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Externally-defined functions with weak linkage should not be tail-called on ARM or AArch64, as the AAELF spec requires normal calls to undefined weak functions to be replaced with a NOP or jump to the next instruction. The behaviour of branch instructions in this situation (as used for tail calls) is implementation-defined, so we cannot rely on the linker replacing the tail call with a return. llvm-svn: 215890
32 lines
830 B
LLVM
32 lines
830 B
LLVM
; RUN: llc -mtriple armv7 -O0 -o - < %s | FileCheck %s -check-prefix CHECK-TAIL
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; RUN: llc -mtriple armv7 -O0 -disable-tail-calls -o - < %s \
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; RUN: | FileCheck %s -check-prefix CHECK-NO-TAIL
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declare i32 @callee(i32 %i)
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declare extern_weak fastcc void @callee_weak()
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define i32 @caller(i32 %i) {
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entry:
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%r = tail call i32 @callee(i32 %i)
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ret i32 %r
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}
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; CHECK-TAIL-LABEL: caller
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; CHECK-TAIL: b callee
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; CHECK-NO-TAIL-LABEL: caller
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; CHECK-NO-TAIL: push {lr}
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; CHECK-NO-TAIL: bl callee
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; CHECK-NO-TAIL: pop {lr}
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; CHECK-NO-TAIL: bx lr
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; Weakly-referenced extern functions cannot be tail-called, as AAELF does
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; not define the behaviour of branch instructions to undefined weak symbols.
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define fastcc void @caller_weak() {
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; CHECK-LABEL: caller_weak:
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; CHECK: bl callee_weak
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tail call void @callee_weak()
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ret void
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}
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