[PATCH][PR target/94542]Don't allow PC-relative addressing for TLS data

[acsawdey via Gcc-patches]

One of the things that address_to_insn_form() is used for is determining 
whether a PC-relative addressing instruction could be used. In 
particular predicate pcrel_external_address and function 
prefixed_paddi_p() both use it for this purpose. So what emerged in 
PR/94542 is that it should be looking to see if the associated 
symbol_ref is a TLS symbol of some kind. TLS symbols cannot be addressed 
with PC-relative. This patch fixes both places in address_to_insn_form() 
where it is looking at a symbol_ref.

Regression tests passed with trunk 
38e62001c576b8c6ba2e08eb4673d69ec4c5b0f9 on ppc64le power9, and 
PC-relative code is now correct. OK for trunk?

Thanks!
   Aaron

2020-04-10  Aaron Sawdey  <acsaw...@linux.ibm.com>

        PR target/94542
        * config/rs6000/rs6000.c (address_to_insn_form): Do not attempt to
        use PC-relative addressing for TLS references.
diff --git a/gcc/config/rs6000/rs6000.c b/gcc/config/rs6000/rs6000.c
index 2b6613bcb7e..c77e60a718f 100644
--- a/gcc/config/rs6000/rs6000.c
+++ b/gcc/config/rs6000/rs6000.c
@@ -24824,15 +24824,21 @@ address_to_insn_form (rtx addr,
   if (GET_RTX_CLASS (GET_CODE (addr)) == RTX_AUTOINC)
     return INSN_FORM_UPDATE;
 
-  /* Handle PC-relative symbols and labels.  Check for both local and external
-     symbols.  Assume labels are always local.  */
+  /* Handle PC-relative symbols and labels.  Check for both local and
+     external symbols.  Assume labels are always local. TLS symbols
+     are not PC-relative.  */
   if (TARGET_PCREL)
     {
-      if (SYMBOL_REF_P (addr) && !SYMBOL_REF_LOCAL_P (addr))
-	return INSN_FORM_PCREL_EXTERNAL;
-
-      if (SYMBOL_REF_P (addr) || LABEL_REF_P (addr))
+      if (LABEL_REF_P (addr))
 	return INSN_FORM_PCREL_LOCAL;
+
+      if (SYMBOL_REF_P (addr) && !SYMBOL_REF_TLS_MODEL (addr))
+	{
+	  if (!SYMBOL_REF_LOCAL_P (addr))
+	    return INSN_FORM_PCREL_EXTERNAL;
+	  else
+	    return INSN_FORM_PCREL_LOCAL;
+	}
     }
 
   if (GET_CODE (addr) == CONST)
@@ -24866,14 +24872,19 @@ address_to_insn_form (rtx addr,
     return INSN_FORM_BAD;
 
   /* Check for local and external PC-relative addresses.  Labels are always
-     local.  */
+     local.  TLS symbols are not PC-relative.  */
   if (TARGET_PCREL)
     {
-      if (SYMBOL_REF_P (op0) && !SYMBOL_REF_LOCAL_P (op0))
-	return INSN_FORM_PCREL_EXTERNAL;
-
-      if (SYMBOL_REF_P (op0) || LABEL_REF_P (op0))
+      if (LABEL_REF_P (op0))
 	return INSN_FORM_PCREL_LOCAL;
+
+      if (SYMBOL_REF_P (op0) && !SYMBOL_REF_TLS_MODEL (op0))
+	{
+	  if (!SYMBOL_REF_LOCAL_P (op0))
+	    return INSN_FORM_PCREL_EXTERNAL;
+	  else
+	    return INSN_FORM_PCREL_LOCAL;
+	}
     }
 
   /* If it isn't PC-relative, the address must use a base register.  */