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llvm-project/llvm/test/CodeGen/X86/xray-tail-call-sled.ll

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[XRay] Detect and emit sleds for sibling/tail calls Summary: This change promotes the 'isTailCall(...)' member function to TargetInstrInfo as a query interface for determining on a per-target basis whether a given MachineInstr is a tail call instruction. We build upon this in the XRay instrumentation pass to emit special sleds for tail call optimisations, where we emit the correct kind of sled. The tail call sleds look like a mix between the function entry and function exit sleds. Form-wise, the sled comes before the "jmp" instruction that implements the tail call similar to how we do it for the function entry sled. Functionally, because we know this is a tail call, it behaves much like an exit sled -- i.e. at runtime we may use the exit trampolines instead of a different kind of trampoline. A follow-up change to recognise these sleds will be done in compiler-rt, so that we can start intercepting these initially as exits, but also have the option to have different log entries to more accurately reflect that this is actually a tail call. Reviewers: echristo, rSerge, majnemer Subscribers: mehdi_amini, dberris, llvm-commits Differential Revision: https://reviews.llvm.org/D23986 llvm-svn: 280334
2016-09-01 09:29:13 +08:00
; RUN: llc -filetype=asm -o - -mtriple=x86_64-unknown-linux-gnu < %s | FileCheck %s
define i32 @callee() nounwind noinline uwtable "function-instrument"="xray-always" {
; CHECK: .p2align 1, 0x90
; CHECK-LABEL: Lxray_sled_0:
; CHECK-NEXT: .ascii "\353\t"
; CHECK-NEXT: nopw 512(%rax,%rax)
; CHECK-LABEL: Ltmp0:
ret i32 0
; CHECK: .p2align 1, 0x90
; CHECK-LABEL: Lxray_sled_1:
; CHECK-NEXT: retq
; CHECK-NEXT: nopw %cs:512(%rax,%rax)
}
; CHECK: .p2align 4, 0x90
; CHECK-NEXT: .quad .Lxray_synthetic_0
; CHECK-NEXT: .section xray_instr_map,{{.*}}
; CHECK-LABEL: Lxray_synthetic_0:
; CHECK: .quad .Lxray_sled_0
; CHECK: .quad .Lxray_sled_1
define i32 @caller() nounwind noinline uwtable "function-instrument"="xray-always" {
; CHECK: .p2align 1, 0x90
; CHECK-LABEL: Lxray_sled_2:
; CHECK-NEXT: .ascii "\353\t"
; CHECK-NEXT: nopw 512(%rax,%rax)
; CHECK-LABEL: Ltmp1:
; CHECK: .p2align 1, 0x90
; CHECK-LABEL: Lxray_sled_3:
; CHECK-NEXT: .ascii "\353\t"
; CHECK-NEXT: nopw 512(%rax,%rax)
; CHECK-LABEL: Ltmp2:
%retval = tail call i32 @callee()
; CHECK: jmp callee # TAILCALL
ret i32 %retval
}
; CHECK: .p2align 4, 0x90
; CHECK-NEXT: .quad .Lxray_synthetic_1
; CHECK-LABEL: Lxray_synthetic_1:
; CHECK: .quad .Lxray_sled_2
; CHECK: .quad .Lxray_sled_3