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Revert "[SimplifyCFG] propagate branch metadata when creating select"
MemorySanitizer: use-of-uninitialized-value 0x4910e47 in count /mnt/b/sanitizer-buildbot2/sanitizer-x86_64-linux-bootstrap/build/llvm/include/llvm/Support/MathExtras.h:159:12 0x4910e47 in countLeadingZeros<unsigned long> /mnt/b/sanitizer-buildbot2/sanitizer-x86_64-linux-bootstrap/build/llvm/include/llvm/Support/MathExtras.h:183 0x4910e47 in FitWeights /mnt/b/sanitizer-buildbot2/sanitizer-x86_64-linux-bootstrap/build/llvm/lib/Transforms/Utils/SimplifyCFG.cpp:855 0x4910e47 in SimplifyCondBranchToCondBranch /mnt/b/sanitizer-buildbot2/sanitizer-x86_64-linux-bootstrap/build/llvm/lib/Transforms/Utils/SimplifyCFG.cpp:2895 This reverts commit 609f4dd4bf3bc735c8c047a4d4b0a8e9e4d202e2. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@268577 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Vitaly Buka
parent
a8d416d07d
commit
6e64fd8d92
@ -848,7 +848,7 @@ static void GetBranchWeights(TerminatorInst *TI,
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}
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}
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/// Scale each weight so they all fit in uint32_t.
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/// Keep halving the weights until all can fit in uint32_t.
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static void FitWeights(MutableArrayRef<uint64_t> Weights) {
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uint64_t Max = *std::max_element(Weights.begin(), Weights.end());
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if (Max > UINT_MAX) {
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@ -2840,27 +2840,28 @@ static bool SimplifyCondBranchToCondBranch(BranchInst *PBI, BranchInst *BI,
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PBI->setSuccessor(1, OtherDest);
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// Update branch weight for PBI.
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MDBuilder MDB(BI->getContext());
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uint64_t PredTrueWeight, PredFalseWeight, SuccTrueWeight, SuccFalseWeight;
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uint64_t PredCommon, PredOther, SuccCommon, SuccOther;
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bool HasWeights = PBI->extractProfMetadata(PredTrueWeight, PredFalseWeight);
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if (HasWeights)
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HasWeights = BI->extractProfMetadata(SuccTrueWeight, SuccFalseWeight);
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if (HasWeights) {
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PredCommon = PBIOp ? PredFalseWeight : PredTrueWeight;
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PredOther = PBIOp ? PredTrueWeight : PredFalseWeight;
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SuccCommon = BIOp ? SuccFalseWeight : SuccTrueWeight;
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SuccOther = BIOp ? SuccTrueWeight : SuccFalseWeight;
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bool PredHasWeights =
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PBI->extractProfMetadata(PredTrueWeight, PredFalseWeight);
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bool SuccHasWeights =
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BI->extractProfMetadata(SuccTrueWeight, SuccFalseWeight);
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if (PredHasWeights && SuccHasWeights) {
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uint64_t PredCommon = PBIOp ? PredFalseWeight : PredTrueWeight;
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uint64_t PredOther = PBIOp ?PredTrueWeight : PredFalseWeight;
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uint64_t SuccCommon = BIOp ? SuccFalseWeight : SuccTrueWeight;
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uint64_t SuccOther = BIOp ? SuccTrueWeight : SuccFalseWeight;
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// The weight to CommonDest should be PredCommon * SuccTotal +
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// PredOther * SuccCommon.
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// The weight to OtherDest should be PredOther * SuccOther.
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uint64_t NewWeights[2] = {PredCommon * (SuccCommon + SuccOther) +
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PredOther * SuccCommon,
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PredOther * SuccOther};
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// Halve the weights if any of them cannot fit in an uint32_t
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FitWeights(NewWeights);
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PBI->setMetadata(LLVMContext::MD_prof,
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MDB.createBranchWeights(NewWeights[0], NewWeights[1]));
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MDBuilder(BI->getContext())
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.createBranchWeights(NewWeights[0], NewWeights[1]));
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}
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// OtherDest may have phi nodes. If so, add an entry from PBI's
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@ -2879,24 +2880,9 @@ static bool SimplifyCondBranchToCondBranch(BranchInst *PBI, BranchInst *BI,
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Value *PBIV = PN->getIncomingValue(PBBIdx);
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if (BIV != PBIV) {
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// Insert a select in PBI to pick the right value.
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SelectInst *NV = cast<SelectInst>
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Value *NV = cast<SelectInst>
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(Builder.CreateSelect(PBICond, PBIV, BIV, PBIV->getName() + ".mux"));
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PN->setIncomingValue(PBBIdx, NV);
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// Although the select has the same condition as PBI, the original branch
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// weights for PBI do not apply to the new select because the select's
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// 'logical' edges are incoming edges of the phi that is eliminated, not
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// the outgoing edges of PBI.
