[gcc r14-4850] LoongArch: Use explicit relocs for TLS access with -mexplicit-relocs=auto

[gcc r14-4850] LoongArch: Use explicit relocs for TLS access with -mexplicit-relocs=auto

[Xi Ruoyao]

https://gcc.gnu.org/g:95db62f4ad4cfce30b7683a7e3e9f06330e84878

commit r14-4850-g95db62f4ad4cfce30b7683a7e3e9f06330e84878
Author: Xi Ruoyao <xry111@xry111.site>
Date:   Mon Oct 2 13:00:18 2023 +0800

    LoongArch: Use explicit relocs for TLS access with -mexplicit-relocs=auto
    
    The linker does not know how to relax TLS access for LoongArch, so let's
    emit machine instructions with explicit relocs for TLS.
    
    gcc/ChangeLog:
    
            * config/loongarch/loongarch.cc (loongarch_explicit_relocs_p):
            Return true for TLS symbol types if -mexplicit-relocs=auto.
            (loongarch_call_tls_get_addr): Replace TARGET_EXPLICIT_RELOCS
            with la_opt_explicit_relocs != EXPLICIT_RELOCS_NONE.
            (loongarch_legitimize_tls_address): Likewise.
            * config/loongarch/loongarch.md (@tls_low<mode>): Remove
            TARGET_EXPLICIT_RELOCS from insn condition.
    
    gcc/testsuite/ChangeLog:
    
            * gcc.target/loongarch/explicit-relocs-auto-tls-ld-gd.c: New
            test.
            * gcc.target/loongarch/explicit-relocs-auto-tls-le-ie.c: New
            test.

Diff:
---
 gcc/config/loongarch/loongarch.cc                  | 37 ++++++++++++++--------
 gcc/config/loongarch/loongarch.md                  |  2 +-
 .../loongarch/explicit-relocs-auto-tls-ld-gd.c     |  9 ++++++
 .../loongarch/explicit-relocs-auto-tls-le-ie.c     |  6 ++++
 4 files changed, 40 insertions(+), 14 deletions(-)

diff --git a/gcc/config/loongarch/loongarch.cc b/gcc/config/loongarch/loongarch.cc
index c12d77ea1449..c782f571abc5 100644
--- a/gcc/config/loongarch/loongarch.cc
+++ b/gcc/config/loongarch/loongarch.cc
@@ -1936,16 +1936,27 @@ loongarch_explicit_relocs_p (enum loongarch_symbol_type type)
   if (la_opt_explicit_relocs != EXPLICIT_RELOCS_AUTO)
     return la_opt_explicit_relocs == EXPLICIT_RELOCS_ALWAYS;
 
-  /* If we are performing LTO for a final link, and we have the linker
-     plugin so we know the resolution of the symbols, then all GOT
-     references are binding to external symbols or preemptable symbols.
-     So the linker cannot relax them.  */
-  return (in_lto_p
-	  && !flag_incremental_link
-	  && HAVE_LTO_PLUGIN == 2
-	  && (!global_options_set.x_flag_use_linker_plugin
-	      || global_options.x_flag_use_linker_plugin)
-	  && type == SYMBOL_GOT_DISP);
+  switch (type)
+    {
+      case SYMBOL_TLS_IE:
+      case SYMBOL_TLS_LE:
+      case SYMBOL_TLSGD:
+      case SYMBOL_TLSLDM:
+	/* The linker don't know how to relax TLS accesses.  */
+	return true;
+      case SYMBOL_GOT_DISP:
+	/* If we are performing LTO for a final link, and we have the
+	   linker plugin so we know the resolution of the symbols, then
+	   all GOT references are binding to external symbols or
+	   preemptable symbols.  So the linker cannot relax them.  */
+	return (in_lto_p
+		&& !flag_incremental_link
+		&& HAVE_LTO_PLUGIN == 2
+		&& (!global_options_set.x_flag_use_linker_plugin
+		    || global_options.x_flag_use_linker_plugin));
+      default:
+	return false;
+    }
 }
 
