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Re: [PATCH] [RISCV] Support subtraction of .uleb128.


On Wed, 27 Nov 2019 00:11:50 PST (-0800), kuanlinchentw@gmail.com wrote:
The data length of uleb128 is variable.  So linker must recalculate the
value of the subtraction.  The patch leave relocations in object files
so that linker can relocate again after relaxation.

bfd/ChangeLog:
* bfd-in2.h: Regenerated.
* elfnn-riscv.c (write_uleb128): New function.
(perform_relocation): Perform R_RISCV_SUB_ULEB128 and
R_RISCV_SET_ULEB128 relocation.
(riscv_elf_relocate_section): Likewise.
* elfxx-riscv.c (howto_table): Add R_RISCV_SUB_ULEB128 and
R_RISCV_SET_ULEB128.
(riscv_elf_ignore_reloc): New function.
* libbfd.h: Regenerated.
* reloc.c (BFD_RELOC_RISCV_SET_ULEB128, BFD_RELOC_RISCV_SUB_ULEB128):
New relocations to support .uleb128.

gas/ChangeLog:
* config/tc-riscv.c (md_apply_fix): Add BFD_RELOC_RISCV_SET_ULEB128 and
BFD_RELOC_RISCV_SUB_ULEB128.
(riscv_insert_uleb128_fixes): New function.
(riscv_md_end): Scan rs_leb128 fragments.
(riscv_pseudo_table): Remove uleb128.

include/ChangeLog:
* elf/riscv.h ((R_RISCV_SET_ULEB128, (R_RISCV_SUB_ULEB128): Define.

ld/ChangeLog:
* testsuite/ld-riscv-elf/ld-riscv-elf.exp: Add uleb128.
* testsuite/ld-riscv-elf/uleb128.d: New test.
* testsuite/ld-riscv-elf/uleb128.s: New file.

OK to commit?

I'm having a lot of trouble trying to figure out how this works.  LMK if I'm
missing something, there's some comments in line:

From 9f7f0aaa484dee2b32c550f8cca4de18959f01e1 Mon Sep 17 00:00:00 2001
From: Kuan-Lin Chen <rufus@andestech.com>
Date: Thu, 14 Nov 2019 14:24:22 +0800
Subject: [PATCH] RISC-V: Support subtraction of .uleb128.

The data length of uleb128 is variable.  So linker must recalculate the
value of the subtraction.  The patch leave relocations in object files
so that linker can relocate again after relaxation.

bfd/ChangeLog:
        * bfd-in2.h: Regenerated.
        * elfnn-riscv.c (write_uleb128): New function.
        (perform_relocation): Perform R_RISCV_SUB_ULEB128 and
         R_RISCV_SET_ULEB128 relocation.
        (riscv_elf_relocate_section): Likewise.
        * elfxx-riscv.c (howto_table): Add R_RISCV_SUB_ULEB128 and
        R_RISCV_SET_ULEB128.
        (riscv_elf_ignore_reloc): New function.
        * libbfd.h: Regenerated.
        * reloc.c (BFD_RELOC_RISCV_SET_ULEB128, BFD_RELOC_RISCV_SUB_ULEB128):
        New relocations to support .uleb128.

gas/ChangeLog:
        * config/tc-riscv.c (md_apply_fix): Add BFD_RELOC_RISCV_SET_ULEB128 and
        BFD_RELOC_RISCV_SUB_ULEB128.
        (riscv_insert_uleb128_fixes): New function.
        (riscv_md_end): Scan rs_leb128 fragments.
        (riscv_pseudo_table): Remove uleb128.

include/ChangeLog:
        * elf/riscv.h ((R_RISCV_SET_ULEB128, (R_RISCV_SUB_ULEB128): Define.

