[PATCH] x86: Update 'P' operand modifier for -fno-plt
H.J. Lu
hjl.tools@gmail.com
Fri Mar 12 13:20:15 GMT 2021
On Thu, Mar 11, 2021 at 11:21 PM Uros Bizjak <ubizjak@gmail.com> wrote:
>
> On Thu, Mar 11, 2021 at 11:22 PM H.J. Lu <hjl.tools@gmail.com> wrote:
> >
> > Update 'P' operand modifier for -fno-plt to support inline assembly
> > statements. In 64-bit, we can always load function address with
> > @GOTPCREL. In 32-bit, we load function address with @GOT only for
> > non-PIC since PIC register may not be available at call site.
> >
> > gcc/
> >
> > PR target/99504
> > * config/i386/i386.c (ix86_print_operand): Update 'P' handling
> > for -fno-plt.
> >
> > gcc/testsuite/
> >
> > PR target/99504
> > * gcc.target/i386/pr99530-1.c: New test.
> > * gcc.target/i386/pr99530-2.c: Likewise.
> > * gcc.target/i386/pr99530-3.c: Likewise.
> > * gcc.target/i386/pr99530-4.c: Likewise.
> > * gcc.target/i386/pr99530-5.c: Likewise.
> > * gcc.target/i386/pr99530-6.c: Likewise.
> > ---
> > gcc/config/i386/i386.c | 33 +++++++++++++++++++++--
> > gcc/testsuite/gcc.target/i386/pr99530-1.c | 11 ++++++++
> > gcc/testsuite/gcc.target/i386/pr99530-2.c | 11 ++++++++
> > gcc/testsuite/gcc.target/i386/pr99530-3.c | 11 ++++++++
> > gcc/testsuite/gcc.target/i386/pr99530-4.c | 11 ++++++++
> > gcc/testsuite/gcc.target/i386/pr99530-5.c | 11 ++++++++
> > gcc/testsuite/gcc.target/i386/pr99530-6.c | 11 ++++++++
> > 7 files changed, 97 insertions(+), 2 deletions(-)
> > create mode 100644 gcc/testsuite/gcc.target/i386/pr99530-1.c
> > create mode 100644 gcc/testsuite/gcc.target/i386/pr99530-2.c
> > create mode 100644 gcc/testsuite/gcc.target/i386/pr99530-3.c
> > create mode 100644 gcc/testsuite/gcc.target/i386/pr99530-4.c
> > create mode 100644 gcc/testsuite/gcc.target/i386/pr99530-5.c
> > create mode 100644 gcc/testsuite/gcc.target/i386/pr99530-6.c
> >
> > diff --git a/gcc/config/i386/i386.c b/gcc/config/i386/i386.c
> > index 2603333f87b..8733fcecf65 100644
> > --- a/gcc/config/i386/i386.c
> > +++ b/gcc/config/i386/i386.c
> > @@ -12701,7 +12701,8 @@ print_reg (rtx x, int code, FILE *file)
> > y -- print "st(0)" instead of "st" as a register.
> > d -- print duplicated register operand for AVX instruction.
> > D -- print condition for SSE cmp instruction.
> > - P -- if PIC, print an @PLT suffix.
> > + P -- if PIC, print an @PLT suffix. For -fno-plt, load function
> > + address from GOT.
> > p -- print raw symbol name.
> > X -- don't print any sort of PIC '@' suffix for a symbol.
> > & -- print some in-use local-dynamic symbol name.
> > @@ -13445,7 +13446,35 @@ ix86_print_operand (FILE *file, rtx x, int code)
> > x = const0_rtx;
> > }
> >
> > - if (code != 'P' && code != 'p')
> > + if (code == 'P')
> > + {
> > + if (current_output_insn == NULL_RTX
> > + && (TARGET_64BIT || (!flag_pic && HAVE_AS_IX86_GOT32X))
> > + && !TARGET_PECOFF
> > + && !TARGET_MACHO
> > + && ix86_cmodel != CM_LARGE
> > + && ix86_cmodel != CM_LARGE_PIC
> > + && GET_CODE (x) == SYMBOL_REF
> > + && SYMBOL_REF_FUNCTION_P (x)
> > + && (!flag_plt
> > + || (SYMBOL_REF_DECL (x)
> > + && lookup_attribute ("noplt",
> > + DECL_ATTRIBUTES (SYMBOL_REF_DECL (x)))))
> > + && !SYMBOL_REF_LOCAL_P (x))
> > + {
> > + /* For inline assembly statement, load function address
> > + from GOT with 'P' operand modifier to avoid PLT.
> > + NB: This works only with call or jmp. */
> > + const char *xasm;
> > + if (TARGET_64BIT)
> > + xasm = "{*%p0@GOTPCREL(%%rip)|[QWORD PTR %p0@GOTPCREL[rip]]}";
> > + else
> > + xasm = "{*%p0@GOT|[DWORD PTR %p0@GOT]}";
> > + output_asm_insn (xasm, &x);
> > + return;
>
> This should be handled in output_pic_addr_const.
>
call/jmp are special and are handled by ix86_output_call_insn,
not output_pic_addr_const.
H.J.
More information about the Gcc-patches
mailing list