[llvm] r246104 - Assign weights to edges to jump table / bit test header when lowering switch statement.
Cong Hou via llvm-commits
llvm-commits at lists.llvm.org
Wed Aug 26 16:15:33 PDT 2015
Author: conghou
Date: Wed Aug 26 18:15:32 2015
New Revision: 246104
URL: http://llvm.org/viewvc/llvm-project?rev=246104&view=rev
Log:
Assign weights to edges to jump table / bit test header when lowering switch statement.
Currently, when lowering switch statement and a new basic block is built for jump table / bit test header, the edge to this new block is not assigned with a correct weight. This patch collects the edge weight from all its successors and assign this sum of weights to the edge (and also the other fall-through edge). Test cases are adjusted accordingly.
Differential Revision: http://reviews.llvm.org/D12166#fae6eca7
Modified:
llvm/trunk/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp
llvm/trunk/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.h
llvm/trunk/test/CodeGen/ARM/jump-table-islands.ll
llvm/trunk/test/CodeGen/Mips/nacl-align.ll
llvm/trunk/test/CodeGen/X86/switch-jump-table.ll
llvm/trunk/test/CodeGen/X86/switch.ll
llvm/trunk/test/CodeGen/X86/x86-shrink-wrapping.ll
Modified: llvm/trunk/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp?rev=246104&r1=246103&r2=246104&view=diff
==============================================================================
--- llvm/trunk/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp (original)
+++ llvm/trunk/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp Wed Aug 26 18:15:32 2015
@@ -1897,8 +1897,9 @@ void SelectionDAGBuilder::visitBitTestHe
MachineBasicBlock* MBB = B.Cases[0].ThisBB;
- addSuccessorWithWeight(SwitchBB, B.Default);
- addSuccessorWithWeight(SwitchBB, MBB);
+ uint32_t DefaultWeight = getEdgeWeight(SwitchBB, B.Default);
+ addSuccessorWithWeight(SwitchBB, B.Default, DefaultWeight);
+ addSuccessorWithWeight(SwitchBB, MBB, B.Weight);
SDValue BrRange = DAG.getNode(ISD::BRCOND, dl,
MVT::Other, CopyTo, RangeCmp,
@@ -7820,7 +7821,8 @@ bool SelectionDAGBuilder::buildBitTests(
}
BitTestCases.emplace_back(std::move(LowBound), std::move(CmpRange),
SI->getCondition(), -1U, MVT::Other, false,
- ContiguousRange, nullptr, nullptr, std::move(BTI));
+ ContiguousRange, nullptr, nullptr, std::move(BTI),
+ TotalWeight);
BTCluster = CaseCluster::bitTests(Clusters[First].Low, Clusters[Last].High,
BitTestCases.size() - 1, TotalWeight);
@@ -8041,8 +8043,16 @@ void SelectionDAGBuilder::lowerWorkItem(
// The jump block hasn't been inserted yet; insert it here.
MachineBasicBlock *JumpMBB = JT->MBB;
CurMF->insert(BBI, JumpMBB);
- addSuccessorWithWeight(CurMBB, Fallthrough);
- addSuccessorWithWeight(CurMBB, JumpMBB);
+
+ // Collect the sum of weights of outgoing edges from JumpMBB, which will
+ // be the edge weight on CurMBB->JumpMBB.
+ uint32_t JumpWeight = 0;
+ for (auto Succ : JumpMBB->successors())
+ JumpWeight += getEdgeWeight(JumpMBB, Succ);
+ uint32_t FallthruWeight = getEdgeWeight(CurMBB, Fallthrough);
+
+ addSuccessorWithWeight(CurMBB, Fallthrough, FallthruWeight);
+ addSuccessorWithWeight(CurMBB, JumpMBB, JumpWeight);
// The jump table header will be inserted in our current block, do the
// range check, and fall through to our fallthrough block.
