f10e0f7321
Avoid creating new calls to linkonce_odr/weak_odr functions when
merging 2 functions, as this may introduce an infinite call
cycle.
Consider 2 functions below, both present in 2 modules.
Module X
--
define linkonce_odr void @"A"() {
call void @"foo"()
}
define linkonce_odr void @"B"() {
call void @"foo"()
}
---
Module Y
---
global @"g" = @"B"
define linkonce_odr void @"A"() {
%l = load @"g"
call void %l()
}
define linkonce_odr void @"B"() {
call void @"foo"()
}
---
@"A" and @"B" in both modules are semantically equivalent
Module X after function merging:
---
define linkonce_odr void @"A"() {
call void @"foo"()
}
define linkonce_odr void @"B"() {
call void @"A"()
}
---
Module Y is unchanged.
Then the linker picks @"A" from module Y and @"B" from module X. Now there's an infinite call cycle
PR: https://github.com/llvm/llvm-project/pull/125050
26 lines
664 B
LLVM
26 lines
664 B
LLVM
; RUN: opt -S -passes=mergefunc %s | FileCheck %s
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@symbols = linkonce_odr global <{ ptr, ptr }> <{ ptr @f, ptr @g }>
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$f = comdat any
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$g = comdat any
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define linkonce_odr hidden i32 @f(i32 %x, i32 %y) comdat {
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%sum = add i32 %x, %y
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%sum2 = add i32 %x, %sum
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%sum3 = add i32 %x, %sum
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ret i32 %sum3
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}
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define linkonce_odr hidden i32 @g(i32 %x, i32 %y) comdat {
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%sum = add i32 %x, %y
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%sum2 = add i32 %x, %sum
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%sum3 = add i32 %x, %sum
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ret i32 %sum3
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}
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; CHECK-DAG: define private i32 @0(i32 %x, i32 %y) comdat($f)
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; CHECK-DAG: define linkonce_odr hidden i32 @g(i32 %0, i32 %1) comdat {
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; CHECK-DAG: define linkonce_odr hidden i32 @f(i32 %0, i32 %1) {
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