commit b552ddab57a34fe1acb8d714b5f556082600b9e0
Author: law <law@138bc75d-0d04-0410-961f-82ee72b054a4>
Date: Mon Sep 25 23:13:55 2017 +0000
* config/rs6000/rs6000-protos.h (output_probe_stack_range): Update
prototype for new argument.
* config/rs6000/rs6000.c (rs6000_emit_allocate_stack_1): New function,
mostly extracted from rs6000_emit_allocate_stack.
(rs6000_emit_probe_stack_range_stack_clash): New function.
(rs6000_emit_allocate_stack): Call
rs6000_emit_probe_stack_range_stack_clash as needed.
(rs6000_emit_probe_stack_range): Add additional argument
to call to gen_probe_stack_range{si,di}.
(output_probe_stack_range): New.
(output_probe_stack_range_1): Renamed from output_probe_stack_range.
(output_probe_stack_range_stack_clash): New.
(rs6000_emit_prologue): Emit notes into dump file as requested.
* rs6000.md (allocate_stack): Handle -fstack-clash-protection.
(probe_stack_range<P:mode>): Operand 0 is now early-clobbered.
Add additional operand and pass it to output_probe_stack_range.
* lib/target-supports.exp
(check_effective_target_supports_stack_clash_protection): Enable for
rs6000 and powerpc targets.
git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/trunk@253179 138bc75d-0d04-0410-961f-82ee72b054a4
diff --git a/gcc/config/rs6000/rs6000-protos.h b/gcc/config/rs6000/rs6000-protos.h
index 74ad733d1b9..d48aa88f4b1 100644
--- a/gcc/config/rs6000/rs6000-protos.h
+++ b/gcc/config/rs6000/rs6000-protos.h
@@ -134,7 +134,7 @@ extern void rs6000_emit_sCOND (machine_mode, rtx[]);
extern void rs6000_emit_cbranch (machine_mode, rtx[]);
extern char * output_cbranch (rtx, const char *, int, rtx_insn *);
extern char * output_e500_flip_gt_bit (rtx, rtx);
-extern const char * output_probe_stack_range (rtx, rtx);
+extern const char * output_probe_stack_range (rtx, rtx, rtx);
extern bool rs6000_emit_set_const (rtx, rtx);
extern int rs6000_emit_cmove (rtx, rtx, rtx, rtx);
extern int rs6000_emit_vector_cond_expr (rtx, rtx, rtx, rtx, rtx, rtx);
diff --git a/gcc/config/rs6000/rs6000.c b/gcc/config/rs6000/rs6000.c
index 1836e1d147d..8235bff2469 100644
--- a/gcc/config/rs6000/rs6000.c
+++ b/gcc/config/rs6000/rs6000.c
@@ -28133,6 +28133,221 @@ rs6000_emit_stack_tie (rtx fp, bool hard_frame_needed)
emit_insn (gen_stack_tie (gen_rtx_PARALLEL (VOIDmode, p)));
}
+/* Allocate SIZE_INT bytes on the stack using a store with update style insn
+ and set the appropriate attributes for the generated insn. Return the
+ first insn which adjusts the stack pointer or the last insn before
+ the stack adjustment loop.
+
+ SIZE_INT is used to create the CFI note for the allocation.
+
+ SIZE_RTX is an rtx containing the size of the adjustment. Note that
+ since stacks grow to lower addresses its runtime value is -SIZE_INT.
