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binutils/LoongArch-gas-Ignore-.align-if-it-is-at-the-start-of.patch
Xin Wang c5d20fb405 backport master to 2.41 
(cherry picked from commit 76a68d9a00e7769c07675e883426534440db822d)
2024-11-07 09:46:21 +08:00

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9.6 KiB
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From adb3d28328bbf2d17c3a44778497827d7d35124a Mon Sep 17 00:00:00 2001
From: mengqinggang <mengqinggang@loongson.cn>
Date: Tue, 19 Mar 2024 21:09:12 +0800
Subject: [PATCH 076/123] LoongArch: gas: Ignore .align if it is at the start
of a section
Ignore .align if it is at the start of a section and the alignment
can be divided by the section alignment, the section alignment
can ensure this .align has a correct alignment.
---
gas/config/tc-loongarch.c | 134 ++++++++++++++----
.../gas/loongarch/relax-align-first.d | 12 ++
.../gas/loongarch/relax-align-first.s | 7 +
.../ld-loongarch-elf/relax-align-first.d | 15 ++
.../ld-loongarch-elf/relax-align-first.s | 13 ++
ld/testsuite/ld-loongarch-elf/relax.exp | 1 +
6 files changed, 157 insertions(+), 25 deletions(-)
create mode 100644 gas/testsuite/gas/loongarch/relax-align-first.d
create mode 100644 gas/testsuite/gas/loongarch/relax-align-first.s
create mode 100644 ld/testsuite/ld-loongarch-elf/relax-align-first.d
create mode 100644 ld/testsuite/ld-loongarch-elf/relax-align-first.s
diff --git a/gas/config/tc-loongarch.c b/gas/config/tc-loongarch.c
index 1e835f51..110b92e4 100644
--- a/gas/config/tc-loongarch.c
+++ b/gas/config/tc-loongarch.c
@@ -128,6 +128,11 @@ static bool call36 = 0;
#define RELAX_BRANCH_ENCODE(x) \
(BFD_RELOC_LARCH_B16 == (x) ? RELAX_BRANCH_16 : RELAX_BRANCH_21)
+#define ALIGN_MAX_ADDEND(n, max) ((max << 8) | n)
+#define ALIGN_MAX_NOP_BYTES(addend) ((1 << (addend & 0xff)) - 4)
+#define FRAG_AT_START_OF_SECTION(frag) \
+ (0 == frag->fr_address && 0 == frag->fr_fix)
+
enum options
{
OPTION_IGNORE = OPTION_MD_BASE,
@@ -1647,10 +1652,32 @@ md_apply_fix (fixS *fixP, valueT *valP, segT seg ATTRIBUTE_UNUSED)
}
}
+/* Estimate the size of a frag before relaxing. */
+
int
-md_estimate_size_before_relax (fragS *fragp ATTRIBUTE_UNUSED,
- asection *segtype ATTRIBUTE_UNUSED)
+md_estimate_size_before_relax (fragS *fragp, asection *sec)
{
+ /* align pseudo instunctions. */
+ if (rs_align_code == fragp->fr_subtype)
+ {
+ offsetT nop_bytes;
+ if (NULL == fragp->fr_symbol)
+ nop_bytes = fragp->fr_offset;
+ else
+ nop_bytes = ALIGN_MAX_NOP_BYTES (fragp->fr_offset);
+
+ /* Normally, nop_bytes should be >= 4. */
+ gas_assert (nop_bytes > 0);
+
+ if (FRAG_AT_START_OF_SECTION (fragp)
+ && 0 == ((1 << sec->alignment_power) % (nop_bytes + 4)))
+ return (fragp->fr_var = 0);
+ else
+ return (fragp->fr_var = nop_bytes);
+ }
+
+ /* branch instructions and other instructions.
+ branch instructions may become 8 bytes after relaxing. */
return (fragp->fr_var = 4);
}
@@ -1767,8 +1794,7 @@ bool
loongarch_frag_align_code (int n, int max)
{
char *nops;
- symbolS *s;
- expressionS ex;
+ symbolS *s = NULL;
bfd_vma insn_alignment = 4;
bfd_vma bytes = (bfd_vma) 1 << n;
@@ -1783,8 +1809,6 @@ loongarch_frag_align_code (int n, int max)
if (!LARCH_opts.relax)
return false;
- nops = frag_more (worst_case_bytes);
-
/* If max <= 0, ignore max.
If max >= worst_case_bytes, max has no effect.
