Calls from split-stack code to non-split-stack code need to expand
mapped stack memory via __morestack. Even tail calls.
__morestack is quite a surprising function on powerpc in that it calls
back to its caller, and a tail call will continue running in the
context of extra mapped stack.
Bootstrapped and regression tested on power8, and built for power10.
PR target/97107
* config/rs6000/rs6000-internal.h (struct rs6000_stack): Improve
calls_p comment.
* config/rs6000/rs6000-logue.c (rs6000_stack_info): Likewise.
(rs6000_expand_split_stack_prologue): Emit the prologue for
functions that make a sibling call.
diff --git a/gcc/config/rs6000/rs6000-internal.h
b/gcc/config/rs6000/rs6000-internal.h
index 9caef013a71..32681b6cece 100644
--- a/gcc/config/rs6000/rs6000-internal.h
+++ b/gcc/config/rs6000/rs6000-internal.h
@@ -32,7 +32,7 @@ typedef struct rs6000_stack {
int cr_save_p; /* true if the CR reg needs to be saved */
unsigned int vrsave_mask; /* mask of vec registers to save */
int push_p; /* true if we need to allocate stack space */
- int calls_p; /* true if the function makes any calls */
+ int calls_p; /* true if there are non-sibling calls */
int world_save_p; /* true if we're saving *everything*:
r13-r31, cr, f14-f31, vrsave, v20-v31 */
enum rs6000_abi abi; /* which ABI to use */
diff --git a/gcc/config/rs6000/rs6000-logue.c b/gcc/config/rs6000/rs6000-logue.c
index 0f88ec19929..cb08c25c795 100644
--- a/gcc/config/rs6000/rs6000-logue.c
+++ b/gcc/config/rs6000/rs6000-logue.c
@@ -714,7 +714,7 @@ rs6000_stack_info (void)
info->altivec_size = 16 * (LAST_ALTIVEC_REGNO + 1
- info->first_altivec_reg_save);
- /* Does this function call anything? */
+ /* Does this function call anything (apart from sibling calls)? */
info->calls_p = (!crtl->is_leaf || cfun->machine->ra_needs_full_frame);
/* Determine if we need to save the condition code registers. */
@@ -5479,7 +5479,15 @@ rs6000_expand_split_stack_prologue (void)
gcc_assert (flag_split_stack && reload_completed);
if (!info->push_p)
- return;
+ {
+ /* We need the -fsplit-stack prologue for functions that make
+ tail calls. Tail calls don't count against crtl->is_leaf. */
+ for (insn = get_topmost_sequence ()->first; insn; insn = NEXT_INSN
(insn))
+ if (CALL_P (insn))
+ break;
+ if (!insn)
+ return;
+ }
if (global_regs[29])
{
--
Alan Modra
Australia Development Lab, IBM
