diff options
| -rw-r--r-- | llvm/lib/Transforms/Scalar/InductiveRangeCheckElimination.cpp | 64 | ||||
| -rw-r--r-- | llvm/test/Transforms/IRCE/latch-comparison-against-current-value.ll | 245 |
2 files changed, 13 insertions, 296 deletions
diff --git a/llvm/lib/Transforms/Scalar/InductiveRangeCheckElimination.cpp b/llvm/lib/Transforms/Scalar/InductiveRangeCheckElimination.cpp index e625fb463dc..9fa49fdf81f 100644 --- a/llvm/lib/Transforms/Scalar/InductiveRangeCheckElimination.cpp +++ b/llvm/lib/Transforms/Scalar/InductiveRangeCheckElimination.cpp @@ -450,20 +450,10 @@ struct LoopStructure { // equivalent to: // // intN_ty inc = IndVarIncreasing ? 1 : -1; - // pred_ty predicate = IndVarIncreasing - // ? IsSignedPredicate ? ICMP_SLT : ICMP_ULT - // : IsSignedPredicate ? ICMP_SGT : ICMP_UGT; + // pred_ty predicate = IndVarIncreasing ? ICMP_SLT : ICMP_SGT; // - // - // for (intN_ty iv = IndVarStart; predicate(IndVarBase, LoopExitAt); - // iv = IndVarNext) + // for (intN_ty iv = IndVarStart; predicate(iv, LoopExitAt); iv = IndVarBase) // ... body ... - // - // Here IndVarBase is either current or next value of the induction variable. - // in the former case, IsIndVarNext = false and IndVarBase points to the - // Phi node of the induction variable. Otherwise, IsIndVarNext = true and - // IndVarBase points to IV increment instruction. - // Value *IndVarBase; Value *IndVarStart; @@ -471,13 +461,12 @@ struct LoopStructure { Value *LoopExitAt; bool IndVarIncreasing; bool IsSignedPredicate; - bool IsIndVarNext; LoopStructure() : Tag(""), Header(nullptr), Latch(nullptr), LatchBr(nullptr), LatchExit(nullptr), LatchBrExitIdx(-1), IndVarBase(nullptr), IndVarStart(nullptr), IndVarStep(nullptr), LoopExitAt(nullptr), - IndVarIncreasing(false), IsSignedPredicate(true), IsIndVarNext(false) {} + IndVarIncreasing(false), IsSignedPredicate(true) {} template <typename M> LoopStructure map(M Map) const { LoopStructure Result; @@ -493,7 +482,6 @@ struct LoopStructure { Result.LoopExitAt = Map(LoopExitAt); Result.IndVarIncreasing = IndVarIncreasing; Result.IsSignedPredicate = IsSignedPredicate; - Result.IsIndVarNext = IsIndVarNext; return Result; } @@ -841,42 +829,21 @@ LoopStructure::parseLoopStructure(ScalarEvolution &SE, return false; }; - // `ICI` can either be a comparison against IV or a comparison of IV.next. - // Depending on the interpretation, we calculate the start value differently. + // `ICI` is interpreted as taking the backedge if the *next* value of the + // induction variable satisfies some constraint. - // Pair {IndVarBase; IsIndVarNext} semantically designates whether the latch - // comparisons happens against the IV before or after its value is - // incremented. Two valid combinations for them are: - // - // 1) { phi [ iv.start, preheader ], [ iv.next, latch ]; false }, - // 2) { iv.next; true }. - // - // The latch comparison happens against IndVarBase which can be either current - // or next value of the induction variable. const SCEVAddRecExpr *IndVarBase = cast<SCEVAddRecExpr>(LeftSCEV); bool IsIncreasing = false; bool IsSignedPredicate = true; - bool IsIndVarNext = false; ConstantInt *StepCI; if (!IsInductionVar(IndVarBase, IsIncreasing, StepCI)) { FailureReason = "LHS in icmp not induction variable"; return None; } - const SCEV *IndVarStart = nullptr; - // TODO: Currently we only handle comparison against IV, but we can extend - // this analysis to be able to deal with comparison against sext(iv) and such. - if (isa<PHINode>(LeftValue) && - cast<PHINode>(LeftValue)->getParent() == Header) - // The comparison is made against current IV value. - IndVarStart = IndVarBase->getStart(); - else { - // Assume that the comparison is made against next IV value. - const SCEV *StartNext = IndVarBase->getStart(); - const SCEV *Addend = SE.getNegativeSCEV(IndVarBase->getStepRecurrence(SE)); - IndVarStart = SE.getAddExpr(StartNext, Addend); - IsIndVarNext = true; - } + const SCEV *StartNext = IndVarBase->getStart(); + const SCEV *Addend = SE.getNegativeSCEV(IndVarBase->getStepRecurrence(SE)); + const SCEV *IndVarStart = SE.getAddExpr(StartNext, Addend); const SCEV *Step = SE.getSCEV(StepCI); ConstantInt *One = ConstantInt::get(IndVarTy, 1); @@ -1060,7 +1027,6 @@ LoopStructure::parseLoopStructure(ScalarEvolution &SE, Result.IndVarIncreasing = IsIncreasing; Result.LoopExitAt = RightValue; Result.IsSignedPredicate = IsSignedPredicate; - Result.IsIndVarNext = IsIndVarNext; FailureReason = nullptr; @@ -1350,8 +1316,8 @@ LoopConstrainer::RewrittenRangeInfo LoopConstrainer::changeIterationSpaceEnd( BranchToContinuation); NewPHI->addIncoming(PN->getIncomingValueForBlock(Preheader), Preheader); - auto *FixupValue = PN->getIncomingValueForBlock(LS.Latch); - NewPHI->addIncoming(FixupValue, RRI.ExitSelector); + NewPHI->addIncoming(PN->getIncomingValueForBlock(LS.Latch), + RRI.ExitSelector); RRI.PHIValuesAtPseudoExit.push_back(NewPHI); } @@ -1492,6 +1458,7 @@ bool LoopConstrainer::run() { } ExitPreLoopAtSCEV = SE.getAddExpr(*SR.HighLimit, MinusOneS); } + ExitPreLoopAt = Expander.expandCodeFor(ExitPreLoopAtSCEV, IVTy, InsertPt); ExitPreLoopAt->setName("exit.preloop.at"); } @@ -1510,9 +1477,7 @@ bool LoopConstrainer::run() { } ExitMainLoopAtSCEV = SE.getAddExpr(*SR.LowLimit, MinusOneS); } - if (!MainLoopStructure.IsIndVarNext) - ExitMainLoopAtSCEV = SE.getMinusSCEV( - ExitMainLoopAtSCEV, SE.getSCEV(MainLoopStructure.IndVarStep)); + ExitMainLoopAt = Expander.expandCodeFor(ExitMainLoopAtSCEV, IVTy, InsertPt); ExitMainLoopAt->setName("exit.mainloop.at"); } @@ -1735,10 +1700,7 @@ bool InductiveRangeCheckElimination::runOnLoop(Loop *L, LPPassManager &LPM) { } LoopStructure LS = MaybeLoopStructure.getValue(); const SCEVAddRecExpr *IndVar = - cast<SCEVAddRecExpr>(SE.getSCEV(LS.IndVarBase)); - if (LS.IsIndVarNext) - IndVar = cast<SCEVAddRecExpr>(SE.getMinusSCEV(IndVar, - SE.getSCEV(LS.IndVarStep))); + cast<SCEVAddRecExpr>(SE.getMinusSCEV(SE.getSCEV(LS.IndVarBase), SE.getSCEV(LS.IndVarStep))); Optional<InductiveRangeCheck::Range> SafeIterRange; Instruction *ExprInsertPt = Preheader->getTerminator(); diff --git a/llvm/test/Transforms/IRCE/latch-comparison-against-current-value.ll b/llvm/test/Transforms/IRCE/latch-comparison-against-current-value.ll deleted file mode 100644 index 8ad4e3d3967..00000000000 --- a/llvm/test/Transforms/IRCE/latch-comparison-against-current-value.ll +++ /dev/null @@ -1,245 +0,0 @@ -; RUN: opt -verify-loop-info -irce-print-changed-loops -irce -S < %s 2>&1 | FileCheck %s - -; Check that IRCE is able to deal with loops where the latch comparison is -; done against current value of the IV, not the IV.next. - -; CHECK: irce: in function test_01: constrained Loop at depth 1 containing: %loop<header><exiting>,%in.bounds<latch><exiting> -; CHECK: irce: in function test_02: constrained Loop at depth 1 containing: %loop<header><exiting>,%in.bounds<latch><exiting> -; CHECK-NOT: irce: in function test_03: constrained Loop at depth 1 containing: %loop<header><exiting>,%in.bounds<latch><exiting> -; CHECK-NOT: irce: in function test_04: constrained Loop at depth 1 containing: %loop<header><exiting>,%in.bounds<latch><exiting> -; CHECK: irce: in function test_05: constrained Loop at depth 1 containing: %loop<header><exiting>,%in.bounds<latch><exiting> - -; SLT condition for increasing loop from 0 to 100. -define void @test_01(i32* %arr, i32* %a_len_ptr) #0 { - -; CHECK: test_01 -; CHECK: entry: -; CHECK-NEXT: %len = load i32, i32* %a_len_ptr, !range !0 -; CHECK-NEXT: %exit.mainloop.at = add i32 %len, -1 -; CHECK-NEXT: [[COND2:%[^ ]+]] = icmp slt i32 0, %exit.mainloop.at -; CHECK-NEXT: br i1 [[COND2]], label %loop.preheader, label %main.pseudo.exit -; CHECK: loop: -; CHECK-NEXT: %idx = phi i32 [ %idx.next, %in.bounds ], [ 0, %loop.preheader ] -; CHECK-NEXT: %idx.next = add nuw nsw i32 %idx, 1 -; CHECK-NEXT: %abc = icmp slt i32 %idx, %len -; CHECK-NEXT: br i1 true, label %in.bounds, label %out.of.bounds.loopexit1 -; CHECK: in.bounds: -; CHECK-NEXT: %addr = getelementptr i32, i32* %arr, i32 %idx -; CHECK-NEXT: store i32 0, i32* %addr -; CHECK-NEXT: %next = icmp slt i32 %idx, 100 -; CHECK-NEXT: [[COND3:%[^ ]+]] = icmp slt i32 %idx, %exit.mainloop.at -; CHECK-NEXT: br i1 [[COND3]], label %loop, label %main.exit.selector -; CHECK: main.exit.selector: -; CHECK-NEXT: %idx.lcssa = phi i32 [ %idx, %in.bounds ] -; CHECK-NEXT: %idx.next.lcssa = phi i32 [ %idx.next, %in.bounds ] -; CHECK-NEXT: [[COND4:%[^ ]+]] = icmp slt i32 %idx.lcssa, 100 -; CHECK-NEXT: br i1 [[COND4]], label %main.pseudo.exit, label %exit -; CHECK-NOT: loop.preloop: -; CHECK: loop.postloop: -; CHECK-NEXT: %idx.postloop = phi i32 [ %idx.copy, %postloop ], [ %idx.next.postloop, %in.bounds.postloop ] -; CHECK-NEXT: %idx.next.postloop = add nuw nsw i32 %idx.postloop, 1 -; CHECK-NEXT: %abc.postloop = icmp slt i32 %idx.postloop, %len -; CHECK-NEXT: br i1 %abc.postloop, label %in.bounds.postloop, label %out.of.bounds.loopexit - -entry: - %len = load i32, i32* %a_len_ptr, !range !0 - br label %loop - -loop: - %idx = phi i32 [ 0, %entry ], [ %idx.next, %in.bounds ] - %idx.next = add nsw nuw i32 %idx, 1 - %abc = icmp slt i32 %idx, %len - br i1 %abc, label %in.bounds, label %out.of.bounds - -in.bounds: - %addr = getelementptr i32, i32* %arr, i32 %idx - store i32 0, i32* %addr - %next = icmp slt i32 %idx, 100 - br i1 %next, label %loop, label %exit - -out.of.bounds: - ret void - -exit: - ret void -} - -; ULT condition for increasing