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LoopVectorizer: No need to generate pointer disambiguation checks between readonly pointers. 

llvm-svn: 180570
This commit is contained in:
Nadav Rotem 2013-04-25 19:55:03 +00:00
parent d973ca3c51
commit f43cbeee15
2 changed files with 48 additions and 4 deletions
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16
llvm/lib/Transforms/Vectorize/LoopVectorize.cpp
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@ -419,7 +419,7 @@ public:
}
/// Insert a pointer and calculate the start and end SCEVs.
void insert(ScalarEvolution *SE, Loop *Lp, Value *Ptr);
void insert(ScalarEvolution *SE, Loop *Lp, Value *Ptr, bool WritePtr);
/// This flag indicates if we need to add the runtime check.
bool Need;
@ -429,6 +429,8 @@ public:
SmallVector<const SCEV*, 2> Starts;
/// Holds the pointer value at the end of the loop.
SmallVector<const SCEV*, 2> Ends;
/// Holds the information if this pointer is used for writing to memory.
SmallVector<bool, 2> IsWritePtr;
};
/// A POD for saving information about induction variables.
@ -787,7 +789,8 @@ struct LoopVectorize : public LoopPass {
void
LoopVectorizationLegality::RuntimePointerCheck::insert(ScalarEvolution *SE,
Loop *Lp, Value *Ptr) {
Loop *Lp, Value *Ptr,
bool WritePtr) {
const SCEV *Sc = SE->getSCEV(Ptr);
const SCEVAddRecExpr *AR = dyn_cast<SCEVAddRecExpr>(Sc);
assert(AR && "Invalid addrec expression");
@ -796,6 +799,7 @@ LoopVectorizationLegality::RuntimePointerCheck::insert(ScalarEvolution *SE,
Pointers.push_back(Ptr);
Starts.push_back(AR->getStart());
Ends.push_back(ScEnd);
IsWritePtr.push_back(WritePtr);
}
Value *InnerLoopVectorizer::getBroadcastInstrs(Value *V) {
@ -1166,6 +1170,10 @@ InnerLoopVectorizer::addRuntimeCheck(LoopVectorizationLegality *Legal,
for (unsigned i = 0; i < NumPointers; ++i) {
for (unsigned j = i+1; j < NumPointers; ++j) {
// No need to check if two readonly pointers intersect.
if (!PtrRtCheck->IsWritePtr[i] && !PtrRtCheck->IsWritePtr[j])
continue;
Value *Start0 = ChkBuilder.CreateBitCast(Starts[i], PtrArithTy, "bc");
Value *Start1 = ChkBuilder.CreateBitCast(Starts[j], PtrArithTy, "bc");
Value *End0 = ChkBuilder.CreateBitCast(Ends[i], PtrArithTy, "bc");
@ -2678,7 +2686,7 @@ bool LoopVectorizationLegality::canVectorizeMemory() {
for (MI = ReadWrites.begin(), ME = ReadWrites.end(); MI != ME; ++MI) {
Value *V = (*MI).first;
if (hasComputableBounds(V)) {
PtrRtCheck.insert(SE, TheLoop, V);
PtrRtCheck.insert(SE, TheLoop, V, true);
DEBUG(dbgs() << "LV: Found a runtime check ptr:" << *V <<"\n");
} else {
CanDoRT = false;
@ -2688,7 +2696,7 @@ bool LoopVectorizationLegality::canVectorizeMemory() {
for (MI = Reads.begin(), ME = Reads.end(); MI != ME; ++MI) {
Value *V = (*MI).first;
if (hasComputableBounds(V)) {
PtrRtCheck.insert(SE, TheLoop, V);
PtrRtCheck.insert(SE, TheLoop, V, false);
DEBUG(dbgs() << "LV: Found a runtime check ptr:" << *V <<"\n");
} else {
CanDoRT = false;

36
llvm/test/Transforms/LoopVectorize/runtime-check-readonly.ll Normal file
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@ -0,0 +1,36 @@
; RUN: opt < %s -loop-vectorize -force-vector-unroll=1 -force-vector-width=4 -dce -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: add_ints
;CHECK: br
;CHECK: getelementptr
;CHECK-NEXT: getelementptr
;CHECK-NEXT: icmp uge
;CHECK-NEXT: icmp uge
;CHECK-NEXT: icmp uge
;CHECK-NEXT: icmp uge
;CHECK-NEXT: and
;CHECK: ret
define void @add_ints(i32* nocapture %A, i32* nocapture %B, i32* nocapture %C) {
entry:
br label %for.body
for.body:
%indvars.iv = phi i64 [ 0, %entry ], [ %indvars.iv.next, %for.body ]
%arrayidx = getelementptr inbounds i32* %B, i64 %indvars.iv
%0 = load i32* %arrayidx, align 4
%arrayidx2 = getelementptr inbounds i32* %C, i64 %indvars.iv
%1 = load i32* %arrayidx2, align 4
%add = add nsw i32 %1, %0
%arrayidx4 = getelementptr inbounds i32* %A, i64 %indvars.iv
store i32 %add, i32* %arrayidx4, 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, 200
br i1 %exitcond, label %for.end, label %for.body
for.end:
ret void
}