From: Iain Sandoe <iain@sandoe.co.uk>
Date: Mon, 3 May 2021 07:22:53 +0000 (+0100)
Subject: Darwin, X86: Adjust call clobbers to allow for lazy-binding [PR 100152].
X-Git-Tag: basepoints/gcc-13~6087
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=41bd1b190358fce213f5add8396faf14a32d5c23;p=thirdparty%2Fgcc.git

Darwin, X86: Adjust call clobbers to allow for lazy-binding [PR 100152].

We allow public functions defined in a TU to bind locally for PIC
code (the default) on 64bit Mach-O.

If such functions are not inlined, we cannot tell at compile-time if
they might be called via the lazy symbol resolver (this can depend on
options given at link-time).  Therefore, we must assume that the lazy
resolver could be used which clobbers R11 and R10.

Signed-off-by: Iain Sandoe <iain@sandoe.co.uk>

gcc/ChangeLog:

	PR target/100152
	* config/i386/i386-expand.c (ix86_expand_call): If a call is
	to a non-local-binding, or local but to a public symbol, then
	assume that it might be indirected via the lazy symbol binder.
	Mark R10 and R10 as clobbered in that case.
---

diff --git a/gcc/config/i386/i386-expand.c b/gcc/config/i386/i386-expand.c
index 65764ad88c56..69ea79e6123b 100644
--- a/gcc/config/i386/i386-expand.c
+++ b/gcc/config/i386/i386-expand.c
@@ -8410,6 +8410,7 @@ ix86_expand_call (rtx retval, rtx fnaddr, rtx callarg1,
     pop = NULL;
   gcc_assert (!TARGET_64BIT || !pop);
 
+  rtx addr = XEXP (fnaddr, 0);
   if (TARGET_MACHO && !TARGET_64BIT)
     {
 #if TARGET_MACHO
@@ -8422,7 +8423,6 @@ ix86_expand_call (rtx retval, rtx fnaddr, rtx callarg1,
       /* Static functions and indirect calls don't need the pic register.  Also,
 	 check if PLT was explicitly avoided via no-plt or "noplt" attribute, making
 	 it an indirect call.  */
-      rtx addr = XEXP (fnaddr, 0);
       if (flag_pic
 	  && GET_CODE (addr) == SYMBOL_REF
 	  && !SYMBOL_REF_LOCAL_P (addr))
@@ -8585,6 +8585,20 @@ ix86_expand_call (rtx retval, rtx fnaddr, rtx callarg1,
 	}
     }
 
+  if (TARGET_MACHO && TARGET_64BIT && !sibcall
+      && ((GET_CODE (addr) == SYMBOL_REF && !SYMBOL_REF_LOCAL_P (addr))
+	  || !fndecl || TREE_PUBLIC (fndecl)))
+    {
+      /* We allow public functions defined in a TU to bind locally for PIC
+	 code (the default) on 64bit Mach-O.
+	 If such functions are not inlined, we cannot tell at compile-time if
+	 they will be called via the lazy symbol resolver (this can depend on
+	 options given at link-time).  Therefore, we must assume that the lazy
+	 resolver could be used which clobbers R11 and R10.  */
+      clobber_reg (&use, gen_rtx_REG (DImode, R11_REG));
+      clobber_reg (&use, gen_rtx_REG (DImode, R10_REG));
+    }
+
   if (vec_len > 1)
     call = gen_rtx_PARALLEL (VOIDmode, gen_rtvec_v (vec_len, vec));
   rtx_insn *call_insn = emit_call_insn (call);