[llvm] r366570 - [MachineCSE][MachinePRE] Avoid hoisting code from code regions into hot BBs.
Kai Luo via llvm-commits
llvm-commits at lists.llvm.org
Fri Jul 19 05:58:16 PDT 2019
Author: lkail
Date: Fri Jul 19 05:58:16 2019
New Revision: 366570
URL: http://llvm.org/viewvc/llvm-project?rev=366570&view=rev
Log:
[MachineCSE][MachinePRE] Avoid hoisting code from code regions into hot BBs.
Summary:
Current PRE hoists common computations into
CMBB = DT->findNearestCommonDominator(MBB, MBB1).
However, if CMBB is in a hot loop body, we might get performance
degradation.
Differential Revision: https://reviews.llvm.org/D64394
Modified:
llvm/trunk/lib/CodeGen/MachineCSE.cpp
llvm/trunk/test/CodeGen/AArch64/O3-pipeline.ll
llvm/trunk/test/CodeGen/ARM/O3-pipeline.ll
llvm/trunk/test/CodeGen/PowerPC/machine-pre.ll
llvm/trunk/test/CodeGen/X86/O3-pipeline.ll
Modified: llvm/trunk/lib/CodeGen/MachineCSE.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/CodeGen/MachineCSE.cpp?rev=366570&r1=366569&r2=366570&view=diff
==============================================================================
--- llvm/trunk/lib/CodeGen/MachineCSE.cpp (original)
+++ llvm/trunk/lib/CodeGen/MachineCSE.cpp Fri Jul 19 05:58:16 2019
@@ -21,6 +21,7 @@
#include "llvm/Analysis/AliasAnalysis.h"
#include "llvm/Analysis/CFG.h"
#include "llvm/CodeGen/MachineBasicBlock.h"
+#include "llvm/CodeGen/MachineBlockFrequencyInfo.h"
#include "llvm/CodeGen/MachineDominators.h"
#include "llvm/CodeGen/MachineFunction.h"
#include "llvm/CodeGen/MachineFunctionPass.h"
@@ -66,6 +67,7 @@ namespace {
AliasAnalysis *AA;
MachineDominatorTree *DT;
MachineRegisterInfo *MRI;
+ MachineBlockFrequencyInfo *MBFI;
public:
static char ID; // Pass identification
@@ -83,6 +85,8 @@ namespace {
AU.addPreservedID(MachineLoopInfoID);
AU.addRequired<MachineDominatorTree>();
AU.addPreserved<MachineDominatorTree>();
+ AU.addRequired<MachineBlockFrequencyInfo>();
+ AU.addPreserved<MachineBlockFrequencyInfo>();
}
void releaseMemory() override {
@@ -133,6 +137,11 @@ namespace {
bool isPRECandidate(MachineInstr *MI);
bool ProcessBlockPRE(MachineDominatorTree *MDT, MachineBasicBlock *MBB);
bool PerformSimplePRE(MachineDominatorTree *DT);
+ /// Heuristics to see if it's beneficial to move common computations of MBB
+ /// and MBB1 to CandidateBB.
+ bool isBeneficalToHoistInto(MachineBasicBlock *CandidateBB,
+ MachineBasicBlock *MBB,
+ MachineBasicBlock *MBB1);
};
} // end anonymous namespace
@@ -802,6 +811,9 @@ bool MachineCSE::ProcessBlockPRE(Machine
if (!CMBB->isLegalToHoistInto())
continue;
+ if (!isBeneficalToHoistInto(CMBB, MBB, MBB1))
+ continue;
+
// Two instrs are partial redundant if their basic blocks are reachable
// from one to another but one doesn't dominate another.
