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release/21.x: [lld][LoongArch] Check that the relocation addend is zero before applying relaxation to R_LARCH_GOT_PC_{HI20,LO12} (#151264) #151470

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Aug 1, 2025
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release/21.x: [lld][LoongArch] Check that the relocation addend is zero before applying relaxation to R_LARCH_GOT_PC_{HI20,LO12} (#151264) #151470

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

uint64_t dest = 0;
Expand Down
59 changes: 45 additions & 14 deletions lld/test/ELF/loongarch-relax-pc-hi20-lo12.s
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@@ -1,22 +1,23 @@
# REQUIRES: loongarch
# RUN: rm -rf %t && split-file %s %t && cd %t

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

# RUN: ld.lld --section-start=.text=0x10000 --section-start=.data=0x14000 %t.32.o -o %t.32
# RUN: ld.lld --section-start=.text=0x10000 --section-start=.data=0x14000 %t.64.o -o %t.64
# RUN: llvm-objdump -td --no-show-raw-insn %t.32 | FileCheck --check-prefixes=RELAX %s
# RUN: llvm-objdump -td --no-show-raw-insn %t.64 | FileCheck --check-prefixes=RELAX %s
# RUN: ld.lld --section-start=.text=0x10000 --section-start=.data=0x14000 a.32.o -o a.32
# RUN: ld.lld --section-start=.text=0x10000 --section-start=.data=0x14000 a.64.o -o a.64
# RUN: llvm-objdump -td --no-show-raw-insn a.32 | FileCheck --check-prefixes=RELAX %s
# RUN: llvm-objdump -td --no-show-raw-insn a.64 | FileCheck --check-prefixes=RELAX %s

# RUN: ld.lld --section-start=.text=0x10000 --section-start=.data=0x14000 %t.32.o -shared -o %t.32s
# RUN: ld.lld --section-start=.text=0x10000 --section-start=.data=0x14000 %t.64.o -shared -o %t.64s
# RUN: llvm-objdump -td --no-show-raw-insn %t.32s | FileCheck --check-prefixes=RELAX %s
# RUN: llvm-objdump -td --no-show-raw-insn %t.64s | FileCheck --check-prefixes=RELAX %s
# RUN: ld.lld --section-start=.text=0x10000 --section-start=.data=0x14000 a.32.o -shared -o a.32s
# RUN: ld.lld --section-start=.text=0x10000 --section-start=.data=0x14000 a.64.o -shared -o a.64s
# RUN: llvm-objdump -td --no-show-raw-insn a.32s | FileCheck --check-prefixes=RELAX %s
# RUN: llvm-objdump -td --no-show-raw-insn a.64s | FileCheck --check-prefixes=RELAX %s

# RUN: ld.lld --section-start=.text=0x10000 --section-start=.data=0x410000 %t.32.o -o %t.32o
# RUN: ld.lld --section-start=.text=0x10000 --section-start=.data=0x410000 %t.64.o -o %t.64o
# RUN: llvm-objdump -td --no-show-raw-insn %t.32o | FileCheck --check-prefixes=NORELAX32 %s
# RUN: llvm-objdump -td --no-show-raw-insn %t.64o | FileCheck --check-prefixes=NORELAX64 %s
# RUN: ld.lld --section-start=.text=0x10000 --section-start=.data=0x410000 a.32.o -o a.32o
# RUN: ld.lld --section-start=.text=0x10000 --section-start=.data=0x410000 a.64.o -o a.64o
# RUN: llvm-objdump -td --no-show-raw-insn a.32o | FileCheck --check-prefixes=NORELAX32 %s
# RUN: llvm-objdump -td --no-show-raw-insn a.64o | FileCheck --check-prefixes=NORELAX64 %s

# RELAX-LABEL: <_start>:
## offset = 0x14000 - 0x10000 = 4096<<2
Expand Down Expand Up @@ -49,6 +50,25 @@
# NORELAX64-NEXT: pcalau12i $a0, 1024
# NORELAX64-NEXT: ld.d $a0, $a0, 8


## GOT references with non-zero addends. No relaxation.
# RUN: llvm-mc --filetype=obj --triple=loongarch32 -mattr=+relax nonzero.s -o nonzero.32.o
# RUN: llvm-mc --filetype=obj --triple=loongarch64 -mattr=+relax nonzero.s -o nonzero.64.o
# RUN: ld.lld --section-start=.text=0x10000 --section-start=.data=0x14000 nonzero.32.o -o nonzero.32
# RUN: ld.lld --section-start=.text=0x10000 --section-start=.data=0x14000 nonzero.64.o -o nonzero.64
# RUN: llvm-objdump -td --no-show-raw-insn nonzero.32 | FileCheck --check-prefixes=NONZERO32 %s
# RUN: llvm-objdump -td --no-show-raw-insn nonzero.64 | FileCheck --check-prefixes=NONZERO64 %s

# NONZERO32-LABEL: <_start>:
# NONZERO32-NEXT: 10000: pcalau12i $a0, 4
# NONZERO32-NEXT: ld.w $a0, $a0, 8

# NONZERO64-LABEL: <_start>:
# NONZERO64-NEXT: 10000: pcalau12i $a0, 4
# NONZERO64-NEXT: ld.d $a0, $a0, 12


#--- a.s
.section .text
.global _start
_start:
Expand All @@ -60,3 +80,14 @@ _start:
.section .data
sym:
.zero 4


#--- nonzero.s
.section .text
.global _start
_start:
la.got $a0, sym+4

.section .data
sym:
.zero 4
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