On Thu, May 27, 2021 at 6:50 PM Richard Sandiford
<richard.sandif...@arm.com> wrote:
>
> Jakub Jelinek <ja...@redhat.com> writes:
> > On Thu, May 27, 2021 at 01:07:09PM +0800, Hongtao Liu via Gcc-patches wrote:
> >> + /* Flag used for call_insn indicates it's a fake call. */
> >> + RTX_FLAG (insn, used) = 1;
> >
> >> + /* CALL_INSN use "used" flag to indicate it's a fake call. */
> >> + if (i == STACK_POINTER_REGNUM
> >> + && !RTX_FLAG (insn_info->insn, used))
> >
> >> - && ! SIBLING_CALL_P (insn))
> >> + && ! SIBLING_CALL_P (insn)
> >> + && !RTX_FLAG (insn, used))
> >
> >> - /* 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;
> >> @@ -57,7 +57,8 @@ requires_stack_frame_p (rtx_insn *insn, HARD_REG_SET
> >> prologue_used,
> >> HARD_REG_SET hardregs;
> >> unsigned regno;
> >>
> >> - if (CALL_P (insn))
> >> + /* CALL_INSN use "used" flag to indicate it's a fake call. */
> >> + if (CALL_P (insn) && !RTX_FLAG (insn, used))
> >> return !SIBLING_CALL_P (insn);
> >
> > Please define a macro for this in rtl.h (and mention it above used;
> > member too in a comment, see all the other comments in there), like:
> > /* 1 if RTX is a call_insn for a fake call. */
> > #define FAKE_CALL_P(RTX) \
> > (RTL_FLAG_CHECK1 ("FAKE_CALL_P", (RTX), CALL_INSN)->used)
Changed.
> > Though, I'm also not sure if used can be actually used for this,
> > because it is used e.g. in emit-rtl.c for verification of RTL sharing.
>
> I thought it should be OK, since:
>
> - copy_rtx_if_shared_1 and mark_used_flags do nothing for insns
> - verify_rtx_sharing is only called for parts of an insn, rather than
> an insn itself
>
> I guess an alternative would be to add a new rtx_code for fake call
> insns and use CALL_P to test for both. However, that would lose the
> property that the default behaviour is conservatively correct
> (even for direct checks of CALL_INSN), so the flag IMO seems better.
>
> Thanks,
> Richard
>
> > Though, it seems no other rtl flag is free for CALL_INSN.
> > Could this fake call flag sit on the CALL rtx instead?
> >
> > Jakub
Updated separate patch for the middle-end part.
--
BR,
Hongtao
From 537822e0d54aa324c520a4b504dcfe882b363c7b Mon Sep 17 00:00:00 2001
From: liuhongt <hongtao....@intel.com>
Date: Tue, 1 Jun 2021 09:00:57 +0800
Subject: [PATCH 1/2] 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.
---
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 e0a70fcd830..817f7722cb2 100644
--- a/gcc/final.c
+++ b/gcc/final.c
@@ -4109,7 +4109,8 @@ 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;
+}
+
/* 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. */
--
2.18.1
