From f38041dc3e51d1dd437b5fae852c27ffcc68c800 Mon Sep 17 00:00:00 2001 From: Serguei Katkov Date: Mon, 22 Jan 2018 07:47:02 +0000 Subject: [PATCH] Revert [SCEV] Fix isLoopEntryGuardedByCond usage It causes buildbot failures. New added assert is fired. It seems not all usages of isLoopEntryGuardedByCond are fixed. llvm-svn: 323079 --- llvm/lib/Analysis/ScalarEvolution.cpp | 12 +---- .../Scalar/InductiveRangeCheckElimination.cpp | 19 ++++---- llvm/test/Transforms/IndVarSimplify/inner-loop.ll | 54 ---------------------- 3 files changed, 10 insertions(+), 75 deletions(-) delete mode 100644 llvm/test/Transforms/IndVarSimplify/inner-loop.ll diff --git a/llvm/lib/Analysis/ScalarEvolution.cpp b/llvm/lib/Analysis/ScalarEvolution.cpp index e252470..7a9fddf 100644 --- a/llvm/lib/Analysis/ScalarEvolution.cpp +++ b/llvm/lib/Analysis/ScalarEvolution.cpp @@ -8669,8 +8669,7 @@ bool ScalarEvolution::isKnownPredicate(ICmpInst::Predicate Pred, bool RightGuarded = false; if (LAR) { const Loop *L = LAR->getLoop(); - if (isAvailableAtLoopEntry(RHS, L) && - isLoopEntryGuardedByCond(L, Pred, LAR->getStart(), RHS) && + if (isLoopEntryGuardedByCond(L, Pred, LAR->getStart(), RHS) && isLoopBackedgeGuardedByCond(L, Pred, LAR->getPostIncExpr(*this), RHS)) { if (!RAR) return true; LeftGuarded = true; @@ -8678,8 +8677,7 @@ bool ScalarEvolution::isKnownPredicate(ICmpInst::Predicate Pred, } if (RAR) { const Loop *L = RAR->getLoop(); - if (isAvailableAtLoopEntry(LHS, L) && - isLoopEntryGuardedByCond(L, Pred, LHS, RAR->getStart()) && + if (isLoopEntryGuardedByCond(L, Pred, LHS, RAR->getStart()) && isLoopBackedgeGuardedByCond(L, Pred, LHS, RAR->getPostIncExpr(*this))) { if (!LAR) return true; RightGuarded = true; @@ -9060,12 +9058,6 @@ bool ScalarEvolution::isLoopEntryGuardedByCond(const Loop *L, ICmpInst::Predicate Pred, const SCEV *LHS, const SCEV *RHS) { - // Both LHS and RHS must be available at loop entry. - assert(isAvailableAtLoopEntry(LHS, L) && - "LHS is not available at Loop Entry"); - assert(isAvailableAtLoopEntry(RHS, L) && - "RHS is not available at Loop Entry"); - // Interpret a null as meaning no loop, where there is obviously no guard // (interprocedural conditions notwithstanding). if (!L) return false; diff --git a/llvm/lib/Transforms/Scalar/InductiveRangeCheckElimination.cpp b/llvm/lib/Transforms/Scalar/InductiveRangeCheckElimination.cpp index 1af77d8..c8e58a1 100644 --- a/llvm/lib/Transforms/Scalar/InductiveRangeCheckElimination.cpp +++ b/llvm/lib/Transforms/Scalar/InductiveRangeCheckElimination.cpp @@ -934,9 +934,9 @@ LoopStructure::parseLoopStructure(ScalarEvolution &SE, return None; } - if (!SE.isAvailableAtLoopEntry(RightSCEV, &L) || - !SE.isLoopEntryGuardedByCond(&L, BoundPred, IndVarStart, - SE.getAddExpr(RightSCEV, Step))) { + if (!SE.isLoopEntryGuardedByCond( + &L, BoundPred, IndVarStart, + SE.getAddExpr(RightSCEV, Step))) { FailureReason = "Induction variable start not bounded by upper limit"; return None; } @@ -948,8 +948,7 @@ LoopStructure::parseLoopStructure(ScalarEvolution &SE, RightValue = B.CreateAdd(RightValue, One); } } else { - if (!SE.isAvailableAtLoopEntry(RightSCEV, &L) || - !SE.isLoopEntryGuardedByCond(&L, BoundPred, IndVarStart, RightSCEV)) { + if (!SE.isLoopEntryGuardedByCond(&L, BoundPred, IndVarStart, RightSCEV)) { FailureReason = "Induction variable start not bounded by upper limit"; return None; } @@ -1015,10 +1014,9 @@ LoopStructure::parseLoopStructure(ScalarEvolution &SE, return None; } - if (!SE.isAvailableAtLoopEntry(RightSCEV, &L) || - !SE.isLoopEntryGuardedByCond( - &L, BoundPred, IndVarStart, - SE.getMinusSCEV(RightSCEV, SE.getOne(RightSCEV->getType())))) { + if (!SE.isLoopEntryGuardedByCond( + &L, BoundPred, IndVarStart, + SE.getMinusSCEV(RightSCEV, SE.getOne(RightSCEV->getType())))) { FailureReason = "Induction variable start not bounded by lower limit"; return None; } @@ -1030,8 +1028,7 @@ LoopStructure::parseLoopStructure(ScalarEvolution &SE, RightValue = B.CreateSub(RightValue, One); } } else { - if (!SE.isAvailableAtLoopEntry(RightSCEV, &L) || - !SE.isLoopEntryGuardedByCond(&L, BoundPred, IndVarStart, RightSCEV)) { + if (!SE.isLoopEntryGuardedByCond(&L, BoundPred, IndVarStart, RightSCEV)) { FailureReason = "Induction variable start not bounded by lower limit"; return None; } diff --git a/llvm/test/Transforms/IndVarSimplify/inner-loop.ll b/llvm/test/Transforms/IndVarSimplify/inner-loop.ll deleted file mode 100644 index 328987c..0000000 --- a/llvm/test/Transforms/IndVarSimplify/inner-loop.ll +++ /dev/null @@ -1,54 +0,0 @@ -; RUN: opt < %s -indvars -S | FileCheck %s - -; This is regression test for the bug in ScalarEvolution::isKnownPredicate. -; It does not check whether SCEV is available at loop entry before invoking -; and utility function isLoopEntryGuardedByCond and that leads to miscompile. - -target datalayout = "e-m:e-i64:64-f80:128-n8:16:32:64-S128-ni:1" -target triple = "x86_64-unknown-linux-gnu" - -declare void @foo(i64) -declare void @bar(i32) - -define void @test(i8* %arr) { -entry: - br label %outer_header - -outer_header: - %i = phi i32 [40, %entry], [%i.next, %outer_latch] - %i.64 = sext i32 %i to i64 - br label %inner_header - -inner_header: - %j = phi i32 [27, %outer_header], [%j.next, %inner_backedge] - %j1 = zext i32 %j to i64 -; The next 4 lines are required for avoid widening of %j and -; SCEV at %cmp would not be AddRec. - %gep = getelementptr inbounds i8, i8* %arr, i64 %j1 - %ld = load i8, i8* %gep - %ec = icmp eq i8 %ld, 0 - br i1 %ec, label %return, label %inner_backedge - -inner_backedge: - %cmp = icmp ult i32 %j, %i - %s = select i1 %cmp, i32 %i, i32 %j -; Select should not be simplified because if -; %i == 26 and %j == 27, %s should be equal to %j. -; In case of a bug the instruction is simplified to -; %s = select i1 true, i32 %0, i32 %j -; CHECK-NOT: %s = select i1 true - call void @bar(i32 %s) - %j.next = add nsw i32 %j, -2 - %cond = icmp ult i32 %j, 3 - br i1 %cond, label %outer_latch, label %inner_header - -outer_latch: - %i.next = add i32 %i, -1 - %cond2 = icmp sgt i32 %i.next, 13 -; This line is just for forcing widening of %i - call void @foo(i64 %i.64) - br i1 %cond2, label %outer_header, label %return - -return: - ret void -} -- 2.7.4