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Fix Codegen adding a second exit out of region 

executeScopConditionally would destroy a predecessor region if it the
scop's entry was the region's exit block by forking it to polly.start
and thus creating a secnd exit out of the region. This patch "shrinks"
the predecessor region s.t. polly.split_new_and_old is not the 
region's exit anymore. 

llvm-svn: 245294
This commit is contained in:
Michael Kruse 2015-08-18 13:14:42 +00:00
parent a6593ff613
commit d2b0360197
2 changed files with 43 additions and 0 deletions
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12
polly/lib/CodeGen/Utils.cpp
View File

@ -103,6 +103,18 @@ BasicBlock *polly::executeScopConditionally(Scop &S, Pass *P, Value *RTC) {
splitEdge(EnteringBB, EntryBB, ".split_new_and_old", &DT, &LI, &RI);
SplitBlock->setName("polly.split_new_and_old");
// If EntryBB is the exit block of the region that includes Prev, exclude
// SplitBlock from that region by making it itself the exit block. This is
// trivially possible because there is just one edge to EnteringBB.
// This is necessary because we will add an outgoing edge from SplitBlock,
// which would violate the single exit block requirement of PrevRegion.
Region *PrevRegion = RI.getRegionFor(EnteringBB);
while (PrevRegion->getExit() == EntryBB) {
PrevRegion->replaceExit(SplitBlock);
PrevRegion = PrevRegion->getParent();
}
RI.setRegionFor(SplitBlock, PrevRegion);
// Create a join block
BasicBlock *ExitingBB = R.getExitingBlock();
BasicBlock *ExitBB = R.getExit();

31
polly/test/Isl/CodeGen/split_edge_of_exit.ll Normal file
View File

@ -0,0 +1,31 @@
; RUN: opt %loadPolly -polly-detect-unprofitable -polly-no-early-exit -polly-detect -analyze < %s | FileCheck %s
; RUN: opt %loadPolly -polly-detect-unprofitable -polly-no-early-exit -polly-codegen -verify-region-info -analyze < %s
;
; This is a scop directly precedented by a region, i.e. the scop's entry is the
; region's exit block. This test is to ensure that the RegionInfo is correctly
; preserved.
;
; CHECK: Valid Region for Scop: region2 => return
;
define void @f1(i64* %A, i64 %N) nounwind {
entry:
br label %region1
region1:
%indvar1 = phi i64 [ 0, %entry ], [ %indvar1.next, %region1 ]
fence seq_cst
%indvar1.next = add nsw i64 %indvar1, 1
%exitcond1 = icmp eq i64 %indvar1.next, %N
br i1 %exitcond1, label %region2, label %region1
region2:
%indvar2 = phi i64 [ 0, %region1 ], [ %indvar2.next, %region2 ]
%scevgep2 = getelementptr i64, i64* %A, i64 %indvar2
store i64 %indvar2, i64* %scevgep2
%indvar2.next = add nsw i64 %indvar2, 1
%exitcond2 = icmp eq i64 %indvar2.next, %N
br i1 %exitcond2, label %return, label %region2
return:
ret void
}