From 9a23f96e919ba91587d077b1d399246dde4002dd Mon Sep 17 00:00:00 2001
From: Alan Modra <amodra@gmail.com>
Date: Wed, 30 Aug 2017 20:35:35 +0930
Subject: PowerPC TPREL16_HA/LO reloc optimization

In the TLS GD/LD to LE optimization, ld replaces a sequence like

 addi 3,2,x@got@tlsgd		R_PPC64_GOT_TLSGD16	x
 bl __tls_get_addr(x@tlsgd)	R_PPC64_TLSGD		x
				R_PPC64_REL24		__tls_get_addr
 nop

with

 addis 3,13,x@tprel@ha		R_PPC64_TPREL16_HA	x
 addi 3,3,x@tprel@l		R_PPC64_TPREL16_LO	x
 nop

When the tprel offset is small, this can be further optimized to

 nop
 addi 3,13,x@tprel
 nop

bfd/
	* elf64-ppc.c (struct ppc_link_hash_table): Add do_tls_opt.
	(ppc64_elf_tls_optimize): Set it.
	(ppc64_elf_relocate_section): Nop addis on TPREL16_HA, and convert
	insn on TPREL16_LO and TPREL16_LO_DS relocs to use r13 when
	addis would add zero.
	* elf32-ppc.c (struct ppc_elf_link_hash_table): Add do_tls_opt.
	(ppc_elf_tls_optimize): Set it.
	(ppc_elf_relocate_section): Nop addis on TPREL16_HA, and convert
	insn on TPREL16_LO relocs to use r2 when addis would add zero.
gold/
	* powerpc.cc (Target_powerpc::Relocate::relocate): Nop addis on
	TPREL16_HA, and convert insn on TPREL16_LO and TPREL16_LO_DS
	relocs to use r2/r13 when addis would add zero.
ld/
	* testsuite/ld-powerpc/tls.s: Add calls with tls markers.
	* testsuite/ld-powerpc/tls32.s: Likewise.
	* testsuite/ld-powerpc/powerpc.exp: Run tls marker tests.
	* testsuite/ld-powerpc/tls.d: Adjust for TPREL16_HA/LO optimization.
	* testsuite/ld-powerpc/tlsexe.d: Likewise.
	* testsuite/ld-powerpc/tlsexetoc.d: Likewise.
	* testsuite/ld-powerpc/tlsld.d: Likewise.
	* testsuite/ld-powerpc/tlsmark.d: Likewise.
	* testsuite/ld-powerpc/tlsopt4.d: Likewise.
	* testsuite/ld-powerpc/tlstoc.d: Likewise.
---
 bfd/elf32-ppc.c | 40 +++++++++++++++++++++++++++++++++++++++-
 1 file changed, 39 insertions(+), 1 deletion(-)

(limited to 'bfd/elf32-ppc.c')

diff --git a/bfd/elf32-ppc.c b/bfd/elf32-ppc.c
index a5d8193..2bdba9f 100644
--- a/bfd/elf32-ppc.c
+++ b/bfd/elf32-ppc.c
@@ -3345,6 +3345,9 @@ struct ppc_elf_link_hash_table
   unsigned int local_ifunc_resolver:1;
   unsigned int maybe_local_ifunc_resolver:1;
 
+  /* Set if tls optimization is enabled.  */
+  unsigned int do_tls_opt:1;
+
   /* The size of PLT entries.  */
   int plt_entry_size;
   /* The distance between adjacent PLT slots.  */
@@ -5631,6 +5634,7 @@ ppc_elf_tls_optimize (bfd *obfd ATTRIBUTE_UNUSED,
 	      symtab_hdr->contents = (unsigned char *) locsyms;
 	  }
       }
+  htab->do_tls_opt = 1;
   return TRUE;
 }
 
@@ -8426,10 +8430,44 @@ ppc_elf_relocate_section (bfd *output_bfd,
 	}
 
       addend = rel->r_addend;
-      tls_type = 0;
       howto = NULL;
       if (r_type < R_PPC_max)
 	howto = ppc_elf_howto_table[r_type];
+
+      switch (r_type)
+	{
+	default:
+	  break;
+
+	case R_PPC_TPREL16_HA:
+	  if (htab->do_tls_opt && relocation + addend + 0x8000 < 0x10000)
+	    {
+	      bfd_byte *p = contents + (rel->r_offset & ~3);
+	      unsigned int insn = bfd_get_32 (input_bfd, p);
+	      if ((insn & ((0x3f << 26) | 0x1f << 16))
+		  != ((15u << 26) | (2 << 16)) /* addis rt,2,imm */)
+		/* xgettext:c-format */
+		info->callbacks->minfo
+		  (_("%H: warning: %s unexpected insn %#x.\n"),
+		   input_bfd, input_section, rel->r_offset, howto->name, insn);
+	      else
+		bfd_put_32 (input_bfd, NOP, p);
+	    }
+	  break;
+
+	case R_PPC_TPREL16_LO:
+	  if (htab->do_tls_opt && relocation + addend + 0x8000 < 0x10000)
+	    {
+	      bfd_byte *p = contents + (rel->r_offset & ~3);
+	      unsigned int insn = bfd_get_32 (input_bfd, p);
+	      insn &= ~(0x1f << 16);
+	      insn |= 2 << 16;
+	      bfd_put_32 (input_bfd, insn, p);
+	    }
+	  break;
+	}
+
+      tls_type = 0;
       switch (r_type)
 	{
 	default:
-- 
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