if (CMBB != MBB1) {
@@ -854,6 +866,18 @@ bool MachineCSE::PerformSimplePRE(Machin
return Changed;
}
+bool MachineCSE::isBeneficalToHoistInto(MachineBasicBlock *CandidateBB,
+ MachineBasicBlock *MBB,
+ MachineBasicBlock *MBB1) {
+ if (CandidateBB->getParent()->getFunction().hasMinSize())
+ return true;
+ assert(DT->dominates(CandidateBB, MBB) && "CandidateBB should dominate MBB");
+ assert(DT->dominates(CandidateBB, MBB1) &&
+ "CandidateBB should dominate MBB1");
+ return MBFI->getBlockFreq(CandidateBB) <=
+ MBFI->getBlockFreq(MBB) + MBFI->getBlockFreq(MBB1);
+}
+
bool MachineCSE::runOnMachineFunction(MachineFunction &MF) {
if (skipFunction(MF.getFunction()))
return false;
@@ -863,6 +887,7 @@ bool MachineCSE::runOnMachineFunction(Ma
MRI = &MF.getRegInfo();
AA = &getAnalysis<AAResultsWrapperPass>().getAAResults();
DT = &getAnalysis<MachineDominatorTree>();
+ MBFI = &getAnalysis<MachineBlockFrequencyInfo>();
LookAheadLimit = TII->getMachineCSELookAheadLimit();
bool ChangedPRE, ChangedCSE;
ChangedPRE = PerformSimplePRE(DT);
Modified: llvm/trunk/test/CodeGen/AArch64/O3-pipeline.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/CodeGen/AArch64/O3-pipeline.ll?rev=366570&r1=366569&r2=366570&view=diff
==============================================================================
--- llvm/trunk/test/CodeGen/AArch64/O3-pipeline.ll (original)
+++ llvm/trunk/test/CodeGen/AArch64/O3-pipeline.ll Fri Jul 19 05:58:16 2019
@@ -98,9 +98,9 @@
; CHECK-NEXT: MachineDominator Tree Construction
; CHECK-NEXT: Machine Natural Loop Construction
; CHECK-NEXT: Early Machine Loop Invariant Code Motion
+; CHECK-NEXT: Machine Block Frequency Analysis
; CHECK-NEXT: Machine Common Subexpression Elimination
; CHECK-NEXT: MachinePostDominator Tree Construction
-; CHECK-NEXT: Machine Block Frequency Analysis
; CHECK-NEXT: Machine code sinking
; CHECK-NEXT: Peephole Optimizations
; CHECK-NEXT: Remove dead machine instructions
Modified: llvm/trunk/test/CodeGen/ARM/O3-pipeline.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/CodeGen/ARM/O3-pipeline.ll?rev=366570&r1=366569&r2=366570&view=diff
==============================================================================
--- llvm/trunk/test/CodeGen/ARM/O3-pipeline.ll (original)
+++ llvm/trunk/test/CodeGen/ARM/O3-pipeline.ll Fri Jul 19 05:58:16 2019
@@ -72,9 +72,9 @@
; CHECK-NEXT: MachineDominator Tree Construction
; CHECK-NEXT: Machine Natural Loop Construction
; CHECK-NEXT: Early Machine Loop Invariant Code Motion
+; CHECK-NEXT: Machine Block Frequency Analysis
; CHECK-NEXT: Machine Common Subexpression Elimination
; CHECK-NEXT: MachinePostDominator Tree Construction
-; CHECK-NEXT: Machine Block Frequency Analysis
; CHECK-NEXT: Machine code sinking
; CHECK-NEXT: Peephole Optimizations
