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[lld][LoongArch] Check that the relocation addend is zero before applying relaxation to R_LARCH_GOT_PC_{HI20,LO12} (#151264)
Linker relaxation to R_LARCH_GOT_PC_{HI20,LO12} is only possible when the addend of the relocation is zero. Note: For `ld.bfd`, GOT references with non-zero addends will trigger an assert in LoongArch, but `lld` handles these cases without any errors. ``` ld.bfd: BFD (GNU Binutils) 2.44.0 assertion fail /usr/src/debug/binutils/binutils-gdb/bfd/elfnn-loongarch.c:4248 ```
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‎lld/ELF/Arch/LoongArch.cpp

Lines changed: 6 additions & 3 deletions
Original file line numberDiff line numberDiff line change
@@ -809,10 +809,13 @@ static void relaxPCHi20Lo12(Ctx &ctx, const InputSection &sec, size_t i,
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// address.
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// Meanwhile skip undefined, preemptible and STT_GNU_IFUNC symbols, because
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// these symbols may be resolve in runtime.
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// Moreover, relaxation can only occur if the addends of both relocations are
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// zero for GOT references.
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if (rHi20.type == R_LARCH_GOT_PC_HI20 &&
813-
(!rHi20.sym->isDefined() || rHi20.sym->isPreemptible ||
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rHi20.sym->isGnuIFunc() ||
815-
(ctx.arg.isPic && !cast<Defined>(*rHi20.sym).section)))
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(!rHi20.sym || rHi20.sym != rLo12.sym || !rHi20.sym->isDefined() ||
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rHi20.sym->isPreemptible || rHi20.sym->isGnuIFunc() ||
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(ctx.arg.isPic && !cast<Defined>(*rHi20.sym).section) ||
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rHi20.addend != 0 || rLo12.addend != 0))
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return;
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uint64_t dest = 0;

‎lld/test/ELF/loongarch-relax-pc-hi20-lo12.s

Lines changed: 45 additions & 14 deletions
Original file line numberDiff line numberDiff line change
@@ -1,22 +1,23 @@
11
# REQUIRES: loongarch
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# RUN: rm -rf %t && split-file %s %t && cd %t
23

3-
# RUN: llvm-mc --filetype=obj --triple=loongarch32 -mattr=+relax %s -o %t.32.o
4-
# RUN: llvm-mc --filetype=obj --triple=loongarch64 -mattr=+relax %s -o %t.64.o
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# RUN: llvm-mc --filetype=obj --triple=loongarch32 -mattr=+relax a.s -o a.32.o
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# RUN: llvm-mc --filetype=obj --triple=loongarch64 -mattr=+relax a.s -o a.64.o
56

6-
# RUN: ld.lld --section-start=.text=0x10000 --section-start=.data=0x14000 %t.32.o -o %t.32
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# RUN: ld.lld --section-start=.text=0x10000 --section-start=.data=0x14000 %t.64.o -o %t.64
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# RUN: llvm-objdump -td --no-show-raw-insn %t.32 | FileCheck --check-prefixes=RELAX %s
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# RUN: llvm-objdump -td --no-show-raw-insn %t.64 | FileCheck --check-prefixes=RELAX %s
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# RUN: ld.lld --section-start=.text=0x10000 --section-start=.data=0x14000 a.32.o -o a.32
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# RUN: ld.lld --section-start=.text=0x10000 --section-start=.data=0x14000 a.64.o -o a.64
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# RUN: llvm-objdump -td --no-show-raw-insn a.32 | FileCheck --check-prefixes=RELAX %s
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# RUN: llvm-objdump -td --no-show-raw-insn a.64 | FileCheck --check-prefixes=RELAX %s
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11-
# RUN: ld.lld --section-start=.text=0x10000 --section-start=.data=0x14000 %t.32.o -shared -o %t.32s
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# RUN: ld.lld --section-start=.text=0x10000 --section-start=.data=0x14000 %t.64.o -shared -o %t.64s
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# RUN: llvm-objdump -td --no-show-raw-insn %t.32s | FileCheck --check-prefixes=RELAX %s
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# RUN: llvm-objdump -td --no-show-raw-insn %t.64s | FileCheck --check-prefixes=RELAX %s
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# RUN: ld.lld --section-start=.text=0x10000 --section-start=.data=0x14000 a.32.o -shared -o a.32s
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# RUN: ld.lld --section-start=.text=0x10000 --section-start=.data=0x14000 a.64.o -shared -o a.64s
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# RUN: llvm-objdump -td --no-show-raw-insn a.32s | FileCheck --check-prefixes=RELAX %s
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# RUN: llvm-objdump -td --no-show-raw-insn a.64s | FileCheck --check-prefixes=RELAX %s
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# RUN: ld.lld --section-start=.text=0x10000 --section-start=.data=0x410000 %t.32.o -o %t.32o
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# RUN: ld.lld --section-start=.text=0x10000 --section-start=.data=0x410000 %t.64.o -o %t.64o
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# RUN: llvm-objdump -td --no-show-raw-insn %t.32o | FileCheck --check-prefixes=NORELAX32 %s
19-
# RUN: llvm-objdump -td --no-show-raw-insn %t.64o | FileCheck --check-prefixes=NORELAX64 %s
17+
# RUN: ld.lld --section-start=.text=0x10000 --section-start=.data=0x410000 a.32.o -o a.32o
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# RUN: ld.lld --section-start=.text=0x10000 --section-start=.data=0x410000 a.64.o -o a.64o
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# RUN: llvm-objdump -td --no-show-raw-insn a.32o | FileCheck --check-prefixes=NORELAX32 %s
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# RUN: llvm-objdump -td --no-show-raw-insn a.64o | FileCheck --check-prefixes=NORELAX64 %s
2021

2122
# RELAX-LABEL: <_start>:
2223
## offset = 0x14000 - 0x10000 = 4096<<2
@@ -49,6 +50,25 @@
4950
# NORELAX64-NEXT: pcalau12i $a0, 1024
5051
# NORELAX64-NEXT: ld.d $a0, $a0, 8
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## GOT references with non-zero addends. No relaxation.
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# RUN: llvm-mc --filetype=obj --triple=loongarch32 -mattr=+relax nonzero.s -o nonzero.32.o
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# RUN: llvm-mc --filetype=obj --triple=loongarch64 -mattr=+relax nonzero.s -o nonzero.64.o
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# RUN: ld.lld --section-start=.text=0x10000 --section-start=.data=0x14000 nonzero.32.o -o nonzero.32
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# RUN: ld.lld --section-start=.text=0x10000 --section-start=.data=0x14000 nonzero.64.o -o nonzero.64
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# RUN: llvm-objdump -td --no-show-raw-insn nonzero.32 | FileCheck --check-prefixes=NONZERO32 %s
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# RUN: llvm-objdump -td --no-show-raw-insn nonzero.64 | FileCheck --check-prefixes=NONZERO64 %s
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# NONZERO32-LABEL: <_start>:
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# NONZERO32-NEXT: 10000: pcalau12i $a0, 4
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# NONZERO32-NEXT: ld.w $a0, $a0, 8
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# NONZERO64-LABEL: <_start>:
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# NONZERO64-NEXT: 10000: pcalau12i $a0, 4
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# NONZERO64-NEXT: ld.d $a0, $a0, 12
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#--- a.s
5272
.section .text
5373
.global _start
5474
_start:
@@ -60,3 +80,14 @@ _start:
6080
.section .data
6181
sym:
6282
.zero 4
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#--- nonzero.s
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.section .text
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.global _start
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_start:
89+
la.got $a0, sym+4
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.section .data
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sym:
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.zero 4

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