From f16376b50552263f101beeadb86ae7409798ccdb Mon Sep 17 00:00:00 2001 From: Dehao Chen Date: Wed, 18 May 2016 22:41:03 +0000 Subject: [PATCH] Follow-up patch of http://reviews.llvm.org/D19948 to handle missing profiles when simplifying CFG. Summary: Set default branch weight to 1:1 if one of the branch has profile missing when simplifying CFG. Reviewers: spatel, davidxl Subscribers: danielcdh, llvm-commits Differential Revision: http://reviews.llvm.org/D20307 llvm-svn: 269995 --- llvm/lib/Transforms/Utils/SimplifyCFG.cpp | 50 ++++++++----- .../SimplifyCFG/preserve-branchweights.ll | 75 ++++++++++--------- 2 files changed, 70 insertions(+), 55 deletions(-) diff --git a/llvm/lib/Transforms/Utils/SimplifyCFG.cpp b/llvm/lib/Transforms/Utils/SimplifyCFG.cpp index 9e5916c3ee81..16e886569e50 100644 --- a/llvm/lib/Transforms/Utils/SimplifyCFG.cpp +++ b/llvm/lib/Transforms/Utils/SimplifyCFG.cpp @@ -2094,6 +2094,29 @@ static bool checkCSEInPredecessor(Instruction *Inst, BasicBlock *PB) { return false; } +/// Return true if either PBI or BI has branch weight available, and store +/// the weights in {Pred|Succ}{True|False}Weight. If one of PBI and BI does +/// not have branch weight, use 1:1 as its weight. +static bool extractPredSuccWeights(BranchInst *PBI, BranchInst *BI, + uint64_t &PredTrueWeight, + uint64_t &PredFalseWeight, + uint64_t &SuccTrueWeight, + uint64_t &SuccFalseWeight) { + bool PredHasWeights = + PBI->extractProfMetadata(PredTrueWeight, PredFalseWeight); + bool SuccHasWeights = + BI->extractProfMetadata(SuccTrueWeight, SuccFalseWeight); + if (PredHasWeights || SuccHasWeights) { + if (!PredHasWeights) + PredTrueWeight = PredFalseWeight = 1; + if (!SuccHasWeights) + SuccTrueWeight = SuccFalseWeight = 1; + return true; + } else { + return false; + } +} + /// If this basic block is simple enough, and if a predecessor branches to us /// and one of our successors, fold the block into the predecessor and use /// logical operations to pick the right destination. @@ -2281,14 +2304,13 @@ bool llvm::FoldBranchToCommonDest(BranchInst *BI, unsigned BonusInstThreshold) { PBI->setCondition(NewCond); uint64_t PredTrueWeight, PredFalseWeight, SuccTrueWeight, SuccFalseWeight; - bool PredHasWeights = - PBI->extractProfMetadata(PredTrueWeight, PredFalseWeight); - bool SuccHasWeights = - BI->extractProfMetadata(SuccTrueWeight, SuccFalseWeight); + bool HasWeights = + extractPredSuccWeights(PBI, BI, PredTrueWeight, PredFalseWeight, + SuccTrueWeight, SuccFalseWeight); SmallVector NewWeights; if (PBI->getSuccessor(0) == BB) { - if (PredHasWeights && SuccHasWeights) { + if (HasWeights) { // PBI: br i1 %x, BB, FalseDest // BI: br i1 %y, TrueDest, FalseDest // TrueWeight is TrueWeight for PBI * TrueWeight for BI. @@ -2305,7 +2327,7 @@ bool llvm::FoldBranchToCommonDest(BranchInst *BI, unsigned BonusInstThreshold) { PBI->setSuccessor(0, TrueDest); } if (PBI->getSuccessor(1) == BB) { - if (PredHasWeights && SuccHasWeights) { + if (HasWeights) { // PBI: br i1 %x, TrueDest, BB // BI: br i1 %y, TrueDest, FalseDest // TrueWeight is TrueWeight for PBI * TotalWeight for BI + @@ -2840,18 +2862,10 @@ static bool SimplifyCondBranchToCondBranch(BranchInst *PBI, BranchInst *BI, // Update branch weight for PBI. uint64_t PredTrueWeight, PredFalseWeight, SuccTrueWeight, SuccFalseWeight; uint64_t PredCommon, PredOther, SuccCommon, SuccOther; - bool PredHasWeights = - PBI->extractProfMetadata(PredTrueWeight, PredFalseWeight); - bool SuccHasWeights = - BI->extractProfMetadata(SuccTrueWeight, SuccFalseWeight); - bool HasWeights = PredHasWeights || SuccHasWeights; + bool HasWeights = + extractPredSuccWeights(PBI, BI, PredTrueWeight, PredFalseWeight, + SuccTrueWeight, SuccFalseWeight); if (HasWeights) { - if (!PredHasWeights) { - PredFalseWeight = PredTrueWeight = 1; - } - if (!SuccHasWeights) { - SuccFalseWeight = SuccTrueWeight = 1; - } PredCommon = PBIOp ? PredFalseWeight : PredTrueWeight; PredOther = PBIOp ? PredTrueWeight : PredFalseWeight; SuccCommon = BIOp ? SuccFalseWeight : SuccTrueWeight; @@ -2893,7 +2907,7 @@ static bool SimplifyCondBranchToCondBranch(BranchInst *PBI, BranchInst *BI, // weights for PBI do not apply to the new select because the select's // 'logical' edges are incoming edges of the phi that is eliminated, not // the outgoing edges of PBI. - if (PredHasWeights && SuccHasWeights) { + if (HasWeights) { uint64_t PredCommon = PBIOp ? PredFalseWeight : PredTrueWeight; uint64_t PredOther = PBIOp ? PredTrueWeight : PredFalseWeight; uint64_t SuccCommon = BIOp ? SuccFalseWeight : SuccTrueWeight; diff --git a/llvm/test/Transforms/SimplifyCFG/preserve-branchweights.ll b/llvm/test/Transforms/SimplifyCFG/preserve-branchweights.ll index 57c37871d219..dba5dcf68b0c 100644 --- a/llvm/test/Transforms/SimplifyCFG/preserve-branchweights.ll +++ b/llvm/test/Transforms/SimplifyCFG/preserve-branchweights.ll @@ -29,8 +29,7 @@ define void @fake_weights(i1 %a, i1 %b) { entry: br i1 %a, label %Y, label %X, !prof !12 ; CHECK: %or.cond = and i1 %a.not, %c -; CHECK-NEXT: br i1 %or.cond, label %Z, label %Y -; CHECK-NOT: !prof !0 +; CHECK-NEXT: br i1 %or.cond, label %Z, label %Y, !prof !1 ; CHECK: Y: X: %c = or i1 %b, false @@ -49,7 +48,7 @@ define void @test2(i1 %a, i1 %b) { ; CHECK-LABEL: @test2( entry: br i1 %a, label %X, label %Y, !prof !1 -; CHECK: br i1 %or.cond, label %Z, label %Y, !prof !1 +; CHECK: br i1 %or.cond, label %Z, label %Y, !prof !2 ; CHECK-NOT: !prof X: @@ -67,7 +66,7 @@ Z: define void @test3(i1 %a, i1 %b) { ; CHECK-LABEL: @test3( -; CHECK-NOT: !prof +; CHECK: br i1 %or.cond, label %Z, label %Y, !prof !1 entry: br i1 %a, label %X, label %Y, !prof !1 @@ -86,7 +85,7 @@ Z: define void @test4(i1 %a, i1 %b) { ; CHECK-LABEL: @test4( -; CHECK-NOT: !prof +; CHECK: br i1 %or.cond, label %Z, label %Y, !prof !1 entry: br i1 %a, label %X, label %Y @@ -115,7 +114,7 @@ entry: ; CHECK: switch i32 %N, label %sw2 [ ; CHECK: i32 3, label %sw.bb1 ; CHECK: i32 2, label %sw.bb -; CHECK: ], !prof !2 +; CHECK: ], !prof !3 sw.bb: call void @helper(i32 0) @@ -148,7 +147,7 @@ entry: ; CHECK: i32 3, label %sw.bb1 ; CHECK: i32 2, label %sw.bb ; CHECK: i32 4, label %sw.bb5 -; CHECK: ], !prof !3 +; CHECK: ], !prof !4 sw.bb: call void @helper(i32 0) @@ -183,7 +182,7 @@ define void @test1_swap(i1 %a, i1 %b) { ; CHECK-LABEL: @test1_swap( entry: br i1 %a, label %Y, label %X, !prof !0 -; CHECK: br i1 %or.cond, label %Y, label %Z, !prof !4 +; CHECK: br i1 %or.cond, label %Y, label %Z, !prof !5 X: %c = or i1 %b, false @@ -203,7 +202,7 @@ define void @test7(i1 %a, i1 %b) { entry: %c = or i1 %b, false br i1 %a, label %Y, label %X, !prof !0 -; CHECK: br i1 %brmerge, label %Y, label %Z, !prof !5 +; CHECK: br i1 %brmerge, label %Y, label %Z, !prof !6 X: br i1 %c, label %Y, label %Z, !prof !6 @@ -222,7 +221,7 @@ define void @test8(i64 %x, i64 %y) nounwind { ; CHECK-LABEL: @test8( entry: %lt = icmp slt i64 %x, %y -; CHECK: br i1 %lt, label %a, label %b, !prof !6 +; CHECK: br i1 %lt, label %a, label %b, !prof !7 %qux = select i1 %lt, i32 0, i32 2 switch i32 %qux, label %bees [ i32 0, label %a @@ -255,7 +254,7 @@ entry: ; CHECK: i32 1, label %end ; CHECK: i32 2, label %end ; CHECK: i32 92, label %end -; CHECK: ], !prof !7 +; CHECK: ], !prof !8 a: call void @helper(i32 0) nounwind @@ -293,7 +292,7 @@ lor.end: ; CHECK-LABEL: @test10( ; CHECK: %x.off = add i32 %x, -1 ; CHECK: %switch = icmp ult i32 %x.off, 3 -; CHECK: br i1 %switch, label %lor.end, label %lor.rhs, !prof !8 +; CHECK: br i1 %switch, label %lor.end, label %lor.rhs, !prof !9 } ; Remove dead cases from the switch. @@ -305,7 +304,7 @@ define void @test11(i32 %x) nounwind { ], !prof !8 ; CHECK-LABEL: @test11( ; CHECK: %cond = icmp eq i32 %i, 24 -; CHECK: br i1 %cond, label %c, label %a, !prof !9 +; CHECK: br i1 %cond, label %c, label %a, !prof !10 a: call void @helper(i32 0) nounwind @@ -368,7 +367,7 @@ c: @max_regno = common global i32 0, align 4 define void @test14(i32* %old, i32 %final) { ; CHECK-LABEL: @test14 -; CHECK: br i1 %or.cond, label %for.exit, label %for.inc, !prof !10 +; CHECK: br i1 %or.cond, label %for.exit, label %for.inc, !prof !11 for.cond: br label %for.cond2 for.cond2: @@ -394,7 +393,7 @@ define i32 @HoistThenElseCodeToIf(i32 %n) { ; CHECK-LABEL: @HoistThenElseCodeToIf( ; CHECK-NEXT: entry: ; CHECK-NEXT: [[TOBOOL:%.*]] = icmp eq i32 %n, 0 -; CHECK-NEXT: [[DOT:%.*]] = select i1 [[TOBOOL]], i32 1, i32 234, !prof !11 +; CHECK-NEXT: [[DOT:%.*]] = select i1 [[TOBOOL]], i32 1, i32 234, !prof !12 ; CHECK-NEXT: ret i32 [[DOT]] ; entry: @@ -418,8 +417,8 @@ define i32 @SimplifyCondBranchToCondBranch(i1 %cmpa, i1 %cmpb) { ; CHECK-LABEL: @SimplifyCondBranchToCondBranch( ; CHECK-NEXT: block1: ; CHECK-NEXT: [[BRMERGE:%.*]] = or i1 %cmpa, %cmpb -; CHECK-NEXT: [[DOTMUX:%.*]] = select i1 %cmpa, i32 0, i32 2, !prof !12 -; CHECK-NEXT: [[OUTVAL:%.*]] = select i1 [[BRMERGE]], i32 [[DOTMUX]], i32 1, !prof !13 +; CHECK-NEXT: [[DOTMUX:%.*]] = select i1 %cmpa, i32 0, i32 2, !prof !13 +; CHECK-NEXT: [[OUTVAL:%.*]] = select i1 [[BRMERGE]], i32 [[DOTMUX]], i32 1, !prof !14 ; CHECK-NEXT: ret i32 [[OUTVAL]] ; block1: @@ -445,8 +444,8 @@ define i32 @SimplifyCondBranchToCondBranchSwap(i1 %cmpa, i1 %cmpb) { ; CHECK-NEXT: [[CMPA_NOT:%.*]] = xor i1 %cmpa, true ; CHECK-NEXT: [[CMPB_NOT:%.*]] = xor i1 %cmpb, true ; CHECK-NEXT: [[BRMERGE:%.*]] = or i1 [[CMPA_NOT]], [[CMPB_NOT]] -; CHECK-NEXT: [[DOTMUX:%.