2018-01-30 Jeff Law PR target/84064 * i386.c (ix86_adjust_stack_and_probe_stack_clash): New argument INT_REGISTERS_SAVED. Check it prior to calling get_scratch_register_on_entry. (ix86_adjust_stack_and_probe): Similarly. (ix86_emit_probe_stack_range): Similarly. (ix86_expand_prologue): Corresponding changes. * gcc.target/i386/pr84064: New test. --- gcc/config/i386/i386.c +++ gcc/config/i386/i386.c @@ -12591,10 +12591,14 @@ release_scratch_register_on_entry (struct scratch_reg *sr) This differs from the next routine in that it tries hard to prevent attacks that jump the stack guard. Thus it is never allowed to allocate more than PROBE_INTERVAL bytes of stack space without a suitable - probe. */ + probe. + + INT_REGISTERS_SAVED is true if integer registers have already been + pushed on the stack. */ static void -ix86_adjust_stack_and_probe_stack_clash (const HOST_WIDE_INT size) +ix86_adjust_stack_and_probe_stack_clash (const HOST_WIDE_INT size, + const bool int_registers_saved) { struct machine_function *m = cfun->machine; @@ -12700,6 +12704,12 @@ ix86_adjust_stack_and_probe_stack_clash (const HOST_WIDE_INT size) } else { + /* We expect the GP registers to be saved when probes are used + as the probing sequences might need a scratch register and + the routine to allocate one assumes the integer registers + have already been saved. */ + gcc_assert (int_registers_saved); + struct scratch_reg sr; get_scratch_register_on_entry (&sr); @@ -12758,10 +12768,14 @@ ix86_adjust_stack_and_probe_stack_clash (const HOST_WIDE_INT size) emit_insn (gen_blockage ()); } -/* Emit code to adjust the stack pointer by SIZE bytes while probing it. */ +/* Emit code to adjust the stack pointer by SIZE bytes while probing it. + + INT_REGISTERS_SAVED is true if integer registers have already been + pushed on the stack. */ static void -ix86_adjust_stack_and_probe (const HOST_WIDE_INT size) +ix86_adjust_stack_and_probe (const HOST_WIDE_INT size, + const bool int_registers_saved) { /* We skip the probe for the first interval + a small dope of 4 words and probe that many bytes past the specified size to maintain a protection @@ -12822,6 +12836,12 @@ ix86_adjust_stack_and_probe (const HOST_WIDE_INT size) equality test for the loop condition. */ else { + /* We expect the GP registers to be saved when probes are used + as the probing sequences might need a scratch register and + the routine to allocate one assumes the integer registers + have already been saved. */ + gcc_assert (int_registers_saved); + HOST_WIDE_INT rounded_size; struct scratch_reg sr; @@ -12949,10 +12969,14 @@ output_adjust_stack_and_probe (rtx reg) } /* Emit code to probe a range of stack addresses from FIRST to FIRST+SIZE, - inclusive. These are offsets from the current stack pointer. */ + inclusive. These are offsets from the current stack pointer. + + INT_REGISTERS_SAVED is true if integer registers have already been + pushed on the stack. */ static void -ix86_emit_probe_stack_range (HOST_WIDE_INT first, HOST_WIDE_INT size) +ix86_emit_probe_stack_range (HOST_WIDE_INT first, HOST_WIDE_INT size, + const bool int_registers_saved) { /* See if we have a constant small number of probes to generate. If so, that's the easy case. The run-time loop is made up of 6 insns in the @@ -12980,6 +13004,12 @@ ix86_emit_probe_stack_range (HOST_WIDE_INT first, HOST_WIDE_INT size) equality test for the loop condition. */ else { + /* We expect the GP registers to be saved when probes are used + as the probing sequences might need a scratch register and + the routine to allocate one assumes the integer registers + have already been saved. */ + gcc_assert (int_registers_saved); + HOST_WIDE_INT rounded_size, last; struct scratch_reg sr; @@ -13733,15 +13763,10 @@ ix86_expand_prologue (void) && (flag_stack_check == STATIC_BUILTIN_STACK_CHECK || flag_stack_clash_protection)) { - /* We expect the GP registers to be saved when probes are used - as the probing sequences might need a scratch register and - the routine to allocate one assumes the integer registers - have already been saved. */ - gcc_assert (int_registers_saved); - if (flag_stack_clash_protection) { - ix86_adjust_stack_and_probe_stack_clash (allocate); + ix86_adjust_stack_and_probe_stack_clash (allocate, + int_registers_saved); allocate = 0; } else if (STACK_CHECK_MOVING_SP) @@ -13749,7 +13774,7 @@ ix86_expand_prologue (void) if (!(crtl->is_leaf && !cfun->calls_alloca && allocate <= get_probe_interval ())) { - ix86_adjust_stack_and_probe (allocate); + ix86_adjust_stack_and_probe (allocate, int_registers_saved); allocate = 0; } } @@ -13765,11 +13790,12 @@ ix86_expand_prologue (void) if (crtl->is_leaf && !cfun->calls_alloca) { if (size > get_probe_interval ()) - ix86_emit_probe_stack_range (0, size); + ix86_emit_probe_stack_range (0, size, int_registers_saved); } else ix86_emit_probe_stack_range (0, - size + get_stack_check_protect ()); + size + get_stack_check_protect (), + int_registers_saved); } else { @@ -13778,10 +13804,13 @@ ix86_expand_prologue (void) if (size > get_probe_interval () && size > get_stack_check_protect ()) ix86_emit_probe_stack_range (get_stack_check_protect (), - size - get_stack_check_protect ()); + (size + - get_stack_check_protect ()), + int_registers_saved); } else - ix86_emit_probe_stack_range (get_stack_check_protect (), size); + ix86_emit_probe_stack_range (get_stack_check_protect (), size, + int_registers_saved); } } } --- gcc/testsuite/gcc.target/i386/pr84064.c +++ gcc/testsuite/gcc.target/i386/pr84064.c @@ -0,0 +1,10 @@ +/* { dg-do compile } */ +/* { dg-options "-O2 -march=i686 -fstack-clash-protection" } */ +/* { dg-require-effective-target ia32 } */ + +void +f (void *p1, void *p2) +{ + __builtin_memcpy (p1, p2, 1000); +} +