[InstCombine] Make max size array combine a tunable.
Requested by Sanjoy/Hal a while ago, and forgotten by me
(r283612).
llvm-svn: 294323
diff --git a/llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp b/llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp
index 7ff4238..2daaa2d 100644
--- a/llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp
+++ b/llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp
@@ -230,7 +230,9 @@
return nullptr;
uint64_t ArrayElementCount = Init->getType()->getArrayNumElements();
- if (ArrayElementCount > 1024) return nullptr; // Don't blow up on huge arrays.
+ // Don't blow up on huge arrays.
+ if (ArrayElementCount > MaxArraySizeForCombine)
+ return nullptr;
// There are many forms of this optimization we can handle, for now, just do
// the simple index into a single-dimensional array.
diff --git a/llvm/lib/Transforms/InstCombine/InstCombineInternal.h b/llvm/lib/Transforms/InstCombine/InstCombineInternal.h
index 092cc5e..bfa6964 100644
--- a/llvm/lib/Transforms/InstCombine/InstCombineInternal.h
+++ b/llvm/lib/Transforms/InstCombine/InstCombineInternal.h
@@ -508,6 +508,9 @@
return llvm::computeOverflowForUnsignedAdd(LHS, RHS, DL, &AC, CxtI, &DT);
}
+ /// Maximum size of array considered when transforming.
+ int MaxArraySizeForCombine;
+
private:
/// \brief Performs a few simplifications for operators which are associative
/// or commutative.
diff --git a/llvm/lib/Transforms/InstCombine/InstCombineLoadStoreAlloca.cpp b/llvm/lib/Transforms/InstCombine/InstCombineLoadStoreAlloca.cpp
index e0d7b72..a9f2151 100644
--- a/llvm/lib/Transforms/InstCombine/InstCombineLoadStoreAlloca.cpp
+++ b/llvm/lib/Transforms/InstCombine/InstCombineLoadStoreAlloca.cpp
@@ -609,7 +609,7 @@
// arrays of arbitrary size but this has a terrible impact on compile time.
// The threshold here is chosen arbitrarily, maybe needs a little bit of
// tuning.
- if (NumElements > 1024)
+ if (NumElements > IC.MaxArraySizeForCombine)
return nullptr;
const DataLayout &DL = IC.getDataLayout();
@@ -1114,7 +1114,7 @@
// arrays of arbitrary size but this has a terrible impact on compile time.
// The threshold here is chosen arbitrarily, maybe needs a little bit of
// tuning.
- if (NumElements > 1024)
+ if (NumElements > IC.MaxArraySizeForCombine)
return false;
const DataLayout &DL = IC.getDataLayout();
diff --git a/llvm/lib/Transforms/InstCombine/InstructionCombining.cpp b/llvm/lib/Transforms/InstCombine/InstructionCombining.cpp
index ba65ea6..fb875e6 100644
--- a/llvm/lib/Transforms/InstCombine/InstructionCombining.cpp
+++ b/llvm/lib/Transforms/InstCombine/InstructionCombining.cpp
@@ -82,6 +82,10 @@
EnableExpensiveCombines("expensive-combines",
cl::desc("Enable expensive instruction combines"));
+static cl::opt<unsigned>
+MaxArraySize("instcombine-maxarray-size", cl::init(1024),
+ cl::desc("Maximum array size considered when doing a combine"));
+
Value *InstCombiner::EmitGEPOffset(User *GEP) {
return llvm::EmitGEPOffset(Builder, DL, GEP);
}
@@ -3148,6 +3152,7 @@
InstCombiner IC(Worklist, &Builder, F.optForMinSize(), ExpensiveCombines,
AA, AC, TLI, DT, DL, LI);
+ IC.MaxArraySizeForCombine = MaxArraySize;
Changed |= IC.run();
if (!Changed)