The default value for the option is determined during
-GCC build-time by detecting corresponding assembler support:
-@code{-mexplicit-relocs} if said support is present,
-@code{-mno-explicit-relocs} otherwise.  This option is mostly useful for
-debugging, or interoperation with assemblers different from the build-time
-one.
+limit instruction scheduling but allow linker relaxation.  The default
+value for the option is determined with the assembler capability detected
+during GCC build-time and the setting of @code{-mrelax}:
+@code{-mexplicit-relocs} if the assembler supports relocation operators
+but @code{-mrelax} is not enabled, @code{-mno-explicit-relocs} otherwise.

@opindex mdirect-extern-access

  @item -mdirect-extern-access