+
+ ORIG_SP contains the backchain value that must be stored at *sp. */
+
+static rtx_insn *
+rs6000_emit_allocate_stack_1 (HOST_WIDE_INT size_int, rtx orig_sp)
+{
+ rtx_insn *insn;
+
+ rtx size_rtx = GEN_INT (-size_int);
+ if (size_int > 32767)
+ {
+ rtx tmp_reg = gen_rtx_REG (Pmode, 0);
+ /* Need a note here so that try_split doesn't get confused. */
+ if (get_last_insn () == NULL_RTX)
+ emit_note (NOTE_INSN_DELETED);
+ insn = emit_move_insn (tmp_reg, size_rtx);
+ try_split (PATTERN (insn), insn, 0);
+ size_rtx = tmp_reg;
+ }
+
+ if (Pmode == SImode)
+ insn = emit_insn (gen_movsi_update_stack (stack_pointer_rtx,
+ stack_pointer_rtx,
+ size_rtx,
+ orig_sp));
+ else
+ insn = emit_insn (gen_movdi_di_update_stack (stack_pointer_rtx,
+ stack_pointer_rtx,
+ size_rtx,
+ orig_sp));
+ rtx par = PATTERN (insn);
+ gcc_assert (GET_CODE (par) == PARALLEL);
+ rtx set = XVECEXP (par, 0, 0);
+ gcc_assert (GET_CODE (set) == SET);
+ rtx mem = SET_DEST (set);
+ gcc_assert (MEM_P (mem));
+ MEM_NOTRAP_P (mem) = 1;
+ set_mem_alias_set (mem, get_frame_alias_set ());
+
+ RTX_FRAME_RELATED_P (insn) = 1;
+ add_reg_note (insn, REG_FRAME_RELATED_EXPR,
+ gen_rtx_SET (stack_pointer_rtx,
+ gen_rtx_PLUS (Pmode,
+ stack_pointer_rtx,
+ GEN_INT (-size_int))));
+
+ /* Emit a blockage to ensure the allocation/probing insns are
+ not optimized, combined, removed, etc. Add REG_STACK_CHECK
+ note for similar reasons. */
+ if (flag_stack_clash_protection)
+ {
+ add_reg_note (insn, REG_STACK_CHECK, const0_rtx);
+ emit_insn (gen_blockage ());
+ }
+
+ return insn;
+}
+
+static HOST_WIDE_INT
+get_stack_clash_protection_probe_interval (void)
+{
+ return (HOST_WIDE_INT_1U
+ << PARAM_VALUE (PARAM_STACK_CLASH_PROTECTION_PROBE_INTERVAL));
+}
+
+static HOST_WIDE_INT
+get_stack_clash_protection_guard_size (void)
+{
+ return (HOST_WIDE_INT_1U
+ << PARAM_VALUE (PARAM_STACK_CLASH_PROTECTION_GUARD_SIZE));
+}
+
+/* Allocate ORIG_SIZE bytes on the stack and probe the newly
+ allocated space every STACK_CLASH_PROTECTION_PROBE_INTERVAL bytes.
+
+ COPY_REG, if non-null, should contain a copy of the original
+ stack pointer at exit from this function.
+
+ This is subtly different than the Ada probing in that it tries hard to
+ prevent attacks that jump the stack guard. Thus it is never allowed to
+ allocate more than STACK_CLASH_PROTECTION_PROBE_INTERVAL bytes of stack
+ space without a suitable probe. */
+static rtx_insn *
+rs6000_emit_probe_stack_range_stack_clash (HOST_WIDE_INT orig_size,
+ rtx copy_reg)
+{
+ rtx orig_sp = copy_reg;
+
+ HOST_WIDE_INT probe_interval = get_stack_clash_protection_probe_interval ();
+
+ /* Round the size down to a multiple of PROBE_INTERVAL. */
+ HOST_WIDE_INT rounded_size = ROUND_DOWN (orig_size, probe_interval);
+
+ /* If explicitly requested,
+ or the rounded size is not the same as the original size
+ or the the rounded size is greater than a page,
+ then we will need a copy of the original stack pointer. */
+ if (rounded_size != orig_size
+ || rounded_size > probe_interval
+ || copy_reg)
+ {
+ /* If the caller did not request a copy of the incoming stack
+ pointer, then we use r0 to hold the copy. */
+ if (!copy_reg)
+ orig_sp = gen_rtx_REG (Pmode, 0);
+ emit_move_insn (orig_sp, stack_pointer_rtx);
+ }
+
+ /* There's three cases here.
+
+ One is a single probe which is the most common and most efficiently
+ implemented as it does not have to have a copy of the original
+ stack pointer if there are no residuals.
+
+ Second is unrolled allocation/probes which we use if there's just
+ a few of them. It needs to save the original stack pointer into a
+ temporary for use as a source register in the allocation/probe.