ld/ChangeLog:
        * testsuite/ld-riscv-elf/ld-riscv-elf.exp: Add uleb128.
        * testsuite/ld-riscv-elf/uleb128.d: New test.
        * testsuite/ld-riscv-elf/uleb128.s: New file.
---
 bfd/ChangeLog                              | 14 ++++
 bfd/bfd-in2.h                              |  2 +
 bfd/elfnn-riscv.c                          | 82 ++++++++++++++++++++++
 bfd/elfxx-riscv.c                          | 51 ++++++++++++++
 bfd/libbfd.h                               |  2 +
 bfd/reloc.c                                |  4 ++
 gas/ChangeLog                              |  8 +++
 gas/config/tc-riscv.c                      | 47 ++++++++++++-
 include/ChangeLog                          |  4 ++
 include/elf/riscv.h                        |  2 +
 ld/ChangeLog                               |  6 ++
 ld/testsuite/ld-riscv-elf/ld-riscv-elf.exp |  1 +
 ld/testsuite/ld-riscv-elf/uleb128.d        | 18 +++++
 ld/testsuite/ld-riscv-elf/uleb128.s        | 18 +++++
 14 files changed, 258 insertions(+), 1 deletion(-)
 create mode 100644 ld/testsuite/ld-riscv-elf/uleb128.d
 create mode 100644 ld/testsuite/ld-riscv-elf/uleb128.s

diff --git a/bfd/ChangeLog b/bfd/ChangeLog
index 4a0852e577..d11ffde74c 100644
--- a/bfd/ChangeLog
+++ b/bfd/ChangeLog
@@ -1,3 +1,17 @@
+2019-11-27  Kuan-Lin Chen  <kuanlinchentw@gmail.com>
+
+        * bfd-in2.h: Regenerated.
+        * elfnn-riscv.c (write_uleb128): New function.
+        (perform_relocation): Perform R_RISCV_SUB_ULEB128 and
+         R_RISCV_SET_ULEB128 relocation.
+        (riscv_elf_relocate_section): Likewise.
+        * elfxx-riscv.c (howto_table): Add R_RISCV_SUB_ULEB128 and
+        R_RISCV_SET_ULEB128.
+        (riscv_elf_ignore_reloc): New function.
+        * libbfd.h: Regenerated.
+        * reloc.c (BFD_RELOC_RISCV_SET_ULEB128, BFD_RELOC_RISCV_SUB_ULEB128):
+        New relocations to support .uleb128.
+
 2019-11-27  Alan Modra  <amodra@gmail.com>
PR 23652
diff --git a/bfd/bfd-in2.h b/bfd/bfd-in2.h
index 44902fc8d0..a32708ebc2 100644
--- a/bfd/bfd-in2.h
+++ b/bfd/bfd-in2.h
@@ -4380,6 +4380,8 @@ number for the SBIC, SBIS, SBI and CBI instructions  */
   BFD_RELOC_RISCV_SET16,
   BFD_RELOC_RISCV_SET32,
   BFD_RELOC_RISCV_32_PCREL,
+  BFD_RELOC_RISCV_SET_ULEB128,
+  BFD_RELOC_RISCV_SUB_ULEB128,
/* Renesas RL78 Relocations. */
   BFD_RELOC_RL78_NEG8,
diff --git a/bfd/elfnn-riscv.c b/bfd/elfnn-riscv.c
index 997f786602..075ef6b82d 100644
--- a/bfd/elfnn-riscv.c
+++ b/bfd/elfnn-riscv.c
@@ -1419,6 +1419,26 @@ riscv_global_pointer_value (struct bfd_link_info *info)
   return h->u.def.value + sec_addr (h->u.def.section);
 }
+/* Write VAL in uleb128 format to P, returning a pointer to the
+   following byte.
+   This code is copied from elf-attr.c.  */
+
+static bfd_byte *
+write_uleb128 (bfd_byte *p, unsigned int val)
+{
+  bfd_byte c;
+  do
+    {
+      c = val & 0x7f;
+      val >>= 7;
+      if (val)
+        c |= 0x80;
+      *(p++) = c;
+    }
+  while (val);
+  return p;
+}
+
 /* Emplace a static relocation.  */
static bfd_reloc_status_type
@@ -1512,6 +1532,25 @@ perform_relocation (const reloc_howto_type *howto,
         value = ENCODE_RVC_LUI_IMM (RISCV_CONST_HIGH_PART (value));
       break;
+ case R_RISCV_SET_ULEB128:
+    case R_RISCV_SUB_ULEB128:
+      {
+        unsigned int len = 0;
+        bfd_byte *endp, *p;
+
+        _bfd_read_unsigned_leb128 (input_bfd, contents + rel->r_offset, &len);
+
+        /* Clean the contents value to zero.  Do not reduce the length.  */
+        p = contents + rel->r_offset;
+        endp = p + len -1;
+        memset (p, 0x80, len);
+        *(endp) = 0;
+        p = write_uleb128 (p, value) - 1;
+        if (p < endp)
+          *p |= 0x80;
+        return bfd_reloc_ok;
+      }
+
     case R_RISCV_32:
     case R_RISCV_64:
     case R_RISCV_ADD8:
@@ -1767,6 +1806,8 @@ riscv_elf_relocate_section (bfd *output_bfd,
   struct elf_link_hash_entry **sym_hashes = elf_sym_hashes (input_bfd);
   bfd_vma *local_got_offsets = elf_local_got_offsets (input_bfd);
   bfd_boolean absolute;
+  bfd_vma uleb128_vma;
+  Elf_Internal_Rela *uleb128_rel = NULL;
if (!riscv_init_pcrel_relocs (&pcrel_relocs))
     return FALSE;
@@ -1871,6 +1912,47 @@ riscv_elf_relocate_section (bfd *output_bfd,
         case R_RISCV_DELETE:
           /* These require no special handling beyond perform_relocation.  */
           break;
+        case R_RISCV_SET_ULEB128:
+          if (!uleb128_rel)
+            {
+              /* Save the minuend to use later.  */
+              uleb128_vma = relocation;
+              uleb128_rel = rel;
+              continue;
+            }
+          else
+            {
+              if (uleb128_rel->r_offset != rel->r_offset)
+                {
+                  (*_bfd_error_handler) (_("%pB: relocation %s mismatched. "),
+                                         input_bfd, howto->name);
+                  bfd_set_error (bfd_error_bad_value);
+                }
+              relocation = relocation - uleb128_vma;
+              uleb128_rel = NULL;
+              break;
+            }
+
+        case R_RISCV_SUB_ULEB128:
+          if (uleb128_rel)
+            {
+              if (uleb128_rel->r_offset != rel->r_offset)
+                {
+                  (*_bfd_error_handler) (_("%pB: relocation %s mismatched. "),
+                                         input_bfd, howto->name);
+                  bfd_set_error (bfd_error_bad_value);
+                }
+              relocation = uleb128_vma - relocation;