Similar to gas/write.c relax_segment function rs_align_code case:
@@ -1792,20 +1816,20 @@ loongarch_frag_align_code (int n, int max)
if (max > 0 && (bfd_vma) max < worst_case_bytes)
{
s = symbol_find (now_seg->name);
- ex.X_add_symbol = s;
- ex.X_op = O_symbol;
- ex.X_add_number = (max << 8) | n;
- }
- else
- {
- ex.X_op = O_constant;
- ex.X_add_number = worst_case_bytes;
+ worst_case_bytes = ALIGN_MAX_ADDEND (n, max);
}
- loongarch_make_nops (nops, worst_case_bytes);
+ frag_grow (worst_case_bytes);
+ /* Use relaxable frag for .align.
+ If .align at the start of section, do nothing. Section alignment can
+ ensure correct alignment.
+ If .align is not at the start of a section, reserve NOP instructions
+ and R_LARCH_ALIGN relocation. */
+ nops = frag_var (rs_machine_dependent, worst_case_bytes, worst_case_bytes,
+ rs_align_code, s, worst_case_bytes, NULL);
- fix_new_exp (frag_now, nops - frag_now->fr_literal, 0,
- &ex, false, BFD_RELOC_LARCH_ALIGN);
+ /* Default write NOP for aligned bytes. */
+ loongarch_make_nops (nops, worst_case_bytes);
/* We need to start a new frag after the alignment which may be removed by
the linker, to prevent the assembler from computing static offsets.
@@ -1963,8 +1987,7 @@ loongarch_relaxed_branch_length (fragS *fragp, asection *sec, int update)
}
int
-loongarch_relax_frag (asection *sec ATTRIBUTE_UNUSED,
- fragS *fragp ATTRIBUTE_UNUSED,
+loongarch_relax_frag (asection *sec, fragS *fragp,
long stretch ATTRIBUTE_UNUSED)
{
if (RELAX_BRANCH (fragp->fr_subtype))
@@ -1973,6 +1996,27 @@ loongarch_relax_frag (asection *sec ATTRIBUTE_UNUSED,
fragp->fr_var = loongarch_relaxed_branch_length (fragp, sec, true);
return fragp->fr_var - old_var;
}
+ else if (rs_align_code == fragp->fr_subtype)
+ {
+ offsetT nop_bytes;
+ if (NULL == fragp->fr_symbol)
+ nop_bytes = fragp->fr_offset;
+ else
+ nop_bytes = ALIGN_MAX_NOP_BYTES (fragp->fr_offset);
+
+ /* Normally, nop_bytes should be >= 4. */
+ gas_assert (nop_bytes > 0);
+
+ offsetT old_var = fragp->fr_var;
+ /* If .align at the start of a section, do nothing. Section alignment
+ * can ensure correct alignment. */
+ if (FRAG_AT_START_OF_SECTION (fragp)
+ && 0 == ((1 << sec->alignment_power) % (nop_bytes + 4)))
+ fragp->fr_var = 0;
+ else
+ fragp->fr_var = nop_bytes;
+ return fragp->fr_var - old_var;
+ }
return 0;
}
@@ -2048,13 +2092,53 @@ loongarch_convert_frag_branch (fragS *fragp)
fragp->fr_fix += fragp->fr_var;
}
-/* Relax a machine dependent frag. This returns the amount by which
- the current size of the frag should change. */
+/* Relax .align frag. */
+
+static void
+loongarch_convert_frag_align (fragS *fragp, asection *sec)
+{
+ bfd_byte *buf = (bfd_byte *)fragp->fr_literal + fragp->fr_fix;
+
+ offsetT nop_bytes;
+ if (NULL == fragp->fr_symbol)
+ nop_bytes = fragp->fr_offset;
+ else
+ nop_bytes = ALIGN_MAX_NOP_BYTES (fragp->fr_offset);
+
+ /* Normally, nop_bytes should be >= 4. */
+ gas_assert (nop_bytes > 0);
+
+ if (!(FRAG_AT_START_OF_SECTION (fragp)
+ && 0 == ((1 << sec->alignment_power) % (nop_bytes + 4))))
+ {
+ expressionS exp;
+ exp.X_op = O_symbol;
+ exp.X_add_symbol = fragp->fr_symbol;
+ exp.X_add_number = fragp->fr_offset;
+