+
+ Last is a loop. This is the most uncommon case and least efficient. */
+ rtx_insn *retval = NULL;
+ if (rounded_size == probe_interval)
+ {
+ retval = rs6000_emit_allocate_stack_1 (probe_interval, stack_pointer_rtx);
+
+ dump_stack_clash_frame_info (PROBE_INLINE, rounded_size != orig_size);
+ }
+ else if (rounded_size <= 8 * probe_interval)
+ {
+ /* The ABI requires using the store with update insns to allocate
+ space and store the backchain into the stack
+
+ So we save the current stack pointer into a temporary, then
+ emit the store-with-update insns to store the saved stack pointer
+ into the right location in each new page. */
+ for (int i = 0; i < rounded_size; i += probe_interval)
+ {
+ rtx_insn *insn
+ = rs6000_emit_allocate_stack_1 (probe_interval, orig_sp);
+
+ /* Save the first stack adjustment in RETVAL. */
+ if (i == 0)
+ retval = insn;
+ }
+
+ dump_stack_clash_frame_info (PROBE_INLINE, rounded_size != orig_size);
+ }
+ else
+ {
+ /* Compute the ending address. */
+ rtx end_addr
+ = copy_reg ? gen_rtx_REG (Pmode, 0) : gen_rtx_REG (Pmode, 12);
+ rtx rs = GEN_INT (-rounded_size);
+ rtx_insn *insn;
+ if (add_operand (rs, Pmode))
+ insn = emit_insn (gen_add3_insn (end_addr, stack_pointer_rtx, rs));
+ else
+ {
+ emit_move_insn (end_addr, GEN_INT (-rounded_size));
+ insn = emit_insn (gen_add3_insn (end_addr, end_addr,
+ stack_pointer_rtx));
+ /* Describe the effect of INSN to the CFI engine. */
+ add_reg_note (insn, REG_FRAME_RELATED_EXPR,
+ gen_rtx_SET (end_addr,
+ gen_rtx_PLUS (Pmode, stack_pointer_rtx,
+ rs)));
+ }
+ RTX_FRAME_RELATED_P (insn) = 1;
+
+ /* Emit the loop. */
+ if (TARGET_64BIT)
+ retval = emit_insn (gen_probe_stack_rangedi (stack_pointer_rtx,
+ stack_pointer_rtx, orig_sp,
+ end_addr));
+ else
+ retval = emit_insn (gen_probe_stack_rangesi (stack_pointer_rtx,
+ stack_pointer_rtx, orig_sp,
+ end_addr));
+ RTX_FRAME_RELATED_P (retval) = 1;
+ /* Describe the effect of INSN to the CFI engine. */
+ add_reg_note (retval, REG_FRAME_RELATED_EXPR,
+ gen_rtx_SET (stack_pointer_rtx, end_addr));
+
+ /* Emit a blockage to ensure the allocation/probing insns are
+ not optimized, combined, removed, etc. Other cases handle this
+ within their call to rs6000_emit_allocate_stack_1. */
+ emit_insn (gen_blockage ());
+
+ dump_stack_clash_frame_info (PROBE_LOOP, rounded_size != orig_size);
+ }
+
+ if (orig_size != rounded_size)
+ {
+ /* Allocate (and implicitly probe) any residual space. */
+ HOST_WIDE_INT residual = orig_size - rounded_size;
+
+ rtx_insn *insn = rs6000_emit_allocate_stack_1 (residual, orig_sp);
+
+ /* If the residual was the only allocation, then we can return the
+ allocating insn. */
+ if (!retval)
+ retval = insn;
+ }
+
+ return retval;
+}
+
/* Emit the correct code for allocating stack space, as insns.
If COPY_REG, make sure a copy of the old frame is left there.