Modified: llvm/trunk/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.h
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.h?rev=246104&r1=246103&r2=246104&view=diff
==============================================================================
--- llvm/trunk/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.h (original)
+++ llvm/trunk/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.h Wed Aug 26 18:15:32 2015
@@ -283,12 +283,12 @@ private:
typedef SmallVector<BitTestCase, 3> BitTestInfo;
struct BitTestBlock {
- BitTestBlock(APInt F, APInt R, const Value* SV,
- unsigned Rg, MVT RgVT, bool E, bool CR,
- MachineBasicBlock* P, MachineBasicBlock* D,
- BitTestInfo C):
- First(F), Range(R), SValue(SV), Reg(Rg), RegVT(RgVT), Emitted(E),
- ContiguousRange(CR), Parent(P), Default(D), Cases(std::move(C)) { }
+ BitTestBlock(APInt F, APInt R, const Value *SV, unsigned Rg, MVT RgVT,
+ bool E, bool CR, MachineBasicBlock *P, MachineBasicBlock *D,
+ BitTestInfo C, uint32_t W)
+ : First(F), Range(R), SValue(SV), Reg(Rg), RegVT(RgVT), Emitted(E),
+ ContiguousRange(CR), Parent(P), Default(D), Cases(std::move(C)),
+ Weight(W) {}
APInt First;
APInt Range;
const Value *SValue;
@@ -299,6 +299,7 @@ private:
MachineBasicBlock *Parent;
MachineBasicBlock *Default;
BitTestInfo Cases;
+ uint32_t Weight;
};
/// Minimum jump table density, in percent.
Modified: llvm/trunk/test/CodeGen/ARM/jump-table-islands.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/CodeGen/ARM/jump-table-islands.ll?rev=246104&r1=246103&r2=246104&view=diff
==============================================================================
--- llvm/trunk/test/CodeGen/ARM/jump-table-islands.ll (original)
+++ llvm/trunk/test/CodeGen/ARM/jump-table-islands.ll Wed Aug 26 18:15:32 2015
@@ -13,7 +13,7 @@ define %BigInt @test_moved_jumptable(i1
; CHECK: .long LBB{{[0-9]+_[0-9]+}}-[[JUMP_TABLE]]
; CHECK: [[SKIP_TABLE]]:
-; CHECK: add pc, {{r[0-9]+}}, {{r[0-9]+}}
+; CHECK: add pc, lr, {{r[0-9]+}}
br i1 %tst, label %simple, label %complex
simple:
Modified: llvm/trunk/test/CodeGen/Mips/nacl-align.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/CodeGen/Mips/nacl-align.ll?rev=246104&r1=246103&r2=246104&view=diff
==============================================================================
--- llvm/trunk/test/CodeGen/Mips/nacl-align.ll (original)
+++ llvm/trunk/test/CodeGen/Mips/nacl-align.ll Wed Aug 26 18:15:32 2015
@@ -44,18 +44,17 @@ default:
; CHECK-NEXT: ${{BB[0-9]+_[0-9]+}}:
; CHECK-NEXT: jr $ra
; CHECK-NEXT: addiu $2, $zero, 111
-; CHECK-NEXT: .align 4
; CHECK-NEXT: ${{BB[0-9]+_[0-9]+}}:
; CHECK-NEXT: jr $ra
-; CHECK-NEXT: addiu $2, $zero, 222
+; CHECK-NEXT: addiu $2, $zero, 555
; CHECK-NEXT: .align 4
; CHECK-NEXT: ${{BB[0-9]+_[0-9]+}}:
; CHECK-NEXT: jr $ra
-; CHECK-NEXT: addiu $2, $zero, 333
+; CHECK-NEXT: addiu $2, $zero, 222
; CHECK-NEXT: .align 4
; CHECK-NEXT: ${{BB[0-9]+_[0-9]+}}:
; CHECK-NEXT: jr $ra
-; CHECK-NEXT: addiu $2, $zero, 444
+; CHECK-NEXT: addiu $2, $zero, 333
}
Modified: llvm/trunk/test/CodeGen/X86/switch-jump-table.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/CodeGen/X86/switch-jump-table.ll?rev=246104&r1=246103&r2=246104&view=diff
==============================================================================
--- llvm/trunk/test/CodeGen/X86/switch-jump-table.ll (original)
+++ llvm/trunk/test/CodeGen/X86/switch-jump-table.ll Wed Aug 26 18:15:32 2015
@@ -1,17 +1,18 @@
-; RUN: llc -mtriple=i686-pc-gnu-linux < %s | FileCheck %s
+; RUN: llc -mtriple=i686-pc-gnu-linux < %s | FileCheck %s -check-prefix=CHECK
+; RUN: llc -mtriple=i686-pc-gnu-linux -print-machineinstrs=expand-isel-pseudos %s -o /dev/null 2>&1 | FileCheck %s -check-prefix=CHECK-JT-WEIGHT
; An unreachable default destination is replaced with the most popular case label.
