On Mon, Mar 5, 2018 at 4:20 AM, H.J. Lu <hjl.to...@gmail.com> wrote: > On Tue, Feb 27, 2018 at 11:39 AM, H.J. Lu <hongjiu...@intel.com> wrote: >> For x86 targets, when -fno-plt is used, external functions are called >> via GOT slot, in 64-bit mode: >> >> [bnd] call/jmp *foo@GOTPCREL(%rip) >> >> and in 32-bit mode: >> >> [bnd] call/jmp *foo@GOT[(%reg)] >> >> With -mindirect-branch=, they are converted to, in 64-bit mode: >> >> pushq foo@GOTPCREL(%rip) >> [bnd] jmp __x86_indirect_thunk[_bnd] >> >> and in 32-bit mode: >> >> pushl foo@GOT[(%reg)] >> [bnd] jmp __x86_indirect_thunk[_bnd] >> >> which were incompatible with CFI. In 64-bit mode, since R11 is a scratch >> register, we generate: >> >> movq foo@GOTPCREL(%rip), %r11 >> [bnd] call/jmp __x86_indirect_thunk_[bnd_]r11 >> >> instead. We do it in ix86_output_indirect_branch so that we can use >> the newly proposed R_X86_64_THUNK_GOTPCRELX relocation: >> >> https://groups.google.com/forum/#!topic/x86-64-abi/eED5lzn3_Mg >> >> movq foo@OTPCREL_THUNK(%rip), %r11 >> [bnd] call/jmp __x86_indirect_thunk_[bnd_]r11 >> >> to load GOT slot into R11. If foo is defined locally, linker can can >> convert >> >> movq foo@GOTPCREL_THUNK(%rip), %reg >> call/jmp __x86_indirect_thunk_reg >> >> to >> >> call/jmp foo >> nop 0L(%rax) >> >> In 32-bit mode, since all caller-saved registers, EAX, EDX and ECX, may >> used to function parameters, there is no scratch register available. For >> -fno-plt -fno-pic -mindirect-branch=, we expand external function call >> to: >> >> movl foo@GOT, %reg >> [bnd] call/jmp *%reg >> >> so that it can be converted to >> >> movl foo@GOT, %reg >> [bnd] call/jmp __x86_indirect_thunk_[bnd_]reg >> >> in ix86_output_indirect_branch. Since this is performed during RTL >> expansion, other instructions may be inserted between movl and call/jmp. >> Linker optimization isn't always possible. >> >> Tested on i686 and x86-64. OK for trunk? >> >> >> H.J. >> --- >> gcc/ >> >> PR target/83970 >> * config/i386/constraints.md (Bs): Allow GOT_memory_operand >> for TARGET_LP64 with indirect branch conversion. >> (Bw): Likewise. >> * config/i386/i386.c (ix86_expand_call): Handle -fno-plt with >> -mindirect-branch=. >> (ix86_nopic_noplt_attribute_p): Likewise. >> (ix86_output_indirect_branch): In 64-bit mode, convert function >> call via GOT with R11 as a scratch register using >> __x86_indirect_thunk_r11. >> (ix86_output_call_insn): In 64-bit mode, set xasm to NULL when >> calling ix86_output_indirect_branch with function call via GOT. >> * config/i386/i386.md (*call_got_thunk): New call pattern for >> TARGET_LP64 with indirect branch conversion. >> (*call_value_got_thunk): Likewise. >> >> gcc/testsuite/ >> >> PR target/83970 >> * gcc.target/i386/indirect-thunk-5.c: Updated. >> * gcc.target/i386/indirect-thunk-6.c: Likewise. >> * gcc.target/i386/indirect-thunk-bnd-3.c: Likewise. >> * gcc.target/i386/indirect-thunk-bnd-4.c: Likewise. >> * gcc.target/i386/indirect-thunk-extern-5.c: Likewise. >> * gcc.target/i386/indirect-thunk-extern-6.c: Likewise. >> * gcc.target/i386/indirect-thunk-inline-5.c: Likewise. >> * gcc.target/i386/indirect-thunk-inline-6.c: Likewise. >> * gcc.target/i386/indirect-thunk-13.c: New test. >> * gcc.target/i386/indirect-thunk-14.c: Likewise. >> * gcc.target/i386/indirect-thunk-bnd-5.c: Likewise. >> * gcc.target/i386/indirect-thunk-bnd-6.c: Likewise. >> * gcc.target/i386/indirect-thunk-extern-11.c: Likewise. >> * gcc.target/i386/indirect-thunk-extern-12.c: Likewise. >> * gcc.target/i386/indirect-thunk-inline-8.c: Likewise. >> * gcc.target/i386/indirect-thunk-inline-9.c: Likewise. > > PING: > > https://gcc.gnu.org/ml/gcc-patches/2018-02/msg01527.html >
PING. -- H.J.