; CHECK-NEXT: Remove dead machine instructions
Modified: llvm/trunk/test/CodeGen/PowerPC/machine-pre.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/CodeGen/PowerPC/machine-pre.ll?rev=366570&r1=366569&r2=366570&view=diff
==============================================================================
--- llvm/trunk/test/CodeGen/PowerPC/machine-pre.ll (original)
+++ llvm/trunk/test/CodeGen/PowerPC/machine-pre.ll Fri Jul 19 05:58:16 2019
@@ -8,25 +8,25 @@ define i32 @t(i32 %n, i32 %delta, i32 %a
; CHECK-P9: # %bb.0: # %entry
; CHECK-P9-NEXT: lis r7, 0
; CHECK-P9-NEXT: li r6, 0
+; CHECK-P9-NEXT: li r8, 0
; CHECK-P9-NEXT: li r9, 0
-; CHECK-P9-NEXT: li r10, 0
; CHECK-P9-NEXT: ori r7, r7, 65535
; CHECK-P9-NEXT: .p2align 5
; CHECK-P9-NEXT: .LBB0_1: # %header
; CHECK-P9-NEXT: #
-; CHECK-P9-NEXT: addi r10, r10, 1
-; CHECK-P9-NEXT: cmpw r10, r3
-; CHECK-P9-NEXT: addi r8, r5, 1024
+; CHECK-P9-NEXT: addi r9, r9, 1
+; CHECK-P9-NEXT: cmpw r9, r3
; CHECK-P9-NEXT: blt cr0, .LBB0_4
; CHECK-P9-NEXT: # %bb.2: # %cont
; CHECK-P9-NEXT: #
-; CHECK-P9-NEXT: add r9, r9, r4
-; CHECK-P9-NEXT: cmpw r9, r7
+; CHECK-P9-NEXT: add r8, r8, r4
+; CHECK-P9-NEXT: cmpw r8, r7
; CHECK-P9-NEXT: bgt cr0, .LBB0_1
; CHECK-P9-NEXT: # %bb.3: # %cont.1
-; CHECK-P9-NEXT: mr r6, r8
+; CHECK-P9-NEXT: addi r6, r5, 1024
; CHECK-P9-NEXT: .LBB0_4: # %return
-; CHECK-P9-NEXT: mullw r3, r6, r8
+; CHECK-P9-NEXT: addi r3, r5, 1024
+; CHECK-P9-NEXT: mullw r3, r6, r3
; CHECK-P9-NEXT: blr
entry:
br label %header
@@ -75,16 +75,19 @@ define dso_local signext i32 @foo(i32 si
; CHECK-P9-NEXT: lis r3, 21845
; CHECK-P9-NEXT: add r28, r30, r29
; CHECK-P9-NEXT: ori r27, r3, 21846
-; CHECK-P9-NEXT: b .LBB1_3
+; CHECK-P9-NEXT: b .LBB1_4
; CHECK-P9-NEXT: .p2align 4
; CHECK-P9-NEXT: .LBB1_1: # %sw.bb3
; CHECK-P9-NEXT: #
-; CHECK-P9-NEXT: add r28, r3, r28
+; CHECK-P9-NEXT: mulli r3, r30, 23
; CHECK-P9-NEXT: .LBB1_2: # %sw.epilog
; CHECK-P9-NEXT: #
+; CHECK-P9-NEXT: add r28, r3, r28
+; CHECK-P9-NEXT: .LBB1_3: # %sw.epilog
+; CHECK-P9-NEXT: #
; CHECK-P9-NEXT: cmpwi r28, 1025
-; CHECK-P9-NEXT: bge cr0, .LBB1_6
-; CHECK-P9-NEXT: .LBB1_3: # %while.cond
+; CHECK-P9-NEXT: bge cr0, .LBB1_7
+; CHECK-P9-NEXT: .LBB1_4: # %while.cond
; CHECK-P9-NEXT: #
; CHECK-P9-NEXT: extsw r3, r29
; CHECK-P9-NEXT: bl bar
@@ -101,41 +104,40 @@ define dso_local signext i32 @foo(i32 si
; CHECK-P9-NEXT: add r4, r4, r5
; CHECK-P9-NEXT: slwi r5, r4, 1
; CHECK-P9-NEXT: add r4, r4, r5
-; CHECK-P9-NEXT: subf r5, r4, r3
-; CHECK-P9-NEXT: mulli r4, r29, 13
-; CHECK-P9-NEXT: mulli r3, r30, 23
-; CHECK-P9-NEXT: cmplwi r5, 1
+; CHECK-P9-NEXT: subf r3, r4, r3
+; CHECK-P9-NEXT: cmplwi r3, 1
; CHECK-P9-NEXT: beq cr0, .LBB1_1
-; CHECK-P9-NEXT: # %bb.4: # %while.cond
-; CHECK-P9-NEXT: #
-; CHECK-P9-NEXT: cmplwi r5, 0
-; CHECK-P9-NEXT: bne cr0, .LBB1_2
