Add support for loops that don't start with Zero.

This is important for loops in the LAPACK test-suite.
These loops start at 1 because they are auto-converted from fortran.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@167084 91177308-0d34-0410-b5e6-96231b3b80d8

diff --git a/lib/Transforms/Vectorize/LoopVectorize.cpp b/lib/Transforms/Vectorize/LoopVectorize.cpp
index 431a8478a03baeb9ed7eb301b40267ab97076df0..e82dfa2454fc9926ee89351db07673396e49f4e6 100644 (file)
--- a/lib/Transforms/Vectorize/LoopVectorize.cpp
+++ b/lib/Transforms/Vectorize/LoopVectorize.cpp
@@ -633,6 +633,10 @@ SingleBlockLoopVectorizer::createEmptyLoop(LoopVectorizationLegality *Legal) {
   BasicBlock *ExitBlock = OrigLoop->getExitBlock();
   assert(ExitBlock && "Must have an exit block");
 
+  // The loop index does not have to start at Zero. It starts with this value.
+  OldInduction = Legal->getInduction();
+  Value *StartIdx = OldInduction->getIncomingValueForBlock(BypassBlock);
+
   assert(OrigLoop->getNumBlocks() == 1 && "Invalid loop");
   assert(BypassBlock && "Invalid loop structure");
 
@@ -648,7 +652,6 @@ SingleBlockLoopVectorizer::createEmptyLoop(LoopVectorizationLegality *Legal) {
                                  "scalar.preheader");
   // Find the induction variable.
   BasicBlock *OldBasicBlock = OrigLoop->getHeader();
-  OldInduction = Legal->getInduction();
   assert(OldInduction && "We must have a single phi node.");
   Type *IdxTy = OldInduction->getType();
 
@@ -658,7 +661,6 @@ SingleBlockLoopVectorizer::createEmptyLoop(LoopVectorizationLegality *Legal) {
 
   // Generate the induction variable.
   Induction = Builder.CreatePHI(IdxTy, 2, "index");
-  Constant *Zero = ConstantInt::get(IdxTy, 0);
   Constant *Step = ConstantInt::get(IdxTy, VF);
 
   // Find the loop boundaries.
@@ -682,15 +684,22 @@ SingleBlockLoopVectorizer::createEmptyLoop(LoopVectorizationLegality *Legal) {
 
   // Count holds the overall loop count (N).
   Value *Count = Exp.expandCodeFor(ExitCount, Induction->getType(), Loc);
+
+  // Add the start index to the loop count to get the new end index.
+  Value *IdxEnd = BinaryOperator::CreateAdd(Count, StartIdx, "end.idx", Loc);
+
   // Now we need to generate the expression for N - (N % VF), which is
   // the part that the vectorized body will execute.
   Constant *CIVF = ConstantInt::get(IdxTy, VF);
   Value *R = BinaryOperator::CreateURem(Count, CIVF, "n.mod.vf", Loc);
   Value *CountRoundDown = BinaryOperator::CreateSub(Count, R, "n.vec", Loc);
+  Value *IdxEndRoundDown = BinaryOperator::CreateAdd(CountRoundDown, StartIdx,
+                                                     "end.idx.rnd.down", Loc);
 
   // Now, compare the new count to zero. If it is zero, jump to the scalar part.
   Value *Cmp = CmpInst::Create(Instruction::ICmp, CmpInst::ICMP_EQ,
-                               CountRoundDown, ConstantInt::getNullValue(IdxTy),
+                               IdxEndRoundDown,
+                               StartIdx,
                                "cmp.zero", Loc);
   BranchInst::Create(MiddleBlock, VectorPH, Cmp, Loc);
   // Remove the old terminator.
@@ -699,8 +708,8 @@ SingleBlockLoopVectorizer::createEmptyLoop(LoopVectorizationLegality *Legal) {
   // Add a check in the middle block to see if we have completed
   // all of the iterations in the first vector loop.
   // If (N - N%VF) == N, then we *don't* need to run the remainder.
-  Value *CmpN = CmpInst::Create(Instruction::ICmp, CmpInst::ICMP_EQ, Count,
-                                CountRoundDown, "cmp.n",
+  Value *CmpN = CmpInst::Create(Instruction::ICmp, CmpInst::ICMP_EQ, IdxEnd,
+                                IdxEndRoundDown, "cmp.n",
                                 MiddleBlock->getTerminator());
 
