From c49194969430f0ee817498a7000a979a7a0ded03 Mon Sep 17 00:00:00 2001 From: Florian Hahn Date: Sat, 7 Dec 2019 17:29:07 +0000 Subject: [PATCH] [LV] Pick correct BB as insert point when fixing PHI for FORs. Currently we fail to pick the right insertion point when PreviousLastPart of a first-order-recurrence is a PHI node not in the LoopVectorBody. This can happen when PreviousLastPart is produce in a predicated block. In that case, we should pick the insertion point in the BB the PHI is in. Fixes PR44020. Reviewers: hsaito, fhahn, Ayal, dorit Reviewed By: Ayal Differential Revision: https://reviews.llvm.org/D71071 --- llvm/lib/Transforms/Vectorize/LoopVectorize.cpp | 30 ++++-- .../SystemZ/predicated-first-order-recurrence.ll | 103 +++++++++++++++++++++ 2 files changed, 123 insertions(+), 10 deletions(-) create mode 100644 llvm/test/Transforms/LoopVectorize/SystemZ/predicated-first-order-recurrence.ll diff --git a/llvm/lib/Transforms/Vectorize/LoopVectorize.cpp b/llvm/lib/Transforms/Vectorize/LoopVectorize.cpp index 3d21c93..dd9b44a 100644 --- a/llvm/lib/Transforms/Vectorize/LoopVectorize.cpp +++ b/llvm/lib/Transforms/Vectorize/LoopVectorize.cpp @@ -3556,17 +3556,27 @@ void InnerLoopVectorizer::fixFirstOrderRecurrence(PHINode *Phi) { // among all unrolled iterations, due to the order of their construction. Value *PreviousLastPart = getOrCreateVectorValue(Previous, UF - 1); - // Set the insertion point after the previous value if it is an instruction. + // Find and set the insertion point after the previous value if it is an + // instruction. + BasicBlock::iterator InsertPt; // Note that the previous value may have been constant-folded so it is not - // guaranteed to be an instruction in the vector loop. Also, if the previous - // value is a phi node, we should insert after all the phi nodes to avoid - // breaking basic block verification. - if (LI->getLoopFor(LoopVectorBody)->isLoopInvariant(PreviousLastPart) || - isa(PreviousLastPart)) - Builder.SetInsertPoint(&*LoopVectorBody->getFirstInsertionPt()); - else - Builder.SetInsertPoint( - &*++BasicBlock::iterator(cast(PreviousLastPart))); + // guaranteed to be an instruction in the vector loop. + // FIXME: Loop invariant values do not form recurrences. We should deal with + // them earlier. + if (LI->getLoopFor(LoopVectorBody)->isLoopInvariant(PreviousLastPart)) + InsertPt = LoopVectorBody->getFirstInsertionPt(); + else { + Instruction *PreviousInst = cast(PreviousLastPart); + if (isa(PreviousLastPart)) + // If the previous value is a phi node, we should insert after all the phi + // nodes in the block containing the PHI to avoid breaking basic block + // verification. Note that the basic block may be different to + // LoopVectorBody, in case we predicate the loop. + InsertPt = PreviousInst->getParent()->getFirstInsertionPt(); + else + InsertPt = ++PreviousInst->getIterator(); + } + Builder.SetInsertPoint(&*InsertPt); // We will construct a vector for the recurrence by combining the values for // the current and previous iterations. This is the required shuffle mask. diff --git a/llvm/test/Transforms/LoopVectorize/SystemZ/predicated-first-order-recurrence.ll