The generated code may use hard register 0 as a temporary. */
@@ -28144,7 +28359,6 @@ rs6000_emit_allocate_stack (HOST_WIDE_INT size, rtx copy_reg, int copy_off)
rtx stack_reg = gen_rtx_REG (Pmode, STACK_POINTER_REGNUM);
rtx tmp_reg = gen_rtx_REG (Pmode, 0);
rtx todec = gen_int_mode (-size, Pmode);
- rtx par, set, mem;
if (INTVAL (todec) != -size)
{
@@ -28184,6 +28398,23 @@ rs6000_emit_allocate_stack (HOST_WIDE_INT size, rtx copy_reg, int copy_off)
warning (0, "stack limit expression is not supported");
}
+ if (flag_stack_clash_protection)
+ {
+ if (size < get_stack_clash_protection_guard_size ())
+ dump_stack_clash_frame_info (NO_PROBE_SMALL_FRAME, true);
+ else
+ {
+ rtx_insn *insn = rs6000_emit_probe_stack_range_stack_clash (size,
+ copy_reg);
+
+ /* If we asked for a copy with an offset, then we still need add in
+ the offset. */
+ if (copy_reg && copy_off)
+ emit_insn (gen_add3_insn (copy_reg, copy_reg, GEN_INT (copy_off)));
+ return insn;
+ }
+ }
+
if (copy_reg)
{
if (copy_off != 0)
@@ -28192,38 +28423,11 @@ rs6000_emit_allocate_stack (HOST_WIDE_INT size, rtx copy_reg, int copy_off)
emit_move_insn (copy_reg, stack_reg);
}
- if (size > 32767)
- {
- /* Need a note here so that try_split doesn't get confused. */
- if (get_last_insn () == NULL_RTX)
- emit_note (NOTE_INSN_DELETED);
- insn = emit_move_insn (tmp_reg, todec);
- try_split (PATTERN (insn), insn, 0);
- todec = tmp_reg;
- }
-
- insn = emit_insn (TARGET_32BIT
- ? gen_movsi_update_stack (stack_reg, stack_reg,
- todec, stack_reg)
- : gen_movdi_di_update_stack (stack_reg, stack_reg,
- todec, stack_reg));
/* Since we didn't use gen_frame_mem to generate the MEM, grab
it now and set the alias set/attributes. The above gen_*_update
calls will generate a PARALLEL with the MEM set being the first
operation. */
- par = PATTERN (insn);
- gcc_assert (GET_CODE (par) == PARALLEL);
- set = XVECEXP (par, 0, 0);
- gcc_assert (GET_CODE (set) == SET);
- mem = SET_DEST (set);
- gcc_assert (MEM_P (mem));
- MEM_NOTRAP_P (mem) = 1;
- set_mem_alias_set (mem, get_frame_alias_set ());
-
- RTX_FRAME_RELATED_P (insn) = 1;
- add_reg_note (insn, REG_FRAME_RELATED_EXPR,
- gen_rtx_SET (stack_reg, gen_rtx_PLUS (Pmode, stack_reg,
- GEN_INT (-size))));
+ insn = rs6000_emit_allocate_stack_1 (size, stack_reg);
return insn;
}
@@ -28305,9 +28509,9 @@ rs6000_emit_probe_stack_range (HOST_WIDE_INT first, HOST_WIDE_INT size)
until it is equal to ROUNDED_SIZE. */
if (TARGET_64BIT)
- emit_insn (gen_probe_stack_rangedi (r12, r12, r0));
+ emit_insn (gen_probe_stack_rangedi (r12, r12, stack_pointer_rtx, r0));
else
- emit_insn (gen_probe_stack_rangesi (r12, r12, r0));
+ emit_insn (gen_probe_stack_rangesi (r12, r12, stack_pointer_rtx, r0));
/* Step 4: probe at FIRST + SIZE if we cannot assert at compile-time
@@ -28319,10 +28523,10 @@ rs6000_emit_probe_stack_range (HOST_WIDE_INT first, HOST_WIDE_INT size)
}
/* Probe a range of stack addresses from REG1 to REG2 inclusive. These are
- absolute addresses. */
+ addresses, not offsets. */
-const char *
-output_probe_stack_range (rtx reg1, rtx reg2)
+static const char *
+output_probe_stack_range_1 (rtx reg1, rtx reg2)
{
static int labelno = 0;
char loop_lab[32];
@@ -28357,6 +28561,95 @@ output_probe_stack_range (rtx reg1, rtx reg2)
return "";
}
+/* This function is called when rs6000_frame_related is processing
+ SETs within a PARALLEL, and returns whether the REGNO save ought to
+ be marked RTX_FRAME_RELATED_P. The PARALLELs involved are those
+ for out-of-line register save functions, store multiple, and the
+ Darwin world_save. They may contain registers that don't really
+ need saving. */
+
+static bool
+interesting_frame_related_regno (unsigned int regno)
+{
+ /* Saves apparently of r0 are actually saving LR. It doesn't make
+ sense to substitute the regno here to test save_reg_p (LR_REGNO).
+ We *know* LR needs saving, and dwarf2cfi.c is able to deduce that
+ (set (mem) (r0)) is saving LR from a prior (set (r0) (lr)) marked
+ as frame related. */
+ if (regno == 0)
+ return true;
+ /* If we see CR2 then we are here on a Darwin world save. Saves of
+ CR2 signify the whole CR is being saved. This is a long-standing
+ ABI wart fixed by ELFv2. As for r0/lr there is no need to check
+ that CR needs to be saved. */
+ if (regno == CR2_REGNO)
+ return true;
+ /* Omit frame info for any user-defined global regs. If frame info
+ is supplied for them, frame unwinding will restore a user reg.
