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[XRay][CodeGen][PowerPC] Fix tail exit codegen for XRay in PPC 

Summary:
This fixes code-gen for XRay in PPC. The regression wasn't caught by
codegen tests  which we add in this change.

What happened was the following:

- For tail exits, we used to unconditionally prepend the returns/exits
  with a pseudo-instruction that gets lowered to the instrumentation
  sled (and leave the actual return/exit instruction as-is).
- Changes to the XRay instrumentation pass caused the tail exits to
  suddenly also emit the tail exit pseudo-instruction, since the check
  for whether a return instruction was also a call instruction meant it
  was a tail exit instruction.
- None of the tests caught the regression either due to non-existent
  tests, or the tests being disabled/removed for continuous breakage.

This change re-introduces some of the basic tests and verifies that
we're back to a state that allows the back-end to generate appropriate
XRay instrumented binaries for PPC in the presence of tail exits.

Reviewers: echristo, timshen

Subscribers: nemanjai, kbarton, llvm-commits

Differential Revision: https://reviews.llvm.org/D37570

llvm-svn: 312772
This commit is contained in:
Dean Michael Berris 2017-09-08 01:47:56 +00:00
parent 0ff545c018
commit 711dec260f
5 changed files with 123 additions and 16 deletions
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23
llvm/lib/CodeGen/XRayInstrumentation.cpp
View File

@ -14,8 +14,8 @@
//
//===---------------------------------------------------------------------===//
#include "llvm/ADT/SmallVector.h"
#include "llvm/ADT/STLExtras.h"
#include "llvm/ADT/SmallVector.h"
#include "llvm/ADT/Triple.h"
#include "llvm/CodeGen/MachineBasicBlock.h"
#include "llvm/CodeGen/MachineDominators.h"
@ -109,22 +109,13 @@ void XRayInstrumentation::replaceRetWithPatchableRet(
void XRayInstrumentation::prependRetWithPatchableExit(
MachineFunction &MF, const TargetInstrInfo *TII) {
for (auto &MBB : MF) {
for (auto &T : MBB.terminators()) {
unsigned Opc = 0;
for (auto &MBB : MF)
for (auto &T : MBB.terminators())
if (T.isReturn()) {
Opc = TargetOpcode::PATCHABLE_FUNCTION_EXIT;
// Prepend the return instruction with PATCHABLE_FUNCTION_EXIT.
BuildMI(MBB, T, T.getDebugLoc(),
TII->get(TargetOpcode::PATCHABLE_FUNCTION_EXIT));
}
if (TII->isTailCall(T)) {
Opc = TargetOpcode::PATCHABLE_TAIL_CALL;
}
if (Opc != 0) {
// Prepend the return instruction with PATCHABLE_FUNCTION_EXIT or
// PATCHABLE_TAIL_CALL .
BuildMI(MBB, T, T.getDebugLoc(), TII->get(Opc));
}
}
}
}
bool XRayInstrumentation::runOnMachineFunction(MachineFunction &MF) {
@ -143,7 +134,7 @@ bool XRayInstrumentation::runOnMachineFunction(MachineFunction &MF) {
// Count the number of MachineInstr`s in MachineFunction
int64_t MICount = 0;
for (const auto& MBB : MF)
for (const auto &MBB : MF)
MICount += MBB.size();
// Check if we have a loop.

2
llvm/lib/Target/PowerPC/PPCAsmPrinter.cpp
View File

@ -1131,6 +1131,8 @@ void PPCLinuxAsmPrinter::EmitInstruction(const MachineInstr *MI) {
break;
}
case TargetOpcode::PATCHABLE_TAIL_CALL:
// TODO: Define a trampoline `__xray_FunctionTailExit` and differentiate a
// normal function exit from a tail exit.
case TargetOpcode::PATCHABLE_RET:
// PPC's tail call instruction, e.g. PPC::TCRETURNdi8, doesn't really
// lower to a PPC::B instruction. The PPC::B instruction is generated

44
llvm/test/CodeGen/PowerPC/xray-attribute-instrumentation.ll Normal file
View File

