From: Richard Sandiford <richard.sandiford@arm.com>
Date: Mon, 6 Nov 2023 10:49:58 +0000 (+0000)
Subject: explow: Allow dynamic allocations after vregs
X-Git-Tag: basepoints/gcc-15~4990
X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=a7a45364dddef399bfb550235166df51108a3142;p=thirdparty%2Fgcc.git

explow: Allow dynamic allocations after vregs

This patch allows allocate_dynamic_stack_space to be called before
or after virtual registers have been instantiated.  It uses the
same approach as allocate_stack_local, which already supported this.

gcc/
	* function.h (get_stack_dynamic_offset): Declare.
	* function.cc (get_stack_dynamic_offset): New function,
	split out from...
	(get_stack_dynamic_offset): ...here.
	* explow.cc (allocate_dynamic_stack_space): Handle calls made
	after virtual registers have been instantiated.
---

diff --git a/gcc/explow.cc b/gcc/explow.cc
index 0c03ac350bbe..aa64d5e906cf 100644
--- a/gcc/explow.cc
+++ b/gcc/explow.cc
@@ -1375,12 +1375,16 @@ allocate_dynamic_stack_space (rtx size, unsigned size_align,
   HOST_WIDE_INT stack_usage_size = -1;
   rtx_code_label *final_label;
   rtx final_target, target;
+  rtx addr = (virtuals_instantiated
+	      ? plus_constant (Pmode, stack_pointer_rtx,
+			       get_stack_dynamic_offset ())
+	      : virtual_stack_dynamic_rtx);
 
   /* If we're asking for zero bytes, it doesn't matter what we point
      to since we can't dereference it.  But return a reasonable
      address anyway.  */
   if (size == const0_rtx)
-    return virtual_stack_dynamic_rtx;
+    return addr;
 
   /* Otherwise, show we're calling alloca or equivalent.  */
   cfun->calls_alloca = 1;
@@ -1532,7 +1536,7 @@ allocate_dynamic_stack_space (rtx size, unsigned size_align,
       poly_int64 saved_stack_pointer_delta;
 
       if (!STACK_GROWS_DOWNWARD)
-	emit_move_insn (target, virtual_stack_dynamic_rtx);
+	emit_move_insn (target, force_operand (addr, target));
 
       /* Check stack bounds if necessary.  */
       if (crtl->limit_stack)
@@ -1575,7 +1579,7 @@ allocate_dynamic_stack_space (rtx size, unsigned size_align,
       stack_pointer_delta = saved_stack_pointer_delta;
 
       if (STACK_GROWS_DOWNWARD)
-	emit_move_insn (target, virtual_stack_dynamic_rtx);
+	emit_move_insn (target, force_operand (addr, target));
     }
 
   suppress_reg_args_size = false;
diff --git a/gcc/function.cc b/gcc/function.cc
index afb0b33da9e3..527ea4807b0c 100644
--- a/gcc/function.cc
+++ b/gcc/function.cc
@@ -1943,6 +1943,16 @@ instantiate_decls (tree fndecl)
   vec_free (cfun->local_decls);
 }
 
+/* Return the value of STACK_DYNAMIC_OFFSET for the current function.
+   This is done through a function wrapper so that the macro sees a
+   predictable set of included files.  */
+
+poly_int64
+get_stack_dynamic_offset ()
+{
+  return STACK_DYNAMIC_OFFSET (current_function_decl);
+}
+
 /* Pass through the INSNS of function FNDECL and convert virtual register
    references to hard register references.  */
 
@@ -1954,7 +1964,7 @@ instantiate_virtual_regs (void)
   /* Compute the offsets to use for this function.  */
   in_arg_offset = FIRST_PARM_OFFSET (current_function_decl);
   var_offset = targetm.starting_frame_offset ();
-  dynamic_offset = STACK_DYNAMIC_OFFSET (current_function_decl);
+  dynamic_offset = get_stack_dynamic_offset ();
   out_arg_offset = STACK_POINTER_OFFSET;
 #ifdef FRAME_POINTER_CFA_OFFSET
   cfa_offset = FRAME_POINTER_CFA_OFFSET (current_function_decl);
diff --git a/gcc/function.h b/gcc/function.h
index 5caf1e153eab..29846564bc6f 100644
--- a/gcc/function.h
+++ b/gcc/function.h
@@ -715,6 +715,7 @@ extern vec<edge> convert_jumps_to_returns (basic_block last_bb, bool simple_p,
 extern basic_block emit_return_for_exit (edge exit_fallthru_edge,
 					 bool simple_p);
 extern void reposition_prologue_and_epilogue_notes (void);
+extern poly_int64 get_stack_dynamic_offset ();
 
 /* Returns the name of the current function.  */
 extern const char *fndecl_name (tree);