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[RISCV] Do not outline CFI instructions when they are needed in EH 

We saw a failure caused by unwinding with incomplete CFIs, so we
can't outline CFI instructions when they are needed in EH.

This is a recommit of 0d40688, which was reverted in ce83883 as
related precommit test 360d44e caused some errors.

Reviewed By: luismarques

Differential Revision: https://reviews.llvm.org/D122634
This commit is contained in:
wangpc 2022-04-22 12:22:36 +08:00
parent 6ee890b79e
commit 5c3ea07848
2 changed files with 25 additions and 12 deletions
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7
llvm/lib/Target/RISCV/RISCVInstrInfo.cpp
View File

@ -1246,7 +1246,12 @@ RISCVInstrInfo::getOutliningType(MachineBasicBlock::iterator &MBBI,
if (MI.isPosition()) {
// We can manually strip out CFI instructions later.
if (MI.isCFIInstruction())
return outliner::InstrType::Invisible;
// If current function has exception handling code, we can't outline &
// strip these CFI instructions since it may break .eh_frame section
// needed in unwinding.
return MI.getMF()->getFunction().needsUnwindTableEntry()
? outliner::InstrType::Illegal
: outliner::InstrType::Invisible;
return outliner::InstrType::Illegal;
}

30
llvm/test/CodeGen/RISCV/machine-outliner-throw.ll
View File

@ -1,3 +1,4 @@
; NOTE: Assertions have been autogenerated by utils/update_llc_test_checks.py
; RUN: llc -verify-machineinstrs -enable-machine-outliner -mattr=+m -mtriple=riscv64 < %s | FileCheck %s
; Ensure that we won't outline CFIs when they are needed in unwinding.
@ -5,7 +6,15 @@
define i32 @func1(i32 %x) #0 {
; CHECK-LABEL: func1:
; CHECK: # %bb.0: # %entry
; CHECK-NEXT: call t0, OUTLINED_FUNCTION_0
; CHECK-NEXT: addi sp, sp, -16
; CHECK-NEXT: .cfi_def_cfa_offset 16
; CHECK-NEXT: sd ra, 8(sp) # 8-byte Folded Spill
; CHECK-NEXT: sd s0, 0(sp) # 8-byte Folded Spill
; CHECK-NEXT: .cfi_offset ra, -8
; CHECK-NEXT: .cfi_offset s0, -16
; CHECK-NEXT: mulw a0, a0, a0
; CHECK-NEXT: addiw s0, a0, 1
; CHECK-NEXT: li a0, 4
; CHECK-NEXT: call __cxa_allocate_exception@plt
; CHECK-NEXT: sw s0, 0(a0)
; CHECK-NEXT: lui a1, %hi(_ZTIi)
@ -25,7 +34,15 @@ entry:
define i32 @func2(i32 %x) #0 {
; CHECK-LABEL: func2:
; CHECK: # %bb.0: # %entry
; CHECK-NEXT: call t0, OUTLINED_FUNCTION_0
; CHECK-NEXT: addi sp, sp, -16
; CHECK-NEXT: .cfi_def_cfa_offset 16
; CHECK-NEXT: sd ra, 8(sp) # 8-byte Folded Spill
; CHECK-NEXT: sd s0, 0(sp) # 8-byte Folded Spill
; CHECK-NEXT: .cfi_offset ra, -8
; CHECK-NEXT: .cfi_offset s0, -16
; CHECK-NEXT: mulw a0, a0, a0
; CHECK-NEXT: addiw s0, a0, 1
; CHECK-NEXT: li a0, 4
; CHECK-NEXT: call __cxa_allocate_exception@plt
; CHECK-NEXT: sw s0, 0(a0)
; CHECK-NEXT: lui a1, %hi(_ZTIi)
@ -42,15 +59,6 @@ entry:
unreachable
}
; CHECK-LABEL: OUTLINED_FUNCTION_0:
; CHECK: # %bb.0:
; CHECK-NEXT: addi sp, sp, -16
; CHECK-NEXT: sd ra, 8(sp)
; CHECK-NEXT: sd s0, 0(sp)
; CHECK-NEXT: mulw a0, a0, a0
; CHECK-NEXT: addiw s0, a0, 1
; CHECK-NEXT: li a0, 4
@_ZTIi = external constant i8*
declare i8* @__cxa_allocate_exception(i64)
declare void @__cxa_throw(i8*, i8*, i8*)