@ -0,0 +1,44 @@
; RUN: llc -filetype=asm -o - -mtriple=powerpc64le-unknown-linux-gnu < %s | FileCheck %s
; RUN: llc -filetype=asm -o - -mtriple=powerpc64le-unknown-linux-gnu \
; RUN: -relocation-model=pic < %s | FileCheck %s
define i32 @foo() nounwind noinline uwtable "function-instrument"="xray-always" {
; CHECK-LABEL: .Ltmp0:
; CHECK: b .Ltmp1
; CHECK-NEXT: nop
; CHECK-NEXT: std 0, -8(1)
; CHECK-NEXT: mflr 0
; CHECK-NEXT: bl __xray_FunctionEntry
; CHECK-NEXT: nop
; CHECK-NEXT: mtlr 0
; CHECK-LABEL: .Ltmp1:
ret i32 0
; CHECK-LABEL: .Ltmp2:
; CHECK: blr
; CHECK-NEXT: nop
; CHECK-NEXT: std 0, -8(1)
; CHECK-NEXT: mflr 0
; CHECK-NEXT: bl __xray_FunctionExit
; CHECK-NEXT: nop
; CHECK-NEXT: mtlr 0
}
; CHECK-LABEL: xray_instr_map,"awo",@progbits,.text,unique,1
; CHECK: .Lxray_sleds_start0:
; CHECK-NEXT: .quad .Ltmp0
; CHECK-NEXT: .quad foo
; CHECK-NEXT: .byte 0x00
; CHECK-NEXT: .byte 0x01
; CHECK-NEXT: .byte 0x00
; CHECK-NEXT: .space 13
; CHECK-NEXT: .quad .Ltmp2
; CHECK-NEXT: .quad foo
; CHECK-NEXT: .byte 0x01
; CHECK-NEXT: .byte 0x01
; CHECK-NEXT: .byte 0x00
; CHECK-NEXT: .space 13
; CHECK-NEXT: .Lxray_sleds_end0:
; CHECK-LABEL: xray_fn_idx,"awo",@progbits,.text,unique,1
; CHECK: .p2align 4
; CHECK-NEXT: .quad .Lxray_sleds_start0
; CHECK-NEXT: .quad .Lxray_sleds_end0
; CHECK-NEXT: .text

26
llvm/test/CodeGen/PowerPC/xray-tail-call-hidden.ll Normal file
View File

@ -0,0 +1,26 @@
; RUN: llc -filetype=asm -o - -mtriple=powerpc64le-unknown-linux-gnu < %s | FileCheck %s
declare hidden i32 @callee() nounwind noinline uwtable "function-instrument"="xray-always"
define i32 @caller() nounwind noinline uwtable "function-instrument"="xray-always" {
; CHECK-LABEL: .Ltmp0:
; CHECK: b .Ltmp1
; CHECK-NEXT: nop
; CHECK-NEXT: std 0, -8(1)
; CHECK-NEXT: mflr 0
; CHECK-NEXT: bl __xray_FunctionEntry
; CHECK-NEXT: nop
; CHECK-NEXT: mtlr 0
; CHECK-LABEL: .Ltmp1:
%retval = tail call i32 @callee()
ret i32 %retval
; CHECK-LABEL: .Ltmp2:
; CHECK: b callee
; CHECK-NEXT: nop
; CHECK-NEXT: std 0, -8(1)
; CHECK-NEXT: mflr 0
; CHECK-NEXT: bl __xray_FunctionExit
; CHECK-NEXT: nop
; CHECK-NEXT: mtlr 0
}

44
llvm/test/CodeGen/PowerPC/xray-tail-call-sled.ll Normal file
View File

@ -0,0 +1,44 @@
; RUN: llc -filetype=asm -o - -mtriple=powerpc64le-unknown-linux-gnu < %s | FileCheck %s
define i32 @callee() nounwind noinline uwtable "function-instrument"="xray-always" {
; CHECK-LABEL: .Ltmp0:
; CHECK: b .Ltmp1
; CHECK-NEXT: nop
; CHECK-NEXT: std 0, -8(1)
; CHECK-NEXT: mflr 0
; CHECK-NEXT: bl __xray_FunctionEntry
; CHECK-NEXT: nop
; CHECK-NEXT: mtlr 0
; CHECK-LABEL: .Ltmp1:
ret i32 0
; CHECK-LABEL: .Ltmp2:
; CHECK: blr
; CHECK-NEXT: nop
; CHECK-NEXT: std 0, -8(1)
; CHECK-NEXT: mflr 0
; CHECK-NEXT: bl __xray_FunctionExit
; CHECK-NEXT: nop
; CHECK-NEXT: mtlr 0
}
define i32 @caller() nounwind noinline uwtable "function-instrument"="xray-always" {
; CHECK-LABEL: .Ltmp3:
; CHECK: b .Ltmp4
; CHECK-NEXT: nop
; CHECK-NEXT: std 0, -8(1)
; CHECK-NEXT: mflr 0
; CHECK-NEXT: bl __xray_FunctionEntry
; CHECK-NEXT: nop
; CHECK-NEXT: mtlr 0
; CHECK-LABEL: .Ltmp4:
%retval = tail call i32 @callee()
ret i32 %retval
; CHECK-LABEL: .Ltmp5:
; CHECK: blr
; CHECK-NEXT: nop
; CHECK-NEXT: std 0, -8(1)
; CHECK-NEXT: mflr 0
; CHECK-NEXT: bl __xray_FunctionExit
; CHECK-NEXT: nop
; CHECK-NEXT: mtlr 0
}