[HashRecognize] Don't const-qualify Values in result

[artagnon]

Const-qualifying Values in the analysis result makes them unusable with IRBuilder. The issue was discovered when attempting to use the result of the analysis for a transform.

[llvmbot]

@llvm/pr-subscribers-llvm-analysis

Author: Ramkumar Ramachandra (artagnon)

Changes

Const-qualifying Values in the analysis result makes them unusable with IRBuilder. The issue was discovered when attempting to use the result of the analysis for a transform.

---

Full diff: https://github.com/llvm/llvm-project/pull/144752.diff

2 Files Affected:

• (modified) llvm/include/llvm/Analysis/HashRecognize.h (+6-6)
• (modified) llvm/lib/Analysis/HashRecognize.cpp (+4-4)

diff --git a/llvm/include/llvm/Analysis/HashRecognize.h b/llvm/include/llvm/Analysis/HashRecognize.h
index 8ab68a5dc2cb1..c169383bf7b08 100644
--- a/llvm/include/llvm/Analysis/HashRecognize.h
+++ b/llvm/include/llvm/Analysis/HashRecognize.h
@@ -53,7 +53,7 @@ struct PolynomialInfo {
   // division in the case of CRC. Since polynomial division is an XOR in
   // GF(2^m), this variable must be XOR'ed with RHS in a loop to yield the
   // ComputedValue.
-  const Value *LHS;
+  Value *LHS;
 
   // The generating polynomial, or the RHS of the polynomial division in the
   // case of CRC.
@@ -61,7 +61,7 @@ struct PolynomialInfo {
 
   // The final computed value. This is a remainder of a polynomial division in
   // the case of CRC, which must be zero.
-  const Value *ComputedValue;
+  Value *ComputedValue;
 
   // Set to true in the case of big-endian.
   bool ByteOrderSwapped;
@@ -69,11 +69,11 @@ struct PolynomialInfo {
   // An optional auxiliary checksum that augments the LHS. In the case of CRC,
   // it is XOR'ed with the LHS, so that the computation's final remainder is
   // zero.
-  const Value *LHSAux;
+  Value *LHSAux;
 
-  PolynomialInfo(unsigned TripCount, const Value *LHS, const APInt &RHS,
-                 const Value *ComputedValue, bool ByteOrderSwapped,
-                 const Value *LHSAux = nullptr);
+  PolynomialInfo(unsigned TripCount, Value *LHS, const APInt &RHS,
+                 Value *ComputedValue, bool ByteOrderSwapped,
+                 Value *LHSAux = nullptr);
 };
 
 /// The analysis.
diff --git a/llvm/lib/Analysis/HashRecognize.cpp b/llvm/lib/Analysis/HashRecognize.cpp
index 1edb8b3bdc9a8..f7ac02be2e039 100644
--- a/llvm/lib/Analysis/HashRecognize.cpp
+++ b/llvm/lib/Analysis/HashRecognize.cpp
@@ -442,9 +442,9 @@ getRecurrences(BasicBlock *LoopLatch, const PHINode *IndVar, const Loop &L) {
   return std::make_pair(SimpleRecurrence, ConditionalRecurrence);
 }
 
-PolynomialInfo::PolynomialInfo(unsigned TripCount, const Value *LHS,
-                               const APInt &RHS, const Value *ComputedValue,
-                               bool ByteOrderSwapped, const Value *LHSAux)
+PolynomialInfo::PolynomialInfo(unsigned TripCount, Value *LHS, const APInt &RHS,
+                               Value *ComputedValue, bool ByteOrderSwapped,
+                               Value *LHSAux)
     : TripCount(TripCount), LHS(LHS), RHS(RHS), ComputedValue(ComputedValue),
       ByteOrderSwapped(ByteOrderSwapped), LHSAux(LHSAux) {}
 
@@ -623,7 +623,7 @@ HashRecognize::recognizeCRC() const {
   if (!checkExtractBits(ResultBits, TC, IsZero, *ByteOrderSwapped))
     return ErrBits(ResultBits, TC, *ByteOrderSwapped);
 
-  const Value *LHSAux = SimpleRecurrence ? SimpleRecurrence.Start : nullptr;
+  Value *LHSAux = SimpleRecurrence ? SimpleRecurrence.Start : nullptr;
   return PolynomialInfo(TC, ConditionalRecurrence.Start, GenPoly, ComputedValue,
                         *ByteOrderSwapped, LHSAux);
 }

[pfusik]

LGTM
Are you splitting #143208 to smaller changes?

[artagnon]

Are you splitting #143208 to smaller changes?

Yes, that was always my intent. Hopefully, we can get #143208 enabled by default in the PR: the current blocker is HexagonLoopIdiom, which I think can be fixed with TTI hooks.