[llvm] r268577 - Revert "[SimplifyCFG] propagate branch metadata when creating select"
Vitaly Buka via llvm-commits
llvm-commits at lists.llvm.org
Wed May 4 16:59:33 PDT 2016
Author: vitalybuka
Date: Wed May 4 18:59:33 2016
New Revision: 268577
URL: http://llvm.org/viewvc/llvm-project?rev=268577&view=rev
Log:
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.
Modified:
llvm/trunk/lib/Transforms/Utils/SimplifyCFG.cpp
llvm/trunk/test/Transforms/SimplifyCFG/preserve-branchweights.ll
Modified: llvm/trunk/lib/Transforms/Utils/SimplifyCFG.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/Utils/SimplifyCFG.cpp?rev=268577&r1=268576&r2=268577&view=diff
==============================================================================
--- llvm/trunk/lib/Transforms/Utils/SimplifyCFG.cpp (original)
+++ llvm/trunk/lib/Transforms/Utils/SimplifyCFG.cpp Wed May 4 18:59:33 2016
@@ -848,7 +848,7 @@ static void GetBranchWeights(TerminatorI
}
}
-/// Scale each weight so they all fit in uint32_t.
+/// Keep halving the weights until all can fit in uint32_t.
static void FitWeights(MutableArrayRef<uint64_t> Weights) {
uint64_t Max = *std::max_element(Weights.begin(), Weights.end());
if (Max > UINT_MAX) {
@@ -2840,27 +2840,28 @@ static bool SimplifyCondBranchToCondBran
PBI->setSuccessor(1, OtherDest);
// Update branch weight for PBI.
- MDBuilder MDB(BI->getContext());
uint64_t PredTrueWeight, PredFalseWeight, SuccTrueWeight, SuccFalseWeight;
- uint64_t PredCommon, PredOther, SuccCommon, SuccOther;
- bool HasWeights = PBI->extractProfMetadata(PredTrueWeight, PredFalseWeight);
- if (HasWeights)
- HasWeights = BI->extractProfMetadata(SuccTrueWeight, SuccFalseWeight);
- if (HasWeights) {
- PredCommon = PBIOp ? PredFalseWeight : PredTrueWeight;
- PredOther = PBIOp ? PredTrueWeight : PredFalseWeight;
- SuccCommon = BIOp ? SuccFalseWeight : SuccTrueWeight;
- SuccOther = BIOp ? SuccTrueWeight : SuccFalseWeight;
+ bool PredHasWeights =
+ PBI->extractProfMetadata(PredTrueWeight, PredFalseWeight);
+ bool SuccHasWeights =
+ BI->extractProfMetadata(SuccTrueWeight, SuccFalseWeight);
+ if (PredHasWeights && SuccHasWeights) {
+ uint64_t PredCommon = PBIOp ? PredFalseWeight : PredTrueWeight;
+ uint64_t PredOther = PBIOp ?PredTrueWeight : PredFalseWeight;
+ uint64_t SuccCommon = BIOp ? SuccFalseWeight : SuccTrueWeight;
+ uint64_t SuccOther = BIOp ? SuccTrueWeight : SuccFalseWeight;
// The weight to CommonDest should be PredCommon * SuccTotal +
// PredOther * SuccCommon.
// The weight to OtherDest should be PredOther * SuccOther.
uint64_t NewWeights[2] = {PredCommon * (SuccCommon + SuccOther) +
PredOther * SuccCommon,
PredOther * SuccOther};
+ // Halve the weights if any of them cannot fit in an uint32_t
FitWeights(NewWeights);
PBI->setMetadata(LLVMContext::MD_prof,
- MDB.createBranchWeights(NewWeights[0], NewWeights[1]));
+ MDBuilder(BI->getContext())
+ .createBranchWeights(NewWeights[0], NewWeights[1]));
}
// OtherDest may have phi nodes. If so, add an entry from PBI's
@@ -2879,24 +2880,9 @@ static bool SimplifyCondBranchToCondBran
Value *PBIV = PN->getIncomingValue(PBBIdx);
if (BIV != PBIV) {
// Insert a select in PBI to pick the right value.
