[gcc r12-1252] CALL_INSN may not be a real function call.

[gcc r12-1252] CALL_INSN may not be a real function call.

[hongtao Liu]

https://gcc.gnu.org/g:16465ceb06cc1f65cfca3c0eb2c1ee27ab03bdfd

commit r12-1252-g16465ceb06cc1f65cfca3c0eb2c1ee27ab03bdfd
Author: liuhongt <hongtao.liu@intel.com>
Date:   Tue Jun 1 09:00:57 2021 +0800

    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.

Diff:
---
 gcc/df-scan.c     |  3 ++-
 gcc/final.c       |  3 ++-
 gcc/reg-stack.c   | 18 +++++++++++++++++-
 gcc/rtl.c         |  6 ++++--
 gcc/rtl.h         |  5 +++++
 gcc/shrink-wrap.c |  2 +-
 6 files changed, 31 insertions(+), 6 deletions(-)

diff --git a/gcc/df-scan.c b/gcc/df-scan.c
index 6691c3e8357..1268536b3f0 100644
--- a/gcc/df-scan.c
+++ b/gcc/df-scan.c
@@ -3090,7 +3090,8 @@ df_get_call_refs (class df_collection_rec *collection_rec,
 
   for (i = 0; i < FIRST_PSEUDO_REGISTER; i++)
     {
-      if (i == STACK_POINTER_REGNUM)
+      if (i == STACK_POINTER_REGNUM
+	  && !FAKE_CALL_P (insn_info->insn))
 	/* The stack ptr is used (honorarily) by a CALL insn.  */
 	df_ref_record (DF_REF_BASE, collection_rec, regno_reg_rtx[i],
 		       NULL, bb, insn_info, DF_REF_REG_USE,
diff --git a/gcc/final.c b/gcc/final.c
index 38c3d704170..dba0b0abeb7 100644
--- a/gcc/final.c
+++ b/gcc/final.c
@@ -4106,7 +4106,8 @@ leaf_function_p (void)
   for (insn = get_insns (); insn; insn = NEXT_INSN (insn))
     {
       if (CALL_P (insn)
-	  && ! SIBLING_CALL_P (insn))
+	  && ! SIBLING_CALL_P (insn)
+	  && ! FAKE_CALL_P (insn))
 	return 0;
       if (NONJUMP_INSN_P (insn)
 	  && GET_CODE (PATTERN (insn)) == SEQUENCE
diff --git a/gcc/reg-stack.c b/gcc/reg-stack.c
index 25210f0c17f..1d9ea035cf4 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;
+}
+
 \f
 /* 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;
 
diff --git a/gcc/rtl.c b/gcc/rtl.c
index b0ba1ff684c..aaee882f5ca 100644
--- a/gcc/rtl.c
+++ b/gcc/rtl.c
@@ -395,8 +395,10 @@ shallow_copy_rtx (const_rtx orig MEM_STAT_DECL)
     case SCRATCH:
       break;
     default:
-      /* For all other RTXes clear the used flag on the copy.  */
-      RTX_FLAG (copy, used) = 0;
+      /* For all other RTXes clear the used flag on the copy.
+	 CALL_INSN use "used" flag to indicate it's a fake call.  */
+      if (!INSN_P (orig))
+	RTX_FLAG (copy, used) = 0;
       break;
     }
   return copy;
diff --git a/gcc/rtl.h b/gcc/rtl.h
index 35178b5bfac..5ed0d6dd6fa 100644
--- a/gcc/rtl.h
+++ b/gcc/rtl.h
@@ -839,6 +839,11 @@ struct GTY(()) rtvec_def {
 /* Predicate yielding nonzero iff X is a call insn.  */
 #define CALL_P(X) (GET_CODE (X) == CALL_INSN)
 
+/* 1 if RTX is a call_insn for a fake call.
+   CALL_INSN use "used" flag to indicate it's a fake call.  */
+#define FAKE_CALL_P(RTX)                                        \
+  (RTL_FLAG_CHECK1 ("FAKE_CALL_P", (RTX), CALL_INSN)->used)
+
 /* Predicate yielding nonzero iff X is an insn that cannot jump.  */
 #define NONJUMP_INSN_P(X) (GET_CODE (X) == INSN)
 
diff --git a/gcc/shrink-wrap.c b/gcc/shrink-wrap.c
index ba7b5cd56fd..5e60f34f749 100644
--- a/gcc/shrink-wrap.c
+++ b/gcc/shrink-wrap.c
@@ -57,7 +57,7 @@ requires_stack_frame_p (rtx_insn *insn, HARD_REG_SET prologue_used,
   HARD_REG_SET hardregs;
   unsigned regno;
 
-  if (CALL_P (insn))
+  if (CALL_P (insn) && !FAKE_CALL_P (insn))
     return !SIBLING_CALL_P (insn);
 
   /* We need a frame to get the unique CFA expected by the unwinder.  */