add ShouldChangeType() variant that takes bitwidths

This is more efficient for cases like D12965 where we already have widths.

llvm-svn: 248170

2 files changed, 16 insertions, 6 deletions

diff --git a/llvm/lib/Transforms/InstCombine/InstCombineInternal.h b/llvm/lib/Transforms/InstCombine/InstCombineInternal.h
index 9f5cdcbb329..dbaa5a88ee3 100644
--- a/llvm/lib/Transforms/InstCombine/InstCombineInternal.h
+++ b/llvm/lib/Transforms/InstCombine/InstCombineInternal.h
@@ -341,6 +341,7 @@ public:
                                  const unsigned SIOpd);
 
 private:
+  bool ShouldChangeType(unsigned FromBitWidth, unsigned ToBitWidth) const;
   bool ShouldChangeType(Type *From, Type *To) const;
   Value *dyn_castNegVal(Value *V) const;
   Value *dyn_castFNegVal(Value *V, bool NoSignedZero = false) const;
diff --git a/llvm/lib/Transforms/InstCombine/InstructionCombining.cpp b/llvm/lib/Transforms/InstCombine/InstructionCombining.cpp
index 8c70a1c5895..72548dc69ca 100644
--- a/llvm/lib/Transforms/InstCombine/InstructionCombining.cpp
+++ b/llvm/lib/Transforms/InstCombine/InstructionCombining.cpp
@@ -80,14 +80,12 @@ Value *InstCombiner::EmitGEPOffset(User *GEP) {
   return llvm::EmitGEPOffset(Builder, DL, GEP);
 }
 
-/// Return true if it is desirable to convert a computation from 'From' to 'To'.
+/// Return true if it is desirable to convert an integer computation from a
+/// given bit width to a new bit width.
 /// We don't want to convert from a legal to an illegal type for example or from
 /// a smaller to a larger illegal type.
-bool InstCombiner::ShouldChangeType(Type *From, Type *To) const {
-  assert(From->isIntegerTy() && To->isIntegerTy());
-
-  unsigned FromWidth = From->getPrimitiveSizeInBits();
-  unsigned ToWidth = To->getPrimitiveSizeInBits();
+bool InstCombiner::ShouldChangeType(unsigned FromWidth,
+                                    unsigned ToWidth) const {
   bool FromLegal = DL.isLegalInteger(FromWidth);
   bool ToLegal = DL.isLegalInteger(ToWidth);
 
@@ -104,6 +102,17 @@ bool InstCombiner::ShouldChangeType(Type *From, Type *To) const {
   return true;
 }
 
+/// Return true if it is desirable to convert a computation from 'From' to 'To'.
+/// We don't want to convert from a legal to an illegal type for example or from
+/// a smaller to a larger illegal type.
+bool InstCombiner::ShouldChangeType(Type *From, Type *To) const {
+  assert(From->isIntegerTy() && To->isIntegerTy());
+
+  unsigned FromWidth = From->getPrimitiveSizeInBits();
+  unsigned ToWidth = To->getPrimitiveSizeInBits();
+  return ShouldChangeType(FromWidth, ToWidth);
+}
+
 // Return true, if No Signed Wrap should be maintained for I.
 // The No Signed Wrap flag can be kept if the operation "B (I.getOpcode) C",
 // where both B and C should be ConstantInts, results in a constant that does