+ Also omit frame info for any reg we don't need to save, as that
+ bloats frame info and can cause problems with shrink wrapping.
+ Since global regs won't be seen as needing to be saved, both of
+ these conditions are covered by save_reg_p. */
+ return save_reg_p (regno);
+}
+
+/* Probe a range of stack addresses from REG1 to REG3 inclusive. These are
+ addresses, not offsets.
+
+ REG2 contains the backchain that must be stored into *sp at each allocation.
+
+ This is subtly different than the Ada probing above 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. */
+
+static const char *
+output_probe_stack_range_stack_clash (rtx reg1, rtx reg2, rtx reg3)
+{
+ static int labelno = 0;
+ char loop_lab[32];
+ rtx xops[3];
+
+ HOST_WIDE_INT probe_interval = get_stack_clash_protection_probe_interval ();
+
+ ASM_GENERATE_INTERNAL_LABEL (loop_lab, "LPSRL", labelno++);
+
+ ASM_OUTPUT_INTERNAL_LABEL (asm_out_file, loop_lab);
+
+ /* This allocates and probes. */
+ xops[0] = reg1;
+ xops[1] = reg2;
+ xops[2] = GEN_INT (-probe_interval);
+ if (TARGET_64BIT)
+ output_asm_insn ("stdu %1,%2(%0)", xops);
+ else
+ output_asm_insn ("stwu %1,%2(%0)", xops);
+
+ /* Jump to LOOP_LAB if TEST_ADDR != LAST_ADDR. */
+ xops[0] = reg1;
+ xops[1] = reg3;
+ if (TARGET_64BIT)
+ output_asm_insn ("cmpd 0,%0,%1", xops);
+ else
+ output_asm_insn ("cmpw 0,%0,%1", xops);
+
+ fputs ("\tbne 0,", asm_out_file);
+ assemble_name_raw (asm_out_file, loop_lab);
+ fputc ('\n', asm_out_file);
+
+ return "";
+}
+
+/* Wrapper around the output_probe_stack_range routines. */
+const char *
+output_probe_stack_range (rtx reg1, rtx reg2, rtx reg3)
+{
+ if (flag_stack_clash_protection)
+ return output_probe_stack_range_stack_clash (reg1, reg2, reg3);
+ else
+ return output_probe_stack_range_1 (reg1, reg3);
+}
+
/* Add to 'insn' a note which is PATTERN (INSN) but with REG replaced
with (plus:P (reg 1) VAL), and with REG2 replaced with REPL2 if REG2
is not NULL. It would be nice if dwarf2out_frame_debug_expr could
@@ -29951,6 +30244,13 @@ rs6000_emit_prologue (void)
}
}
+ /* If we are emitting stack probes, but allocate no stack, then
+ just note that in the dump file. */
+ if (flag_stack_clash_protection
+ && dump_file
+ && !info->push_p)
+ dump_stack_clash_frame_info (NO_PROBE_NO_FRAME, false);
+
/* Update stack and set back pointer unless this is V.4,
for which it was done previously. */
if (!WORLD_SAVE_P (info) && info->push_p
diff --git a/gcc/config/rs6000/rs6000.md b/gcc/config/rs6000/rs6000.md
index 3323976a35d..843148e9703 100644
--- a/gcc/config/rs6000/rs6000.md
+++ b/gcc/config/rs6000/rs6000.md
@@ -10386,10 +10386,20 @@
;;
;; First, an insn to allocate new stack space for dynamic use (e.g., alloca).
;; We move the back-chain and decrement the stack pointer.
-
+;;
+;; Operand1 is more naturally reg_or_short_operand. However, for a large
+;; constant alloca, using that predicate will force the generic code to put
+;; the constant size into a register before calling the expander.
+;;
+;; As a result the expander would not have the constant size information
+;; in those cases and would have to generate less efficient code.
+;;
+;; Thus we allow reg_or_cint_operand instead so that the expander can see
+;; the constant size. The value is forced into a register if necessary.