-; CHECK-P9-NEXT: # %bb.5: # %sw.bb
+; CHECK-P9-NEXT: # %bb.5: # %while.cond
; CHECK-P9-NEXT: #
-; CHECK-P9-NEXT: add r28, r4, r28
-; CHECK-P9-NEXT: cmpwi r28, 1025
-; CHECK-P9-NEXT: blt cr0, .LBB1_3
-; CHECK-P9-NEXT: .LBB1_6: # %while.end
-; CHECK-P9-NEXT: lis r5, -13108
-; CHECK-P9-NEXT: ori r5, r5, 52429
-; CHECK-P9-NEXT: mullw r5, r28, r5
-; CHECK-P9-NEXT: lis r6, 13107
-; CHECK-P9-NEXT: ori r6, r6, 13108
-; CHECK-P9-NEXT: cmplw r5, r6
-; CHECK-P9-NEXT: blt cr0, .LBB1_8
-; CHECK-P9-NEXT: # %bb.7: # %if.then8
-; CHECK-P9-NEXT: extsw r4, r4
-; CHECK-P9-NEXT: extsw r5, r28
+; CHECK-P9-NEXT: cmplwi r3, 0
+; CHECK-P9-NEXT: bne cr0, .LBB1_3
+; CHECK-P9-NEXT: # %bb.6: # %sw.bb
+; CHECK-P9-NEXT: #
+; CHECK-P9-NEXT: mulli r3, r29, 13
+; CHECK-P9-NEXT: b .LBB1_2
+; CHECK-P9-NEXT: .LBB1_7: # %while.end
+; CHECK-P9-NEXT: lis r3, -13108
+; CHECK-P9-NEXT: ori r3, r3, 52429
+; CHECK-P9-NEXT: mullw r3, r28, r3
+; CHECK-P9-NEXT: lis r4, 13107
+; CHECK-P9-NEXT: ori r4, r4, 13108
+; CHECK-P9-NEXT: cmplw r3, r4
+; CHECK-P9-NEXT: blt cr0, .LBB1_9
+; CHECK-P9-NEXT: # %bb.8: # %if.then8
+; CHECK-P9-NEXT: mulli r3, r29, 13
+; CHECK-P9-NEXT: mulli r5, r30, 23
+; CHECK-P9-NEXT: extsw r4, r28
; CHECK-P9-NEXT: extsw r3, r3
+; CHECK-P9-NEXT: extsw r5, r5
+; CHECK-P9-NEXT: sub r3, r4, r3
; CHECK-P9-NEXT: sub r4, r5, r4
-; CHECK-P9-NEXT: sub r3, r3, r5
-; CHECK-P9-NEXT: rldicl r4, r4, 1, 63
; CHECK-P9-NEXT: rldicl r3, r3, 1, 63
-; CHECK-P9-NEXT: or r3, r4, r3
-; CHECK-P9-NEXT: b .LBB1_9
-; CHECK-P9-NEXT: .LBB1_8: # %cleanup20
-; CHECK-P9-NEXT: li r3, 0
+; CHECK-P9-NEXT: rldicl r4, r4, 1, 63
+; CHECK-P9-NEXT: or r3, r3, r4
+; CHECK-P9-NEXT: b .LBB1_10
; CHECK-P9-NEXT: .LBB1_9: # %cleanup20
+; CHECK-P9-NEXT: li r3, 0
+; CHECK-P9-NEXT: .LBB1_10: # %cleanup20
; CHECK-P9-NEXT: addi r1, r1, 80
; CHECK-P9-NEXT: ld r0, 16(r1)
; CHECK-P9-NEXT: mtlr r0
Modified: llvm/trunk/test/CodeGen/X86/O3-pipeline.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/CodeGen/X86/O3-pipeline.ll?rev=366570&r1=366569&r2=366570&view=diff
==============================================================================
--- llvm/trunk/test/CodeGen/X86/O3-pipeline.ll (original)
+++ llvm/trunk/test/CodeGen/X86/O3-pipeline.ll Fri Jul 19 05:58:16 2019
@@ -84,9 +84,9 @@
; CHECK-NEXT: MachineDominator Tree Construction
; CHECK-NEXT: Machine Natural Loop Construction
; CHECK-NEXT: Early Machine Loop Invariant Code Motion
+; CHECK-NEXT: Machine Block Frequency Analysis
; CHECK-NEXT: Machine Common Subexpression Elimination
; CHECK-NEXT: MachinePostDominator Tree Construction
-; CHECK-NEXT: Machine Block Frequency Analysis
; CHECK-NEXT: Machine code sinking
; CHECK-NEXT: Peephole Optimizations
; CHECK-NEXT: Remove dead machine instructions
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