[llvm] [DA] Refactor the signature of the Exact SIV test (NFCI) (PR #186386)

[via llvm-commits]

llvmbot wrote:


<!--LLVM PR SUMMARY COMMENT-->

@llvm/pr-subscribers-llvm-analysis

Author: Ryotaro Kasuga (kasuga-fj)

<details>
<summary>Changes</summary>

Change the signature of `exactSIVtest` to directly pass addrecs instead of passing their operands separately. I *think* this change is not mandatory, but it will simplify the code, especially because we will be checking the presence of nsw flags on the addrecs.

---
Full diff: https://github.com/llvm/llvm-project/pull/186386.diff


2 Files Affected:

- (modified) llvm/include/llvm/Analysis/DependenceAnalysis.h (+1-3) 
- (modified) llvm/lib/Analysis/DependenceAnalysis.cpp (+8-7) 


``````````diff
diff --git a/llvm/include/llvm/Analysis/DependenceAnalysis.h b/llvm/include/llvm/Analysis/DependenceAnalysis.h
index 26589571a65e28..cab98726520733 100644
--- a/llvm/include/llvm/Analysis/DependenceAnalysis.h
+++ b/llvm/include/llvm/Analysis/DependenceAnalysis.h
@@ -541,9 +541,7 @@ class DependenceInfo {
   /// Returns true if any possible dependence is disproved.
   /// If there might be a dependence, returns false.
   /// Sets appropriate direction entry.
-  bool exactSIVtest(const SCEV *SrcCoeff, const SCEV *DstCoeff,
-                    const SCEV *SrcConst, const SCEV *DstConst,
-                    const Loop *CurrentSrcLoop, const Loop *CurrentDstLoop,
+  bool exactSIVtest(const SCEVAddRecExpr *Src, const SCEVAddRecExpr *Dst,
                     unsigned Level, FullDependence &Result) const;
 
   /// weakZeroSrcSIVtest - Tests the weak-zero SIV subscript pair
diff --git a/llvm/lib/Analysis/DependenceAnalysis.cpp b/llvm/lib/Analysis/DependenceAnalysis.cpp
index c7aefb20354344..13f560f2958bc3 100644
--- a/llvm/lib/Analysis/DependenceAnalysis.cpp
+++ b/llvm/lib/Analysis/DependenceAnalysis.cpp
@@ -1629,14 +1629,16 @@ inferDomainOfAffine(OverflowSafeSignedAPInt A, OverflowSafeSignedAPInt B,
 // This is a modified version of the original Banerjee algorithm. The original
 // only tested whether Dst depends on Src. This algorithm extends that and
 // returns all the dependencies that exist between Dst and Src.
-bool DependenceInfo::exactSIVtest(const SCEV *SrcCoeff, const SCEV *DstCoeff,
-                                  const SCEV *SrcConst, const SCEV *DstConst,
-                                  const Loop *CurSrcLoop,
-                                  const Loop *CurDstLoop, unsigned Level,
+bool DependenceInfo::exactSIVtest(const SCEVAddRecExpr *Src,
+                                  const SCEVAddRecExpr *Dst, unsigned Level,
                                   FullDependence &Result) const {
   if (!isDependenceTestEnabled(DependenceTestType::ExactSIV))
     return false;
 
+  const SCEV *SrcCoeff = Src->getStepRecurrence(*SE);
+  const SCEV *SrcConst = Src->getStart();
+  const SCEV *DstCoeff = Dst->getStepRecurrence(*SE);
+  const SCEV *DstConst = Dst->getStart();
   LLVM_DEBUG(dbgs() << "\tExact SIV test\n");
   LLVM_DEBUG(dbgs() << "\t    SrcCoeff = " << *SrcCoeff << " = AM\n");
   LLVM_DEBUG(dbgs() << "\t    DstCoeff = " << *DstCoeff << " = BM\n");
@@ -1674,7 +1676,7 @@ bool DependenceInfo::exactSIVtest(const SCEV *SrcCoeff, const SCEV *DstCoeff,
   std::optional<APInt> UM;
   // UM is perhaps unavailable, let's check
   if (const SCEVConstant *CUB =
-          collectConstantUpperBound(CurSrcLoop, Delta->getType())) {
+          collectConstantUpperBound(Src->getLoop(), Delta->getType())) {
     UM = CUB->getAPInt();
     LLVM_DEBUG(dbgs() << "\t    UM = " << *UM << "\n");
   }
@@ -2298,8 +2300,7 @@ bool DependenceInfo::testSIV(const SCEV *Src, const SCEV *Dst, unsigned &Level,
       disproven = weakCrossingSIVtest(SrcCoeff, SrcConst, DstConst, CurSrcLoop,
                                       CurDstLoop, Level, Result);
     else
-      disproven = exactSIVtest(SrcCoeff, DstCoeff, SrcConst, DstConst,
-                               CurSrcLoop, CurDstLoop, Level, Result);
+      disproven = exactSIVtest(SrcAddRec, DstAddRec, Level, Result);
     return disproven || gcdMIVtest(Src, Dst, Result) ||
            symbolicRDIVtest(SrcCoeff, DstCoeff, SrcConst, DstConst, CurSrcLoop,
                             CurDstLoop);

``````````

</details>


https://github.com/llvm/llvm-project/pull/186386