[llvm] r296992 - [SCEV] Decrease the recursion threshold for CompareValueComplexity
Sanjoy Das via llvm-commits
llvm-commits at lists.llvm.org
Sun Mar 5 15:49:18 PST 2017
Author: sanjoy
Date: Sun Mar 5 17:49:17 2017
New Revision: 296992
URL: http://llvm.org/viewvc/llvm-project?rev=296992&view=rev
Log:
[SCEV] Decrease the recursion threshold for CompareValueComplexity
Fixes PR32142.
r287232 accidentally increased the recursion threshold for
CompareValueComplexity from 2 to 32. This change reverses that change
by introducing a separate flag for CompareValueComplexity's threshold.
Modified:
llvm/trunk/lib/Analysis/ScalarEvolution.cpp
llvm/trunk/unittests/Analysis/ScalarEvolutionTest.cpp
Modified: llvm/trunk/lib/Analysis/ScalarEvolution.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Analysis/ScalarEvolution.cpp?rev=296992&r1=296991&r2=296992&view=diff
==============================================================================
--- llvm/trunk/lib/Analysis/ScalarEvolution.cpp (original)
+++ llvm/trunk/lib/Analysis/ScalarEvolution.cpp Sun Mar 5 17:49:17 2017
@@ -132,10 +132,15 @@ static cl::opt<unsigned> AddOpsInlineThr
cl::desc("Threshold for inlining multiplication operands into a SCEV"),
cl::init(500));
-static cl::opt<unsigned>
- MaxCompareDepth("scalar-evolution-max-compare-depth", cl::Hidden,
- cl::desc("Maximum depth of recursive compare complexity"),
- cl::init(32));
+static cl::opt<unsigned> MaxSCEVCompareDepth(
+ "scalar-evolution-max-scev-compare-depth", cl::Hidden,
+ cl::desc("Maximum depth of recursive SCEV complexity comparisons"),
+ cl::init(32));
+
+static cl::opt<unsigned> MaxValueCompareDepth(
+ "scalar-evolution-max-value-compare-depth", cl::Hidden,
+ cl::desc("Maximum depth of recursive value complexity comparisons"),
+ cl::init(2));
static cl::opt<unsigned>
MaxAddExprDepth("scalar-evolution-max-addexpr-depth", cl::Hidden,
@@ -496,7 +501,7 @@ static int
CompareValueComplexity(SmallSet<std::pair<Value *, Value *>, 8> &EqCache,
const LoopInfo *const LI, Value *LV, Value *RV,
unsigned Depth) {
- if (Depth > MaxCompareDepth || EqCache.count({LV, RV}))
+ if (Depth > MaxValueCompareDepth || EqCache.count({LV, RV}))
return 0;
// Order pointer values after integer values. This helps SCEVExpander form
@@ -583,7 +588,7 @@ static int CompareSCEVComplexity(
if (LType != RType)
return (int)LType - (int)RType;
- if (Depth > MaxCompareDepth || EqCacheSCEV.count({LHS, RHS}))
+ if (Depth > MaxSCEVCompareDepth || EqCacheSCEV.count({LHS, RHS}))
return 0;
// Aside from the getSCEVType() ordering, the particular ordering
// isn't very important except that it's beneficial to be consistent,
Modified: llvm/trunk/unittests/Analysis/ScalarEvolutionTest.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/unittests/Analysis/ScalarEvolutionTest.cpp?rev=296992&r1=296991&r2=296992&view=diff
==============================================================================
--- llvm/trunk/unittests/Analysis/ScalarEvolutionTest.cpp (original)
+++ llvm/trunk/unittests/Analysis/ScalarEvolutionTest.cpp Sun Mar 5 17:49:17 2017
@@ -465,7 +465,7 @@ TEST_F(ScalarEvolutionsTest, Commutative
});
}
-TEST_F(ScalarEvolutionsTest, SCEVCompareComplexity) {
+TEST_F(ScalarEvolutionsTest, CompareSCEVComplexity) {
FunctionType *FTy =
FunctionType::get(Type::getVoidTy(Context), std::vector<Type *>(), false);
Function *F = cast<Function>(M.getOrInsertFunction("f", FTy));
@@ -532,6 +532,42 @@ TEST_F(ScalarEvolutionsTest, SCEVCompare
EXPECT_NE(nullptr, SE.getSCEV(Acc[0]));
}
+TEST_F(ScalarEvolutionsTest, CompareValueComplexity) {
+ IntegerType *IntPtrTy = M.getDataLayout().getIntPtrType(Context);
+ PointerType *IntPtrPtrTy = IntPtrTy->getPointerTo();
+
+ FunctionType *FTy =
+ FunctionType::get(Type::getVoidTy(Context), {IntPtrTy, IntPtrTy}, false);
+ Function *F = cast<Function>(M.getOrInsertFunction("f", FTy));
+ BasicBlock *EntryBB = BasicBlock::Create(Context, "entry", F);
+
+ Value *X = &*F->arg_begin();
+ Value *Y = &*std::next(F->arg_begin());
+
+ const int ValueDepth = 10;
+ for (int i = 0; i < ValueDepth; i++) {
+ X = new LoadInst(new IntToPtrInst(X, IntPtrPtrTy, "", EntryBB), "",
+ /*isVolatile*/ false, EntryBB);
+ Y = new LoadInst(new IntToPtrInst(Y, IntPtrPtrTy, "", EntryBB), "",
+ /*isVolatile*/ false, EntryBB);
+ }
+
+ auto *MulA = BinaryOperator::CreateMul(X, Y, "", EntryBB);
+ auto *MulB = BinaryOperator::CreateMul(Y, X, "", EntryBB);
+ ReturnInst::Create(Context, nullptr, EntryBB);
+
+ // This test isn't checking for correctness. Today making A and B resolve to
+ // the same SCEV would require deeper searching in CompareValueComplexity,
+ // which will slow down compilation. However, this test can fail (with LLVM's
+ // behavior still being correct) if we ever have a smarter
+ // CompareValueComplexity that is both fast and more accurate.
+
+ ScalarEvolution SE = buildSE(*F);
+ auto *A = SE.getSCEV(MulA);
+ auto *B = SE.getSCEV(MulB);
+ EXPECT_NE(A, B);
+}
+
TEST_F(ScalarEvolutionsTest, SCEVAddExpr) {
Type *Ty32 = Type::getInt32Ty(Context);
Type *ArgTys[] = {Type::getInt64Ty(Context), Ty32};
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