[llvm-commits] [llvm] r112589 - in /llvm/trunk: lib/Transforms/Scalar/JumpThreading.cpp test/Transforms/JumpThreading/2010-08-31-InfiniteRecursion.ll
Owen Anderson
resistor at mac.com
Tue Aug 31 00:36:35 PDT 2010
Author: resistor
Date: Tue Aug 31 02:36:34 2010
New Revision: 112589
URL: http://llvm.org/viewvc/llvm-project?rev=112589&view=rev
Log:
More Chris-inspired JumpThreading fixes: use ConstantExpr to correctly constant-fold undef, and be more careful with its return value.
This actually exposed an infinite recursion bug in ComputeValueKnownInPredecessors which theoretically already existed (in JumpThreading's
handling of and/or of i1's), but never manifested before. This patch adds a tracking set to prevent this case.
Added:
llvm/trunk/test/Transforms/JumpThreading/2010-08-31-InfiniteRecursion.ll
Modified:
llvm/trunk/lib/Transforms/Scalar/JumpThreading.cpp
Modified: llvm/trunk/lib/Transforms/Scalar/JumpThreading.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/Scalar/JumpThreading.cpp?rev=112589&r1=112588&r2=112589&view=diff
==============================================================================
--- llvm/trunk/lib/Transforms/Scalar/JumpThreading.cpp (original)
+++ llvm/trunk/lib/Transforms/Scalar/JumpThreading.cpp Tue Aug 31 02:36:34 2010
@@ -16,7 +16,6 @@
#include "llvm/IntrinsicInst.h"
#include "llvm/LLVMContext.h"
#include "llvm/Pass.h"
-#include "llvm/Analysis/ConstantFolding.h"
#include "llvm/Analysis/InstructionSimplify.h"
#include "llvm/Analysis/LazyValueInfo.h"
#include "llvm/Analysis/Loads.h"
@@ -25,6 +24,7 @@
#include "llvm/Transforms/Utils/SSAUpdater.h"
#include "llvm/Target/TargetData.h"
#include "llvm/ADT/DenseMap.h"
+#include "llvm/ADT/DenseSet.h"
#include "llvm/ADT/Statistic.h"
#include "llvm/ADT/STLExtras.h"
#include "llvm/ADT/SmallPtrSet.h"
@@ -78,6 +78,7 @@
#else
SmallSet<AssertingVH<BasicBlock>, 16> LoopHeaders;
#endif
+ DenseSet<std::pair<Value*, BasicBlock*> > RecursionSet;
public:
static char ID; // Pass identification
JumpThreading() : FunctionPass(ID) {}
@@ -270,12 +271,17 @@
///
bool JumpThreading::
ComputeValueKnownInPredecessors(Value *V, BasicBlock *BB,PredValueInfo &Result){
+ if (!RecursionSet.insert(std::make_pair(V, BB)).second)
+ return false;
+
// If V is a constantint, then it is known in all predecessors.
if (isa<ConstantInt>(V) || isa<UndefValue>(V)) {
ConstantInt *CI = dyn_cast<ConstantInt>(V);
for (pred_iterator PI = pred_begin(BB), E = pred_end(BB); PI != E; ++PI)
Result.push_back(std::make_pair(CI, *PI));
+
+ RecursionSet.erase(std::make_pair(V, BB));
return true;
}
@@ -310,9 +316,11 @@
Result.push_back(std::make_pair(dyn_cast<ConstantInt>(PredCst), P));
}
+ RecursionSet.erase(std::make_pair(V, BB));
return !Result.empty();
}
+ RecursionSet.erase(std::make_pair(V, BB));
return false;
}
@@ -328,10 +336,15 @@
PN->getIncomingBlock(i), BB);
// LVI returns null is no value could be determined.
if (!CI) continue;
- ConstantInt *CInt = dyn_cast<ConstantInt>(CI);
- Result.push_back(std::make_pair(CInt, PN->getIncomingBlock(i)));
+ if (ConstantInt *CInt = dyn_cast<ConstantInt>(CI))
+ Result.push_back(std::make_pair(CInt, PN->getIncomingBlock(i)));
+ else if (isa<UndefValue>(CI))
+ Result.push_back(std::make_pair((ConstantInt*)0,
+ PN->getIncomingBlock(i)));
}
}
+
+ RecursionSet.erase(std::make_pair(V, BB));
return !Result.empty();
}
@@ -346,8 +359,10 @@
ComputeValueKnownInPredecessors(I->getOperand(0), BB, LHSVals);
ComputeValueKnownInPredecessors(I->getOperand(1), BB, RHSVals);
- if (LHSVals.empty() && RHSVals.empty())
+ if (LHSVals.empty() && RHSVals.empty()) {
+ RecursionSet.erase(std::make_pair(V, BB));
return false;
+ }
ConstantInt *InterestingVal;
if (I->getOpcode() == Instruction::Or)
@@ -374,6 +389,8 @@
Result.back().first = InterestingVal;
}
}
+
+ RecursionSet.erase(std::make_pair(V, BB));
return !Result.empty();
}
@@ -382,38 +399,48 @@
isa<ConstantInt>(I->getOperand(1)) &&
cast<ConstantInt>(I->getOperand(1))->isOne()) {
ComputeValueKnownInPredecessors(I->getOperand(0), BB, Result);
- if (Result.empty())
+ if (Result.empty()) {
+ RecursionSet.erase(std::make_pair(V, BB));
return false;
+ }
// Invert the known values.
for (unsigned i = 0, e = Result.size(); i != e; ++i)
if (Result[i].first)
Result[i].first =
cast<ConstantInt>(ConstantExpr::getNot(Result[i].first));
+
+ RecursionSet.erase(std::make_pair(V, BB));
return true;
}
// Try to simplify some other binary operator values.