   BranchInst::Create(ExitBlock, ScalarPH, CmpN, MiddleBlock->getTerminator());
@@ -709,10 +718,10 @@ SingleBlockLoopVectorizer::createEmptyLoop(LoopVectorizationLegality *Legal) {
 
   // Create i+1 and fill the PHINode.
   Value *NextIdx = Builder.CreateAdd(Induction, Step, "index.next");
-  Induction->addIncoming(Zero, VectorPH);
+  Induction->addIncoming(StartIdx, VectorPH);
   Induction->addIncoming(NextIdx, VecBody);
   // Create the compare.
-  Value *ICmp = Builder.CreateICmpEQ(NextIdx, CountRoundDown);
+  Value *ICmp = Builder.CreateICmpEQ(NextIdx, IdxEndRoundDown);
   Builder.CreateCondBr(ICmp, MiddleBlock, VecBody);
 
   // Now we have two terminators. Remove the old one from the block.
@@ -720,7 +729,7 @@ SingleBlockLoopVectorizer::createEmptyLoop(LoopVectorizationLegality *Legal) {
 
   // Fix the scalar body iteration count.
   unsigned BlockIdx = OldInduction->getBasicBlockIndex(ScalarPH);
-  OldInduction->setIncomingValue(BlockIdx, CountRoundDown);
+  OldInduction->setIncomingValue(BlockIdx, IdxEndRoundDown);
 
   // Get ready to start creating new instructions into the vectorized body.
   Builder.SetInsertPoint(VecBody->getFirstInsertionPt());
@@ -748,7 +757,6 @@ SingleBlockLoopVectorizer::createEmptyLoop(LoopVectorizationLegality *Legal) {
   LoopBypassBlock = BypassBlock;
 }
 
-
 /// This function returns the identity element (or neutral element) for
 /// the operation K.
 static unsigned
@@ -1518,10 +1526,9 @@ bool LoopVectorizationLegality::isInductionVariable(PHINode *Phi) {
     return false;
   }
   const SCEV *Step = AR->getStepRecurrence(*SE);
-  const SCEV *Start = AR->getStart();
 
-  if (!Step->isOne() || !Start->isZero()) {
-    DEBUG(dbgs() << "LV: PHI does not start at zero or steps by one.\n");
+  if (!Step->isOne()) {
+    DEBUG(dbgs() << "LV: PHI stride does not equal one.\n");
     return false;
   }
   return true;

