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If the tail-callee and caller give the same bits via the same signext/zeroext attribute then a tail-call should be allowed, since the extension has already been done by the callee. llvm-svn: 188159
57 lines
1.6 KiB
LLVM
57 lines
1.6 KiB
LLVM
; RUN: llc -mtriple=x86_64-apple-darwin -o - %s | FileCheck %s
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; Simple case: completely identical returns, even with extensions, shouldn't be
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; a barrier to tail calls.
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declare zeroext i1 @give_bool()
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define zeroext i1 @test_bool() {
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; CHECK-LABEL: test_bool:
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; CHECK: jmp
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%call = tail call zeroext i1 @give_bool()
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ret i1 %call
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}
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; Here, there's more zero extension to be done between the call and the return,
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; so a tail call is impossible (well, according to current Clang practice
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; anyway. The AMD64 ABI isn't crystal clear on the matter).
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declare zeroext i32 @give_i32()
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define zeroext i8 @test_i32() {
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; CHECK-LABEL: test_i32:
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; CHECK: callq _give_i32
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; CHECK: movzbl %al, %eax
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; CHECK: ret
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%call = tail call zeroext i32 @give_i32()
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%val = trunc i32 %call to i8
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ret i8 %val
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}
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; Here, one function is zeroext and the other is signext. To the extent that
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; these both mean something they are incompatible so no tail call is possible.
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declare zeroext i16 @give_unsigned_i16()
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define signext i16 @test_incompatible_i16() {
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; CHECK-LABEL: test_incompatible_i16:
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; CHECK: callq _give_unsigned_i16
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; CHECK: cwtl
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; CHECK: ret
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%call = tail call zeroext i16 @give_unsigned_i16()
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ret i16 %call
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}
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declare inreg i32 @give_i32_inreg()
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define i32 @test_inreg_to_normal() {
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; CHECK-LABEL: test_inreg_to_normal:
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; CHECK: callq _give_i32_inreg
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; CHECK: ret
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%val = tail call inreg i32 @give_i32_inreg()
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ret i32 %val
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}
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define inreg i32 @test_normal_to_inreg() {
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; CHECK-LABEL: test_normal_to_inreg:
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; CHECK: callq _give_i32
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; CHECK: ret
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%val = tail call i32 @give_i32()
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ret i32 %val
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}
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