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36d0cb3fd9
This matches GCC and MSVC's behaviour, and saves on code size. We were already not extending i1 return values on x86_64 after r127766. This takes that patch further by applying it to x86 target as well, and also for i8 and i16. The ABI docs have been unclear about the required behaviour here. The new i386 psABI [1] clearly states (Table 2.4, page 14) that i1, i8, and i16 return vales do not need to be extended beyond 8 bits. The x86_64 ABI doc is being updated to say the same [2]. Differential Revision: http://reviews.llvm.org/D16907 [1]. https://01.org/sites/default/files/file_attach/intel386-psabi-1.0.pdf [2]. https://groups.google.com/d/msg/x86-64-abi/E8O33onbnGQ/_RFWw_ixDQAJ llvm-svn: 260133
57 lines
1.7 KiB
LLVM
57 lines
1.7 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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; FIXME: The high 24 bits returned from test_i32 are undefined; do tail call!
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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: 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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; FIXME: The high 16 bits returned are undefined; do tail call!
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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: 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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