RISC-V: Group linker relaxation features

It does not only deduplicate multiple relaxation feature detection,
but enable more complex features so that querying the feature availability
will get too slow if we perform it per-relocation (not per-section).

Even if that wouldn't happen any time soon, it will improve the
maintainability around the linker relaxation code.

bfd/ChangeLog:

	* elfnn-riscv.c (RISCV_RELAX_RVC, RISCV_RELAX_GP): New.
	(relax_func_t): Add new relax_features argument.
	(_bfd_riscv_relax_call): Likewise.  Move feature detection to
	_bfd_riscv_relax_section.  Use bool for simplicity.
	(_bfd_riscv_relax_lui): Likewise.  Move feature detection to
	_bfd_riscv_relax_section.
	(_bfd_riscv_relax_tls_le): Likewise but features are not used.
	(_bfd_riscv_relax_align): Likewise but features are not used.
	(_bfd_riscv_relax_pc): Likewise.  Move feature detection to
	_bfd_riscv_relax_section.
	(_bfd_riscv_relax_section): Detect relaxation-related features
	and pass the flags to each relaxation function.  Use the PIC
	feature flag generated by itself.

Author: a4lg

bfd/elfnn-riscv.c

@@ -4085,6 +4085,11 @@ _bfd_riscv_elf_merge_private_bfd_data (bfd *ibfd, struct bfd_link_info *info)
   return false;
 }
 
+/* Enabled relaxation features to use.  */
+#define RISCV_RELAX_RVC   0x01U
+#define RISCV_RELAX_GP    0x02U
+#define RISCV_RELAX_PIC   0x04U
+
 /* A second format for recording PC-relative hi relocations.  This stores the
    information required to relax them to GP-relative addresses.  */
 
@@ -4471,7 +4476,8 @@ typedef bool (*relax_func_t) (bfd *, asection *, asection *,
 			      Elf_Internal_Rela *,
 			      bfd_vma, bfd_vma, bfd_vma, bool *,
 			      riscv_pcgp_relocs *,
-			      bool undefined_weak);
+			      bool undefined_weak,
+			      unsigned relax_features);
 
 /* Relax AUIPC + JALR into JAL.  */
 
@@ -4484,13 +4490,15 @@ _bfd_riscv_relax_call (bfd *abfd, asection *sec, asection *sym_sec,
 		       bfd_vma reserve_size ATTRIBUTE_UNUSED,
 		       bool *again,
 		       riscv_pcgp_relocs *pcgp_relocs,
-		       bool undefined_weak ATTRIBUTE_UNUSED)
+		       bool undefined_weak ATTRIBUTE_UNUSED,
+		       unsigned relax_features)
 {
   bfd_byte *contents = elf_section_data (sec)->this_hdr.contents;
   bfd_vma foff = symval - (sec_addr (sec) + rel->r_offset);
   bool near_zero = (symval + RISCV_IMM_REACH / 2) < RISCV_IMM_REACH;
+  bool rvc = (relax_features & RISCV_RELAX_RVC) != 0;
   bfd_vma auipc, jalr;
-  int rd, r_type, len = 4, rvc = elf_elfheader (abfd)->e_flags & EF_RISCV_RVC;
+  int rd, r_type, len = 4;
 
   /* If the call crosses section boundaries, an alignment directive could
      cause the PC-relative offset to later increase, so we need to add in the
@@ -4505,7 +4513,8 @@ _bfd_riscv_relax_call (bfd *abfd, asection *sec, asection *sym_sec,
     }
 
   /* See if this function call can be shortened.  */
-  if (!VALID_JTYPE_IMM (foff) && !(!bfd_link_pic (link_info) && near_zero))
+  if (!VALID_JTYPE_IMM (foff)
+      && !(!(relax_features & RISCV_RELAX_PIC) && near_zero))
     return true;
 
   /* Shorten the function call.  */
@@ -4590,15 +4599,16 @@ _bfd_riscv_relax_lui (bfd *abfd,
 		      bfd_vma reserve_size,
 		      bool *again,
 		      riscv_pcgp_relocs *pcgp_relocs,
-		      bool undefined_weak)
+		      bool undefined_weak,
+		      unsigned relax_features)
 {
   struct riscv_elf_link_hash_table *htab = riscv_elf_hash_table (link_info);
   bfd_byte *contents = elf_section_data (sec)->this_hdr.contents;
   /* Can relax to x0 even when gp relaxation is disabled.  */
-  bfd_vma gp = htab->params->relax_gp
+  bfd_vma gp = (relax_features & RISCV_RELAX_GP) != 0
 	       ? riscv_global_pointer_value (link_info)
 	       : 0;
-  int use_rvc = elf_elfheader (abfd)->e_flags & EF_RISCV_RVC;
+  bool use_rvc = (relax_features & RISCV_RELAX_RVC) != 0;
 
