From: Johannes Doerfert Date: Sun, 3 Apr 2016 11:12:39 +0000 (+0000) Subject: [FIX] Do not create a SCoP in the presence of infinite loops X-Git-Tag: llvmorg-3.9.0-rc1~10142 X-Git-Url: http://review.tizen.org/git/?a=commitdiff_plain;h=7dcceb82e9b9799e620923ea05a47f6eb47a3dda;p=platform%2Fupstream%2Fllvm.git [FIX] Do not create a SCoP in the presence of infinite loops If a loop has no exiting blocks the region covering we use during schedule genertion might not cover that loop properly. For now we bail out as we would not optimize these loops anyway. llvm-svn: 265260 --- diff --git a/polly/lib/Analysis/ScopDetection.cpp b/polly/lib/Analysis/ScopDetection.cpp index 594d656..c0dba12 100644 --- a/polly/lib/Analysis/ScopDetection.cpp +++ b/polly/lib/Analysis/ScopDetection.cpp @@ -1029,8 +1029,14 @@ bool ScopDetection::canUseISLTripCount(Loop *L, // Ensure the loop has valid exiting blocks as well as latches, otherwise we // need to overapproximate it as a boxed loop. SmallVector LoopControlBlocks; - L->getLoopLatches(LoopControlBlocks); L->getExitingBlocks(LoopControlBlocks); + + // Loops without exiting blocks cannot be handled by the schedule generation + // as it depends on a region covering that is not given. + if (LoopControlBlocks.empty()) + return false; + + L->getLoopLatches(LoopControlBlocks); for (BasicBlock *ControlBB : LoopControlBlocks) { if (!isValidCFG(*ControlBB, true, false, Context)) return false; diff --git a/polly/lib/Analysis/ScopInfo.cpp b/polly/lib/Analysis/ScopInfo.cpp index b61d9fa..f3271c2 100644 --- a/polly/lib/Analysis/ScopInfo.cpp +++ b/polly/lib/Analysis/ScopInfo.cpp @@ -3618,8 +3618,15 @@ void Scop::buildSchedule(ScopDetection &SD, LoopInfo &LI) { Loop *L = getLoopSurroundingRegion(getRegion(), LI); LoopStackTy LoopStack({LoopStackElementTy(L, nullptr, 0)}); buildSchedule(getRegion().getNode(), LoopStack, SD, LI); - assert(LoopStack.size() == 1 && LoopStack.back().L == L); - Schedule = LoopStack[0].Schedule; + assert(!LoopStack.empty()); + if (LoopStack.size() == 1 && LoopStack.back().L == L) { + Schedule = LoopStack[0].Schedule; + } else { + // If something went wrong we have to cleanup. + assert(!hasFeasibleRuntimeContext()); + while (!LoopStack.empty()) + isl_schedule_free(LoopStack.pop_back_val().Schedule); + } } /// To generate a schedule for the elements in a Region we traverse the Region @@ -3662,9 +3669,22 @@ void Scop::buildSchedule(Region *R, LoopStackTy &LoopStack, ScopDetection &SD, // iterator. If it is set we have to explore the next sub-region/block from // the iterator (if any) to guarantee progress. If it is not set we first try // the next queued sub-region/blocks. + unsigned RemainingWork = WorkList.size() + DelayList.size() + 1; while (!WorkList.empty() || !DelayList.empty()) { + Loop *LastLoop = LoopStack.back().L; RegionNode *RN; + // FIXME: We will bail out if we cannot make progress. So far that is only + // known to happen in the presence of infinite loops without an exit + // edge. For such cases there is no region covering only the loop and + // our reasoning fails. + if (WorkList.size() + DelayList.size() >= RemainingWork) { + invalidate(INFINITELOOP, R->getEntry()->getTerminator()->getDebugLoc()); + LastLoop = nullptr; + } + + RemainingWork = WorkList.size() + DelayList.size(); + if ((LastRNWaiting && !WorkList.empty()) || DelayList.size() == 0) { RN = WorkList.front(); WorkList.pop_front(); @@ -3678,9 +3698,8 @@ void Scop::buildSchedule(Region *R, LoopStackTy &LoopStack, ScopDetection &SD, if (!getRegion().contains(L)) L = OuterScopLoop; - Loop *LastLoop = LoopStack.back().L; if (LastLoop != L) { - if (!LastLoop->contains(L)) { + if (LastLoop && !LastLoop->contains(L)) { LastRNWaiting = true; DelayList.push_back(RN); continue; diff --git a/polly/test/ScopInfo/schedule-constuction-endless-loop1.ll b/polly/test/ScopInfo/schedule-constuction-endless-loop1.ll new file mode 100644 index 0000000..50af71b --- /dev/null +++ b/polly/test/ScopInfo/schedule-constuction-endless-loop1.ll @@ -0,0 +1,34 @@ +; RUN: opt %loadPolly -polly-scops -analyze < %s | FileCheck %s +; +; Check that we do not build a SCoP and do not crash. +; +; CHECK-NOT: Statements +; +target datalayout = "e-m:e-i64:64-f80:128-n8:16:32:64-S128" + +; Function Attrs: nounwind uwtable +define void @int_upsample(i32* %A) { +entry: + %0 = load i8, i8* undef, align 1 + %conv7 = zext i8 %0 to i32 + br label %while.body.preheader + +while.body.preheader: ; preds = %entry + br label %while.body + +while.body: ; preds = %if.end, %while.body.preheader + %outrow.036 = phi i32 [ %add23, %if.end ], [ 0, %while.body.preheader ] + br i1 true, label %if.end, label %while.body16 + +while.body16: ; preds = %while.body16, %while.body + br label %while.body16 + +if.end: ; preds = %while.body + store i32 0, i32* %A + %add23 = add nuw nsw i32 %outrow.036, 1 + %cmp = icmp slt i32 %add23, 0 + br i1 %cmp, label %while.body, label %while.end24 + +while.end24: ; preds = %if.end + ret void +} diff --git a/polly/test/ScopInfo/schedule-constuction-endless-loop2.ll b/polly/test/ScopInfo/schedule-constuction-endless-loop2.ll new file mode 100644 index 0000000..d190ddd --- /dev/null +++ b/polly/test/ScopInfo/schedule-constuction-endless-loop2.ll @@ -0,0 +1,37 @@ +; RUN: opt %loadPolly -polly-scops -analyze < %s | FileCheck %s +; +; Check that we do not build a SCoP and do not crash. +; +; CHECK-NOT: Statements +; +target datalayout = "e-m:e-i64:64-f80:128-n8:16:32:64-S128" + +; Function Attrs: nounwind uwtable +define void @int_upsample(i32* %A) { +entry: + %0 = load i8, i8* undef, align 1 + %conv7 = zext i8 %0 to i32 + br label %while.body.preheader + +while.body.preheader: ; preds = %entry + br label %while.body + +while.body: ; preds = %if.end, %while.body.preheader + %outrow.036 = phi i32 [ %add23, %if.end ], [ 0, %while.body.preheader ] + br i1 true, label %if.end, label %while.body16 + +while.body16: ; preds = %while.body16, %while.body + br label %while.body16.split + +while.body16.split: + br label %while.body16 + +if.end: ; preds = %while.body + store i32 0, i32* %A + %add23 = add nuw nsw i32 %outrow.036, 1 + %cmp = icmp slt i32 %add23, 0 + br i1 %cmp, label %while.body, label %while.end24 + +while.end24: ; preds = %if.end + ret void +} diff --git a/polly/test/ScopInfo/two-loops-one-infinite.ll b/polly/test/ScopInfo/two-loops-one-infinite.ll index 21a4f4e..974194f 100644 --- a/polly/test/ScopInfo/two-loops-one-infinite.ll +++ b/polly/test/ScopInfo/two-loops-one-infinite.ll @@ -1,16 +1,8 @@ ; RUN: opt %loadPolly -polly-scops -analyze < %s | FileCheck %s ; -; Verify we detect and create the SCoP correctly +; Verify we do not create a SCoP in the presence of infinite loops. ; -; CHECK: Statements { -; CHECK-NEXT: Stmt_while_body_us -; CHECK-NEXT: Domain := -; CHECK-NEXT: [a13] -> { Stmt_while_body_us[] }; -; CHECK-NEXT: Schedule := -; CHECK-NEXT: [a13] -> { Stmt_while_body_us[] -> [] }; -; CHECK-NEXT: MustWriteAccess := [Reduction Type: NONE] [Scalar: 1] -; CHECK-NEXT: [a13] -> { Stmt_while_body_us[] -> MemRef_uuu[] }; -; CHECK-NEXT: } +; CHECK-NOT: Statements ; target datalayout = "e-m:e-p:32:32-i64:64-v128:64:128-a:0:32-n8:16:32-S64"