-define void @sum2(i32 %x, i32* %to) {
-; CHECK-LABEL: sum2:
+define void @foo(i32 %x, i32* %to) {
+; CHECK-LABEL: foo:
; CHECK: movl 4(%esp), [[REG:%e[a-z]{2}]]
; CHECK: cmpl $3, [[REG]]
-; CHECK: jbe .LBB0_1
+; CHECK: ja .LBB0_6
+; CHECK-NEXT: # BB#1:
+; CHECK-NEXT: jmpl *.LJTI0_0(,[[REG]],4)
; CHECK: movl $4
; CHECK: retl
-; CHECK-LABEL: .LBB0_1:
-; CHECK-NEXT: jmpl *.LJTI0_0(,[[REG]],4)
entry:
switch i32 %x, label %default [
@@ -48,5 +49,44 @@ default:
; CHECK-NEXT: .long .LBB0_3
; CHECK-NEXT: .long .LBB0_4
; CHECK-NEXT: .long .LBB0_5
-; CHECK-NOT: .long
}
+
+; Check if branch probabilities are correctly assigned to the jump table.
+
+define void @bar(i32 %x, i32* %to) {
+; CHECK-JT-WEIGHT-LABEL: bar:
+; CHECK-JT-WEIGHT: Successors according to CFG: BB#6(16) BB#8(96)
+; CHECK-JT-WEIGHT: Successors according to CFG: BB#1(16) BB#2(16) BB#3(16) BB#4(16) BB#5(32)
+
+entry:
+ switch i32 %x, label %default [
+ i32 0, label %bb0
+ i32 1, label %bb1
+ i32 2, label %bb2
+ i32 3, label %bb3
+ i32 4, label %bb4
+ i32 5, label %bb4
+ ], !prof !1
+bb0:
+ store i32 0, i32* %to
+ br label %exit
+bb1:
+ store i32 1, i32* %to
+ br label %exit
+bb2:
+ store i32 2, i32* %to
+ br label %exit
+bb3:
+ store i32 3, i32* %to
+ br label %exit
+bb4:
+ store i32 4, i32* %to
+ br label %exit
+default:
+ store i32 5, i32* %to
+ br label %exit
+exit:
+ ret void
+}
+
+!1 = !{!"branch_weights", i32 16, i32 16, i32 16, i32 16, i32 16, i32 16, i32 16}
Modified: llvm/trunk/test/CodeGen/X86/switch.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/CodeGen/X86/switch.ll?rev=246104&r1=246103&r2=246104&view=diff
==============================================================================
--- llvm/trunk/test/CodeGen/X86/switch.ll (original)
+++ llvm/trunk/test/CodeGen/X86/switch.ll Wed Aug 26 18:15:32 2015
@@ -90,7 +90,7 @@ return: ret void
; but with 6-8, the whole switch is suitable for a jump table.
; CHECK-LABEL: jt_is_better
; CHECK: cmpl $8
-; CHECK: jbe
+; CHECK: ja
; CHECK: jmpq *.LJTI
}
Modified: llvm/trunk/test/CodeGen/X86/x86-shrink-wrapping.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/CodeGen/X86/x86-shrink-wrapping.ll?rev=246104&r1=246103&r2=246104&view=diff
==============================================================================
--- llvm/trunk/test/CodeGen/X86/x86-shrink-wrapping.ll (original)
+++ llvm/trunk/test/CodeGen/X86/x86-shrink-wrapping.ll Wed Aug 26 18:15:32 2015
@@ -532,7 +532,11 @@ declare hidden fastcc %struct.temp_slot*
;
; CHECK: movl $24599, [[TMP2:%e[a-z]+]]
; CHECK-NEXT: btl [[TMP]], [[TMP2]]
-; CHECK-NEXT: jb [[CLEANUP]]
+; CHECK-NEXT: jae [[LOR_LHS_FALSE:LBB[0-9_]+]]
+;
+; CHECK: [[CLEANUP]]: ## %cleanup
+; DISABLE: popq
+; CHECK-NEXT: retq
;
; CHECK: [[LOR_LHS_FALSE]]: ## %lor.lhs.false
; CHECK: cmpl $134, %e[[BF_LOAD2]]
@@ -551,10 +555,6 @@ declare hidden fastcc %struct.temp_slot*
; CHECK-NEXT: je [[CLEANUP]]
;
; CHECK: movb $1, 57(%rax)
-;
-; CHECK: [[CLEANUP]]: ## %cleanup
-; DISABLE: popq
-; CHECK-NEXT: retq
define void @useLEA(%struct.rtx_def* readonly %x) {
entry:
%cmp = icmp eq %struct.rtx_def* %x, null
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