Add support for reduction variables when IF-conversion is enabled.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@169288 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Nadav Rotem 2012-12-04 18:17:33 +00:00
parent 4b3aafb4b2
commit f6088d126e
2 changed files with 71 additions and 10 deletions

View File

@ -1133,8 +1133,8 @@ InnerLoopVectorizer::vectorizeLoop(LoopVectorizationLegality *Legal) {
// Reductions do not have to start at zero. They can start with
// any loop invariant values.
VecRdxPhi->addIncoming(VectorStart, VecPreheader);
unsigned SelfEdgeIdx = (RdxPhi)->getBasicBlockIndex(LoopScalarBody);
Value *Val = getVectorValue(RdxPhi->getIncomingValue(SelfEdgeIdx));
Value *Val =
getVectorValue(RdxPhi->getIncomingValueForBlock(OrigLoop->getLoopLatch()));
VecRdxPhi->addIncoming(Val, LoopVectorBody);
// Before each round, move the insertion point right between
@ -1201,8 +1201,11 @@ InnerLoopVectorizer::vectorizeLoop(LoopVectorizationLegality *Legal) {
// Fix the scalar loop reduction variable with the incoming reduction sum
// from the vector body and from the backedge value.
int IncomingEdgeBlockIdx = (RdxPhi)->getBasicBlockIndex(LoopScalarBody);
int SelfEdgeBlockIdx = (IncomingEdgeBlockIdx ? 0 : 1); // The other block.
int IncomingEdgeBlockIdx =
(RdxPhi)->getBasicBlockIndex(OrigLoop->getLoopLatch());
assert(IncomingEdgeBlockIdx >= 0 && "Invalid block index");
// Pick the other block.
int SelfEdgeBlockIdx = (IncomingEdgeBlockIdx ? 0 : 1);
(RdxPhi)->setIncomingValue(SelfEdgeBlockIdx, Scalar0);
(RdxPhi)->setIncomingValue(IncomingEdgeBlockIdx, RdxDesc.LoopExitInstr);
}// end of for each redux variable.
@ -1961,11 +1964,13 @@ bool LoopVectorizationLegality::AddReductionVar(PHINode *Phi,
if (Phi->getNumIncomingValues() != 2)
return false;
// Find the possible incoming reduction variable.
BasicBlock *BB = Phi->getParent();
int SelfEdgeIdx = Phi->getBasicBlockIndex(BB);
int InEdgeBlockIdx = (SelfEdgeIdx ? 0 : 1); // The other entry.
Value *RdxStart = Phi->getIncomingValue(InEdgeBlockIdx);
// Reduction variables are only found in the loop header block.
if (Phi->getParent() != TheLoop->getHeader())
return false;
// Obtain the reduction start value from the value that comes from the loop
// preheader.
Value *RdxStart = Phi->getIncomingValueForBlock(TheLoop->getLoopPreheader());
// ExitInstruction is the single value which is used outside the loop.
// We only allow for a single reduction value to be used outside the loop.
@ -2003,9 +2008,17 @@ bool LoopVectorizationLegality::AddReductionVar(PHINode *Phi,
FoundStartPHI = true;
continue;
}
// We allow in-loop PHINodes which are not the original reduction PHI
// node. If this PHI is the only user of Iter (happens in IF w/ no ELSE
// structure) then don't skip this PHI.
if (isa<PHINode>(U) && U->getParent() != TheLoop->getHeader() &&
TheLoop->contains(U->getParent()) && Iter->getNumUses() > 1)
continue;
// Check if we found the exit user.
BasicBlock *Parent = U->getParent();
if (Parent != BB) {
if (!TheLoop->contains(Parent)) {
// We must have a single exit instruction.
if (ExitInstruction != 0)
return false;

View File

@ -58,3 +58,51 @@ if.end:
for.end:
ret i32 undef
}
; int func(int *A, int n) {
; unsigned sum = 0;
; for (int i = 0; i < n; ++i)
; if (A[i] > 30)
; sum += A[i] + 2;
;
; return sum;
; }
;CHECK: @reduction_func
;CHECK: load <4 x i32>
;CHECK: icmp sgt <4 x i32>
;CHECK: add <4 x i32>
;CHECK: select <4 x i1>
;CHECK: ret i32
define i32 @reduction_func(i32* nocapture %A, i32 %n) nounwind uwtable readonly ssp {
entry:
%cmp10 = icmp sgt i32 %n, 0
br i1 %cmp10, label %for.body, label %for.end
for.body: ; preds = %entry, %for.inc
%indvars.iv = phi i64 [ %indvars.iv.next, %for.inc ], [ 0, %entry ]
%sum.011 = phi i32 [ %sum.1, %for.inc ], [ 0, %entry ]
%arrayidx = getelementptr inbounds i32* %A, i64 %indvars.iv
%0 = load i32* %arrayidx, align 4
%cmp1 = icmp sgt i32 %0, 30
br i1 %cmp1, label %if.then, label %for.inc
if.then: ; preds = %for.body
%add = add i32 %sum.011, 2
%add4 = add i32 %add, %0
br label %for.inc
for.inc: ; preds = %for.body, %if.then
%sum.1 = phi i32 [ %add4, %if.then ], [ %sum.011, %for.body ]
%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 %for.end, label %for.body
for.end: ; preds = %for.inc, %entry
%sum.0.lcssa = phi i32 [ 0, %entry ], [ %sum.1, %for.inc ]
ret i32 %sum.0.lcssa
}