GCC gives me -Wmaybe-uninitialized for both of these.

+              uleb128_rel = NULL;
+              break;
+            }
+          else
+            {
+              /* Save the subtrahend to use later.  */
+              uleb128_vma = relocation;
+              uleb128_rel = rel;
+              continue;
+            }
case R_RISCV_GOT_HI20:
           if (h != NULL)
diff --git a/bfd/elfxx-riscv.c b/bfd/elfxx-riscv.c
index 245717f70f..c136ba2207 100644
--- a/bfd/elfxx-riscv.c
+++ b/bfd/elfxx-riscv.c
@@ -38,6 +38,8 @@
    relocations for the debug info.  */
 static bfd_reloc_status_type riscv_elf_add_sub_reloc
   (bfd *, arelent *, asymbol *, void *, asection *, bfd *, char **);
+static bfd_reloc_status_type riscv_elf_ignore_reloc
+  (bfd *, arelent *, asymbol *, void *, asection *, bfd *, char **);
/* The relocation table used for SHT_RELA sections. */ @@ -855,8 +857,41 @@ static reloc_howto_type howto_table[] =
          0,                                /* src_mask */
          MINUS_ONE,                        /* dst_mask */
          FALSE),                        /* pcrel_offset */
+
+  /* The length of unsigned-leb128 is variant, just assume the
+     size is one byte here.  */
+  HOWTO (R_RISCV_SET_ULEB128,                /* type */
+         0,                                /* rightshift */
+         0,                                /* size */
+         0,                                /* bitsize */
+         FALSE,                                /* pc_relative */
+         0,                                /* bitpos */
+         complain_overflow_dont,        /* complain_on_overflow */
+         riscv_elf_ignore_reloc,        /* special_function */
+         "R_RISCV_SET_ULEB128",                /* name */
+         FALSE,                                /* partial_inplace */
+         0,                                /* src_mask */
+         0,                                /* dst_mask */
+         FALSE),                        /* pcrel_offset */