*]] = select i1 [[CMPA_NOT]], i32 0, i32 2, !prof !14 -; CHECK-NEXT: [[OUTVAL:%.*]] = select i1 [[BRMERGE]], i32 [[DOTMUX]], i32 1, !prof !15 +; CHECK-NEXT: [[DOTMUX:%.*]] = select i1 [[CMPA_NOT]], i32 0, i32 2, !prof !15 +; CHECK-NEXT: [[OUTVAL:%.*]] = select i1 [[BRMERGE]], i32 [[DOTMUX]], i32 1, !prof !16 ; CHECK-NEXT: ret i32 [[OUTVAL]] ; block1: @@ -470,8 +469,8 @@ define i32 @SimplifyCondBranchToCondBranchSwapMissingWeight(i1 %cmpa, i1 %cmpb) ; CHECK-NEXT: [[CMPA_NOT:%.*]] = xor i1 %cmpa, true ; CHECK-NEXT: [[CMPB_NOT:%.*]] = xor i1 %cmpb, true ; CHECK-NEXT: [[BRMERGE:%.*]] = or i1 [[CMPA_NOT]], [[CMPB_NOT]] -; CHECK-NEXT: [[DOTMUX:%.*]] = select i1 [[CMPA_NOT]], i32 0, i32 2 -; CHECK-NEXT: [[OUTVAL:%.*]] = select i1 [[BRMERGE]], i32 [[DOTMUX]], i32 1, !prof !16 +; CHECK-NEXT: [[DOTMUX:%.*]] = select i1 [[CMPA_NOT]], i32 0, i32 2, !prof !17 +; CHECK-NEXT: [[OUTVAL:%.*]] = select i1 [[BRMERGE]], i32 [[DOTMUX]], i32 1, !prof !18 ; CHECK-NEXT: ret i32 [[OUTVAL]] ; block1: @@ -506,21 +505,23 @@ exit: !14 = !{!"branch_weights", i32 4, i32 7} ; CHECK: !0 = !{!"branch_weights", i32 5, i32 11} -; CHECK: !1 = !{!"branch_weights", i32 1, i32 5} -; CHECK: !2 = !{!"branch_weights", i32 7, i32 1, i32 2} -; CHECK: !3 = !{!"branch_weights", i32 49, i32 12, i32 24, i32 35} -; CHECK: !4 = !{!"branch_weights", i32 11, i32 5} -; CHECK: !5 = !{!"branch_weights", i32 17, i32 15} -; CHECK: !6 = !{!"branch_weights", i32 9, i32 7} -; CHECK: !7 = !{!"branch_weights", i32 17, i32 9, i32 8, i32 7, i32 17} -; CHECK: !8 = !{!"branch_weights", i32 24, i32 33} -; CHECK: !9 = !{!"branch_weights", i32 8, i32 33} +; CHECK: !1 = !{!"branch_weights", i32 1, i32 3} +; CHECK: !2 = !{!"branch_weights", i32 1, i32 5} +; CHECK: !3 = !{!"branch_weights", i32 7, i32 1, i32 2} +; CHECK: !4 = !{!"branch_weights", i32 49, i32 12, i32 24, i32 35} +; CHECK: !5 = !{!"branch_weights", i32 11, i32 5} +; CHECK: !6 = !{!"branch_weights", i32 17, i32 15} +; CHECK: !7 = !{!"branch_weights", i32 9, i32 7} +; CHECK: !8 = !{!"branch_weights", i32 17, i32 9, i32 8, i32 7, i32 17} +; CHECK: !9 = !{!"branch_weights", i32 24, i32 33} +; CHECK: !10 = !{!"branch_weights", i32 8, i32 33} ;; The false weight prints out as a negative integer here, but inside llvm, we ;; treat the weight as an unsigned integer. -; CHECK: !10 = !{!"branch_weights", i32 112017436, i32 -735157296} -; CHECK: !11 = !{!"branch_weights", i32 3, i32 5} -; CHECK: !12 = !{!"branch_weights", i32 22, i32 12} -; CHECK: !13 = !{!"branch_weights", i32 34, i32 21} -; CHECK: !14 = !{!"branch_weights", i32 33, i32 14} -; CHECK: !15 = !{!"branch_weights", i32 47, i32 8} -; CHECK: !16 = !{!"branch_weights", i32 8, i32 2} +; CHECK: !11 = !{!"branch_weights", i32 112017436, i32 -735157296} +; CHECK: !12 = !{!"branch_weights", i32 3, i32 5} +; CHECK: !13 = !{!"branch_weights", i32 22, i32 12} +; CHECK: !14 = !{!"branch_weights", i32 34, i32 21} +; CHECK: !15 = !{!"branch_weights", i32 33, i32 14} +; CHECK: !16 = !{!"branch_weights", i32 47, i32 8} +; CHECK: !17 = !{!"branch_weights", i32 6, i32 2} +; CHECK: !18 = !{!"branch_weights", i32 8, i32 2}