   BFD_ASSERT (rel->r_offset + 4 <= sec->size);
 
@@ -4703,7 +4713,8 @@ _bfd_riscv_relax_tls_le (bfd *abfd,
 			 bfd_vma reserve_size ATTRIBUTE_UNUSED,
 			 bool *again,
 			 riscv_pcgp_relocs *pcgp_relocs,
-			 bool undefined_weak ATTRIBUTE_UNUSED)
+			 bool undefined_weak ATTRIBUTE_UNUSED,
+			 unsigned relax_features ATTRIBUTE_UNUSED)
 {
   /* See if this symbol is in range of tp.  */
   if (RISCV_CONST_HIGH_PART (tpoff (link_info, symval)) != 0)
@@ -4745,7 +4756,8 @@ _bfd_riscv_relax_align (bfd *abfd, asection *sec,
 			bfd_vma reserve_size ATTRIBUTE_UNUSED,
 			bool *again ATTRIBUTE_UNUSED,
 			riscv_pcgp_relocs *pcgp_relocs ATTRIBUTE_UNUSED,
-			bool undefined_weak ATTRIBUTE_UNUSED)
+			bool undefined_weak ATTRIBUTE_UNUSED,
+			unsigned relax_features ATTRIBUTE_UNUSED)
 {
   bfd_byte *contents = elf_section_data (sec)->this_hdr.contents;
   bfd_vma alignment = 1, pos;
@@ -4805,11 +4817,12 @@ _bfd_riscv_relax_pc (bfd *abfd ATTRIBUTE_UNUSED,
 		     bfd_vma reserve_size,
 		     bool *again,
 		     riscv_pcgp_relocs *pcgp_relocs,
-		     bool undefined_weak)
+		     bool undefined_weak,
+		     unsigned relax_features)
 {
   struct riscv_elf_link_hash_table *htab = riscv_elf_hash_table (link_info);
   /* Can relax to x0 even when gp relaxation is disabled.  */
-  bfd_vma gp = htab->params->relax_gp
+  bfd_vma gp = (relax_features & RISCV_RELAX_GP) != 0
 	       ? riscv_global_pointer_value (link_info)
 	       : 0;
 
@@ -4965,6 +4978,15 @@ _bfd_riscv_relax_section (bfd *abfd, asection *sec,
   bfd_vma max_alignment, reserve_size = 0;
   riscv_pcgp_relocs pcgp_relocs;
   static asection *first_section = NULL;
+  unsigned relax_features = 0;
+
+  /* Detect available/enabled relaxation features.  */
+  if (elf_elfheader (abfd)->e_flags & EF_RISCV_RVC)
+    relax_features |= RISCV_RELAX_RVC;
+  if (htab->params->relax_gp)
+    relax_features |= RISCV_RELAX_GP;
+  if (bfd_link_pic (info))
+    relax_features |= RISCV_RELAX_PIC;
 
   *again = false;
 
@@ -5032,7 +5054,7 @@ _bfd_riscv_relax_section (bfd *abfd, asection *sec,
 		   || type == R_RISCV_TPREL_LO12_I
 		   || type == R_RISCV_TPREL_LO12_S)
 	    relax_func = _bfd_riscv_relax_tls_le;
-	  else if (!bfd_link_pic (info)
+	  else if (!(relax_features & RISCV_RELAX_PIC)
 		   && (type == R_RISCV_PCREL_HI20
 		       || type == R_RISCV_PCREL_LO12_I
 		       || type == R_RISCV_PCREL_LO12_S))
@@ -5145,7 +5167,7 @@ _bfd_riscv_relax_section (bfd *abfd, asection *sec,
 
 	  /* This line has to match the check in riscv_elf_relocate_section
 	     in the R_RISCV_CALL[_PLT] case.  */
-	  if (bfd_link_pic (info) && h->plt.offset != MINUS_ONE)
+	  if ((relax_features & RISCV_RELAX_PIC) && h->plt.offset != MINUS_ONE)
 	    {
 	      sym_sec = htab->elf.splt;
 	      symval = h->plt.offset;
@@ -5208,7 +5230,7 @@ _bfd_riscv_relax_section (bfd *abfd, asection *sec,
 
       if (!relax_func (abfd, sec, sym_sec, info, rel, symval,
 		       max_alignment, reserve_size, again,
-		       &pcgp_relocs, undefined_weak))
+		       &pcgp_relocs, undefined_weak, relax_features))
 	goto fail;
     }