diff --git a/test/Transforms/LoopVectorize/X86/avx1.ll b/test/Transforms/LoopVectorize/X86/avx1.ll
new file mode 100644 (file)
index 0000000..a2d176a
--- /dev/null
+++ b/test/Transforms/LoopVectorize/X86/avx1.ll
@@ -0,0 +1,49 @@
+; RUN: opt < %s  -loop-vectorize -mtriple=x86_64-apple-macosx10.8.0 -mcpu=corei7-avx -S | FileCheck %s
+
+target datalayout = "e-p:64:64:64-i1:8:8-i8:8:8-i16:16:16-i32:32:32-i64:64:64-f32:32:32-f64:64:64-v64:64:64-v128:128:128-a0:0:64-s0:64:64-f80:128:128-n8:16:32:64-S128"
+target triple = "x86_64-apple-macosx10.8.0"
+
+;CHECK: @read_mod_write_single_ptr
+;CHECK: load <8 x float>
+;CHECK: ret i32
+define i32 @read_mod_write_single_ptr(float* nocapture %a, i32 %n) nounwind uwtable ssp {
+  %1 = icmp sgt i32 %n, 0
+  br i1 %1, label %.lr.ph, label %._crit_edge
+
+.lr.ph:                                           ; preds = %0, %.lr.ph
+  %indvars.iv = phi i64 [ %indvars.iv.next, %.lr.ph ], [ 0, %0 ]
+  %2 = getelementptr inbounds float* %a, i64 %indvars.iv
+  %3 = load float* %2, align 4
+  %4 = fmul float %3, 3.000000e+00
+  store float %4, float* %2, align 4
+  %indvars.iv.next = add i64 %indvars.iv, 1
+  %lftr.wideiv = trunc i64 %indvars.iv.next to i32
+  %exitcond = icmp eq i32 %lftr.wideiv, %n
+  br i1 %exitcond, label %._crit_edge, label %.lr.ph
+
+._crit_edge:                                      ; preds = %.lr.ph, %0
+  ret i32 undef
+}
+
+
+;CHECK: @read_mod_i64
+;CHECK: load <8 x i64>
+;CHECK: ret i32
+define i32 @read_mod_i64(i64* nocapture %a, i32 %n) nounwind uwtable ssp {
+  %1 = icmp sgt i32 %n, 0
+  br i1 %1, label %.lr.ph, label %._crit_edge
+
+.lr.ph:                                           ; preds = %0, %.lr.ph
+  %indvars.iv = phi i64 [ %indvars.iv.next, %.lr.ph ], [ 0, %0 ]
+  %2 = getelementptr inbounds i64* %a, i64 %indvars.iv
+  %3 = load i64* %2, align 4
+  %4 = mul i64 %3, 3
+  store i64 %4, i64* %2, align 4
+  %indvars.iv.next = add i64 %indvars.iv, 1
+  %lftr.wideiv = trunc i64 %indvars.iv.next to i32
+  %exitcond = icmp eq i32 %lftr.wideiv, %n
+  br i1 %exitcond, label %._crit_edge, label %.lr.ph
+
+._crit_edge:                                      ; preds = %.lr.ph, %0
+  ret i32 undef
+}

diff --git a/test/Transforms/LoopVectorize/start-non-zero.ll b/test/Transforms/LoopVectorize/start-non-zero.ll
new file mode 100644 (file)
index 0000000..257df05
--- /dev/null
+++ b/test/Transforms/LoopVectorize/start-non-zero.ll
@@ -0,0 +1,35 @@
+; RUN: opt < %s -loop-vectorize -force-vector-width=4 -instcombine -S | FileCheck %s
+
+target datalayout = "e-p:64:64:64-i1:8:8-i8:8:8-i16:16:16-i32:32:32-i64:64:64-f32:32:32-f64:64:64-v64:64:64-v128:128:128-a0:0:64-s0:64:64-f80:128:128-n8:16:32:64-S128"
+target triple = "x86_64-apple-macosx10.8.0"
+
+;CHECK: @start_at_nonzero
+;CHECK: mul <4 x i32>
+;CHECK: ret i32
+define i32 @start_at_nonzero(i32* nocapture %a, i32 %start, i32 %end) nounwind uwtable ssp {
+entry:
+  %cmp3 = icmp slt i32 %start, %end
+  br i1 %cmp3, label %for.body.lr.ph, label %for.end
+
+for.body.lr.ph:                                   ; preds = %entry
+  %0 = sext i32 %start to i64
+  br label %for.body
+
+for.body:                                         ; preds = %for.body.lr.ph, %for.body
+  %indvars.iv = phi i64 [ %0, %for.body.lr.ph ], [ %indvars.iv.next, %for.body ]
+  %arrayidx = getelementptr inbounds i32* %a, i64 %indvars.iv
+  %1 = load i32* %arrayidx, align 4, !tbaa !0
+  %mul = mul nsw i32 %1, 333
+  store i32 %mul, i32* %arrayidx, align 4, !tbaa !0
+  %indvars.iv.next = add i64 %indvars.iv, 1
+  %2 = trunc i64 %indvars.iv.next to i32
+  %cmp = icmp slt i32 %2, %end
+  br i1 %cmp, label %for.body, label %for.end
+
+for.end:                                          ; preds = %for.body, %entry
+  ret i32 4
+}
+
+!0 = metadata !{metadata !"int", metadata !1}
+!1 = metadata !{metadata !"omnipotent char", metadata !2}
+!2 = metadata !{metadata !"Simple C/C++ TBAA"}