} else if (BinaryOperator *BO = dyn_cast<BinaryOperator>(I)) {
- // AND or OR of a value with itself is that value.
ConstantInt *CI = dyn_cast<ConstantInt>(BO->getOperand(1));
- if (CI && (BO->getOpcode() == Instruction::And ||
- BO->getOpcode() == Instruction::Or)) {
+ if (CI) {
SmallVector<std::pair<ConstantInt*, BasicBlock*>, 8> LHSVals;
ComputeValueKnownInPredecessors(BO->getOperand(0), BB, LHSVals);
- for (unsigned i = 0, e = LHSVals.size(); i != e; ++i)
+
+ // Try to use constant folding to simplify the binary operator.
+ for (unsigned i = 0, e = LHSVals.size(); i != e; ++i) {
+ Constant *Folded = 0;
if (LHSVals[i].first == 0) {
- ConstantInt *Zero =
- cast<ConstantInt>(ConstantInt::get(BO->getType(), 0));
- Result.push_back(std::make_pair(Zero, LHSVals[i].second));
- } else if (Constant *Folded = ConstantExpr::get(BO->getOpcode(),
- LHSVals[i].first, CI)) {
- Result.push_back(std::make_pair(cast<ConstantInt>(Folded),
- LHSVals[i].second));
+ Folded = ConstantExpr::get(BO->getOpcode(),
+ UndefValue::get(BO->getType()),
+ CI);
+ } else {
+ Folded = ConstantExpr::get(BO->getOpcode(), LHSVals[i].first, CI);
}
-
- return !Result.empty();
+
+ if (ConstantInt *FoldedCInt = dyn_cast<ConstantInt>(Folded))
+ Result.push_back(std::make_pair(FoldedCInt, LHSVals[i].second));
+ else if (isa<UndefValue>(Folded))
+ Result.push_back(std::make_pair((ConstantInt*)0, LHSVals[i].second));
+ }
}
+
+ RecursionSet.erase(std::make_pair(V, BB));
+ return !Result.empty();
}
// Handle compare with phi operand, where the PHI is defined in this block.
@@ -446,6 +473,7 @@
Result.push_back(std::make_pair(CI, PredBB));
}
+ RecursionSet.erase(std::make_pair(V, BB));
return !Result.empty();
}
@@ -472,25 +500,32 @@
Result.push_back(std::make_pair(cast<ConstantInt>(ResC), P));
}
+ RecursionSet.erase(std::make_pair(V, BB));
return !Result.empty();
}
- // Try to find a constant value for the LHS of an equality comparison,
+ // Try to find a constant value for the LHS of a comparison,
// and evaluate it statically if we can.
if (Constant *CmpConst = dyn_cast<Constant>(Cmp->getOperand(1))) {
SmallVector<std::pair<ConstantInt*, BasicBlock*>, 8> LHSVals;
ComputeValueKnownInPredecessors(I->getOperand(0), BB, LHSVals);
for (unsigned i = 0, e = LHSVals.size(); i != e; ++i) {
+ Constant * Folded = 0;
if (LHSVals[i].first == 0)
- Result.push_back(std::make_pair((ConstantInt*)0,
- LHSVals[i].second));
- else if (Constant *Folded = ConstantExpr::getCompare(
- Cmp->getPredicate(), LHSVals[i].first, CmpConst))
- Result.push_back(std::make_pair(cast<ConstantInt>(Folded),
- LHSVals[i].second));
+ Folded = ConstantExpr::getCompare(Cmp->getPredicate(),
+ UndefValue::get(CmpConst->getType()), CmpConst);
+ else
+ Folded = ConstantExpr::getCompare(Cmp->getPredicate(),
+ LHSVals[i].first, CmpConst);
+
+ if (ConstantInt *FoldedCInt = dyn_cast<ConstantInt>(Folded))
+ Result.push_back(std::make_pair(FoldedCInt, LHSVals[i].second));
+ else if (isa<UndefValue>(Folded))
+ Result.push_back(std::make_pair((ConstantInt*)0,LHSVals[i].second));
}
+ RecursionSet.erase(std::make_pair(V, BB));
return !Result.empty();
}
}
@@ -505,9 +540,11 @@
Result.push_back(std::make_pair(CInt, *PI));
}
+ RecursionSet.erase(std::make_pair(V, BB));
return !Result.empty();
}
+ RecursionSet.erase(std::make_pair(V, BB));
return false;
}
@@ -1126,8 +1163,9 @@
return false;
SmallVector<std::pair<ConstantInt*, BasicBlock*>, 8> PredValues;
- if (!ComputeValueKnownInPredecessors(Cond, BB, PredValues))
