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MipsDelaySlotFiller: Update registers def-uses for BUNDLE instructions 

Summary:
In commit b91f239485 I updated the
MipsDelaySlotFiller to skip BUNDLE instructions.
However, in addition to not considering BUNDLE instructions for the delay
slot, we also need to ensure that the register def-use information is
updated. Not updating this information caused run-time crashes (when using
the out-of-tree CHERI backend) since later definitions could be overwritten
with earlier register values.

Reviewers: atanasyan
Reviewed By: atanasyan
Differential Revision: https://reviews.llvm.org/D72254
This commit is contained in:
Alex Richardson 2020-01-07 12:31:18 +00:00
parent 1444e6e2e6
commit 646ca7d7e7
2 changed files with 114 additions and 2 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

12
llvm/lib/Target/Mips/MipsDelaySlotFiller.cpp
View File

@ -416,8 +416,14 @@ bool RegDefsUses::update(const MachineInstr &MI, unsigned Begin, unsigned End) {
for (unsigned I = Begin; I != End; ++I) {
const MachineOperand &MO = MI.getOperand(I);
if (MO.isReg() && MO.getReg())
HasHazard |= checkRegDefsUses(NewDefs, NewUses, MO.getReg(), MO.isDef());
if (MO.isReg() && MO.getReg()) {
if (checkRegDefsUses(NewDefs, NewUses, MO.getReg(), MO.isDef())) {
LLVM_DEBUG(dbgs() << DEBUG_TYPE ": found register hazard for operand "
<< I << ": ";
MO.dump());
HasHazard = true;
}
}
}
Defs |= NewDefs;
@ -698,6 +704,8 @@ bool MipsDelaySlotFiller::searchRange(MachineBasicBlock &MBB, IterTy Begin,
if (CurrI->isBundle()) {
LLVM_DEBUG(dbgs() << DEBUG_TYPE ": ignoring BUNDLE instruction: ";
CurrI->dump());
// However, we still need to update the register def-use information.
RegDU.update(*CurrI, 0, CurrI->getNumOperands());
continue;
}

104
llvm/test/CodeGen/Mips/delay-slot-filler-bundled-insts-def-use.mir Normal file
View File

@ -0,0 +1,104 @@
# NOTE: Assertions have been autogenerated by utils/update_mir_test_checks.py
## Check that the delay-slot filler looks at the registers defined by BUNDLE instructions
# RUN: llc %s -run-pass=mips-delay-slot-filler -verify-machineinstrs -o - | FileCheck %s
--- |
; ModuleID = '/Users/alex/cheri/llvm-project/llvm/test/CodeGen/Mips/delay-test.ll'
source_filename = "/Users/alex/cheri/llvm-project/llvm/test/CodeGen/Mips/delay-test.ll"
target datalayout = "E-m:e-i8:8:32-i16:16:32-i64:64-n32:64-S128"
target triple = "mips64-unknown-freebsd"
; Function Attrs: nounwind
define i64 @test(i1 %cond) local_unnamed_addr #0 {
entry:
br i1 %cond, label %err, label %return
err: ; preds = %entry
unreachable
return: ; preds = %entry
ret i64 1
}
attributes #0 = { nounwind }
...
---
name: test
alignment: 8
exposesReturnsTwice: false
legalized: false
regBankSelected: false
selected: false
failedISel: false
tracksRegLiveness: true
hasWinCFI: false
registers: []
liveins:
- { reg: '$a0_64', virtual-reg: '' }
frameInfo:
isFrameAddressTaken: false
isReturnAddressTaken: false
hasStackMap: false
hasPatchPoint: false
stackSize: 0
offsetAdjustment: 0
maxAlignment: 1
adjustsStack: false
hasCalls: false
stackProtector: ''
maxCallFrameSize: 0
cvBytesOfCalleeSavedRegisters: 0
hasOpaqueSPAdjustment: false
hasVAStart: false
hasMustTailInVarArgFunc: false
localFrameSize: 0
savePoint: ''
restorePoint: ''
fixedStack: []
stack: []
callSites: []
constants: []
machineFunctionInfo: {}
body: |
; CHECK-LABEL: name: test
; CHECK: bb.0.entry:
; CHECK: successors: %bb.2(0x00000001), %bb.1(0x7fffffff)
; CHECK: renamable $at = SLL renamable $a0, 0, implicit killed $a0_64
; CHECK: renamable $at = ANDi killed renamable $at, 1
; CHECK: $v0_64 = DADDiu $zero_64, 1
; CHECK: $v0_64 = DADDiu $v0_64, 1
; CHECK: BUNDLE implicit-def $v0_64 {
; CHECK: $v0_64 = DADDiu $zero_64, 1
; CHECK: $v0_64 = DADDiu $v0_64, 1
; CHECK: }
; CHECK: BNE killed renamable $at, $zero, %bb.2, implicit-def $at {
; CHECK: NOP
; CHECK: }
; CHECK: bb.1.return:
; CHECK: PseudoReturn64 undef $ra_64, implicit killed $v0_64 {
; CHECK: NOP
; CHECK: }
; CHECK: bb.2.err:
bb.0.entry:
successors: %bb.1(0x00000001), %bb.2(0x7fffffff)
liveins: $a0_64
renamable $at = SLL renamable $a0, 0, implicit killed $a0_64
renamable $at = ANDi killed renamable $at, 1
; Check that none of these instructions are hoisted after the BUNDLE to avoid
; incorrect values from being
$v0_64 = DADDiu $zero_64, 1
$v0_64 = DADDiu $v0_64, 1
BUNDLE implicit-def $v0_64 {
$v0_64 = DADDiu $zero_64, 1
$v0_64 = DADDiu $v0_64, 1
}
BNE killed renamable $at, $zero, %bb.1, implicit-def $at
bb.2.return:
liveins: $v0_64
PseudoReturn64 undef $ra_64, implicit killed $v0_64
bb.1.err:
...