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llvm-mirror/test/Instrumentation/InstrProfiling/runtime-counter-relocation.ll
Petr Hosek 1aff1e2660 [InstrProfiling] Use weak alias for bias variable
We need the compiler generated variable to override the weak symbol of
the same name inside the profile runtime, but using LinkOnceODRLinkage
results in weak symbol being emitted in which case the symbol selected
by the linker is going to depend on the order of inputs which can be
fragile.

This change replaces the use of weak definition inside the runtime with
a weak alias. We place the compiler generated symbol inside a COMDAT
group so dead definition can be garbage collected by the linker.

We also disable the use of runtime counter relocation on Darwin since
Mach-O doesn't support weak external references, but Darwin already uses
a different continous mode that relies on overmapping so runtime counter
relocation isn't needed there.

Differential Revision: https://reviews.llvm.org/D105176
2021-07-19 12:23:51 -07:00

27 lines
1.2 KiB
LLVM

; RUN: opt < %s -S -instrprof | FileCheck %s
; RUN: opt < %s -S -instrprof -runtime-counter-relocation | FileCheck -check-prefixes=RELOC %s
target triple = "x86_64-unknown-linux-gnu"
@__profn_foo = private constant [3 x i8] c"foo"
; RELOC: $__llvm_profile_counter_bias = comdat any
; RELOC: @__llvm_profile_counter_bias = linkonce_odr hidden global i64 0, comdat
; CHECK-LABEL: define void @foo
; CHECK-NEXT: %pgocount = load i64, i64* getelementptr inbounds ([1 x i64], [1 x i64]* @__profc_foo, i64 0, i64 0)
; CHECK-NEXT: %1 = add i64 %pgocount, 1
; CHECK-NEXT: store i64 %1, i64* getelementptr inbounds ([1 x i64], [1 x i64]* @__profc_foo, i64 0, i64 0)
; RELOC-LABEL: define void @foo
; RELOC-NEXT: %1 = load i64, i64* @__llvm_profile_counter_bias
; RELOC-NEXT: %2 = add i64 ptrtoint ([1 x i64]* @__profc_foo to i64), %1
; RELOC-NEXT: %3 = inttoptr i64 %2 to i64*
; RELOC-NEXT: %pgocount = load i64, i64* %3
; RELOC-NEXT: %4 = add i64 %pgocount, 1
; RELOC-NEXT: store i64 %4, i64* %3
define void @foo() {
call void @llvm.instrprof.increment(i8* getelementptr inbounds ([3 x i8], [3 x i8]* @__profn_foo, i32 0, i32 0), i64 0, i32 1, i32 0)
ret void
}
declare void @llvm.instrprof.increment(i8*, i64, i32, i32)