loop from 0 to 100. -define void @test_02(i32* %arr, i32* %a_len_ptr) #0 { - -; CHECK: test_02 -; CHECK: entry: -; CHECK-NEXT: %len = load i32, i32* %a_len_ptr, !range !0 -; CHECK-NEXT: %exit.mainloop.at = add i32 %len, -1 -; CHECK-NEXT: [[COND2:%[^ ]+]] = icmp ult i32 0, %exit.mainloop.at -; CHECK-NEXT: br i1 [[COND2]], label %loop.preheader, label %main.pseudo.exit -; CHECK: loop: -; CHECK-NEXT: %idx = phi i32 [ %idx.next, %in.bounds ], [ 0, %loop.preheader ] -; CHECK-NEXT: %idx.next = add nuw nsw i32 %idx, 1 -; CHECK-NEXT: %abc = icmp ult i32 %idx, %len -; CHECK-NEXT: br i1 true, label %in.bounds, label %out.of.bounds.loopexit1 -; CHECK: in.bounds: -; CHECK-NEXT: %addr = getelementptr i32, i32* %arr, i32 %idx -; CHECK-NEXT: store i32 0, i32* %addr -; CHECK-NEXT: %next = icmp ult i32 %idx, 100 -; CHECK-NEXT: [[COND3:%[^ ]+]] = icmp ult i32 %idx, %exit.mainloop.at -; CHECK-NEXT: br i1 [[COND3]], label %loop, label %main.exit.selector -; CHECK: main.exit.selector: -; CHECK-NEXT: %idx.lcssa = phi i32 [ %idx, %in.bounds ] -; CHECK-NEXT: %idx.next.lcssa = phi i32 [ %idx.next, %in.bounds ] -; CHECK-NEXT: [[COND4:%[^ ]+]] = icmp ult i32 %idx.lcssa, 100 -; CHECK-NEXT: br i1 [[COND4]], label %main.pseudo.exit, label %exit -; CHECK-NOT: loop.preloop: -; CHECK: loop.postloop: -; CHECK-NEXT: %idx.postloop = phi i32 [ %idx.copy, %postloop ], [ %idx.next.postloop, %in.bounds.postloop ] -; CHECK-NEXT: %idx.next.postloop = add nuw nsw i32 %idx.postloop, 1 -; CHECK-NEXT: %abc.postloop = icmp ult i32 %idx.postloop, %len -; CHECK-NEXT: br i1 %abc.postloop, label %in.bounds.postloop, label %out.of.bounds.loopexit - -entry: - %len = load i32, i32* %a_len_ptr, !range !0 - br label %loop - -loop: - %idx = phi i32 [ 0, %entry ], [ %idx.next, %in.bounds ] - %idx.next = add nsw nuw i32 %idx, 1 - %abc = icmp ult i32 %idx, %len - br i1 %abc, label %in.bounds, label %out.of.bounds - -in.bounds: - %addr = getelementptr i32, i32* %arr, i32 %idx - store i32 0, i32* %addr - %next = icmp ult i32 %idx, 100 - br i1 %next, label %loop, label %exit - -out.of.bounds: - ret void - -exit: - ret void -} - -; Same as test_01, but comparison happens against IV extended to a wider type. -; This test ensures that IRCE rejects it and does not falsely assume that it was -; a comparison against iv.next. -; TODO: We can actually extend the recognition to cover this case. -define void @test_03(i32* %arr, i64* %a_len_ptr) #0 { - -; CHECK: test_03 - -entry: - %len = load i64, i64* %a_len_ptr, !range !1 - br label %loop - -loop: - %idx = phi i32 [ 0, %entry ], [ %idx.next, %in.bounds ] - %idx.next = add nsw nuw i32 %idx, 1 - %idx.ext = sext i32 %idx to i64 - %abc = icmp slt i64 %idx.ext, %len - br i1 %abc, label %in.bounds, label %out.of.bounds - -in.bounds: - %addr = getelementptr i32, i32* %arr, i32 %idx - store i32 0, i32* %addr - %next = icmp slt i32 %idx, 100 - br i1 %next, label %loop, label %exit - -out.of.bounds: - ret void - -exit: - ret void -} - -; Same as test_02, but comparison happens against IV extended to a wider type. -; This test ensures that IRCE rejects it and does not falsely assume that it was -; a comparison against