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[lld][ELF] Fix a corner case of elf::getLoongArchPageDelta #71907

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[lld][ELF] Fix a corner case of elf::getLoongArchPageDelta #71907

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4 changes: 4 additions & 0 deletions lld/ELF/Arch/LoongArch.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -159,6 +159,10 @@ uint64_t elf::getLoongArchPageDelta(uint64_t dest, uint64_t pc) {
bool negativeA = lo12(dest) > 0x7ff;
bool negativeB = (result & 0x8000'0000) != 0;

// A corner case; directly return the expected result.
if (result == 0xfff'fffff'fffff'000 && negativeA)
return 0xfff'fffff'00000'000;

if (negativeA)
result += 0x1000;
if (negativeA && !negativeB)
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11 changes: 5 additions & 6 deletions lld/test/ELF/loongarch-pc-aligned.s
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Expand Up @@ -260,18 +260,17 @@
# EXTREME15-NEXT: lu32i.d $t0, -349526
# EXTREME15-NEXT: lu52i.d $t0, $t0, -1093

## FIXME: Correct %pc64_lo20 should be 0xfffff (-1) and %pc64_hi12 should be 0xfff (-1), but current values are:
## page delta = 0x0000000000000000, page offset = 0x888
## page delta = 0xffffffff00000000, page offset = 0x888
## %pc_lo12 = 0x888 = -1912
## %pc_hi20 = 0x00000 = 0
## %pc64_lo20 = 0x00000 = 0
## %pc64_hi12 = 0x00000 = 0
## %pc64_lo20 = 0xfffff = -1
## %pc64_hi12 = 0xfff = -1
# RUN: ld.lld %t/extreme.o --section-start=.rodata=0x0000000012344888 --section-start=.text=0x0000000012345678 -o %t/extreme16
# RUN: llvm-objdump -d --no-show-raw-insn %t/extreme16 | FileCheck %s --check-prefix=EXTREME16
# EXTREME16: addi.d $t0, $zero, -1912
# EXTREME16-NEXT: pcalau12i $t1, 0
# EXTREME16-NEXT: lu32i.d $t0, 0
# EXTREME16-NEXT: lu52i.d $t0, $t0, 0
# EXTREME16-NEXT: lu32i.d $t0, -1
# EXTREME16-NEXT: lu52i.d $t0, $t0, -1

#--- a.s
.rodata
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