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LiveIntervals: Split live intervals on multiple dead defs 

This is a follow-up to D67448.

Split live intervals with multiple dead defs during the initial
execution of the live interval analysis, but do it outside of the
function createAndComputeVirtRegInterval.

Differential Revision: https://reviews.llvm.org/D68666
This commit is contained in:
Krzysztof Parzyszek 2019-10-30 08:21:27 -05:00
parent 83a55c6a57
commit 43144ffa91
4 changed files with 21 additions and 11 deletions
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2
llvm/include/llvm/CodeGen/LiveIntervals.h
View File

@ -469,7 +469,7 @@ class VirtRegMap;
void computeLiveInRegUnits();
void computeRegUnitRange(LiveRange&, unsigned Unit);
void computeVirtRegInterval(LiveInterval&);
bool computeVirtRegInterval(LiveInterval&);
using ShrinkToUsesWorkList = SmallVector<std::pair<SlotIndex, VNInfo*>, 16>;
void extendSegmentsToUses(LiveRange &Segments,

17
llvm/lib/CodeGen/LiveIntervals.cpp
View File

@ -191,12 +191,12 @@ LiveInterval* LiveIntervals::createInterval(unsigned reg) {
}
/// Compute the live interval of a virtual register, based on defs and uses.
void LiveIntervals::computeVirtRegInterval(LiveInterval &LI) {
bool LiveIntervals::computeVirtRegInterval(LiveInterval &LI) {
assert(LRCalc && "LRCalc not initialized.");
assert(LI.empty() && "Should only compute empty intervals.");
LRCalc->reset(MF, getSlotIndexes(), DomTree, &getVNInfoAllocator());
LRCalc->calculate(LI, MRI->shouldTrackSubRegLiveness(LI.reg));
computeDeadValues(LI, nullptr);
return computeDeadValues(LI, nullptr);
}
void LiveIntervals::computeVirtRegs() {
@ -204,7 +204,12 @@ void LiveIntervals::computeVirtRegs() {
unsigned Reg = Register::index2VirtReg(i);
if (MRI->reg_nodbg_empty(Reg))
continue;
createAndComputeVirtRegInterval(Reg);
LiveInterval &LI = createEmptyInterval(Reg);
bool NeedSplit = computeVirtRegInterval(LI);
if (NeedSplit) {
SmallVector<LiveInterval*, 8> SplitLIs;
splitSeparateComponents(LI, SplitLIs);
}
}
}
@ -500,6 +505,8 @@ bool LiveIntervals::shrinkToUses(LiveInterval *li,
bool LiveIntervals::computeDeadValues(LiveInterval &LI,
SmallVectorImpl<MachineInstr*> *dead) {
bool MayHaveSplitComponents = false;
bool HaveDeadDef = false;
for (VNInfo *VNI : LI.valnos) {
if (VNI->isUnused())
continue;
@ -530,6 +537,10 @@ bool LiveIntervals::computeDeadValues(LiveInterval &LI,
MachineInstr *MI = getInstructionFromIndex(Def);
assert(MI && "No instruction defining live value");
MI->addRegisterDead(LI.reg, TRI);
if (HaveDeadDef)
MayHaveSplitComponents = true;
HaveDeadDef = true;
if (dead && MI->allDefsAreDead()) {
LLVM_DEBUG(dbgs() << "All defs dead: " << Def << '\t' << *MI);
dead->push_back(MI);

8
llvm/test/DebugInfo/WebAssembly/dbg-value-move-reg-stackify.mir
View File

@ -1,10 +1,10 @@
# RUN: llc < %s -run-pass=wasm-reg-stackify -x=mir 2>&1 | FileCheck %s
# CHECK: body:
# CHECK: %1:i32 = I32_WRAP_I64 %0,
# CHECK-NEXT: DBG_VALUE %1,
# CHECK-NEXT: %1:i32 = CALL_i32 @bar,
# CHECK-NEXT: DBG_VALUE %1,
# CHECK: dead %3:i32 = I32_WRAP_I64 %0,
# CHECK-NEXT: DBG_VALUE %1:i32
# CHECK-NEXT: dead %2:i32 = CALL_i32 @bar,
# CHECK-NEXT: DBG_VALUE %1:i32,
# CHECK-NEXT: %[[NEWREG:.*]]:i32 = CALL_i32 @bar,
# CHECK-NEXT: DBG_VALUE %[[NEWREG]],
# CHECK-NEXT: CALL_VOID @foo, %[[NEWREG]],

5
llvm/test/DebugInfo/X86/live-debug-vars-discard-invalid.mir
View File

@ -1,5 +1,4 @@
# FIXME: Fix machine verifier issues and remove -verify-machineinstrs=0. PR39481.
# RUN: llc -mtriple=x86_64-linux-gnu -start-before greedy -stop-after virtregrewriter -o - -verify-machineinstrs=0 %s | FileCheck %s
# RUN: llc -mtriple=x86_64-linux-gnu -start-before greedy -stop-after virtregrewriter -o - -verify-machineinstrs %s | FileCheck %s
--- |
; ModuleID = '<stdin>'
@ -115,7 +114,7 @@ body: |
# CHECK-NEXT: dead renamable $rcx = IMPLICIT_DEF
# CHECK-NEXT: dead renamable $rcx = IMPLICIT_DEF
# CHECK-NEXT: dead renamable $rcx = IMPLICIT_DEF
# CHECK-NEXT: DBG_VALUE $rcx, $noreg, !18, !DIExpression()
# CHECK-NEXT: DBG_VALUE $noreg, $noreg, !18, !DIExpression()
# CHECK-LABEL: bb.3:
# CHECK: dead renamable $rcx = IMPLICIT_DEF