+ if (!ComputeValueKnownInPredecessors(Cond, BB, PredValues)) {
return false;
+ }
assert(!PredValues.empty() &&
"ComputeValueKnownInPredecessors returned true with no values");
Added: llvm/trunk/test/Transforms/JumpThreading/2010-08-31-InfiniteRecursion.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transforms/JumpThreading/2010-08-31-InfiniteRecursion.ll?rev=112589&view=auto
==============================================================================
--- llvm/trunk/test/Transforms/JumpThreading/2010-08-31-InfiniteRecursion.ll (added)
+++ llvm/trunk/test/Transforms/JumpThreading/2010-08-31-InfiniteRecursion.ll Tue Aug 31 02:36:34 2010
@@ -0,0 +1,91 @@
+; RUN: opt < %s -jump-threading -disable-output
+; ModuleID = 'bugpoint-reduced-simplified.bc'
+target datalayout = "e-p:64:64:64-i1:8:8-i8:8:8-i16:16:16-i32:32:32-i64:64:64-f32:32:32-f64:64:64-v64:64:64-v128:128:128-a0:0:64-s0:64:64-f80:128:128-n8:16:32:64"
+target triple = "x86_64-apple-darwin10.4"
+
+define void @encode_one_macroblock_highfast() nounwind ssp {
+entry:
+ switch i32 undef, label %bb13 [
+ i32 1, label %bb10
+ i32 2, label %bb12
+ ]
+
+bb10: ; preds = %entry
+ unreachable
+
+bb12: ; preds = %entry
+ unreachable
+
+bb13: ; preds = %entry
+ br i1 undef, label %bb137, label %bb292
+
+bb137: ; preds = %bb13
+ br i1 undef, label %bb150, label %bb154
+
+bb150: ; preds = %bb137
+ unreachable
+
+bb154: ; preds = %bb137
+ br i1 undef, label %bb292, label %bb246
+
+bb246: ; preds = %bb154
+ br i1 undef, label %bb292, label %bb247
+
+bb247: ; preds = %bb246
+ br i1 undef, label %bb248, label %bb292
+
+bb248: ; preds = %bb247
+ br i1 undef, label %bb249, label %bb292
+
+bb249: ; preds = %bb248
+ br i1 undef, label %bb254, label %bb250
+
+bb250: ; preds = %bb249
+ unreachable
+
+bb254: ; preds = %bb249
+ br i1 undef, label %bb292, label %bb255
+
+bb255: ; preds = %bb288.bb289.loopexit_crit_edge, %bb254
+ br i1 undef, label %bb.nph.split.us, label %bb269
+
+bb.nph.split.us: ; preds = %bb255
+ br i1 undef, label %bb.nph.split.us.split.us, label %bb269.us.us31
+
+bb.nph.split.us.split.us: ; preds = %bb.nph.split.us
+ br i1 undef, label %bb269.us.us, label %bb269.us.us.us
+
+bb269.us.us.us: ; preds = %bb287.us.us.us, %bb.nph.split.us.split.us
+ %indvar = phi i64 [ %indvar.next, %bb287.us.us.us ], [ 0, %bb.nph.split.us.split.us ] ; <i64> [#uses=1]
+ %0 = icmp eq i16 undef, 0 ; <i1> [#uses=1]
+ br i1 %0, label %bb287.us.us.us, label %bb286.us.us.us
+
+bb287.us.us.us: ; preds = %bb269.us.us.us
+ %indvar.next = add i64 %indvar, 1 ; <i64> [#uses=2]
+ %exitcond = icmp eq i64 %indvar.next, 4 ; <i1> [#uses=1]
+ br i1 %exitcond, label %bb288.bb289.loopexit_crit_edge, label %bb269.us.us.us
+
+bb286.us.us.us: ; preds = %bb269.us.us.us
+ unreachable
+
+bb269.us.us: ; preds = %bb287.us.us, %bb.nph.split.us.split.us
+ br i1 undef, label %bb287.us.us, label %bb286.us.us
+
+bb287.us.us: ; preds = %bb269.us.us
+ br i1 undef, label %bb288.bb289.loopexit_crit_edge, label %bb269.us.us
+
+bb286.us.us: ; preds = %bb269.us.us
+ unreachable
+
+bb269.us.us31: ; preds = %bb.nph.split.us
+ unreachable
+
+bb269: ; preds = %bb255
+ unreachable
+
+bb288.bb289.loopexit_crit_edge: ; preds = %bb287.us.us, %bb287.us.us.us
+ br i1 undef, label %bb292, label %bb255
+
+bb292: ; preds = %bb288.bb289.loopexit_crit_edge, %bb254, %bb248, %bb247, %bb246, %bb154, %bb13
+ unreachable
+}
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