[RS6000] PR97107, libgo fails to build for power10

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.

	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 9caef013a719fc0b3a93e5427476dcb7728131d1..32681b6cececee2a5113d8802ce881b725f3a9fd 100644 (file)
--- 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 0f88ec19929123cae833ce671dca6467126a1dcf..d90cd5736e1ad60cbe9f78806ce46f4c299f2bd4 100644 (file)
--- 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 +5479,18 @@ 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.
+        Note that we are called inside a sequence.  get_insns will
+        just return that (as yet empty) sequence, so instead we
+        access the function rtl with get_topmost_sequence.  */
+      for (insn = get_topmost_sequence ()->first; insn; insn = NEXT_INSN (insn))
+       if (CALL_P (insn))
+         break;
+      if (!insn)
+       return;
+    }
 
   if (global_regs[29])
     {