b/llvm/test/Transforms/LoopVectorize/SystemZ/predicated-first-order-recurrence.ll new file mode 100644 index 0000000..7c5b5c5 --- /dev/null +++ b/llvm/test/Transforms/LoopVectorize/SystemZ/predicated-first-order-recurrence.ll @@ -0,0 +1,103 @@ +; NOTE: Assertions have been autogenerated by utils/update_test_checks.py +; RUN: opt -loop-vectorize -mtriple=s390x-ibm-linux -mcpu=z13 -force-vector-width=2 -S %s | FileCheck %s + +; Test case from PR44020. + +; In func_21, %rec forms a first order recurrence and we predicate to avoid +; scalar iteration overhead for a low trip count loop. Make sure we pick +; the correct insertion point when fixing first order recurrences. + +@A = external dso_local global [5 x i32], align 4 +@B = external dso_local global [5 x i32], align 4 + +define void @func_21() { +; CHECK-LABEL: @func_21( +; CHECK-NEXT: entry: +; CHECK-NEXT: br i1 false, label [[SCALAR_PH:%.*]], label [[VECTOR_PH:%.*]] +; CHECK: vector.ph: +; CHECK-NEXT: br label [[VECTOR_BODY:%.*]] +; CHECK: vector.body: +; CHECK-NEXT: [[INDEX:%.*]] = phi i64 [ 0, [[VECTOR_PH]] ], [ [[INDEX_NEXT:%.*]], [[PRED_STORE_CONTINUE4:%.*]] ] +; CHECK-NEXT: [[VECTOR_RECUR:%.*]] = phi <2 x i32> [ , [[VECTOR_PH]] ], [ [[TMP12:%.*]], [[PRED_STORE_CONTINUE4]] ] +; CHECK-NEXT: [[BROADCAST_SPLATINSERT:%.*]] = insertelement <2 x i64> undef, i64 [[INDEX]], i32 0 +; CHECK-NEXT: [[BROADCAST_SPLAT:%.*]] = shufflevector <2 x i64> [[BROADCAST_SPLATINSERT]], <2 x i64> undef, <2 x i32> zeroinitializer +; CHECK-NEXT: [[INDUCTION:%.*]] = add <2 x i64> [[BROADCAST_SPLAT]], +; CHECK-NEXT: [[TMP0:%.*]] = add i64 [[INDEX]], 0 +; CHECK-NEXT: [[TMP1:%.*]] = add i64 [[INDEX]], 1 +; CHECK-NEXT: [[TMP2:%.*]] = icmp ule <2 x i64> [[INDUCTION]], +; CHECK-NEXT: [[TMP3:%.*]] = extractelement <2 x i1> [[TMP2]], i32 0 +; CHECK-NEXT: br i1 [[TMP3]], label [[PRED_LOAD_IF:%.*]], label [[PRED_LOAD_CONTINUE:%.*]] +; CHECK: pred.load.if: +; CHECK-NEXT: [[TMP4:%.*]] = getelementptr inbounds [5 x i32], [5 x i32]* @A, i64 0, i64 [[TMP0]] +; CHECK-NEXT: [[TMP5:%.*]] = load i32, i32* [[TMP4]], align 4 +; CHECK-NEXT: [[TMP6:%.*]] = insertelement <2 x i32> undef, i32 [[TMP5]], i32 0 +; CHECK-NEXT: br label [[PRED_LOAD_CONTINUE]] +; CHECK: pred.load.continue: +; CHECK-NEXT: [[TMP7:%.*]] = phi <2 x i32> [ undef, [[VECTOR_BODY]] ], [ [[TMP6]], [[PRED_LOAD_IF]] ] +; CHECK-NEXT: [[TMP8:%.*]] = extractelement <2 x i1> [[TMP2]], i32 1 +; CHECK-NEXT: br i1 [[TMP8]], label [[PRED_LOAD_IF1:%.*]], label [[PRED_LOAD_CONTINUE2:%.*]] +; CHECK: pred.load.if1: +; CHECK-NEXT: [[TMP9:%.*]] = getelementptr inbounds [5 x i32], [5 x i32]* @A, i64 0, i64 [[TMP1]] +; CHECK-NEXT: [[TMP10:%.*]] = load i32, i32* [[TMP9]], align 4 +; CHECK-NEXT: [[TMP11:%.*]] = insertelement <2 x i32> [[TMP7]], i32 [[TMP10]], i32 1 +; CHECK-NEXT: br label [[PRED_LOAD_CONTINUE2]] +; CHECK: pred.load.continue2: +; CHECK-NEXT: [[TMP12]] = phi <2 x i32> [ [[TMP7]], [[PRED_LOAD_CONTINUE]] ], [ [[TMP11]], [[PRED_LOAD_IF1]] ] +; CHECK-NEXT: [[TMP13:%.*]] = shufflevector <2 x i32> [[VECTOR_RECUR]], <2 x i32> [[TMP12]], <2 x i32> +; CHECK-NEXT: [[TMP14:%.