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[BOLT] Skip PLT search for zero-value weak reference symbols (llvm#69136
) Take a common weak reference pattern for example ``` __attribute__((weak)) void undef_weak_fun(); if (&undef_weak_fun) undef_weak_fun(); ``` In this case, an undefined weak symbol `undef_weak_fun` has an address of zero, and Bolt incorrectly changes the relocation for the corresponding symbol to symbol@PLT, leading to incorrect runtime behavior.
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// This test checks whether BOLT can correctly handle relocations against weak symbols. | ||
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// RUN: %clang %cflags -Wl,-z,notext -shared -Wl,-q %s -o %t.so | ||
// RUN: llvm-bolt %t.so -o %t.so.bolt | ||
// RUN: llvm-nm -n %t.so.bolt > %t.out.txt | ||
// RUN: llvm-objdump -dj .rodata %t.so.bolt >> %t.out.txt | ||
// RUN: FileCheck %s --input-file=%t.out.txt | ||
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# CHECK: w func_1 | ||
# CHECK: {{0+}}[[#%x,ADDR:]] W func_2 | ||
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# CHECK: {{.*}} <.rodata>: | ||
# CHECK-NEXT: {{.*}} .word 0x00000000 | ||
# CHECK-NEXT: {{.*}} .word 0x00000000 | ||
# CHECK-NEXT: {{.*}} .word 0x{{[0]+}}[[#ADDR]] | ||
# CHECK-NEXT: {{.*}} .word 0x00000000 | ||
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.text | ||
.weak func_2 | ||
.weak func_1 | ||
.global wow | ||
.type wow, %function | ||
wow: | ||
bl func_1 | ||
bl func_2 | ||
ret | ||
.type func_2, %function | ||
func_2: | ||
ret | ||
.section .rodata | ||
.LC0: | ||
.xword func_1 | ||
.LC1: | ||
.xword func_2 |