binutils: relax LUI to C.LUI

4 files changed, 62 insertions, 10 deletions

diff --git a/binutils/bfd/elfnn-riscv.c b/binutils/bfd/elfnn-riscv.c
index 67f0d87..bd086d6 100644
--- a/binutils/bfd/elfnn-riscv.c
+++ b/binutils/bfd/elfnn-riscv.c
@@ -1531,6 +1531,12 @@ perform_relocation (const reloc_howto_type *howto,
       value = ENCODE_RVC_J_IMM (value);
       break;
 
+    case R_RISCV_RVC_LUI:
+      if (!VALID_RVC_LUI_IMM (RISCV_CONST_HIGH_PART (value)))
+	return bfd_reloc_overflow;
+      value = ENCODE_RVC_LUI_IMM (RISCV_CONST_HIGH_PART (value));
+      break;
+
     case R_RISCV_32:
     case R_RISCV_64:
     case R_RISCV_ADD8:
@@ -1800,9 +1806,10 @@ riscv_elf_relocate_section (bfd *output_bfd, struct bfd_link_info *info,
 	  /* These require nothing of us at all.  */
 	  continue;
 
+	case R_RISCV_HI20:
 	case R_RISCV_BRANCH:
 	case R_RISCV_RVC_BRANCH:
-	case R_RISCV_HI20:
+	case R_RISCV_RVC_LUI:
 	  /* These require no special handling beyond perform_relocation.  */
 	  break;
 
@@ -2712,19 +2719,42 @@ _bfd_riscv_relax_lui (bfd *abfd, asection *sec,
 		      bfd_vma symval,
 		      bfd_boolean *again)
 {
+  bfd_byte *contents = elf_section_data (sec)->this_hdr.contents;
   bfd_vma gp = riscv_global_pointer_value (link_info);
+  int use_rvc = elf_elfheader (abfd)->e_flags & EF_RISCV_RVC;
 
-  /* Bail out if this symbol isn't in range of either gp or x0.  */
-  if (!VALID_ITYPE_IMM (symval - gp) && !(symval < RISCV_IMM_REACH/2))
-    return TRUE;
-
-  /* We can delete the unnecessary AUIPC. The corresponding LO12 reloc
-     will be converted to GPREL during relocation.  */
   BFD_ASSERT (rel->r_offset + 4 <= sec->size);
-  rel->r_info = ELFNN_R_INFO (0, R_RISCV_NONE);
 
-  *again = TRUE;
-  return riscv_relax_delete_bytes (abfd, sec, rel->r_offset, 4);
+  /* Is the reference in range of x0 or gp?  */
+  if (VALID_ITYPE_IMM (symval - gp) || (symval < RISCV_IMM_REACH/2))
+    {
+      /* We can delete the unnecessary AUIPC. The corresponding LO12 reloc
+         will be converted to gp- or x0-relative during relocation.  */
+      rel->r_info = ELFNN_R_INFO (0, R_RISCV_NONE);
+
+      *again = TRUE;
+      return riscv_relax_delete_bytes (abfd, sec, rel->r_offset, 4);
+    }
+
+  /* Can we relax LUI to C.LUI?  Alignment might move the section forward;
+     account for this assuming page alignment at worst.  */
+  if (use_rvc
+      && VALID_RVC_LUI_IMM (RISCV_CONST_HIGH_PART (symval))
+      && VALID_RVC_LUI_IMM (RISCV_CONST_HIGH_PART (symval + ELF_MAXPAGESIZE)))
+    {
+      /* Replace LUI with C.LUI.  */
+      bfd_vma lui = bfd_get_32 (abfd, contents + rel->r_offset);
+      lui = (lui & (OP_MASK_RD << OP_SH_RD)) | MATCH_C_LUI;
+      bfd_put_32 (abfd, lui, contents + rel->r_offset);
+
+      /* Replace the R_RISCV_HI20 reloc.  */
+      rel->r_info = ELFNN_R_INFO (ELFNN_R_SYM (rel->r_info), R_RISCV_RVC_LUI);
+
+      *again = TRUE;
+      return riscv_relax_delete_bytes (abfd, sec, rel->r_offset + 2, 2);
+    }
+
+  return TRUE;
 }
 
 /* Relax non-PIC TLS references.  */
diff --git a/binutils/bfd/elfxx-riscv.c b/binutils/bfd/elfxx-riscv.c
index 6053a74..447b791 100644
--- a/binutils/bfd/elfxx-riscv.c
+++ b/binutils/bfd/elfxx-riscv.c
@@ -674,6 +674,21 @@ static reloc_howto_type howto_table[] =
 	 0,				/* src_mask */
 	 ENCODE_RVC_J_IMM (-1U),	/* dst_mask */
 	 TRUE),				/* pcrel_offset */
+
+  /* High 6 bits of 18-bit absolute address.  */
+  HOWTO (R_RISCV_RVC_LUI,		/* type */
+	 0,				/* rightshift */
+	 2,				/* size */
+	 32,				/* bitsize */
+	 FALSE,				/* pc_relative */
+	 0,				/* bitpos */
+	 complain_overflow_dont,	/* complain_on_overflow */
+	 bfd_elf_generic_reloc,		/* special_function */
+	 "R_RISCV_RVC_LUI",		/* name */
+	 FALSE,				/* partial_inplace */
+	 0,				/* src_mask */
+	 ENCODE_RVC_IMM (-1U),		/* dst_mask */
+	 FALSE),			/* pcrel_offset */
 };
 