*]] = extractelement <2 x i1> [[TMP2]], i32 0 +; CHECK-NEXT: br i1 [[TMP14]], label [[PRED_STORE_IF:%.*]], label [[PRED_STORE_CONTINUE:%.*]] +; CHECK: pred.store.if: +; CHECK-NEXT: [[TMP15:%.*]] = getelementptr inbounds [5 x i32], [5 x i32]* @B, i64 0, i64 [[TMP0]] +; CHECK-NEXT: [[TMP16:%.*]] = extractelement <2 x i32> [[TMP13]], i32 0 +; CHECK-NEXT: store i32 [[TMP16]], i32* [[TMP15]], align 4 +; CHECK-NEXT: br label [[PRED_STORE_CONTINUE]] +; CHECK: pred.store.continue: +; CHECK-NEXT: [[TMP17:%.*]] = extractelement <2 x i1> [[TMP2]], i32 1 +; CHECK-NEXT: br i1 [[TMP17]], label [[PRED_STORE_IF3:%.*]], label [[PRED_STORE_CONTINUE4]] +; CHECK: pred.store.if3: +; CHECK-NEXT: [[TMP18:%.*]] = getelementptr inbounds [5 x i32], [5 x i32]* @B, i64 0, i64 [[TMP1]] +; CHECK-NEXT: [[TMP19:%.*]] = extractelement <2 x i32> [[TMP13]], i32 1 +; CHECK-NEXT: store i32 [[TMP19]], i32* [[TMP18]], align 4 +; CHECK-NEXT: br label [[PRED_STORE_CONTINUE4]] +; CHECK: pred.store.continue4: +; CHECK-NEXT: [[INDEX_NEXT]] = add i64 [[INDEX]], 2 +; CHECK-NEXT: [[TMP20:%.*]] = icmp eq i64 [[INDEX_NEXT]], 6 +; CHECK-NEXT: br i1 [[TMP20]], label [[MIDDLE_BLOCK:%.*]], label [[VECTOR_BODY]], !llvm.loop !0 +; CHECK: middle.block: +; CHECK-NEXT: [[VECTOR_RECUR_EXTRACT:%.*]] = extractelement <2 x i32> [[TMP12]], i32 1 +; CHECK-NEXT: [[VECTOR_RECUR_EXTRACT_FOR_PHI:%.*]] = extractelement <2 x i32> [[TMP12]], i32 0 +; CHECK-NEXT: br i1 true, label [[EXIT:%.*]], label [[SCALAR_PH]] +; CHECK: scalar.ph: +; CHECK-NEXT: [[SCALAR_RECUR_INIT:%.*]] = phi i32 [ [[VECTOR_RECUR_EXTRACT]], [[MIDDLE_BLOCK]] ], [ 0, [[ENTRY:%.*]] ] +; CHECK-NEXT: [[BC_RESUME_VAL:%.*]] = phi i64 [ 6, [[MIDDLE_BLOCK]] ], [ 0, [[ENTRY]] ] +; CHECK-NEXT: br label [[LOOP:%.*]] +; CHECK: loop: +; CHECK-NEXT: [[SCALAR_RECUR:%.*]] = phi i32 [ [[SCALAR_RECUR_INIT]], [[SCALAR_PH]] ], [ [[LV:%.*]], [[LOOP]] ] +; CHECK-NEXT: [[INDVARS_IV:%.*]] = phi i64 [ [[BC_RESUME_VAL]], [[SCALAR_PH]] ], [ [[INDVARS_IV_NEXT:%.*]], [[LOOP]] ] +; CHECK-NEXT: [[A_PTR:%.*]] = getelementptr inbounds [5 x i32], [5 x i32]* @A, i64 0, i64 [[INDVARS_IV]] +; CHECK-NEXT: [[LV]] = load i32, i32* [[A_PTR]], align 4 +; CHECK-NEXT: [[B_PTR:%.*]] = getelementptr inbounds [5 x i32], [5 x i32]* @B, i64 0, i64 [[INDVARS_IV]] +; CHECK-NEXT: store i32 [[SCALAR_RECUR]], i32* [[B_PTR]], align 4 +; CHECK-NEXT: [[INDVARS_IV_NEXT]] = add nuw nsw i64 [[INDVARS_IV]], 1 +; CHECK-NEXT: [[EXITCOND:%.*]] = icmp eq i64 [[INDVARS_IV_NEXT]], 5 +; CHECK-NEXT: br i1 [[EXITCOND]], label [[EXIT]], label [[LOOP]], !llvm.loop !2 +; CHECK: exit: +; CHECK-NEXT: ret void +; +entry: + br label %loop + +loop: ; preds = %loop, %entry + %rec = phi i32 [ 0, %entry], [ %lv, %loop ] + %indvars.iv = phi i64 [ 0, %entry], [ %indvars.iv.next, %loop ] + %A.ptr= getelementptr inbounds [5 x i32], [5 x i32]* @A, i64 0, i64 %indvars.iv + %lv = load i32, i32* %A.ptr, align 4 + %B.ptr = getelementptr inbounds [5 x i32], [5 x i32]* @B, i64 0, i64 %indvars.iv + store i32 %rec, i32* %B.ptr, align 4 + %indvars.iv.next = add nuw nsw i64 %indvars.iv, 1 + %exitcond = icmp eq i64 %indvars.iv.next, 5 + br i1 %exitcond, label %exit, label %loop + +exit: ; preds = %loop + ret void +} -- 2.7.4