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As Ana Pazos pointed out, these have to be restored to their incoming values before a function returns; i.e. before the tail call. So they can't be used correctly as the destination register. llvm-svn: 210525
34 lines
978 B
LLVM
34 lines
978 B
LLVM
; RUN: llc -verify-machineinstrs -mtriple=arm64-apple-ios7.0 -o - %s | FileCheck %s
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@var = global void()* zeroinitializer
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declare void @bar()
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define void @foo() {
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; CHECK-LABEL: foo:
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%func = load void()** @var
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; Calling a function encourages @foo to use a callee-saved register,
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; which makes it a natural choice for the tail call itself. But we don't
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; want that: the final "br xN" has to use a temporary or argument
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; register.
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call void @bar()
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tail call void %func()
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; CHECK: br {{x([0-79]|1[0-8])}}
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ret void
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}
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; No matter how tempting it is, LLVM should not use x30 since that'll be
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; restored to its incoming value before the "br".
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define void @test_x30_tail() {
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; CHECK-LABEL: test_x30_tail:
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; CHECK: mov [[DEST:x[0-9]+]], x30
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; CHECK: br [[DEST]]
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%addr = call i8* @llvm.returnaddress(i32 0)
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%faddr = bitcast i8* %addr to void()*
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tail call void %faddr()
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ret void
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}
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declare i8* @llvm.returnaddress(i32)
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