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[AArch64] Fix verifier error when outlining indirect calls 

The MachineOutliner for AArch64 transforms indirect calls into indirect
tail calls, replacing the call with the TCRETURNri pseudo-instruction.
This pseudo lowers to a BR, but has the isCall and isReturn flags set.

The problem is that TCRETURNri takes a tcGPR64 as the register argument,
to prevent indiret tail-calls from using caller-saved registers. The
indirect calls transformed by the outliner could use caller-saved
registers. This is fine, because the outliner ensures that the register
is available at all call sites. However, this causes a verifier failure
when the register is not in tcGPR64. The fix is to add a new
pseudo-instruction like TCRETURNri, but which accepts any GPR.

Differential revision: https://reviews.llvm.org/D52829

llvm-svn: 343959
This commit is contained in:
Oliver Stannard 2018-10-08 09:18:48 +00:00
parent 5af6c1496a
commit 9ecdac8ee0
4 changed files with 53 additions and 5 deletions
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3
llvm/lib/Target/AArch64/AArch64AsmPrinter.cpp
View File

@ -590,7 +590,8 @@ void AArch64AsmPrinter::EmitInstruction(const MachineInstr *MI) {
// Tail calls use pseudo instructions so they have the proper code-gen
// attributes (isCall, isReturn, etc.). We lower them to the real
// instruction here.
case AArch64::TCRETURNri: {
case AArch64::TCRETURNri:
case AArch64::TCRETURNriALL: {
MCInst TmpInst;
TmpInst.setOpcode(AArch64::BR);
TmpInst.addOperand(MCOperand::createReg(MI->getOperand(0).getReg()));

2
llvm/lib/Target/AArch64/AArch64InstrInfo.cpp
View File

@ -5461,7 +5461,7 @@ void AArch64InstrInfo::buildOutlinedFrame(
TailOpcode = AArch64::TCRETURNdi;
} else {
assert(Call->getOpcode() == AArch64::BLR);
TailOpcode = AArch64::TCRETURNri;
TailOpcode = AArch64::TCRETURNriALL;
}
MachineInstr *TC = BuildMI(MF, DebugLoc(), get(TailOpcode))
.add(Call->getOperand(0))

6
llvm/lib/Target/AArch64/AArch64InstrInfo.td
View File

@ -6635,6 +6635,12 @@ let isCall = 1, isTerminator = 1, isReturn = 1, isBarrier = 1, Uses = [SP] in {
Sched<[WriteBrReg]>;
def TCRETURNri : Pseudo<(outs), (ins tcGPR64:$dst, i32imm:$FPDiff), []>,
Sched<[WriteBrReg]>;
// Indirect tail-call with any register allowed, used by MachineOutliner when
// this is proven safe.
// FIXME: If we have to add any more hacks like this, we should instead relax
// some verifier checks for outlined functions.
def TCRETURNriALL : Pseudo<(outs), (ins GPR64:$dst, i32imm:$FPDiff), []>,
Sched<[WriteBrReg]>;
}
def : Pat<(AArch64tcret tcGPR64:$dst, (i32 timm:$FPDiff)),

47
llvm/test/CodeGen/AArch64/machine-outliner-thunk.ll
View File

@ -12,7 +12,7 @@ define i32 @a() {
; CHECK-NEXT: str x30, [sp, #-16]! // 8-byte Folded Spill
; CHECK-NEXT: .cfi_def_cfa_offset 16
; CHECK-NEXT: .cfi_offset w30, -16
; CHECK-NEXT: bl OUTLINED_FUNCTION_0
; CHECK-NEXT: bl [[OUTLINED_DIRECT:OUTLINED_FUNCTION_[0-9]+]]
; CHECK-NEXT: add w0, w0, #8 // =8
; CHECK-NEXT: ldr x30, [sp], #16 // 8-byte Folded Reload
; CHECK-NEXT: ret
@ -28,7 +28,7 @@ define i32 @b() {
; CHECK-NEXT: str x30, [sp, #-16]! // 8-byte Folded Spill
; CHECK-NEXT: .cfi_def_cfa_offset 16
; CHECK-NEXT: .cfi_offset w30, -16
; CHECK-NEXT: bl OUTLINED_FUNCTION_0
; CHECK-NEXT: bl [[OUTLINED_DIRECT]]
; CHECK-NEXT: add w0, w0, #88 // =88
; CHECK-NEXT: ldr x30, [sp], #16 // 8-byte Folded Reload
; CHECK-NEXT: ret
@ -38,7 +38,48 @@ entry:
ret i32 %cx
}
; CHECK-LABEL: OUTLINED_FUNCTION_0:
define hidden i32 @c(i32 (i32, i32, i32, i32)* %fptr) {
; CHECK-LABEL: c:
; CHECK: // %bb.0: // %entry
; CHECK-NEXT: str x30, [sp, #-16]! // 8-byte Folded Spill
; CHECK-NEXT: .cfi_def_cfa_offset 16
; CHECK-NEXT: .cfi_offset w30, -16
; CHECK-NEXT: bl [[OUTLINED_INDIRECT:OUTLINED_FUNCTION_[0-9]+]]
; CHECK-NEXT: add w0, w0, #8 // =8
; CHECK-NEXT: ldr x30, [sp], #16 // 8-byte Folded Reload
; CHECK-NEXT: ret
entry:
%call = tail call i32 %fptr(i32 1, i32 2, i32 3, i32 4)
%add = add nsw i32 %call, 8
ret i32 %add
}
define hidden i32 @d(i32 (i32, i32, i32, i32)* %fptr) {
; CHECK-LABEL: d:
; CHECK: // %bb.0: // %entry
; CHECK-NEXT: str x30, [sp, #-16]! // 8-byte Folded Spill
; CHECK-NEXT: .cfi_def_cfa_offset 16
; CHECK-NEXT: .cfi_offset w30, -16
; CHECK-NEXT: bl [[OUTLINED_INDIRECT]]
; CHECK-NEXT: add w0, w0, #88 // =88
; CHECK-NEXT: ldr x30, [sp], #16 // 8-byte Folded Reload
; CHECK-NEXT: ret
entry:
%call = tail call i32 %fptr(i32 1, i32 2, i32 3, i32 4)
%add = add nsw i32 %call, 88
ret i32 %add
}
; CHECK: [[OUTLINED_INDIRECT]]:
; CHECK: // %bb.0:
; CHECK-NEXT: mov x8, x0
; CHECK-NEXT: orr w0, wzr, #0x1
; CHECK-NEXT: orr w1, wzr, #0x2
; CHECK-NEXT: orr w2, wzr, #0x3
; CHECK-NEXT: orr w3, wzr, #0x4
; CHECK-NEXT: br x8
; CHECK: [[OUTLINED_DIRECT]]:
; CHECK: // %bb.0:
; CHECK-NEXT: orr w0, wzr, #0x1
; CHECK-NEXT: orr w1, wzr, #0x2