 /* A mapping from BFD reloc types to RISC-V ELF reloc types.  */
@@ -723,6 +738,7 @@ static const struct elf_reloc_map riscv_reloc_map[] =
   { BFD_RELOC_RISCV_ALIGN, R_RISCV_ALIGN },
   { BFD_RELOC_RISCV_RVC_BRANCH, R_RISCV_RVC_BRANCH },
   { BFD_RELOC_RISCV_RVC_JUMP, R_RISCV_RVC_JUMP },
+  { BFD_RELOC_RISCV_RVC_LUI, R_RISCV_RVC_LUI },
 };
 
 /* Given a BFD reloc type, return a howto structure.  */
diff --git a/binutils/include/elf/riscv.h b/binutils/include/elf/riscv.h
index b066951..c250b65 100644
--- a/binutils/include/elf/riscv.h
+++ b/binutils/include/elf/riscv.h
@@ -76,6 +76,7 @@ START_RELOC_NUMBERS (elf_riscv_reloc_type)
   RELOC_NUMBER (R_RISCV_ALIGN, 43)
   RELOC_NUMBER (R_RISCV_RVC_BRANCH, 44)
   RELOC_NUMBER (R_RISCV_RVC_JUMP, 45)
+  RELOC_NUMBER (R_RISCV_RVC_LUI, 46)
 END_RELOC_NUMBERS (R_RISCV_max)
 
 /* Processor specific flags for the ELF header e_flags field.  */
diff --git a/binutils/include/opcode/riscv.h b/binutils/include/opcode/riscv.h
index 5e13826..dd30c64 100644
--- a/binutils/include/opcode/riscv.h
+++ b/binutils/include/opcode/riscv.h
@@ -71,6 +71,8 @@ static const char * const riscv_pred_succ[16] = {
   ((RV_X(x, 21, 10) << 1) | (RV_X(x, 20, 1) << 11) | (RV_X(x, 12, 8) << 12) | (RV_IMM_SIGN(x) << 20))
 #define EXTRACT_RVC_IMM(x) \
   (RV_X(x, 2, 5) | (-RV_X(x, 12, 1) << 5))
+#define EXTRACT_RVC_LUI_IMM(x) \
+  (EXTRACT_RVC_IMM (x) << RISCV_IMM_BITS)
 #define EXTRACT_RVC_SIMM3(x) \
   (RV_X(x, 10, 2) | (-RV_X(x, 12, 1) << 2))
 #define EXTRACT_RVC_ADDI4SPN_IMM(x) \
@@ -106,6 +108,8 @@ static const char * const riscv_pred_succ[16] = {
   ((RV_X(x, 1, 10) << 21) | (RV_X(x, 11, 1) << 20) | (RV_X(x, 12, 8) << 12) | (RV_X(x, 20, 1) << 31))
 #define ENCODE_RVC_IMM(x) \
   ((RV_X(x, 0, 5) << 2) | (RV_X(x, 5, 1) << 12))
+#define ENCODE_RVC_LUI_IMM(x) \
+  ENCODE_RVC_IMM ((x) >> RISCV_IMM_BITS)
 #define ENCODE_RVC_SIMM3(x) \
   (RV_X(x, 0, 3) << 10)
 #define ENCODE_RVC_ADDI4SPN_IMM(x) \
@@ -135,6 +139,7 @@ static const char * const riscv_pred_succ[16] = {
 #define VALID_UTYPE_IMM(x) (EXTRACT_UTYPE_IMM(ENCODE_UTYPE_IMM(x)) == (x))
 #define VALID_UJTYPE_IMM(x) (EXTRACT_UJTYPE_IMM(ENCODE_UJTYPE_IMM(x)) == (x))
 #define VALID_RVC_IMM(x) (EXTRACT_RVC_IMM(ENCODE_RVC_IMM(x)) == (x))
+#define VALID_RVC_LUI_IMM(x) (EXTRACT_RVC_LUI_IMM(ENCODE_RVC_LUI_IMM(x)) == (x))
 #define VALID_RVC_SIMM3(x) (EXTRACT_RVC_SIMM3(ENCODE_RVC_SIMM3(x)) == (x))
 #define VALID_RVC_ADDI4SPN_IMM(x) (EXTRACT_RVC_ADDI4SPN_IMM(ENCODE_RVC_ADDI4SPN_IMM(x)) == (x))
 #define VALID_RVC_ADDI16SP_IMM(x) (EXTRACT_RVC_ADDI16SP_IMM(ENCODE_RVC_ADDI16SP_IMM(x)) == (x))