I don't understand how this could possibly work: uleb128s can be long, so we
can't just treat them as a single byte.  I'm having trouble testing it, though,
as I can't figure out how to emit R_RISCV_SET_ULEB128 alone.  For example, when
I try to insert a uleb128 in the assembler I'm not even getting a relocation:

   .text
   .globl _start
   _start:
           nop
   .L0:
           nop
   .L1:
   uleb_l0:
           addi x0, x0, 1
           .uleb128 .L0
           # Manually fix up the alignment, as .align is broken.
           .rept 3
           .byte 0xAA
           .endr
           addi x0, x0, 2
$ objdump -dr
   test.o:     file format elf64-littleriscv
Disassembly of section .text: 0000000000000000 <_start>:
      0:   00000013                nop
      4:   00000013                nop
0000000000000008 <uleb_l0>:
      8:   00100013                li      zero,1
      c:   aa04                    fsd     fs1,16(a2)
      e:   aaaa                    fsd     fa0,336(sp)
     10:   00200013                li      zero,2

so then when I link I'm just getting the wrong value entirely.

   test:     file format elf64-littleriscv
Disassembly of section .text: 0000000000010078 <_start>:
      10078:       00000013                nop
      1007c:       00000013                nop
0000000000010080 <uleb_l0>:
      10080:       00100013                li      zero,1
      10084:       aa04                    fsd     fs1,16(a2)
      10086:       aaaa                    fsd     fa0,336(sp)
      10088:       00200013                li      zero,2

+  /* The length of unsigned-leb128 is variant, just assume the
+     size is one byte here.  */
+  HOWTO (R_RISCV_SUB_ULEB128,                /* type */
+         0,                                /* rightshift */
+         0,                                /* size */
+         0,                                /* bitsize */
+         FALSE,                                /* pc_relative */
+         0,                                /* bitpos */
+         complain_overflow_dont,        /* complain_on_overflow */
+         riscv_elf_ignore_reloc,        /* special_function */
+         "R_RISCV_SUB_ULEB128",                /* name */
+         FALSE,                                /* partial_inplace */
+         0,                                /* src_mask */
+         0,                                /* dst_mask */
+         FALSE),                        /* pcrel_offset */
 };

I can get a R_RISCV_SUB_ULEB128, but it appears to be both producing the wrong
value and garbaging up bytes after the relocation.  For example:

   .text
   .globl _start
   _start:
           nop
   .L0:
           nop
   .L1:
   uleb_l1_l0:
           addi x0, x0, 1
           .uleb128 .L1 - .L0
           # Manually fix up the alignment, as .align is broken
           .rept 3
           .byte 0xAA
           .endr
           addi x0, x0, 2

produces the relocation

   test.o:     file format elf64-littleriscv
Disassembly of section .text: 0000000000000000 <_start>:
      0:   00000013                nop
0000000000000004 <.L0>:
      4:   00000013                nop
0000000000000008 <uleb_l1_l0>:
      8:   00100013                li      zero,1
      c:   aa04                    fsd     fs1,16(a2)
                           c: R_RISCV_SET_ULEB128  .L1
                           c: R_RISCV_SUB_ULEB128  .L0
      e:   aaaa                    fsd     fa0,336(sp)
     10:   00200013                li      zero,2

but then goes and corrupts the resulting executable


   test:     file format elf64-littleriscv
   Disassembly of section .text:
0000000000010078 <_start>:
      10078:       00000013                nop
      1007c:       00000013                nop
0000000000010080 <uleb_l1_l0>:
      10080:       00100013                li      zero,1
      10084:       ff84                    sd      s1,56(a5)
      10086:       000ffffb                0xffffb
      1008a:       0020                    addi    s0,sp,8

I can't think of a way to make this work aside from just emitting uleb128s at
their full length, which would make them work but would really defeat the
purpose of the format.  I guess we could then relax these, but that seems like
a lot of work.