iv.next. -; TODO: We can actually extend the recognition to cover this case. -define void @test_04(i32* %arr, i64* %a_len_ptr) #0 { - -; CHECK: test_04 - -entry: - %len = load i64, i64* %a_len_ptr, !range !1 - br label %loop - -loop: - %idx = phi i32 [ 0, %entry ], [ %idx.next, %in.bounds ] - %idx.next = add nsw nuw i32 %idx, 1 - %idx.ext = sext i32 %idx to i64 - %abc = icmp ult i64 %idx.ext, %len - br i1 %abc, label %in.bounds, label %out.of.bounds - -in.bounds: - %addr = getelementptr i32, i32* %arr, i32 %idx - store i32 0, i32* %addr - %next = icmp ult i32 %idx, 100 - br i1 %next, label %loop, label %exit - -out.of.bounds: - ret void - -exit: - ret void -} - -define void @test_05(i32* %arr, i32* %a_len_ptr) #0 { - -; CHECK: test_05 -; CHECK: entry: -; CHECK-NEXT: %len = load i32, i32* %a_len_ptr, !range !0 -; CHECK-NEXT: %exit.mainloop.at = add i32 %len, -1 -; CHECK-NEXT: br i1 true, label %loop.preloop.preheader, label %preloop.pseudo.exit -; CHECK: loop.preloop: -; CHECK-NEXT: %idx.preloop = phi i32 [ %idx.next.preloop, %in.bounds.preloop ], [ -10, %loop.preloop.preheader ] -; CHECK-NEXT: %idx.next.preloop = add i32 %idx.preloop, 1 -; CHECK-NEXT: %c1.preloop = icmp sge i32 %idx.preloop, 0 -; CHECK-NEXT: %c2.preloop = icmp slt i32 %idx.preloop, %len -; CHECK-NEXT: %abc.preloop = and i1 %c1.preloop, %c2.preloop -; CHECK-NEXT: br i1 %abc.preloop, label %in.bounds.preloop, label %out.of.bounds.loopexit -; CHECK: in.bounds.preloop: -; CHECK-NEXT: %addr.preloop = getelementptr i32, i32* %arr, i32 %idx.preloop -; CHECK-NEXT: store i32 0, i32* %addr.preloop -; CHECK-NEXT: %next.preloop = icmp slt i32 %idx.preloop, 100 -; CHECK-NEXT: [[COND3:%[^ ]+]] = icmp slt i32 %idx.preloop, 0 -; CHECK-NEXT: br i1 [[COND3]], label %loop.preloop, label %preloop.exit.selector -; CHECK: loop.postloop: -; CHECK-NEXT: %idx.postloop = phi i32 [ %idx.copy, %postloop ], [ %idx.next.postloop, %in.bounds.postloop ] -; CHECK-NEXT: %idx.next.postloop = add i32 %idx.postloop, 1 -; CHECK-NEXT: %c1.postloop = icmp sge i32 %idx.postloop, 0 -; CHECK-NEXT: %c2.postloop = icmp slt i32 %idx.postloop, %len -; CHECK-NEXT: %abc.postloop = and i1 %c1.postloop, %c2.postloop -; CHECK-NEXT: br i1 %abc.postloop, label %in.bounds.postloop, label %out.of.bounds.loopexit2 -; CHECK: in.bounds.postloop: -; CHECK-NEXT: %addr.postloop = getelementptr i32, i32* %arr, i32 %idx.postloop -; CHECK-NEXT: store i32 0, i32* %addr.postloop -; CHECK-NEXT: %next.postloop = icmp slt i32 %idx.postloop, 100 -; CHECK-NEXT: br i1 %next.postloop, label %loop.postloop, label %exit.loopexit - -entry: - %len = load i32, i32* %a_len_ptr, !range !0 - br label %loop - -loop: - %idx = phi i32 [-10, %entry ], [ %idx.next, %in.bounds ] - %idx.next = add i32 %idx, 1 - %c1 = icmp sge i32 %idx, 0 - %c2 = icmp slt i32 %idx, %len - %abc = and i1 %c1, %c2 - br i1 %abc, label %in.bounds, label %out.of.bounds - -in.bounds: - %addr = getelementptr i32, i32* %arr, i32 %idx - store i32 0, i32* %addr - %next = icmp slt i32 %idx, 100 - br i1 %next, label %loop, label %exit - -out.of.bounds: - ret void - -exit: - ret void -} - -!0 = !{i32 0, i32 50} -!1 = !{i64 0, i64 50} |
