From 19046ec19c4931f025cd4730eb43e9203ada6bb7 Mon Sep 17 00:00:00 2001 From: Hal Finkel Date: Sun, 18 Aug 2013 00:16:23 +0000 Subject: Fix SCEVExpander creating distinct duplicate PHI entries This fixes SCEVExpander so that it does not create multiple distinct induction variables for duplicate PHI entries. Specifically, given some code like this: do.body6: ; preds = %do.body6, %do.body6, %if.then5 %end.0 = phi i8* [ undef, %if.then5 ], [ %incdec.ptr, %do.body6 ], [ %incdec.ptr, %do.body6 ] ... Note that it is legal to have multiple entries for a basic block so long as the associated value is the same. So the above input is okay, but expanding an AddRec in this loop could produce code like this: do.body6: ; preds = %do.body6, %do.body6, %if.then5 %indvar = phi i64 [ %indvar.next, %do.body6 ], [ %indvar.next1, %do.body6 ], [ 0, %if.then5 ] %end.0 = phi i8* [ undef, %if.then5 ], [ %incdec.ptr, %do.body6 ], [ %incdec.ptr, %do.body6 ] ... %indvar.next = add i64 %indvar, 1 %indvar.next1 = add i64 %indvar, 1 And this is not legal because there are two PHI entries for %do.body6 each with a distinct value. Unfortunately, I don't have an in-tree test case. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@188614 91177308-0d34-0410-b5e6-96231b3b80d8 --- lib/Analysis/ScalarEvolutionExpander.cpp | 5 +++++ 1 file changed, 5 insertions(+) (limited to 'lib/Analysis/ScalarEvolutionExpander.cpp') diff --git a/lib/Analysis/ScalarEvolutionExpander.cpp b/lib/Analysis/ScalarEvolutionExpander.cpp index c434b40c7c..14ba33003d 100644 --- a/lib/Analysis/ScalarEvolutionExpander.cpp +++ b/lib/Analysis/ScalarEvolutionExpander.cpp @@ -14,6 +14,7 @@ //===----------------------------------------------------------------------===// #include "llvm/Analysis/ScalarEvolutionExpander.h" +#include "llvm/ADT/SmallSet.h" #include "llvm/ADT/STLExtras.h" #include "llvm/Analysis/LoopInfo.h" #include "llvm/Analysis/TargetTransformInfo.h" @@ -1342,9 +1343,13 @@ Value *SCEVExpander::visitAddRecExpr(const SCEVAddRecExpr *S) { Header->begin()); rememberInstruction(CanonicalIV); + SmallSet PredSeen; Constant *One = ConstantInt::get(Ty, 1); for (pred_iterator HPI = HPB; HPI != HPE; ++HPI) { BasicBlock *HP = *HPI; + if (!PredSeen.insert(HP)) + continue; + if (L->contains(HP)) { // Insert a unit add instruction right before the terminator // corresponding to the back-edge. -- cgit v1.2.3