+;;
(define_expand "allocate_stack"
[(set (match_operand 0 "gpc_reg_operand" "")
- (minus (reg 1) (match_operand 1 "reg_or_short_operand" "")))
+ (minus (reg 1) (match_operand 1 "reg_or_cint_operand" "")))
(set (reg 1)
(minus (reg 1) (match_dup 1)))]
""
@@ -10399,6 +10409,15 @@
rtx neg_op0;
rtx insn, par, set, mem;
+ /* By allowing reg_or_cint_operand as the predicate we can get
+ better code for stack-clash-protection because we do not lose
+ size information. But the rest of the code expects the operand
+ to be reg_or_short_operand. If it isn't, then force it into
+ a register. */
+ rtx orig_op1 = operands[1];
+ if (!reg_or_short_operand (operands[1], Pmode))
+ operands[1] = force_reg (Pmode, operands[1]);
+
emit_move_insn (chain, stack_bot);
/* Check stack bounds if necessary. */
@@ -10411,6 +10430,51 @@
emit_insn (gen_cond_trap (LTU, available, operands[1], const0_rtx));
}
+ /* Allocate and probe if requested.
+ This may look similar to the loop we use for prologue allocations,
+ but it is critically different. For the former we know the loop
+ will iterate, but do not know that generally here. The former
+ uses that knowledge to rotate the loop. Combining them would be
+ possible with some performance cost. */
+ if (flag_stack_clash_protection)
+ {
+ rtx rounded_size, last_addr, residual;
+ HOST_WIDE_INT probe_interval;
+ compute_stack_clash_protection_loop_data (&rounded_size, &last_addr,
+ &residual, &probe_interval,
+ orig_op1);
+
+ /* We do occasionally get in here with constant sizes, we might
+ as well do a reasonable job when we obviously can. */
+ if (rounded_size != const0_rtx)
+ {
+ rtx loop_lab, end_loop;
+ bool rotated = CONST_INT_P (rounded_size);
+
+ emit_stack_clash_protection_probe_loop_start (&loop_lab, &end_loop,
+ last_addr, rotated);
+
+ if (Pmode == SImode)
+ emit_insn (gen_movsi_update_stack (stack_pointer_rtx,
+ stack_pointer_rtx,
+ GEN_INT (-probe_interval),
+ chain));
+ else
+ emit_insn (gen_movdi_di_update_stack (stack_pointer_rtx,
+ stack_pointer_rtx,
+ GEN_INT (-probe_interval),
+ chain));
+ emit_stack_clash_protection_probe_loop_end (loop_lab, end_loop,
+ last_addr, rotated);
+ }
+
+ /* Now handle residuals. We just have to set operands[1] correctly
+ and let the rest of the expander run. */
+ operands[1] = residual;
+ if (!CONST_INT_P (residual))
+ operands[1] = force_reg (Pmode, operands[1]);
+ }
+
if (GET_CODE (operands[1]) != CONST_INT
|| INTVAL (operands[1]) < -32767
|| INTVAL (operands[1]) > 32768)
@@ -11549,12 +11613,13 @@
(set_attr "length" "4")])
(define_insn "probe_stack_range<P:mode>"
- [(set (match_operand:P 0 "register_operand" "=r")
+ [(set (match_operand:P 0 "register_operand" "=&r")
(unspec_volatile:P [(match_operand:P 1 "register_operand" "0")
- (match_operand:P 2 "register_operand" "r")]
+ (match_operand:P 2 "register_operand" "r")
+ (match_operand:P 3 "register_operand" "r")]
UNSPECV_PROBE_STACK_RANGE))]
""
- "* return output_probe_stack_range (operands[0], operands[2]);"
+ "* return output_probe_stack_range (operands[0], operands[2], operands[3]);"
[(set_attr "type" "three")])
;; Compare insns are next. Note that the RS/6000 has two types of compares,
diff --git a/gcc/testsuite/lib/target-supports.exp b/gcc/testsuite/lib/target-supports.exp
index cb58a2be35f..02eb2066393 100644
--- a/gcc/testsuite/lib/target-supports.exp
+++ b/gcc/testsuite/lib/target-supports.exp
@@ -8385,12 +8385,12 @@ proc check_effective_target_arm_coproc4_ok { } {
proc check_effective_target_supports_stack_clash_protection { } {
# Temporary until the target bits are fully ACK'd.
-# if { [istarget aarch*-*-*]
-# || [istarget powerpc*-*-*] || [istarget rs6000*-*-*] } {
+# if { [istarget aarch*-*-*] } {
# return 1
# }
if { [istarget x86_64-*-*] || [istarget i?86-*-*]
+ || [istarget powerpc*-*-*] || [istarget rs6000*-*-*]
|| [istarget s390*-*-*] } {
return 1
}