+
 /* A mapping from BFD reloc types to RISC-V ELF reloc types.  */
struct elf_reloc_map
@@ -917,6 +952,8 @@ static const struct elf_reloc_map riscv_reloc_map[] =
   { BFD_RELOC_RISCV_SET16, R_RISCV_SET16 },
   { BFD_RELOC_RISCV_SET32, R_RISCV_SET32 },
   { BFD_RELOC_RISCV_32_PCREL, R_RISCV_32_PCREL },
+  { BFD_RELOC_RISCV_SET_ULEB128, R_RISCV_SET_ULEB128 },
+  { BFD_RELOC_RISCV_SUB_ULEB128, R_RISCV_SUB_ULEB128 },
 };
/* Given a BFD reloc type, return a howto structure. */
@@ -1011,6 +1048,20 @@ riscv_elf_add_sub_reloc (bfd *abfd,
   return bfd_reloc_ok;
 }
+/* Special handler for relocations which don't have to be relocated.
+   This function just simply return bfd_reloc_ok.  */
+static bfd_reloc_status_type
+riscv_elf_ignore_reloc (bfd *abfd ATTRIBUTE_UNUSED, arelent *reloc_entry,
+                        asymbol *symbol ATTRIBUTE_UNUSED,
+                        void *data ATTRIBUTE_UNUSED, asection *input_section,
+                        bfd *output_bfd, char **error_message ATTRIBUTE_UNUSED)
+{
+  if (output_bfd != NULL)
+    reloc_entry->address += input_section->output_offset;
+
+  return bfd_reloc_ok;
+}
+
 /* Parsing subset version.
Return Value:
diff --git a/bfd/libbfd.h b/bfd/libbfd.h
index 77b732ee4b..7aa8f91504 100644
--- a/bfd/libbfd.h
+++ b/bfd/libbfd.h
@@ -2327,6 +2327,8 @@ static const char *const bfd_reloc_code_real_names[] = { "@@uninitialized@@",
   "BFD_RELOC_RISCV_SET16",
   "BFD_RELOC_RISCV_SET32",
   "BFD_RELOC_RISCV_32_PCREL",
+  "BFD_RELOC_RISCV_SET_ULEB128",
+  "BFD_RELOC_RISCV_SUB_ULEB128",
   "BFD_RELOC_RL78_NEG8",
   "BFD_RELOC_RL78_NEG16",
   "BFD_RELOC_RL78_NEG24",
diff --git a/bfd/reloc.c b/bfd/reloc.c
index b00b79f319..9b8b75ad21 100644
--- a/bfd/reloc.c
+++ b/bfd/reloc.c
@@ -5212,6 +5212,10 @@ ENUMX
   BFD_RELOC_RISCV_SET32
 ENUMX
   BFD_RELOC_RISCV_32_PCREL
+ENUMX
+  BFD_RELOC_RISCV_SET_ULEB128
+ENUMX
+  BFD_RELOC_RISCV_SUB_ULEB128
 ENUMDOC
   RISC-V relocations.
diff --git a/gas/ChangeLog b/gas/ChangeLog
index 09991524da..e53ac0895b 100644
--- a/gas/ChangeLog
+++ b/gas/ChangeLog
@@ -1,3 +1,11 @@
+2019-11-27  Kuan-Lin Chen  <kuanlinchentw@gmail.com>
+
+        * config/tc-riscv.c (md_apply_fix): Add BFD_RELOC_RISCV_SET_ULEB128 and
+        BFD_RELOC_RISCV_SUB_ULEB128.
+        (riscv_insert_uleb128_fixes): New function.
+        (riscv_md_end): Scan rs_leb128 fragments.
+        (riscv_pseudo_table): Remove uleb128.
+
 2019-11-25  Andrew Pinski  <apinski@marvell.com>
* config/tc-aarch64.c (md_begin): Use correct
diff --git a/gas/config/tc-riscv.c b/gas/config/tc-riscv.c
index e50505138e..c35c591c0a 100644
--- a/gas/config/tc-riscv.c
+++ b/gas/config/tc-riscv.c
@@ -2392,6 +2392,9 @@ md_apply_fix (fixS *fixP, valueT *valP, segT seg ATTRIBUTE_UNUSED)
     case BFD_RELOC_RISCV_SUB32:
     case BFD_RELOC_RISCV_SUB64:
     case BFD_RELOC_RISCV_RELAX:
+    /* cvt_frag_to_fill () has called output_leb128 ().  */
+    case BFD_RELOC_RISCV_SET_ULEB128:
+    case BFD_RELOC_RISCV_SUB_ULEB128:
       break;
case BFD_RELOC_RISCV_TPREL_HI20:
@@ -3127,11 +3130,54 @@ riscv_set_public_attributes (void)
     riscv_write_out_arch_attr ();
 }
+/* Scan uleb128 subtraction expressions and insert fixups for them.
+   e.g., .uleb128 .L1 - .L0
+   Becuase relaxation may change the value of the subtraction, we
+   must resolve them in link-time.  */
+
+static void
+riscv_insert_uleb128_fixes (bfd *abfd ATTRIBUTE_UNUSED,
+                            asection *sec, void *xxx ATTRIBUTE_UNUSED)
+{
+  segment_info_type *seginfo = seg_info (sec);
+  struct frag *fragP;
+
+  subseg_set (sec, 0);
+
+  for (fragP = seginfo->frchainP->frch_root;
+       fragP; fragP = fragP->fr_next)
+    {
+      expressionS *exp, *exp_dup;
+
+      if (fragP->fr_type != rs_leb128  || fragP->fr_symbol == NULL)
+        continue;
+
+      exp = symbol_get_value_expression (fragP->fr_symbol);
+
+      if (exp->X_op != O_subtract)
+        continue;

