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[Fix] Rewire the Region after a unconditional entry edge is created 

We use SplitEdge to split a conditional entry edge of the SCoP region.
  However, SplitEdge can cause two different situations (depending on
  whether or not the edge is critical). This patch tests
  which one is present and deals with the former unhandled one.

  It also refactors and unifies the case we have to change the basic
  blocks of the SCoP to new ones (see replaceScopAndRegionEntry).

llvm-svn: 217802
This commit is contained in:
Johannes Doerfert 2014-09-15 18:34:45 +00:00
parent 6865d6f08a
commit 0fe35dd088
2 changed files with 111 additions and 11 deletions
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59
polly/lib/Support/ScopHelper.cpp
View File

@ -86,33 +86,70 @@ BasicBlock *polly::createSingleExitEdge(Region *R, Pass *P) {
return SplitBlockPredecessors(BB, Preds, ".region", P);
}
static void replaceScopAndRegionEntry(polly::Scop *S, BasicBlock *OldEntry,
BasicBlock *NewEntry) {
for (polly::ScopStmt *Stmt : *S)
if (Stmt->getBasicBlock() == OldEntry) {
Stmt->setBasicBlock(NewEntry);
break;
}
S->getRegion().replaceEntryRecursive(NewEntry);
}
BasicBlock *polly::simplifyRegion(Scop *S, Pass *P) {
Region *R = &S->getRegion();
// The entering block for the region.
BasicBlock *EnteringBB = R->getEnteringBlock();
BasicBlock *OldEntry = R->getEntry();
BasicBlock *NewEntry = nullptr;
// Create single entry edge if the region has multiple entry edges.
if (!EnteringBB) {
BasicBlock *OldEntry = R->getEntry();
BasicBlock *NewEntry = SplitBlock(OldEntry, OldEntry->begin(), P);
for (ScopStmt *Stmt : *S)
if (Stmt->getBasicBlock() == OldEntry) {
Stmt->setBasicBlock(NewEntry);
break;
}
R->replaceEntryRecursive(NewEntry);
NewEntry = SplitBlock(OldEntry, OldEntry->begin(), P);
EnteringBB = OldEntry;
}
// Create an unconditional entry edge.
if (EnteringBB->getTerminator()->getNumSuccessors() != 1) {
EnteringBB = SplitEdge(EnteringBB, R->getEntry(), P);
BasicBlock *EntryBB = NewEntry ? NewEntry : OldEntry;
BasicBlock *SplitEdgeBB = SplitEdge(EnteringBB, EntryBB, P);
// Once the edge between EnteringBB and EntryBB is split, two cases arise.
// The first is simple. The new block is inserted between EnteringBB and
// EntryBB. In this case no further action is needed. However it might
// happen (if the splitted edge is not critical) that the new block is
// inserted __after__ EntryBB causing the following situation:
//
// EnteringBB
// |
// / \
// | \-> some_other_BB_not_in_R
// V
// EntryBB
// |
// V
// SplitEdgeBB
//
// In this case we need to swap the role of EntryBB and SplitEdgeBB.
// Check which case SplitEdge produced:
if (SplitEdgeBB->getTerminator()->getSuccessor(0) == EntryBB) {
// First (simple) case.
EnteringBB = SplitEdgeBB;
} else {
// Second (complicated) case.
NewEntry = SplitEdgeBB;
EnteringBB = EntryBB;
}
EnteringBB->setName("polly.entering.block");
}
if (NewEntry)
replaceScopAndRegionEntry(S, OldEntry, NewEntry);
// Create single exit edge if the region has multiple exit edges.
if (!R->getExitingBlock()) {
BasicBlock *NewExit = createSingleExitEdge(R, P);

63
polly/test/Isl/CodeGen/loop_with_conditional_entry_edge_splited_hard_case.ll Normal file
View File

@ -0,0 +1,63 @@
; RUN: opt %loadPolly -polly-codegen-isl -S < %s | FileCheck %s
;
; Test case to trigger the hard way of creating a unique entering
; edge for the SCoP. It is triggered because the entering edge
; here: %while.begin --> %if is __not__ critical.
;
; int f(void);
; void jd(int b, int *A) {
; while (f()) {
; if (b)
; for (int i = 0; i < 1024; i++)
; A[i] = i;
; }
; }
;
target datalayout = "e-m:e-i64:64-f80:128-n8:16:32:64-S128"
define void @jd(i32 %b, i32* %A) {
entry:
br label %while.begin
; CHECK: while.begin:
while.begin:
; CHECK: %call = call i32 @f()
%call = call i32 @f()
; CHECK: %tobool = icmp eq i32 %call, 0
%tobool = icmp eq i32 %call, 0
; CHECK: br i1 %tobool, label %while.end, label %polly.entering.block
br i1 %tobool, label %while.end, label %if
; CHECK: polly.entering.block:
; CHECK: br label %polly.split_new_and_old
; CHECK: polly.split_new_and_old:
; CHECK: br i1 true, label %polly.start, label %if.split
; CHECK: if.split:
if: ; preds = %while.begin
; CHECK: %tobool2 = icmp eq i32 %b, 0
%tobool2 = icmp eq i32 %b, 0
; CHECK: br i1 %tobool2, label %while.begin{{[a-zA-Z._]*}}, label %for.cond
br i1 %tobool2, label %while.begin, label %for.cond
for.cond: ; preds = %for.inc, %if
%indvars.iv = phi i64 [ %indvars.iv.next, %for.inc ], [ 0, %if ]
%exitcond = icmp ne i64 %indvars.iv, 1024
br i1 %exitcond, label %for.body, label %while.begin
for.body: ; preds = %for.cond
%arrayidx = getelementptr inbounds i32* %A, i64 %indvars.iv
%tmp = trunc i64 %indvars.iv to i32
store i32 %tmp, i32* %arrayidx, align 4
br label %for.inc
for.inc: ; preds = %for.body
%indvars.iv.next = add nuw nsw i64 %indvars.iv, 1
br label %for.cond
while.end: ; preds = %entry, %for.cond
ret void
}
declare i32 @f()