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if (HasWeights) {
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// The weight to PredCommonDest should be PredCommon * SuccTotal.
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// The weight to PredOtherDest should be PredOther * SuccCommon.
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uint64_t NewWeights[2] = {PredCommon * (SuccCommon + SuccOther),
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PredOther * SuccCommon};
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FitWeights(NewWeights);
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NV->setMetadata(LLVMContext::MD_prof,
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MDB.createBranchWeights(NewWeights[0], NewWeights[1]));
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}
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}
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}
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@ -412,48 +412,22 @@ return:
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ret i32 %retval.0
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}
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; The selects should have freshly calculated branch weights.
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; The 1st select should have branch weights equal to the 1st branch.
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; The 2nd select should have freshly calculated branch weights.
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define i32 @SimplifyCondBranchToCondBranch(i1 %cmpa, i1 %cmpb) {
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; CHECK-LABEL: @SimplifyCondBranchToCondBranch(
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; CHECK-NEXT: block1:
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; CHECK-NEXT: [[BRMERGE:%.*]] = or i1 %cmpa, %cmpb
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; CHECK-NEXT: [[DOTMUX:%.*]] = select i1 %cmpa, i32 0, i32 2, !prof !12
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; CHECK-NEXT: [[OUTVAL:%.*]] = select i1 [[BRMERGE]], i32 [[DOTMUX]], i32 1, !prof !13
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; CHECK-NEXT: [[BRMERGE:%.*]] = or i1 %cmpb, %cmpa
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; CHECK-NEXT: [[DOTMUX:%.*]] = select i1 %cmpb, i32 0, i32 2
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; CHECK-NEXT: [[OUTVAL:%.*]] = select i1 [[BRMERGE]], i32 [[DOTMUX]], i32 1, !prof !12
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; CHECK-NEXT: ret i32 [[OUTVAL]]
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;
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block1:
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br i1 %cmpa, label %block3, label %block2, !prof !13
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br i1 %cmpb, label %block3, label %block2, !prof !0
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block2:
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br i1 %cmpb, label %block3, label %exit, !prof !14
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block3:
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%cowval = phi i32 [ 2, %block2 ], [ 0, %block1 ]
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br label %exit
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exit:
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%outval = phi i32 [ %cowval, %block3 ], [ 1, %block2 ]
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ret i32 %outval
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}
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; Swap the operands of the compares to verify that the weights update correctly.
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define i32 @SimplifyCondBranchToCondBranchSwap(i1 %cmpa, i1 %cmpb) {
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; CHECK-LABEL: @SimplifyCondBranchToCondBranchSwap(
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; CHECK-NEXT: block1:
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; CHECK-NEXT: [[CMPA_NOT:%.*]] = xor i1 %cmpa, true
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; CHECK-NEXT: [[CMPB_NOT:%.*]] = xor i1 %cmpb, true
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; CHECK-NEXT: [[BRMERGE:%.*]] = or i1 [[CMPA_NOT]], [[CMPB_NOT]]
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; CHECK-NEXT: [[DOTMUX:%.*]] = select i1 [[CMPA_NOT]], i32 0, i32 2, !prof !14
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; CHECK-NEXT: [[OUTVAL:%.*]] = select i1 [[BRMERGE]], i32 [[DOTMUX]], i32 1, !prof !15
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; CHECK-NEXT: ret i32 [[OUTVAL]]
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;
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block1:
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br i1 %cmpa, label %block2, label %block3, !prof !13
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block2:
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br i1 %cmpb, label %exit, label %block3, !prof !14
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br i1 %cmpa, label %block3, label %exit, !prof !2
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block3:
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%cowval = phi i32 [ 2, %block2 ], [ 0, %block1 ]
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@ -478,8 +452,6 @@ exit:
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!10 = !{!"branch_weights", i32 672646, i32 21604207}
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!11 = !{!"branch_weights", i32 6960, i32 21597248}
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!12 = !{!"these_are_not_the_branch_weights_you_are_looking_for", i32 3, i32 5}
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!13 = !{!"branch_weights", i32 2, i32 3}
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!14 = !{!"branch_weights", i32 4, i32 7}
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; CHECK: !0 = !{!"branch_weights", i32 5, i32 11}
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; CHECK: !1 = !{!"branch_weights", i32 1, i32 5}
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@ -495,8 +467,5 @@ exit:
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;; treat the weight as an unsigned integer.
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; CHECK: !10 = !{!"branch_weights", i32 112017436, i32 -735157296}
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; CHECK: !11 = !{!"branch_weights", i32 3, i32 5}
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; CHECK: !12 = !{!"branch_weights", i32 22, i32 12}
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; CHECK: !13 = !{!"branch_weights", i32 34, i32 21}
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; CHECK: !14 = !{!"branch_weights", i32 33, i32 14}
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; CHECK: !15 = !{!"branch_weights", i32 47, i32 8}
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; CHECK: !12 = !{!"branch_weights", i32 14, i32 10}
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