Presumably that's why I can't get a _SET alone.

+
+      /* Only unsigned leb128 can be handle.  */
+      gas_assert (fragP->fr_subtype == 0);
+      exp_dup = xmemdup (exp, sizeof (*exp), sizeof (*exp));
+      exp_dup->X_op = O_symbol;
+      exp_dup->X_op_symbol = NULL;
+
+      /* Insert relocations to resolve the subtraction in link-time.  */
+      fix_new_exp (fragP, fragP->fr_fix, 0,
+                   exp_dup, 0, BFD_RELOC_RISCV_SET_ULEB128);
+      exp_dup->X_add_symbol = exp->X_op_symbol;
+      fix_new_exp (fragP, fragP->fr_fix, 0,
+                   exp_dup, 0, BFD_RELOC_RISCV_SUB_ULEB128);
+    }
+}
+
 /* Called after all assembly has been done.  */
void
 riscv_md_end (void)
 {
+  bfd_map_over_sections (stdoutput, riscv_insert_uleb128_fixes, NULL);
   riscv_set_public_attributes ();
 }
@@ -3215,7 +3261,6 @@ static const pseudo_typeS riscv_pseudo_table[] =
   {"dtprelword", s_dtprel, 4},
   {"dtpreldword", s_dtprel, 8},
   {"bss", s_bss, 0},
-  {"uleb128", s_riscv_leb128, 0},
   {"sleb128", s_riscv_leb128, 1},
   {"insn", s_riscv_insn, 0},
   {"attribute", s_riscv_attribute, 0},
diff --git a/include/ChangeLog b/include/ChangeLog
index 47bb86cf71..c290b245c6 100644
--- a/include/ChangeLog
+++ b/include/ChangeLog
@@ -1,3 +1,7 @@
+2019-11-27  Kuan-Lin Chen  <kuanlinchentw@gmail.com>
+
+        * elf/riscv.h ((R_RISCV_SET_ULEB128, (R_RISCV_SUB_ULEB128): Define.
+
 2019-11-25  Alan Modra  <amodra@gmail.com>
* coff/ti.h (GET_SCNHDR_SIZE, PUT_SCNHDR_SIZE, GET_SCN_SCNLEN),
diff --git a/include/elf/riscv.h b/include/elf/riscv.h
index 2f98aa4a3e..030679b35f 100644
--- a/include/elf/riscv.h
+++ b/include/elf/riscv.h
@@ -88,6 +88,8 @@ START_RELOC_NUMBERS (elf_riscv_reloc_type)
   RELOC_NUMBER (R_RISCV_SET16, 55)
   RELOC_NUMBER (R_RISCV_SET32, 56)
   RELOC_NUMBER (R_RISCV_32_PCREL, 57)
+  RELOC_NUMBER (R_RISCV_SET_ULEB128, 58)
+  RELOC_NUMBER (R_RISCV_SUB_ULEB128, 59)
 END_RELOC_NUMBERS (R_RISCV_max)
/* Processor specific flags for the ELF header e_flags field. */
diff --git a/ld/ChangeLog b/ld/ChangeLog
index 969ab78035..5c2e406101 100644
--- a/ld/ChangeLog
+++ b/ld/ChangeLog
@@ -1,3 +1,9 @@
+2019-11-27  Kuan-Lin Chen  <kuanlinchentw@gmail.com>
+
+        * testsuite/ld-riscv-elf/ld-riscv-elf.exp: Add uleb128.
+        * testsuite/ld-riscv-elf/uleb128.d: New test.
+        * testsuite/ld-riscv-elf/uleb128.s: New file.
+
 2019-11-26  Martin Liska  <mliska@suse.cz>
* scripttempl/arclinux.sc: Add .text.sorted.* which is sorted
diff --git a/ld/testsuite/ld-riscv-elf/ld-riscv-elf.exp b/ld/testsuite/ld-riscv-elf/ld-riscv-elf.exp
