[llvm] [DA] batch delinearization (PR #170519)

[Ryotaro Kasuga via llvm-commits]

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@@ -3328,16 +3341,78 @@ bool DependenceInfo::tryDelinearizeParametricSize(
   if (!SrcAR || !DstAR || !SrcAR->isAffine() || !DstAR->isAffine())
     return false;
 
+  SmallVector<const SCEV *, 4> Sizes;
+
+  // Try to use cached results from BatchDelinearization.
+  // This provides better precision by using terms from all accesses.
+  if (BatchDelin && BatchDelin->isPopulated()) {
+    const auto *CachedSizes = BatchDelin->getArraySizes(SrcBase);
+    if (CachedSizes) {
+      // Check element size compatibility.
+      const SCEV *CachedElemSize = BatchDelin->getElementSize(SrcBase);
+      if (CachedElemSize && CachedElemSize == ElementSize) {
+        Sizes.assign(CachedSizes->begin(), CachedSizes->end());
+
+        // Try to use pre-computed subscripts if available.
+        const auto *SrcSubs = BatchDelin->getSubscripts(Src);
+        const auto *DstSubs = BatchDelin->getSubscripts(Dst);
+        if (SrcSubs && DstSubs) {
+          SrcSubscripts.assign(SrcSubs->begin(), SrcSubs->end());
+          DstSubscripts.assign(DstSubs->begin(), DstSubs->end());
+
+          if (SrcSubscripts.size() >= 2 && DstSubscripts.size() >= 2 &&
+              SrcSubscripts.size() == DstSubscripts.size()) {
+            LLVM_DEBUG(dbgs() << "Using cached delinearization results\n");
+
+            // Validate the cached subscripts.
+            if (!DisableDelinearizationChecks)
+              if (!validateDelinearizationResult(*SE, Sizes, SrcSubscripts,
+                                                 SrcPtr) ||
+                  !validateDelinearizationResult(*SE, Sizes, DstSubscripts,
+                                                 DstPtr))
+                return false;
+
+            return true;
+          }
+        }
+
+        // Cache had sizes but not pre-computed subscripts for these
+        // instructions, or pre-computed subscripts failed validation.
+        // Compute subscripts using cached sizes.
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kasuga-fj wrote:

Can this happen? If so, why? And does it make sense to compute them here?

https://github.com/llvm/llvm-project/pull/170519