* config/i386/i386.c (ix86_emit_restore_reg_using_pop): Prototype. (ix86_adjust_stack_and_probe_stack_clash): Use a push/pop sequence to probe at the start of a noreturn function. * gcc.target/i386/stack-check-12.c: New test diff -Nrup a/gcc/config/i386/i386.c b/gcc/config/i386/i386.c --- a/gcc/config/i386/i386.c 2017-11-03 13:35:17.641528205 -0600 +++ b/gcc/config/i386/i386.c 2017-11-03 13:37:39.489361692 -0600 @@ -64,6 +64,7 @@ along with GCC; see the file COPYING3. #include "tree-flow.h" static rtx legitimize_dllimport_symbol (rtx, bool); +static void ix86_emit_restore_reg_using_pop (rtx); #ifndef CHECK_STACK_LIMIT #define CHECK_STACK_LIMIT (-1) @@ -9884,8 +9885,14 @@ ix86_adjust_stack_and_probe_stack_clash we just probe when we cross PROBE_INTERVAL. */ if (TREE_THIS_VOLATILE (cfun->decl)) { - emit_stack_probe (plus_constant (Pmode, stack_pointer_rtx, - -GET_MODE_SIZE (word_mode))); + /* We can safely use any register here since we're just going to push + its value and immediately pop it back. But we do try and avoid + argument passing registers so as not to introduce dependencies in + the pipeline. For 32 bit we use %esi and for 64 bit we use %rax. */ + rtx dummy_reg = gen_rtx_REG (word_mode, TARGET_64BIT ? AX_REG : SI_REG); + rtx insn = emit_insn (gen_push (dummy_reg)); + RTX_FRAME_RELATED_P (insn) = 1; + ix86_emit_restore_reg_using_pop (dummy_reg); emit_insn (gen_blockage ()); } diff -Nrup a/gcc/testsuite/gcc.target/i386/stack-check-12.c b/gcc/testsuite/gcc.target/i386/stack-check-12.c --- a/gcc/testsuite/gcc.target/i386/stack-check-12.c 1969-12-31 17:00:00.000000000 -0700 +++ b/gcc/testsuite/gcc.target/i386/stack-check-12.c 2017-11-03 13:36:15.104055651 -0600 @@ -0,0 +1,19 @@ +/* { dg-do compile } */ +/* { dg-options "-O2 -fstack-clash-protection -mtune=generic -fomit-frame-pointer" } */ +/* { dg-require-effective-target supports_stack_clash_protection } */ + +__attribute__ ((noreturn)) void exit (int); + +__attribute__ ((noreturn)) void +f (void) +{ + asm volatile ("nop" ::: "edi"); + exit (1); +} + +/* { dg-final { scan-assembler-not "or\[ql\]" } } */ +/* { dg-final { scan-assembler "pushl %esi" { target ia32 } } } */ +/* { dg-final { scan-assembler "popl %esi" { target ia32 } } }*/ +/* { dg-final { scan-assembler "pushq %rax" { target { ! ia32 } } } } */ +/* { dg-final { scan-assembler "popq %rax" { target { ! ia32 } } } }*/ +