index 7aabbdd641..809e40f08d 100644
--- a/ld/testsuite/ld-riscv-elf/ld-riscv-elf.exp
+++ b/ld/testsuite/ld-riscv-elf/ld-riscv-elf.exp
@@ -38,6 +38,7 @@ if [istarget "riscv*-*-*"] {
     run_dump_test "attr-merge-priv-spec"
     run_dump_test "attr-merge-arch-failed-01"
     run_dump_test "attr-merge-stack-align-failed"
+    run_dump_test "uleb128"
     run_ld_link_tests {
         { "Weak reference 32" "-T weakref.ld -melf32lriscv" ""
             "-march=rv32i -mabi=ilp32" {weakref32.s}
diff --git a/ld/testsuite/ld-riscv-elf/uleb128.d b/ld/testsuite/ld-riscv-elf/uleb128.d
new file mode 100644
index 0000000000..a921478e98
--- /dev/null
+++ b/ld/testsuite/ld-riscv-elf/uleb128.d
@@ -0,0 +1,18 @@
+#source: uleb128.s
+#as: -march=rv32ic
+#ld: -melf32lriscv
+#objdump: -d
+
+.*:[         ]+file format .*
+
+Disassembly of section .text:
+
+.* <_start>:
+.*jal.*<bar>
+.*jal.*<bar>
+.*jal.*<bar>
+.*jal.*<bar>
+.*jal.*<bar>
+.*jal.*<bar>
+.*:[         ]+0e0c.*
+#pass
diff --git a/ld/testsuite/ld-riscv-elf/uleb128.s b/ld/testsuite/ld-riscv-elf/uleb128.s
new file mode 100644
index 0000000000..f7d23be163
--- /dev/null
+++ b/ld/testsuite/ld-riscv-elf/uleb128.s
@@ -0,0 +1,18 @@
+.text
+.globl bar
+.globl _start
+.option rvc
+.align 2
+_start:
+.L0:
+        .rept 6
+        call bar
+        .endr
+.align 2
+.L1:
+        .uleb128 .L1 - .L0
+        .uleb128 .L2 - .L0
+.L2:
+.align 2
+bar:
+        nop

It looks like alignment is broken here after uleb128s, but it's not actually
triggering an error in all cases.  Having two of them in this test case doesn't
trigger the issue, but an odd number does.  For example, the following source

   .text
   .globl _start
   .align 2
   _start:
           .uleb128 _start
   .align 2
   _end:
           nop

links _end to a misaligned symbol

   Disassembly of section .text:
0000000000010078 <_start>:
           ...
0000000000010079 <_end>:
      10079:       00000013                nop
      1007d:       0000                    unimp
           ...

I'm assuming that's because norvc assumes 4-byte alignment in text sections, so
it's just eliding the alingment directives.  With RVC I do get an error message

   .text
   .globl _start
   .option rvc
   .align 2
   _start:
           .uleb128 _start
   .align 2
   _end:
           nop

   ./install/bin/riscv64-unknown-linux-gnu-ld: test.o(.text+0x1): 3 bytes required for alignment to 4-byte boundary, but only 2 present
   ./install/bin/riscv64-unknown-linux-gnu-ld: can't relax section: bad value



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