- SelectInst *NV = cast<SelectInst>
+ Value *NV = cast<SelectInst>
(Builder.CreateSelect(PBICond, PBIV, BIV, PBIV->getName() + ".mux"));
PN->setIncomingValue(PBBIdx, NV);
- // Although the select has the same condition as PBI, the original branch
- // 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 (HasWeights) {
- // The weight to PredCommonDest should be PredCommon * SuccTotal.
- // The weight to PredOtherDest should be PredOther * SuccCommon.
- uint64_t NewWeights[2] = {PredCommon * (SuccCommon + SuccOther),
- PredOther * SuccCommon};
-
- FitWeights(NewWeights);
-
- NV->setMetadata(LLVMContext::MD_prof,
- MDB.createBranchWeights(NewWeights[0], NewWeights[1]));
- }
}
}
Modified: llvm/trunk/test/Transforms/SimplifyCFG/preserve-branchweights.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transforms/SimplifyCFG/preserve-branchweights.ll?rev=268577&r1=268576&r2=268577&view=diff
==============================================================================
--- llvm/trunk/test/Transforms/SimplifyCFG/preserve-branchweights.ll (original)
+++ llvm/trunk/test/Transforms/SimplifyCFG/preserve-branchweights.ll Wed May 4 18:59:33 2016
@@ -412,48 +412,22 @@ return:
ret i32 %retval.0
}
-; The selects should have freshly calculated branch weights.
+; The 1st select should have branch weights equal to the 1st branch.
+; The 2nd select should have freshly calculated branch weights.
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: [[BRMERGE:%.*]] = or i1 %cmpb, %cmpa
+; CHECK-NEXT: [[DOTMUX:%.*]] = select i1 %cmpb, i32 0, i32 2
+; CHECK-NEXT: [[OUTVAL:%.*]] = select i1 [[BRMERGE]], i32 [[DOTMUX]], i32 1, !prof !12
; CHECK-NEXT: ret i32 [[OUTVAL]]
;
block1:
- br i1 %cmpa, label %block3, label %block2, !prof !13
+ br i1 %cmpb, label %block3, label %block2, !prof !0
block2:
- br i1 %cmpb, label %block3, label %exit, !prof !14
-
-block3:
- %cowval = phi i32 [ 2, %block2 ], [ 0, %block1 ]
- br label %exit
-
-exit:
- %outval = phi i32 [ %cowval, %block3 ], [ 1, %block2 ]
- ret i32 %outval
-}
-
-; Swap the operands of the compares to verify that the weights update correctly.
-
-define i32 @SimplifyCondBranchToCondBranchSwap(i1 %cmpa, i1 %cmpb) {
-; CHECK-LABEL: @SimplifyCondBranchToCondBranchSwap(
-; CHECK-NEXT: block1:
-; 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: ret i32 [[OUTVAL]]
-;
-block1:
- br i1 %cmpa, label %block2, label %block3, !prof !13
-
-block2:
- br i1 %cmpb, label %exit, label %block3, !prof !14
+ br i1 %cmpa, label %block3, label %exit, !prof !2
block3:
%cowval = phi i32 [ 2, %block2 ], [ 0, %block1 ]
@@ -478,8 +452,6 @@ exit:
!10 = !{!"branch_weights", i32 672646, i32 21604207}
!11 = !{!"branch_weights", i32 6960, i32 21597248}
!12 = !{!"these_are_not_the_branch_weights_you_are_looking_for", i32 3, i32 5}
-!13 = !{!"branch_weights", i32 2, i32 3}
-!14 = !{!"branch_weights", i32 4, i32 7}
; CHECK: !0 = !{!"branch_weights", i32 5, i32 11}
; CHECK: !1 = !{!"branch_weights", i32 1, i32 5}
@@ -495,8 +467,5 @@ exit:
;; 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: !12 = !{!"branch_weights", i32 14, i32 10}
More information about the llvm-commits
mailing list