[polly] r217802 - [Fix] Rewire the Region after a unconditional entry edge is created
Johannes Doerfert
doerfert at cs.uni-saarland.de
Mon Sep 15 11:34:45 PDT 2014
Author: jdoerfert
Date: Mon Sep 15 13:34:45 2014
New Revision: 217802
URL: http://llvm.org/viewvc/llvm-project?rev=217802&view=rev
Log:
[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).
Added:
polly/trunk/test/Isl/CodeGen/loop_with_conditional_entry_edge_splited_hard_case.ll
Modified:
polly/trunk/lib/Support/ScopHelper.cpp
Modified: polly/trunk/lib/Support/ScopHelper.cpp
URL: http://llvm.org/viewvc/llvm-project/polly/trunk/lib/Support/ScopHelper.cpp?rev=217802&r1=217801&r2=217802&view=diff
==============================================================================
--- polly/trunk/lib/Support/ScopHelper.cpp (original)
+++ polly/trunk/lib/Support/ScopHelper.cpp Mon Sep 15 13:34:45 2014
@@ -86,33 +86,70 @@ BasicBlock *polly::createSingleExitEdge(
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);
Added: polly/trunk/test/Isl/CodeGen/loop_with_conditional_entry_edge_splited_hard_case.ll
URL: http://llvm.org/viewvc/llvm-project/polly/trunk/test/Isl/CodeGen/loop_with_conditional_entry_edge_splited_hard_case.ll?rev=217802&view=auto
==============================================================================
--- polly/trunk/test/Isl/CodeGen/loop_with_conditional_entry_edge_splited_hard_case.ll (added)
+++ polly/trunk/test/Isl/CodeGen/loop_with_conditional_entry_edge_splited_hard_case.ll Mon Sep 15 13:34:45 2014
@@ -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()
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