+ fixS *fixp = fix_new_exp (fragp, buf - (bfd_byte *)fragp->fr_literal,
+ nop_bytes, &exp, false, BFD_RELOC_LARCH_ALIGN);
+ fixp->fx_file = fragp->fr_file;
+ fixp->fx_line = fragp->fr_line;
+
+ buf += nop_bytes;
+ }
+
+ gas_assert (buf == (bfd_byte *)fragp->fr_literal
+ + fragp->fr_fix + fragp->fr_var);
+
+ fragp->fr_fix += fragp->fr_var;
+}
+
+/* Relax a machine dependent frag. */
void
-md_convert_frag (bfd *abfd ATTRIBUTE_UNUSED, segT asec ATTRIBUTE_UNUSED,
- fragS *fragp)
+md_convert_frag (bfd *abfd ATTRIBUTE_UNUSED, segT asec, fragS *fragp)
{
- gas_assert (RELAX_BRANCH (fragp->fr_subtype));
- loongarch_convert_frag_branch (fragp);
+ gas_assert (RELAX_BRANCH (fragp->fr_subtype)
+ || rs_align_code == fragp->fr_subtype);
+ if (RELAX_BRANCH (fragp->fr_subtype))
+ loongarch_convert_frag_branch (fragp);
+ else if (rs_align_code == fragp->fr_subtype)
+ loongarch_convert_frag_align (fragp, asec);
}
diff --git a/gas/testsuite/gas/loongarch/relax-align-first.d b/gas/testsuite/gas/loongarch/relax-align-first.d
new file mode 100644
index 00000000..ec0698b6
--- /dev/null
+++ b/gas/testsuite/gas/loongarch/relax-align-first.d
@@ -0,0 +1,12 @@
+#as:
+#objdump: -dr
+
+.*:[ ]+file format .*
+
+
+Disassembly of section .text:
+0* <.text>:
+[ ]+0:[ ]+4c000020[ ]+ret
+Disassembly of section abc:
+0* <abc>:
+[ ]+0:[ ]+4c000020[ ]+ret
diff --git a/gas/testsuite/gas/loongarch/relax-align-first.s b/gas/testsuite/gas/loongarch/relax-align-first.s
new file mode 100644
index 00000000..a4c3d68f
--- /dev/null
+++ b/gas/testsuite/gas/loongarch/relax-align-first.s
@@ -0,0 +1,7 @@
+.text
+.align 3
+ret
+
+.section "abc", "ax"
+.align 4, ,4
+ret
diff --git a/ld/testsuite/ld-loongarch-elf/relax-align-first.d b/ld/testsuite/ld-loongarch-elf/relax-align-first.d
new file mode 100644
index 00000000..9a4fad8e
--- /dev/null
+++ b/ld/testsuite/ld-loongarch-elf/relax-align-first.d
@@ -0,0 +1,15 @@
+#ld: -e0
+#objdump: -d
+
+.*:[ ]+file format .*
+
+
+Disassembly of section aaa:
+0000000120000078 <aaa>:
+[ ]+120000078:[ ]+4c000020[ ]+ret
+Disassembly of section bbb:
+0000000120000080 <bbb>:
+[ ]+120000080:[ ]+4c000020[ ]+ret
+Disassembly of section ccc:
+0000000120000090 <__bss_start-0x4004>:
+[ ]+120000090:[ ]+4c000020[ ]+ret
diff --git a/ld/testsuite/ld-loongarch-elf/relax-align-first.s b/ld/testsuite/ld-loongarch-elf/relax-align-first.s
new file mode 100644
index 00000000..0a9115b5
--- /dev/null
+++ b/ld/testsuite/ld-loongarch-elf/relax-align-first.s
@@ -0,0 +1,13 @@
+# If .align at the start of a section, do not add NOP instructions
+# and do not emit R_LARCH_ALIGN relocations.
+# Section alignment can ensure correct alignment.
+.section "aaa", "ax"
+ret
+
+.section "bbb", "ax"
+.align 3
+ret
+
+.section "ccc", "ax"
+.align 4, ,4
+ret
diff --git a/ld/testsuite/ld-loongarch-elf/relax.exp b/ld/testsuite/ld-loongarch-elf/relax.exp
index f378b93b..7274218f 100644
--- a/ld/testsuite/ld-loongarch-elf/relax.exp
+++ b/ld/testsuite/ld-loongarch-elf/relax.exp
@@ -20,6 +20,7 @@
#
if [istarget loongarch64-*-*] {
+ run_dump_test "relax-align-first"
if [isbuild loongarch64-*-*] {
set testname "loongarch relax .exe build"
--
2.33.0
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