CALL_INSN may not be a real function call.

Use "used" flag for CALL_INSN to indicate it's a fake call. If it's a
fake call, it won't have its own function stack.

gcc/ChangeLog

	PR target/82735
	* df-scan.c (df_get_call_refs): When call_insn is a fake call,
	it won't use stack pointer reg.
	* final.c (leaf_function_p): When call_insn is a fake call, it
	won't affect caller as a leaf function.
	* reg-stack.c (callee_clobbers_any_stack_reg): New.
	(subst_stack_regs): When call_insn doesn't clobber any stack
	reg, don't clear the arguments.
	* rtl.c (shallow_copy_rtx): Don't clear flag used when orig is
	a insn.
	* shrink-wrap.c (requires_stack_frame_p): No need for stack
	frame for a fake call.
	* rtl.h (FAKE_CALL_P): New macro.

1 files changed, 17 insertions, 1 deletions

diff --git a/gcc/reg-stack.c b/gcc/reg-stack.c
index 25210f0c..1d9ea03 100644
--- a/gcc/reg-stack.c
+++ b/gcc/reg-stack.c
@@ -174,6 +174,7 @@
 #include "reload.h"
 #include "tree-pass.h"
 #include "rtl-iter.h"
+#include "function-abi.h"
 
 #ifdef STACK_REGS
 
@@ -2368,6 +2369,18 @@ subst_asm_stack_regs (rtx_insn *insn, stack_ptr regstack)
 	    }
       }
 }
+
+/* Return true if a function call is allowed to alter some or all bits
+   of any stack reg.  */
+static bool
+callee_clobbers_any_stack_reg (const function_abi & callee_abi)
+{
+  for (unsigned regno = FIRST_STACK_REG; regno <= LAST_STACK_REG; regno++)
+    if (callee_abi.clobbers_at_least_part_of_reg_p (regno))
+      return true;
+  return false;
+}
+
 
 /* Substitute stack hard reg numbers for stack virtual registers in
    INSN.  Non-stack register numbers are not changed.  REGSTACK is the
@@ -2382,7 +2395,10 @@ subst_stack_regs (rtx_insn *insn, stack_ptr regstack)
   bool control_flow_insn_deleted = false;
   int i;
 
-  if (CALL_P (insn))
+  /* If the target of the call doesn't clobber any stack registers,
+     Don't clear the arguments.  */
+  if (CALL_P (insn)
+      && callee_clobbers_any_stack_reg (insn_callee_abi (insn)))
     {
       int top = regstack->top;