 /* Returns the number of instructions necessary to reference a symbol.  */
@@ -2753,7 +2764,7 @@ loongarch_call_tls_get_addr (rtx sym, enum loongarch_symbol_type type, rtx v0)
 
   start_sequence ();
 
-  if (TARGET_EXPLICIT_RELOCS)
+  if (la_opt_explicit_relocs != EXPLICIT_RELOCS_NONE)
     {
       /* Split tls symbol to high and low.  */
       rtx high = gen_rtx_HIGH (Pmode, copy_rtx (loc));
@@ -2918,7 +2929,7 @@ loongarch_legitimize_tls_address (rtx loc)
 	  tp = gen_rtx_REG (Pmode, THREAD_POINTER_REGNUM);
 	  tmp1 = gen_reg_rtx (Pmode);
 	  dest = gen_reg_rtx (Pmode);
-	  if (TARGET_EXPLICIT_RELOCS)
+	  if (la_opt_explicit_relocs != EXPLICIT_RELOCS_NONE)
 	    {
 	      tmp2 = loongarch_unspec_address (loc, SYMBOL_TLS_IE);
 	      tmp3 = gen_reg_rtx (Pmode);
@@ -2955,7 +2966,7 @@ loongarch_legitimize_tls_address (rtx loc)
 	  tmp1 = gen_reg_rtx (Pmode);
 	  dest = gen_reg_rtx (Pmode);
 
-	  if (TARGET_EXPLICIT_RELOCS)
+	  if (la_opt_explicit_relocs != EXPLICIT_RELOCS_NONE)
 	    {
 	      tmp2 = loongarch_unspec_address (loc, SYMBOL_TLS_LE);
 	      tmp3 = gen_reg_rtx (Pmode);
diff --git a/gcc/config/loongarch/loongarch.md b/gcc/config/loongarch/loongarch.md
index bec73f1bc916..695c8eb9a6f2 100644
--- a/gcc/config/loongarch/loongarch.md
+++ b/gcc/config/loongarch/loongarch.md
@@ -2257,7 +2257,7 @@
 	(unspec:P [(mem:P (lo_sum:P (match_operand:P 1 "register_operand" "r")
 				    (match_operand:P 2 "symbolic_operand" "")))]
 	UNSPEC_TLS_LOW))]
-  "TARGET_EXPLICIT_RELOCS"
+  ""
   "addi.<d>\t%0,%1,%L2"
   [(set_attr "type" "arith")
    (set_attr "mode" "<MODE>")])
diff --git a/gcc/testsuite/gcc.target/loongarch/explicit-relocs-auto-tls-ld-gd.c b/gcc/testsuite/gcc.target/loongarch/explicit-relocs-auto-tls-ld-gd.c
new file mode 100644
index 000000000000..957ff98df622
--- /dev/null
+++ b/gcc/testsuite/gcc.target/loongarch/explicit-relocs-auto-tls-ld-gd.c
@@ -0,0 +1,9 @@
+/* { dg-do compile } */
+/* { dg-options "-O2 -fPIC -mexplicit-relocs=auto" } */
+
+__thread int a __attribute__((visibility("hidden")));
+extern __thread int b __attribute__((visibility("default")));
+
+int test() { return a + b; }
+
+/* { dg-final { scan-assembler-not "la.tls" { target tls_native } } } */
diff --git a/gcc/testsuite/gcc.target/loongarch/explicit-relocs-auto-tls-le-ie.c b/gcc/testsuite/gcc.target/loongarch/explicit-relocs-auto-tls-le-ie.c
new file mode 100644
index 000000000000..78898cfc6ab0
--- /dev/null
+++ b/gcc/testsuite/gcc.target/loongarch/explicit-relocs-auto-tls-le-ie.c
@@ -0,0 +1,6 @@
+/* { dg-do compile } */
+/* { dg-options "-O2 -mexplicit-relocs=auto" } */
+
+#include "explicit-relocs-auto-tls-ld-gd.c"
+
+/* { dg-final { scan-assembler-not "la.tls" { target tls_native } } } */